Handbook of Water and Used Water Purification

The stringent regulations by users and stakeholders have raised the bar for the quality of water and wastewater treatment. Additionally, the requirement of the end users for the best techno-commercial process has forced the industrial players to employ new and appropriate technologies for water treatment. When it comes to pretreatment processes, there is no doubt that precipitation, coagulation, and flocculation (followed by sedimentation and/or filtration) are among the most effective steps. Though the aforementioned terms are often used interchangeably to describe the physicochemical processes involved in destabilizing the charges and agglomeration followed by the removal of the particles, there exists distinct definitions for the same as defined by Bratby (Coagulation and flocculation with an emphasis on water and waste water treatment, 1st edn. Uplands Press Ltd., Croydon, 1980). Chemical precipitation is a unit process in which undesirable dissolved ions are reacted to form insoluble salts for removal downstream. Coagulation/flocculation on the other hand is the result of the two different and independently occurring reactions which includes destabilization of surface charges (actual coagulation) and transport. The larger agglomerates formed after coagulation by transport are called flocs and hence the name “flocculation.” Coagulation is essentially a time-independent process because the term only involves the process of overcoming various forces on the surface of a particle so that the gravitational forces can take over to settle the particles. On the other hand, flocculation is a time-consuming process where the agglomerates are formed that become larger and larger. The flocculation (or transport) processes are usually the rate-determining steps, as they are much slower than the coagulation (or destabilization) processes.This chapter aims to summarize the recent developments in the field of precipitation-coagulation-flocculation and have a deeper look at the intricate techniques that govern these unit processes. The industrial purview as well as the technologies used by WABAG to encompass these terminologies will also be discussed. Some important terms that are relevant in the grand scheme of precipitation, coagulation, and flocculation will be discussed along with some case studies.The scope of water treatment technologies is ever-changing, and hence the future of coagulation and flocculation will also be discussed in the concluding paragraphs. In spite of the numerous benefits of these processes, it is plagued with problems of danger posed due to the presence of inorganic coagulants, sludge disposal, inefficient removal capabilities by different coagulants, as well as the difficulties faced when implementing lab-scale results to full-scale installations. Hence, the current recommendations available to improve the process will also be stated with future directions for helping to improve one of the most conventional treatment processes in water and wastewater treatment.

Sedimentation is a physical water treatment process used to settle out colloidal and suspended solids in water under the influence of gravity. It is one of the widely used conventional water treatment methods. The terms sedimentation and settling are used interchangeably. A sedimentation basin is also referred to as a sedimentation tank, settling basin, or settling tank and as a clarifier. The process of removal of turbidity caused by fine suspended solids, colloidal impurities, and organic color from the raw water is termed as clarification which comprises coagulation, flocculation, and sedimentation steps.There are two basic forms of sedimentation based on the shape of the particles, unhindered and hindered settling. On the basis of concentration and tendency of particles to interact, there are four types of settling which can occur such as discrete particle, flocculant, hindered or zone, and compression settling.There are three basic geometrical shapes commonly used for sedimentation basins in water treatment: rectangular, circular, and square. The choice of selection of the shape of the basin mainly depends on the site conditions. Various configurations in each type of geometrical shape are presented along with their appurtenances. The high-rate clarifiers such as lamella clarifiers and tube settlers are also discussed. Comparison of various clarification systems such as lamella clarifier and sludge blanket clarifiers is also made with a detailed description on pulsator clarifier.

This chapter provides an overview on diverse flotation technologies with the main discussion point being dissolved air flotation (DAF). Flotation is a clarification process which can be described as the opposite to sedimentation. Instead of precipitating the particles, flotation relies on the attachment of bubbles onto suspended matter, hence driving them to the surface of the water against gravity. The contaminated water is firstly coagulated and flocculated, and flows by gravity into the flotation tank where the flocs collide with bubbles and the newly formed aggregates rise to the water surface. The top sludge layer is removed while the clarified water is withdrawn from the bottom. Many parameters influence the clarification performance of DAF, the most important being the coagulation pretreatment and bubble size. The addition of chemicals and pH adjustment during coagulation modifies the particle properties and thus insures an optimal bubble attachment. In comparison, bubble size heavily influences the flotation performance. Large bubbles generate turbulent flows which can disturb the top sludge layer. In contrast, bubbles that are too small have a reduced rise velocity and thus decrease the overall performance. However, for DAF applications small bubble sizes are preferred. Dissolved air-flotation is mainly employed for the removal of algae and turbidity and possesses many applications such as sludge thickening, drinking water production, primary or secondary clarification of diverse industrial effluents, and seawater pretreatment. Furthermore, with the addition of surfactants the removal of dissolved ions can also be achieved. The flexibility of DAF should not be underestimated. Flotation comes in many variants and can be tailored to the desired purpose. This is further exemplified with two case studies.

The following chapter shall provide an overview about granular media filtration. Within this framework, key insights into construction, operation, and modeling are provided. Nevertheless, membrane and cake filtration are also briefly discussed. Filtration is one of the oldest water treatment technologies and is based on the retention of solids by a filter media letting the water pass through while holding the suspended particles back. Filtration has experienced much development and has found widespread applications in many areas of water treatment. The great popularity is a result of its extensive customizability and simplicity, thus achieving good treatment results with an uncomplicated operation. Due to the different choices of filter media, operation modes, and construction, filtration units can be tailored to each application. This is exemplified in four cases studies from different water treatment fields, ranging from drinking water production to treatment and reuse of effluents. Regeneration of the media and regular backwashing procedures are essential insuring long lifetimes and optimal treatment results. Filtration performance and operation can be modeled with the basic and very general Darcy law, with the empirical Kozeny equation, which considers the effects of the pore structure of the medium on flow, or with the Ergun equation, which is an extension of Darcy’s law and additionally takes into account the effects of particle inertia and the frictional behavior of the fluid in porous media.

Adsorption is the adhering of substances from gases or liquids onto the interface of two phases, mainly onto solids. In water and used water purification, adsorption is applied for the removal of dissolved impurities. The most common process is application of activated carbon for removal of organic substances. But there are also special applications such as removal of Arsenic or other inorganic impurities using media other than activated carbon. Activated carbon can either be granular based or in the powdered form and its application depends on the treatment requirements and final water quality expectations. Activated carbon filtration (ACF) is mostly used as a polishing stage in water treatment processes and is gaining renewed focus in the recent years for its effectiveness in removing emerging contaminants called “micropollutants.” The process can be deeply understood if the relations governing the adsorption processes will be studied along with the different process schemes that are adopted in the water and wastewater domain. Hence, various design aspects of the ACF will be briefed along with important relations. Subsequently, three case studies would be presented which highlights the diverse areas where activated carbon is useful in tackling different contaminants across different areas of the globe.

Membrane filtration technology has revolutionized particle filtration in the water and waste water treatment sector. In contrast to classical fixed bed media filtration (see Chap. 4, “Filtration in Water and Used Water Purification”), membrane technology provides complete particle retention, regardless of the applied feed quality. In addition, mechanical disinfection is achieved by retention of germs and viruses to a great extent, depending on the applied membrane pore size. Membrane filtration may be used for all sorts of water qualities.Several system types are readily available on the market. For MF and UF, various membrane types such as flat sheet, mainly used in MBR application or combined flat sheet-hollow fiber, are being used. An increasing demand can be seen in the use of ceramic membranes for heavy duty applications. The most widely spread membrane type are hollow fibers. Those may be used in two different ways: in pressure driven membrane systems (filtration mostly inside-out) and in submerged membrane systems (filtration outside-in). Some products on the market also combine features of both systems.The choice of the most suitable membrane filtration type should always be made based on comprehensive consideration of reigning hydraulic and spatial boundary conditions, as well as the membrane performance itself in respect to the water type to be treated.While a submerged membrane system may be integrated in an existing tank or basin and therefore economize space, a pressure-driven membrane system may make use of available upstream pressure for the filtration as a driving force.Membrane material and structure is critical for its chemical and mechanical resistance. A membrane fiber basing on acetyl cellulose may not tolerate severe chemical cleaning. A thin membrane capillary may eventually break and ask for repair intervention.Therefore, in projects with strong emphasis on total hydraulic yield, achievable peak performance, minimized chemical consumption and liable process stability, piloting of different membrane filtration systems may be essential for a successful project outcome.The key for stable operation is, besides the chosen membrane type and system, the applied cleaning strategy. Cleaning may be triggered by timer, volume treated, TMP, or permeability. It is done by a combination of water backwash (BW), process air, and backwash with or circulation of chemical agents. Those are either dosed inline or else prepared in a stirred tank. Manifold chemical agents are used, such as bases, acids, and/or oxidants. CIPs are performed once to twice a year, in order to prevent irreversible fouling of the membranes. During CIP, membranes are exposed to higher chemical concentrations and longer soaking times than during normal cleaning. Membrane cleaning may take from 30 s (e.g., BW) up to 30 min (CEB) or 4–12 h (CIP).Because of the frequent cleaning intervals, membrane filtration requires a high grade of process automation. Accordingly, treatment steps have to be designed with enough redundancies in order to be able to compensate nonproduction time of trains being cleaned.

Oxidation in fresh water and used water purification means utilizing an oxidizing agent to convert contaminants into less dangerous or non-toxic compounds. This treatment reduces organic and inorganic impurities including viruses, heavy metals, and organic waste, which can harm humans and the environment. Oxidizing chemicals including chlorine, ozone, hydrogen peroxide, and potassium permanganate react with contaminants to create by-products that can be easily removed from the water. Used water treatment is an important part of the water management. Water oxidation removes pollutants and pathogens and ensures safe and pure drinking water. Its use in water and wastewater treatment plants has greatly reduced waterborne illnesses and protected the environment. Some oxidants such as ozone and hydrogen peroxide have the lowest impact on the environment when used in reasonable quantities.

Advanced oxidation processes have widespread application in drinking water and used water purification as many of the reactions involve destruction of organic and inorganic pollutants present in it. A characteristic of advanced oxidation processes is the capability of exploiting hydroxyl radical’s high reactivity by oxidizing these pollutants through their mineralization into even less reactive pollutants. This chapter describes various processes that employ different mechanisms by which such radicals are formed. These methods can use a mechanism alone or numerous mechanisms at a time to enhance the performance of that particular method. Major advantages and drawbacks of such methods are also discussed within the sections. Some remarks upon the economics and treatment efficiency of individual process are provided on the basis of the operating cost and post treatment of the effluent generated after the process.

Disinfection in water treatment has a long tradition. In the course of time, five processes/agents have established themselves in water technology. Free chlorine Chlorine dioxide Ozone Chloramine (combined chlorine) Ultraviolet light This chapter shows the different characteristics of the five types of disinfection. The necessary elements of the installations and basic information for dimensioning are also showed for all processes/agents. Furthermore pros and cons of the different types are discussed and some practical hints and examples are introduced.

The following chapter provides an overview of desalination and demineralization technologies, such as ion exchange (IE), reverse osmosis (RO), nanofiltration (NF), electrodialysis (ED), and electrodeionization (EDI). Desalination and demineralization describe processes in which dissolved salts are removed from seawater, brackish, or used water, thus producing fresh water. The presented technologies are interlinked with other chapters, therefore providing a more comprehensive explanation.RO and NF comprise membranes for the retention of salts. While RO is unselective and can achieve a high salt rejection, NF only attains a partial desalination, as the rejection of monovalent ions is not as efficient. ED is also a membrane technology; however, it integrates an electric process. In this framework, by applying an electric current, the ions migrate towards the respective electrodes and are retained by ion exchange membranes, thus achieving the separation of different salts. In contrast to membrane technologies, IE accomplishes the removal of dissolved ions with ion exchange resins. These resins include diverse functional groups which swap out the dissolved ions with H+ and OH−. Finally, EDI is a combination of ED and IE. This technology is mainly employed for the production of ultrapure water and although the salt rejection is not as high as in conventional IE, the continuous operation makes it a technology worth considering.RO and EDR gradually gained importance reasoning to less energy demand in water production. Requirement of high quality water in industries gave more importance to the development of IE processes aiming to produce very high quality water demanded by few industries. The implementation of different desalination and demineralization technologies is illustrated with three different case studies.

The chapter is covering basics of water distillation and its fundamentals.Distillation is evaporation with subsequent condensation. The vapors formed are condensed by cooling, i.e., they are transformed from the gaseous state back to the liquid state. It is one of the oldest methods of separating liquid or molten substances.In the process of water purification, the source of water could be any type, e.g., be it seawater, contaminated brackish water, wastewater from industry containing any combinations of polluting chemicals or dissolved salts in it, etc. This chapter is primarily focused on the process using distillation as a unit process in recovering high-quality water on any of above sources.

Commercial and industrial activities produce wastewater that constitutes a significant environmental risk. Various treatment methods reduce the wastewater’s harmful effects. A promising path to minimize these effects is crystallization, offering a sustainable wastewater treatment solution and an effective method for salt recovery. Crystallization is a separation process that relies on the solid crystal formation from a solution and removes dissolved salts and other impurities from wastewater, producing clean water and recoverable salts. Temperature, concentration, or chemical composition variations control the process. The changes cause dissolved substances to become supersaturated and form solid crystals, which separate from the liquid. The benefits of using crystallization for wastewater treatment are numerous. The process is highly efficient and removes even tiny amounts of dissolved salts and other impurities from the wastewater. Further, crystallization requires less energy than other treatment methods. In addition, crystallization is lower in operational costs and needs less space than other processes. Finally, crystallization offers a promising solution to the wastewater treatment challenge. By utilizing this separation process, we can develop sustainable strategies for managing wastewater and protecting our environment.

Used water consists largely of organic carbon, either as a solution or particulate matter. Apart from organic compounds, nitrogen and phosphorus also number among the main used water constituents. The overall objective of biological treatment is to reduce these dissolved and particulate biodegradable constituents to an extent that prevents them from inducing a further deterioration in the receiving waters and its communities. This biological treatment is carried out by different groups of microorganisms, but it is bacteria that are primarily responsible for the conversion processes, and depending upon how the biomass exists in the reactor, biological treatment can be divided into suspended and attached growth. Hybrid processes represent a new chapter in biological used water treatment and combine the benefits of both suspended and attached growth processes. Three different types of biochemical processes can occur as used water is treated: carbon, nitrogen, and phosphorus removal. In order to remove these pollutants, various reactor’s configuration and combination of anaerobic, anoxic, and aerobic conditions are required. This chapter deals with these conversion processes and basic removal mechanisms, and process schemes and treatment methods are also described.

The anaerobic process is a treatment step in which organic matter is broken down into simpler components under anaerobic conditions. The process begins with hydrolysis, followed by acidogenesis and acetogenesis. Methanogenesis is the final step in anaerobic degradation and marks the point at which the final products, CH4 and CO2, leave the process in gaseous form. Each of these steps is carried out by different groups of bacteria. Moreover, there is a symbiotic relationship between methanogenic and acetogenic bacteria, which means that both bacteria types only survive in teamwork. The whole process is an effective method of converting unstable organic matter into a more stabilized form and also results in a considerable reduction of solid matter. The nature of organic matter, pH, temperature, nutrients, and the presence of toxic compounds constitute environmental factors that influence the biological reactions. Anaerobic processes can not only be employed to treat highly loaded used water, but also solid materials such are sewage sludge, organic farm waste, municipal solid waste, green/botanical waste, organic industrial and commercial waste, etc. Anaerobic digesters are usually used to treat solid materials, whereas UASB reactors are utilized for treating used water.

When rainwater filters through the soil and rocks, many things get dissolved in it such as small quantity of iron and manganese. This water, when sips through bed of rocks, becomes groundwater. Iron and manganese concentration can change drastically as the geology and territory change. Presence of Fe and Mn can give a reddish-brown color and unpleasant odor to the water. Presence of excess iron and manganese imparts unusual taste to the drinking water. It also stains the household items like storage tanks, washing machine, etc. When complexed with other organic compounds, Fe and Mn removal can be challenging sometimes. This chapter explains some of the common methods used to remove these compounds, potential risks involved in employing these techniques, and their advantages. Common industrial practices are aeration and chemical precipitation and are being used extensively.

Denitrification of groundwater for drinking water production has become more and more important in the recent time, due to the increasing nitrate concentration in aquifers. In this context, biological denitrification has become a popular means of controlling this contamination. This method is based on the conversion of nitrate to nitrogen gas by bacteria under low-oxygen conditions, resulting in a complete elimination of nitrate and not just its separation. Its good results and benefits make it an ideal technology to remove nitrate from groundwater sources. Although the principle behind the technology is simple, its application can be complicated because parameters such as carbon substrate, temperature, and pH influence its effectiveness. The most commonly used carbon sources are methanol, ethanol, and acetic acid. The right choice depends on plant specifications, economic factors, and general access to the substrate. On the other side, temperature can affect the well-being of bacteria and thus affect denitrification. Low temperatures decrease the denitrification performance considerably. In comparison, the pH value of the groundwater is in most cases already in the slightly basic range and thus in the optimum, so that no adjustments are necessary.

The nitrate concentration of some groundwater wells is an issue for drinking water quality. This poses a serious health risk, since the intake of large nitrate quantities is harmful for the human health. In this context, physical processes for nitrate removal are very popular methods to counter this problem. Electrodialysis, reverse osmosis, and ion exchange have proven to be very efficient methods to lower the rising nitrate concentrations. Due to their relative simplicity, reliability, and high desalination, they are often implemented. Although excellent results can be achieved, correct process parameters are necessary. In electrodialysis, desalination is generally mainly dependent on voltage, although other parameters such as flow rate, limiting current, and temperature also affect membrane diffusion. Furthermore, for nitrate removal nitrate-selective membranes are preferably used. In case of electrodialysis and reverse osmosis, membrane scaling and fouling are major issues that need to be addressed. On the other hand, ion exchange has the disadvantage that the resins used must be regenerated at regular intervals, which increases the amount of chemicals required. In all this physical processes, brine disposal is an important topic and its safe discharge must be ensured. Possible solutions are safe disposal into a sewage system, a further treatment, or the use as irrigation water.

Membrane filtration is proven to be an effective barrier against many microbes and is being employed for the removal of particulates to produce drinking water as described by Baker, R. W. (Membrane technology and applications, 3rd edn. Wiley, Menlo Park, 2012). With this in mind, ultrafiltration (UF) has been employed at many water treatment plants throughout the world. Ultrafiltration is a membrane process that employs very fine pores with sizes of approximately 0.01–0.05 μm. Accordingly, particles that are larger than this cutoff are removed, while dissolved ions and molecules with low molecular weights are allowed to pass as described by Lahnsteiner et al. (Freshwater membrane filtration – international case studies. In: Proceedings of the Actualna Problematika u Vodoopskrbi i Odvodnji Conference held at Bol, Croatia, October 24–28, 2012). A drinking water treatment plant (WTP) of capacity 1 MGD (4546 m3/d) was set up in the Indian capital city of Delhi to serve the athletes and the officials housed in the Commonwealth Games Village (CWGV) in 2010. This WTP has the aforementioned UF polymeric membranes as the heart of the installation. VA TECH WABAG India Ltd was commissioned with the construction and operation of the plant (Design, Build, Operate [DBO] contract).This project represented the first Indian drinking water treatment plant to employ UF, and the process consists of aeration, lime softening, coagulation, flocculation, sedimentation, pH adjustment, clarification followed by UF with disinfection using UV, and chlorination as the final treatment step. This case study explores the prestigious project and will explain the basis of the setup as well as the technology behind this state of the art installation. It will in detail also look into the process, the treatment scheme, and the operational background utilized for this WTP which will provide a clear picture of the installation.

The following chapter shall provide a comprehensive overview of the water treatment plant (WTP) located in Brčko, Bosnia and Herzegovina. Due to the rising drinking and industrial water demand, VA TECH WABAG© was commissioned to build a second WTP for the production of drinking water from surface water. The WTP comprises multi-barrier treatment system focused on the removal of suspended matter and total organic carbon (TOC). The raw water is abstracted from the adjoining Save River and pre-oxidized before being flocculated and clarified in lamella clarifiers. The downstream filtration then removes the remaining suspended solids. The following main ozonation and biological activated carbon (BAC) filtration are responsible for the elimination of organic compounds and other contaminants. Finally, the BAC filtrate is disinfected with chlorine dioxide (ClO2) and distributed into the water network. The presented technologies are interlinked with other chapters, thus providing a more detailed explanation.

The following chapter describes the WABAG El Raswa water treatment plants (WTP) located in Port Said City, Egypt. The El Raswa water treatment complex comprises five drinking water treatment plants, where WABAG built the last two of them. These two WTPs have a capacity of 133,000 m3/d and 80,000 m3/d and are based on a multistage treatment system targeting different contaminants, mainly suspended solids and microorganisms. The raw water is sourced from the Nile River through an agricultural channel. The involved technologies are coarse and fine screening, pre-chlorination, sedimentation in clariflocculators, rapid gravity filtration, and final disinfection by chlorination. Although seasonal fluctuations are minimal, the rapid growth of algae creates taste and odor problems in winter months. As a result, the WTPs include a powdered activated carbon dosing system to confront this issue. Constant monitoring at different treatment stages insures optimal operating conditions, allowing the dosage of different chemicals to be adjusted according to the water quality and flow. Opposed to the old plants, the new WABAG plants are fully automated.

The 100,000 m3/d Maynilad Putatan Water Treatment Plant is the largest water treatment plant in the Philippines based on microfiltrationMicrofiltration (MF) and reverse osmosisReverse osmosis (RO). It is also the first facility to use Laguna Lake as the raw water source.During the operation of the plant, several problems were encountered on the treated water quality due to high fluctuating levels of ammonia and total organic carbon (TOC)/assimilable organic carbon (AOC) and turbidity levels from the Laguna Lake. These problems reduced the life of the MF/RO membranes, thus increasing the chemical cleaning frequency and the consequent operating costs.WABAG proposed to conduct a pilot testing for a biological aerated filter to address the issues regarding the AOC, ammonia, and turbidity levels. WABAG, after successful demonstration of the process with the pilot plant, was later awarded the project for the realization of a full-scale biological aerated filter plant along with upgradation – rehabilitation of the other upstream process units in the existing plant. The project was carried out in two phases with the following scope of works: installation of a biological aerated filterBiological aerated filter (BAF), modification of the dissolved air flotationDissolved air flotation (DAF), and expansion of the plant capacity up to 150,000 m3/d by addition of ultrafiltrationUltrafiltration (UF).

Despite the fact that global water is apparently abundant, almost half of the world faces water scarcity. Owing to the alarming rise in the population level along with increasing demand of water due to the change in lifestyle, providing fresh water will be a big challenge in the near future. Considering this acuteness, freshwater production using desalination is one of the prospective and promising solutions in the years to come.The current chapter emphasizes on the thermal desalination methods used for the production of fresh water. The main desalination technologies discussed in the chapter are multistage flash and multi-effect distillation, thermal vapor compression, and mechanical vapor compression. A description regarding each of these technologies along with their discrete design configuration and materials used for the plant construction has also been discussed in detail.

Multi-effect distillation (MED) desalination technology has always been a proven method to produce fresh water for drinking and industrial purposes. One such project was executed by WABAG Group in 2010 in Suralaya power generation facility, Indonesia.The following case study provides salient information along with certain features and pictures about the MED desalination plant. A short process description also explains the function of MED technology. The plant has a capacity to produce 6000 m3/d of boiler feed water required for one of the coal-fired power generation stations in Suralaya. A part of this water shall also be used as drinking water.The project was engineered by the WABAG team in Vienna and executed successfully by the Indian team in 2010 making it one of the vital reference projects for WABAG in thermal desalination business.

The main sources of water supply to the south Indian Chennai city are from five major reservoirs in and around the city which depend on monsoon rainfall and hence became not reliable due to the climate change. Chennai city faced several severe droughts in the last 20 years. Depletion of groundwater increased the demand-supply gap multifold. Hence, Government of Tamil Nadu and Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) resorted to desalination as an alternate source to bridge the demand-supply gap to certain extent and built two 100,000 m3/d desalination plants, one in Minjur commissioned in July 2010 and one in Nemmeli commissioned in February 2013 (Wikipedia, The free encyclopedia. Chennai Metropolitan Water Supply and Sewerage Board. Available via https://en.wikipedia.org/wiki/Chennai_Metropolitan_Water_Supply_and_Sewerage_Board. Accessed 14 Oct 2023 (2023)). CMWSSB’s 100,000 m3/d Nemmeli desalination plant was contracted to be built and operated and maintained for 7 years by VA Tech Wabag. The desalination plant had been a savior when the normal monsoon rains failed. The Nemmeli desalination plant operated at high availability meeting the production target fixed by CMWSSB since 2013.Based on the seawater study carried out by the consultant MECON, the plant was contracted to be designed for total suspended solids (TSS) of 50 mg/L and total dissolved solids (TDS) of 41,900 mg/L. The plant is fully automatic built with state of the art technology consisting of intake system, upflow filter, disc filters, ultrafiltration (UF) system, RO system, remineralization system, and outfall system. Pressure exchangers that recover brine energy enables plant operation with low specific energy consumption. The plant meets all environmental regulations. Material of construction selected for piping, valves, and pumps ensures minimum or no seawater corrosion and longer plant life.The plant though was inaugurated by then CM on 22 February 2013, due to teething troubles in achieving treated feedwater flow to RO, few modifications were required and the plant was demonstrated for full capacity operation in the last week of December 2013. The plant was approved by CMWSSB for commercial operation from 8 January 2014. The PGTR was held up awaiting completion of painting of project UF permeate tanks and potable water tanks. The PGTR was completed in the last week of June 2014 and the plant was handed over for O&M from 1 July 2014.The plant was operating at almost full capacity as per the CMWSSB’s demand until September 2015. The TSS of seawater started increasing above 150 mg/L on few days in a month. Increased TSS in seawater resulted in fouling of disc filters and UF and reducing the UF permeate output by 10–15% which led to operating the RO system at 85,000–90,000 m3/d. Since recurrence of high TSS was persistent and gradually increased in number of occurrences in a month, CMWSSB advised Wabag to improve the pretreatment system to remove the excess TSS and recuperate the plant capability to produce 100,000 m3/d consistently.Wabag submitted the proposal to CMWSSB to introduce lamella clarifier in the pretreatment system to control the TSS in seawater. The proposal included reuse of disc filter and UF backwash water, by passing them through lamella clarifier and augment the capacity of the plant by 10,000 m3/d with additional seawater recovered. The plant with lamella clarifier commissioned in October 2017 resulted in a robust pretreatment system and was able to operate successfully at almost full capacity until December 2019, meeting the demand from the client CMWSSB. During the Piety cyclone, in December 2018, the plant was able to operate with seawater TSS up to 1478 mg/L. The lamella clarifier was able to bring down the TSS in seawater from 1478 to <30 mg/L.Since February 2019, the plant is faced with a challenge of operating with seawater having high COD/TOC and light white particles.The paper presents the salient design features and the operating experience of the Nemmeli desalination plant, modifications carried out, along with the factors influencing the Capex and Opex of a SWRO desalination plant.

Sequencing batch reactors employ a type of activated sludge process with a fill-and-draw operation in which the entire biological treatment procedure and clarification take place in a single reactor. The main steps of the SBR process consist of filling, mixing, aeration, settling, decanting, and idling, which are carried out in a predefined, timed sequence. There are a variety of SBR process options, and through the application of differing filling, mixing, and aeration strategies it is possible to achieve a range of nutrient removal objectives, which makes SBR both extremely efficient and flexible. Decanters represent important components in SBR plants and have to meet high standards of functionality, flexibility, and reliability. On the basis of long-term experience in the design of SBR plants, WABAG has optimized this technology and as a special feature has designed an advanced motor-driven decanter, which is presented in this chapter. A type of configuration matrix with a fixed, time-oriented sequence for the filling, reacting, settling, and decanting phases is often employed for the control of the SBR process. However, with the help of modern equipment, it is possible to increase the efficiency of standard SBR reactors and thus save costs by adapting the cycle time and optimizing the duration of the individual treatment steps. The latest development of the SBR system involves the application of granular activated sludge like that from the Nereda process, which offers several advantages over the conventional SBR such as reductions in both the space and power requirement, lower chemical consumption, and improved toxic and shock load tolerance. WABAG is a cooperation partner of Royal Haskoning DHV and has already built several Nereda® SBR plants.

The two-stage, activated sludge process is utilized in plants possessing two separate, activated sludge circuits. It consists of high-loaded first and low-loaded second stages and was developed in the 1970s in Europe in order to treat high-strength used water influents. Subsequently, the tightening of the effluent discharge requirements with respect to nitrogen and phosphorus in the 1990s meant that the process ceased to make further progress. However, in the twenty-first century, it is attracting significant attention, as it offers great potential for the improvement of the net energy balance of used water treatment plants. On the one hand, as compared to the conventional activated sludge system, the high-loaded stage facilitates increased COD capture in the activated sludge, and on the other, alternative methods for backload treatment as a replacement for the conventional nitrification/denitrification enhance process efficiency. Therefore, numerous researchers are investigating the increased carbon capture mechanisms of the high-loaded sludge and the implementation of the nitritation and anammox process as a backload treatment.

The Hard-Hofsteig used water treatment plant was built in its original form in the 1970s. However, population growth and increasing demand for more extensive nutrient removal then led to plant expansion. The first plant enlargement was carried out in 1997, but for the second, which was planned for completion between 2012 and 2014, insufficient space was available. Therefore, in order to solve this problem, a two-stage hybrid concept was selected. This is a patented, two-stage activated sludge process for extensive nutrient removal, which consists of a high-loaded first stage and a low-loaded second stage, with a combination of two sludge cycles for enhanced nitrogen removal.This case study considers the upgrade of the Hard-Hofsteig UWTP, which doubled its capacity through the employment of the hybrid concept without any alteration of the plant footprint. In fact, plant capacity was increased from 170,000 PE to 270,000 PE at very low cost, and operational data analyses indicate stable performance.

The Tehran South used water treatment plant was built in several phases between 2005 and 2012. The plant design employs a conventional activated sludge process (see chapter “Activated Sludge Processes in Municipal Used Water Purification”) with carbon removal and partial nitrification. It is divided into four parallel lines and serves more than 2.1 million people. Trickling filters are integrated into the biological stage to nitrify the backload water from dewatering. The water line consists of an inlet pumping station, mechanical pretreatment, primary sedimentation tanks, aeration tanks, trickling filters (see chapter “Trickling Filters in Municipal Used Water Purification”), and a chlorination unit. The disinfected effluent is reclaimed for irrigation, thus indicating a highly effective nutrient removal approach. The sludge line includes the mechanical thickening of waste activated sludge, the gravity thickening of primary sludge, anaerobic sludge digestion, and sludge dewatering. The operation of the plant is challenging because the hydraulic load shows an untypical pattern for a large catchment area, which causes extreme variations in the raw used water characteristics. The plant produces renewable energy through the conversion of the organic matter into biogas by anaerobic digestion, which in combination with the low-energy requirement of the trickling filters ensures energy-efficient and resource conserving operation.

In the moving bed biofilm reactor process (MBBR) the sludge is growing as a biofilm on a mobile carrier, mostly made out of plastic material. The carrier is retained in its compartment using retention devices. Aeration and/or mixing ensure a homogeneous exposure of the outside biofilm to the bulk environment.MBBR allows for a higher biomass concentration in the reactor, thus reducing necessary reactor volume and footprint. The process is mostly diffusion limited and therefore diffusion of substrates through the biofilm is essential for understanding MBBR design. Since modeling of the process becomes complex and analytical solutions are not available, numerical solutions are required for precise design, even if approximate degradation rates are existing.Furthermore, hydraulics inside of MBBR are important to understand. When not correctly designed, carrier displacement toward the outlet retention devices occurs, which can lead to loss of process performance and/or clogging of the reactor.Finally, being a biofilm process, the MBBR process is more stable toward toxic shocks than activated sludge treatment. Especially slow growing bacteria will take advantage of the biofilm environment, which will enable an MBBR to treatment compounds that are normally nonbiodegradable or even toxic (aromatic compounds, endocrine disrupting substances, etc.).

Membrane bioreactor is a process for biological wastewater treatment based on suspended activated sludge. Sludge flocs and particles are separated from the treated wastewater with membranes. Depending on the application, a big variety of systems and membrane types can be used. In municipal applications, often ultrafiltration membranes with a pore size of 0.01–0.1 μm or microfiltration membranes with a pore size of up to several μm are used. Both membranes are submerged and operated outside-in.Advantages of the membrane bioreactors include the smaller footprint compared to many other biological treatment systems, the excellent effluent quality including partial mechanical disinfection, and large independency of the sludge settling properties.Downsides of the membranes are higher operational cost compared to conventional treatment technologies (including energy, chemicals, and wear parts).The right system should carefully be chosen based on effluent requirements and existing structures or spatial requirements.WABAG used the MBR technology in many WWTP where either space was very limited (e.g., WWTP Zermatt in a man-made cavern inside the mountain) or where the effluent requirement asked for a membrane solution. MBR applications typically include plants, where treatment capacity had to be increased substantially within existing structures of a conventional treatment plant.WABAG mainly applies hollow fiber UF membranes.

The chapter describes the membrane bioreactor (MBR) of the used water (wastewater) treatment plant in Zermatt, Switzerland. The plant is located in a man-made cavern and in 2013 required an upgrade and enlargement. To fulfill this objective, the treatment system was equipped with innovative MBR technology consisting of a denitrification tank, a downstream nitrification unit, and final membrane filtration. In view of the limited space in the cavern, the existing units were repurposed. Various optimization measures enable the MBR to achieve good contaminant removal results and it has proven to be a cost-effective solution that suits the restricted cavern space. The technologies presented are interlinked with other chapters, thus providing a complete picture of the treatment system.The respective denitrification and nitrification tanks provide extensive nitrate and ammonia removal, while membrane filtration is responsible for sludge retention. The MBR possesses two sludge recirculation lines, which ensures adequate contaminant removal. Within this configuration, sludge from the filtration tank is directed into the nitrification unit, while the denitrification tank is supplied with sludge from the nitrification basin. The lines can be adjusted individually, which results in a high degree of flexibility. This advantage is especially beneficial during peak tourism periods and weather changes, when up to tenfold load increases can occur. The formation of yellow sludge in the MBR system is an issue that has been documented for a number of years. This sludge type reduces the hydraulic capacity of the membranes and creates suspensions, which due to their poor settling properties are extremely difficult to remove. The various measures taken by ARA Zermatt to compensate for the negative impacts of yellow sludge are presented.

The occurrence of micropollutants in urban wastewater is one of the current challenges for wastewater treatment. Implementing advanced treatment to minimize their discharge into the aquatic environment is crucial, and the European Commission has proposed corresponding requirements in a revision of the Urban Wastewater Treatment Directive. Based on treatment efficiency and costs, ozonation and activated carbon have been identified as the most promising technologies and are already implemented at full scale in different European countries. Current applications comprise various engineering solutions, including powdered activated carbon, either dosed simultaneously during or after biological treatment, granular activated carbon (GAC) filters, ozonation (O3), and the combination of O3 and GAC. This chapter aims to summarize principles and recent advances in micropollutant abatement. It demonstrates the design, operation, and monitoring of advanced wastewater treatment based on eight case studies employing full-scale micropollutant removal. In addition to minimizing the discharge of micropollutants into the aquatic environment, we also present synergies with future nonpotable reuse applications since requirements for agricultural reuse to cope with increasing climate-induced water scarcity are directly linked to advanced treatment.

Sewage sludge is the largest by-product of used water treatment. Its production is dependent upon influent characteristics and the processes applied. It is composed of a complex, heterogeneous mixture of microorganisms and readily biodegradable organic and inorganic materials. Sludge treatment is a highly complex, expensive, and environmentally sensitive problem. At present, there are a wide variety of sludge treatment processes in operation, which can be employed in various combinations in line with the goal and end usage. Volume reduction and sludge stabilization represent two main sewage sludge treatment objectives. Volume reduction begins with the thickening process during which the sludge solids are concentrated in order to increase the efficiency of further treatment. Sludge dewatering and drying are other methods for volume reduction that go far beyond thickening and reduce water content considerably. Sludge stabilization can be achieved by biological, chemical, and thermal processes and except in the case of alkaline stabilization leads to mass reduction. Other positive effects of sludge stabilization are pathogen removal, a cut in odors, and improved sludge dewaterability.

Anaerobic digestion technology is used largely for the stabilization of the municipal sewage sludge resulting from aerobic used water treatment. During this process, part of the organic fraction of the raw sludge is converted into renewable energy thus increasing the overall energy efficiency of the UWTP. A net reduction in the quantity of solids and the destruction of pathogenic organisms also result. Apart from the environmental factors, a number of operational process parameters, including solid retention time, hydraulic retention time, volatile solids reduction, and sludge pretreatment, have a major effect upon digestion performance. Over time many process modifications have been developed. Besides traditional mesophilic single-stage digesters, two-stage digesters, two-phased digestion processes, and temperature-phased digestion processes are applied, whereby a combination of mesophilic and thermophilic range is possible in each stage or phase. In addition, co-digestion, as well as thermal, mechanical, and chemical pretreatment options known as sludge disintegration, can be used to increase the overall performance of the anaerobic digestion process.

Anaerobic sludge digestion is a natural process in which bacteria decompose organic material, whereby the sludge is stabilized and at the same time, biogas is produced. Owing to sludge stabilization, the sludge volume is reduced and with it, the carbon footprint of the used water treatment plant and transportation costs. This process is highly complex and sensitive and takes place in anaerobic digesters. Anaerobic digesters have been used for decades at municipal used water facilities and are designed to maximize the degradation of organic matter and optimize the growth of the bacteria that generate methane. There are many differing digester shapes and mixing possibilities, but irrespective of the design employed, several operating conditions must exist in order that optimum organic material degradation is attained. For this reason, anaerobic processes, digester design, and digester mixing are closely connected and an understanding of these relationships is very important when choosing and setting up a system.

The continuous anaerobic gas mixing system is suitable for use in sealed digester tanks whether cylindrical, cylindrical spherical, or egg shaped. Its design optimizes the sludge digestion process and produces a more homogenous mix than other systems. The two categories of confined and unconfined gas injection systems are discussed. Wabag’s sequential gas mixing system, which is categorized under unconfined gas mixing system has shown some unique advantages over other mixing systems has been explained in details in this chapter. The items associated with gas mixing system such as gas lances, lance head, and lance bottom diffuser are also explained. The advantages and disadvantages of various types of gas mixing systems are presented. Along with the lance system efficiency, the important design parameters and a comparison on operating data of various gas recirculation systems have been discussed in detail.

The continuous external pump mixing system is suitable for use in fixed cover anaerobic digester tanks whether cylindrical, cylindrical spherical, or egg shaped. External pump mixing systems has gained its importance due to no in-basin moving parts and simple operation. The items associated with external pump mixing system such as recirculation pumps, mixing nozzles, and their arrangements are explained. The advantages and disadvantages of external pump mixing along with their design parameters are also presented.

Biogas produced as a by-product of anaerobic digestion in UWTPs contains 60–70% methane, 30–40% carbon dioxide, and 1–2% of small quantities of other impurities such as ammonia, halogenated organic compounds, hydrogen sulfide, siloxanes, and water vapor. With regard to further biogas utilization, methane is the most valuable component of biogas and can be utilized in cogeneration units. However, although the concentrations of impurities are relatively insignificant, they can have a negative effect upon the cogeneration unit and a varying level of biogas treatment is therefore required that matches the cogeneration technology used. The employment of cogeneration plant at UWTPs can provide an economic, efficient, and sustainable solution for their heat and power requirements. Nonetheless, while biogas utilization is promising from a carbon footprint perspective, challenges remain, due largely to the presence of impurities in the biogas. The most problematic contaminants are H2S, water vapor, and siloxanes, and a variety of methods for their removal are available. With the exception of biological H2S removal, all the other methods use physicochemical processes and in addition, there are many different cogeneration technologies for biogas utilization. This review demonstrates that internal combustion engines are by far the most frequently applied technology in the biogas utilization market, but from environmental perspective, some other techniques such as fuel cells and Stirling engines may become increasingly attractive in the future, as they have inherently low NOX, CO, and VOC emission profiles.

Sludge hydrolysis is the most applied supporting process for anaerobic stabilization of sewage sludge. The aim of sludge hydrolysis is to prepare the sludge for the process of biodegradation; while decreasing the viscosity of sludge, the soluble COD of the sludge is increased with this process (Bishnoi, Effects of thermal hydrolysis pre-treatment on anaerobic digestion of sludge. Master thesis, Virginia Polytechnic Institute and State University, 2012). Specific biogas production ratio over the removed volatile suspended solids is related with the composition of the solids structure. In this way, the utilization of hydrolyzed sludge in anaerobic digesters provides a higher biodegradation rate in comparison to conventional anaerobic sludge digestion (Bishnoi, Effects of thermal hydrolysis pre-treatment on anaerobic digestion of sludge. Master thesis, Virginia Polytechnic Institute and State University, 2012). Resulting of higher loading rates in digesters, reducing the volume needed for anaerobic sludge digestion process via reducing the stabilization time and sludge volume fed to digesters, increased biogas production, and pathogen free and stabilized biosolid products are benefits of the system.The biodegradability of sludge solids can be improved by sludge hydrolysis resulting in solids solubilization. Finally, dewatering after digestion is substantially improved.To improve digestion performance including high specific biogas production, the feasible sludge hydrolysis methods are mechanical, thermal, and chemical sludge hydrolysis methods.

Sludge thickening is the first step in the sludge treatment process and at the same time an important component in sewage sludge management. The volume of sludge after thickening is reduced considerably to less than half of the original amount. Depending upon the physical process employed, sludge thickening can be carried out using gravitational, centrifugal, or buoyancy force. Dissolved air flotation is the only thickening method that utilizes buoyance forces for sludge thickening. Centrifuges use centrifugal forces, whereas gravity thickener, dewatering tables, drum and disk thickeners employ gravitational forces to separate sludge from the water phase. The main factors that influence the selection of the thickener are sludge type, the size of the UWTP plant and the downstream process, the requested sludge concentration, footprint, investment, and operational costs. A gravity thickener is typically used to thicken primary sludge, whereas dissolved air flotation and mechanical thickening are mainly utilized to thicken biological waste sludge. Nonetheless, all of these methods can also be implemented to thicken mixed, chemical and digested sludge. The performance results of each methodology are strongly influenced by the sludge origin and type; however, performance can be improved by applying chemical conditioning. To this end, cationic polymers are used frequently in order to improve the thickening of the waste activated sludge. As a rule, gravity thickeners and centrifuges do not require chemical sludge conditioning, but their performance can be increased by the dosing of flocculants, especially in the case of overloads.

Mechanical dewatering is designed to separate sludge into liquid and solid part. The dewatering performance of the equipment is determined by cake dryness, solid recovery, and drying time. The operating costs, chemical usage, and required maintenance should be considered for design and operation of the dewatering equipment.The principle methods of mechanical dewatering of sludge are centrifuges and filter presses. The mechanical sludge dewatering with filter presses guarantees more efficient volume reduction.If the cake dryness rates of centrifuges and filter presses are compared, the dryness rate of filter press is two times higher on average (GlobalSpec, Dewatering equipment https://www.globalspec.com/learnmore/manufacturing_process_equipment/filtration_separation_products/dewatering_equipment. Accessed 26 June 2021, n.d.). Cake dryness of filter presses is around 40–60% and around 20–30% for centrifuges (GlobalSpec, Dewatering equipment https://www.globalspec.com/learnmore/manufacturing_process_equipment/filtration_separation_products/dewatering_equipment. Accessed 26 June 2021, n.d.). The process time of filter presses is faster than centrifuges and the operating cost as well as the capital cost of filter presses are higher than centrifuges (GlobalSpec, Dewatering equipment https://www.globalspec.com/learnmore/manufacturing_process_equipment/filtration_separation_products/dewatering_equipment. Accessed 26 June 2021, n.d.).

Sludge is produced as a residue of the treatment of industrial and municipal wastewater and includes mostly water and insoluble and semisolid materials. The amount of the sewage sludge has become problematic together with the increasing population in cities and production of more wastewater. Sludge treatment systems have been developed to cope with the increasing amount of sewage sludge. Commonly used sludge treatment systems are sludge thickening, dewatering, drying, and incineration. The main goal of the sludge treatment is to remove the moisture content of the sludge by reducing the volume and weight. Water present in the sludge is also removed by thickening and dewatering process, but the highest volume reduction occurs in sludge drying process.There are many different types of sludge drying method according to the energy sources and applications. The selection of the suitable sludge drying technology according to the plant requirement is of great importance. Sludge characteristics, energy requirement, final use of the dried sludge, and area requirements can be effective on the process selection.

The use of solar sludge drying is a further development of the natural drying process and is aimed at reducing sludge volume and disposal costs. Drying is achieved through the evaporation of the water contained in the sewage sludge. The evaporation rate is increased by the greenhouse effect, as solar radiation is converted into thermal radiation for heating the air in the drying hall. In order to enhance this process, the water-saturated air has to be evacuated through targeted ventilation using circulating air fans and/or the targeted control of the ventilation flaps. High drying values can be achieved even during low solar radiation periods by the employment of additional thermal energy and thus constant sludge quality can be guaranteed throughout the year. Solar driers are characterized by low energy demand of 20–30 kWh/t and are therefore very environment-friendly and have a small CO2 footprint. An optimum drying degree is reached with 70%, however drying degrees of up to 85% are possible. Drying takes place in transparent, semi-closed structures, which support heating and air circulation. Apart from the greenhouse, the main parts of the solar drier are an air exchange system and a sludge turning and mixing device. The most important process parameters are the sludge retention time and the drying capacity in terms of the tones of water eliminated per area and year. At present, there are several manufacturers in the market. Their process set-ups are more or less all identical, but the sludge turning, mixing and distributing devices, which constitute the vital part of the solar drier, are generally patented and therefore differ.

The function of a cooling system is to release the excess heat from industrial production processes or equipment for proper operation. This heat is removed transferring it to cooling medium. Water is the most commonly used cooling medium. Although there are ample sources for cooling water, there might be certain water quality issues mainly involving scaling, corrosion, and biological growth. Therefore, the main issue is to provide the cooling water according to the requirements and standards.The chapter emphasizes on different types of cooling systems, quality parameters, and sources of different water quality issues.

The following chapter shall provide a brief overview of boiler make-up water treatment and conditioning. The treatment differs from case to case depending on the initial and required water quality. Overall, treatment is focused on the removal of suspended solids, TDS, silica, hardness, and dissolved gases. As a result, commonly involved technologies are clarification, filtration, reverse osmosis, ion exchange, and, in some cases, electrodeionization. Dissolved gases are removed via stripping or deaeration. The rule of thumb indicates that higher boiler pressures demand a higher water quality. Therefore, treatment can reach from simple softening to total demineralization. Conditioning of boiler make-up water is accomplished with alkaline agents or dissolved oxygen, thus providing long-term protection against corrosion of the boiler material. The production of high-quality boiler make-up is further illustrated with an exemplary case study. The amount of boiler blowdown to be removed and TDS concentration in the boiler after a certain operation time can be estimated with different formulas.

It is expected that the electricity demand will increase by 70% globally from 2010 to 2035 (avg. 2.2% per year). For this, bulk of the projected capacity additions is expected to come from Thermal Power Plants. Other than India, China, and USA, key growth countries such as Vietnam, Indonesia, Thailand, and Malaysia have majority of their future power generation from Thermal Power Plants. More and more “Super Critical Boiler” applications are seen in current trends, which require high boiler feed pressure. In essence, Condensate Polishing attributes as a critical component in “Thermal Power Plants” to ensure availability, reliability, and assist in achieving optimum performance. High pressure design requirement, coupled with requirement of resin transfer for external regeneration, poses very significant hydraulic and mechanical design challenges for “High Pressure Condensate Polishing”.

Raw water from the lake contains residual values of suspended solids and Fe. Elimination of this pollution is proposed in a clarifier, in the sand filter bed, and with activated carbon. The clarifier will provide production of clarified water to be added to cooling circuit system and further for filtration and for demineralized water production.A high salt concentration in the filtered water determines the reverse osmosis technology as the demineralization step. The demineralization consists of two in series operated stages of reverse osmosis. Permeate from the RO 1° is brought first to an aeration tower. The aeration is included to remove CO2 that is formed after adding sulfuric acid before the RO 1°. The aerated water will be led from accumulation tank to the RO 2°, which ensures high quality of water for the following transport. Both stages of RO will be equipped with supplementary equipment for cleaning. Permeate from RO 2° will be led by pumps to EDI technology (electro deionization). EDI is a separation process, which belongs to the group of electro membrane processes during which comes to separation of negatively charged particles from positively charged ones to corresponding electrodes.The effluents from Demineralization plant and leakages from chemical systems are collected, mixed, and neutralized in the neutralization tanks. Sulfuric acid or caustic soda are dosed into the waste water according to the pH value.Condensate from machine room is delivered to mixed bed filters. The mixed bed is a mixture of strongly cation exchanger and strongly anion exchanger. After polishing in the Mixed Bed Filters, the condensate is led from into condensate circuit in the machine room.Part of the technology of water treatment is also a chemical storage system and a chemical dosing system.

As both the quality and quantity requirements for contaminant-free water increase, the demands for innovative technologies and improved system designs are creating challenges and opportunities for the multitude of industries that require ultrapure water.Ultrapure water (UPW) is required in a wide variety of production processes. Ultrapure water is essential to use for cleaning and dilution purposes in the pharmaceutical industry and as a cleaning agent in the semiconductor industry.The technology of the industry has advanced so rapidly over the past few years that it has redefined cleanliness requirements, specifically with regard to the need for quantitatively removing colloidal silica, particles, total organic carbon (TOC), bacteria, pyrogens (bacterial fragments), and metal ions.

The separation and refinement of petroleum requires sophisticated operational systems, which are optimized in accordance with the properties of the desired product and qualities of the crude oil. Due to the complexity and scale of the processes, refineries can consume vast amounts of water, thus making the water network a key factor in ensuring optimum operative conditions. Identifying the main water consumers and the effluents produced is extremely important for the development and improvement of refinery water management.This chapter provides an overview of oil refinery and petrochemical facility water networks. The main discussion points are water sources, the resulting effluents from diverse petroleum processing steps, and the technologies and treatment system employed. Most importantly, water reuse and recycling within a refinery are also addressed in detail.Surface and groundwater constitute major water sources. Furthermore, many refineries choose to include rainwater and stormwater in their water networks. A topic of increasing importance is the reuse and recycling of refinery effluents to form treated streams as an additional, viable water source. The diversity of refinery water supplies is also further explained with a short example.Owing to their high level of contamination, special emphasis must be placed upon the treatment and handling of oil refinery effluents. This chapter discusses and compares the treatment for these streams and their characteristics in a comprehensive manner. The technologies presented are interlinked with other chapters and thus provide a complete picture of the processes. The refinery effluents addressed include desalter effluent, sour water, spent caustics, oily water, cooling water, and petrochemical effluents. The treatment system consists of numerous technologies, which can be divided up into primary, secondary, and tertiary treatment steps of which the latter is crucial for effluent reuse and recycling. Each of these stages is responsible for the removal of different contaminants.The special treatment of challenging effluents is also discussed. One example in this regard is the handling of spent caustics, in which the effluent frequently undergoes wet air oxidation. This treatment process can be tailored in order to achieve the desired water qualities and in order to illustrate the flexibility of the process within this context, three different wet air oxidation designs are compared. As far as petrochemical processes are concerned, the treatment of the effluent resulting from the production of terephthalic acid and polyethylene terephthalate is described with an example. In addition, this chapter briefly depicts the resemblance between refinery effluent treatment and recycling plants by means of diverse case studies from around the world.Owing to the wish to achieve greater sustainability and a reduction in discharged effluent volumes, the reuse and recycling of effluents down to zero liquid discharge (ZLD) or minimum liquid discharge (MLD) have become a major topic. Zero liquid or minimum liquid discharge systems contain a series of treatment steps, which virtually avoid liquid discharges and produce water (mainly condensates) of the highest quality, thus opening up the possibility of high grade recycling. The scope of refinery effluent reuse is diverse, since the reclaimed water can be implemented in numerous areas. Within this framework, a short case study of an oil refinery in Nigeria is presented. At this refinery, the final reverse osmosis and demineralization units produce high-quality water, which is then reused as boiler makeup. Furthermore, this chapter reviews different technologies and in particular membrane processes such as reverse osmosis and ultrafiltration. Within this context, ceramic membranes are discussed with regard to higher robustness and lower life cycle costs.

The following chapter describes the effluent treatment plant built by VA Tech WABAG for PETRONAS as a part of the refinery and petrochemical integrated development (RAPID) project and other associated facilities at the Pengerang Integrated Complex (PIC) in Pengerang, Southern Johor, Malaysia. The project was developed by a joint venture of Malaysian oil and gas company Petroliam Nasional Berhad (PETRONAS) and Saudi Aramco, which is the national oil company of Saudi Arabia.The treatment facility consists of a multistage system for the handling of seven complex streams and the purification of 66 different effluents. Each stream is handled in its own treatment line, which enables efficient contaminant removal. The technologies presented are interlinked to other chapters, which thus provides more detailed explanations and hence a clearer understanding of the treatment processes. For the main stream, comprised of continuously oil-contaminated water, the treatment consists of a corrugated plate interceptor for oil removal, clarification via DAF, extensive biological treatment, and finally dual media filtration. Other oily streams such as accidentally oil and chemically contaminated water are also purified in a similar manner. In this case study, the focus is on the removal of free oil and suspended solids. The treatment of sanitary wastewater (sanitary used water) requires a final disinfection with NaClO and includes a biological treatment using extended aeration and an anoxic basin. Together with the treatment of the main streams, the handling of special refinery effluents is also described. Within this framework, the treatment of spent caustics and highly nitrogen-contaminated wastewater (highly nitrogen-contaminated used water) are explained. In the case of spent caustic, the effluent undergoes medium-pressure, wet air oxidation, and neutralization for COD and sulfide removal. Conversely, the core technology involved in the treatment of the highly nitrogen-contaminated (nitrile butadiene latex (NBL)) effluents is a Fenton’s oxidation reactor with H2O2 and FeSO4 at pH 3 together with extensive biological treatment for the removal of COD, organic contaminants, and oxidation by-products. All the treated effluents are collected in an observation pond for a quality check prior to being safely disposed into a sea outfall.Other facilities include a sludge treatment unit, a slop oil-handling system, and a volatile organic compound-handling facility, which are required for the by-products generated during the various treatment steps.

During a petrochemical refinery process, high volumes of used water containing organic and/or inorganic compounds are generated. The specific characteristics of refinery used water (wastewater) are directly related to the various manufacturing processes, as well as the refinery plant operation, and emanate from differing raw materials and final products, maintenance works, the shutdown of single plant sections, and process adaptations. Therefore, used water characteristics can vary greatly throughout the day, the week, and the year, both in terms of water quantity and quality (Berne and Cordonnier 1995).Refinery used water requires extensive pretreatment before it can be treated biologically. It is necessary to remove toxic compounds such as hydrogen sulfides, cyanides, or hydrocarbons (oils) because they would negatively influence a biological treatment process. Aerobic biological treatment is a state-of-the-art technology for refinery effluent treatment. Many aerobic bacteria are able to degrade hydrocarbons, phenols, and organic acids and to use such compounds as a substrate. Even toxic cyanide can be converted into nontoxic thiocyanate by a number of bacteria that include Escherichia coli or Bacterium subtilis.A prerequisite for successful biological degradation is that the bacterial community is adapted to the specific used water characteristics, in order that the concentrations of toxic compounds remain below the critical (toxic) values and shock loadings are avoided.Within the context of the aforementioned, this chapter presents a case study describing the design and operational experience of the Petrobrazi used water treatment plant operated by WABAG at the OMV/Petrom-owned refinery and petrochemical complex at Ploiesti, Romania.

“Produced water” is a term used in the oil and gas industry for water which comes out of the reservoirs such as condensed water or injected water or water which has been in the reservoirs before. It is the largest waste stream generated in the oil and gas industry, and consists of a mixture of different compounds, both organic and inorganic.The object of this project was to reduce the pollutants contained in the produced water, in order to discharge the treated water into the river. The main issue with regard to the treatment of this produced water was the elimination of nondegradable COD. For this reason, adsorption using activated carbon technology was implemented and has been shown to be successful. The treatment plant consists of three stages: physical-chemical stage, biological stage, and adsorption on activated carbon. The plant effectively decreased the COD in the produced water by between 92% and 95%.Within the context of the aforementioned, this chapter presents a case study describing the design of a produced water treatment plant built by WABAG in Romania.

The increase in the global population represents a challenge to water management in the food and beverage industries. Accordingly, the objective of the projects presented was to reduce the pollutant content of wastewater (used water), in order to enable the discharge of the treated water into the recipient. The main problems facing the food industry with regard to used water relate to the lowering of COD concentrations and the design of treatment plants with a small footprint for a decrease in the total nitrogen concentration.Within this context, the following chapter presents a short description of two used water treatment plants built by WABAG for the food (snack foods) and beverage industries. The food industry treatment plant described consists of two main stages (physical-chemical stage, biological stage), while the beverage industry treatment plant employs an integrated IFAS system.

This chapter provides an introduction to industrial water reuse and recycling and is interlinked with several specific chapters in this field. The major issues discussed consist of usable raw water sources, water recycling and reuse applications (including quality requirements), drivers for the realization of this management option, and key success factors such as water reuse sustainability; the true value of water; financing; process design including pilot testing, operation, and maintenance; and concentrate management.Major sources are drought-proof municipal and industrial effluents. A special resource is RO concentrate, which can be reused, e.g., for refinery coke quenching. Another option under discussion is the reuse of reclaimed water from one company by another (e.g., in industrial parks/multicompany sites where distances between the companies are relatively short). An unusual resource is river water heavily polluted by municipal and industrial effluents. A brief case study within this context is presented.The topics of water supply security, economic benefits including brand protection and reputational risk management, as well as government policies and the green image of companies are all addressed as main drivers. Economic benefits are obtained mainly through savings of freshwater from the public supply, lower used water discharge fees, and resource recovery. Another economic advantage that is normally omitted from feasibility studies is the increase in water supply security. As an example for the implementation of government policies, the new water reuse guideline from the Indian state of Gujarat is discussed. Green image has also been identified as an important driver, as it is increasingly part of the corporate culture of many enterprises. The related benefits derive from the fact that employees are proud of a green image and are therefore more motivated. In addition, customers are increasingly willing to pay a higher price for sustainable solutions.The major industrial applications are recycling and the reuse of various raw water sources as cooling and boiler make-up water. Within this context, several cases of industrial effluent recycling and the reuse of municipal secondary effluents are discussed in brief. Especially, in the case of the recycling of boiler make-up water, advanced multi-barrier systems (including ultrafiltration and reverse osmosis and mixed bed ion exchange) have been employed in order to meet stringent quality requirements (e.g., for silica) and subsequently to guarantee the power supply for industrial processes such as petrochemical manufacturing. With this in view, it is also very important that the reclamation plants are operated and monitored by well-trained and skilled personnel from the plant owner or a water technology specialist. Another success factor is suitable design, which in many cases is based on pilot tests. Design examples including reuse targets are described (e.g., a UF design comparison for three different reuse applications). Another important topic is concentrate management, which is discussed on the basis of disposal and beneficial reuse (including zero liquid discharge) cases. Apart from technological and operational issues, financing (e.g., public-private partnership/PPP) is addressed, which is very important for the realization of water reuse projects, especially in developing countries. Finally, the overriding importance of sustainability as a key success factor is emphasized and the conclusion drawn that water reuse and recycling solutions have to be ecologically, economically, and socially sustainable in order to provide benefits to all the stakeholders involved.

The following chapter describes the refinery water reclamation plant (WRP) built by VA Tech WABAG in Dahej, India. The WRP, which was commissioned by Reliance Industries Limited, is an excellent example of industrial used water management and reuse. Owing to the growing scarcity of water in the region, a special focus was placed on the reutilization of the treated streams. The WRP is based on the segregated treatment concept, which foresees the categorization of the effluents from differing petrochemical processes by their COD and other contaminant content, and their subsequent targeted treatment. For example, the effluents with a high-COD content resulting from the production of polyethylene terephthalate (PET) and purified terephthalic acid (PTA) are treated via an upflow, anaerobic sludge blanket, followed by a heavy metal removal system, membrane bioreactor, and ion exchange (IX). Similarly, high-COD streams with additional oil content such as oily and sanitary used water undergo flotation via DAF and extensive biological treatment. By contrast, the low-COD effluents are treated with a dual media filter and ultrafiltration. A final reverse osmosis (RO) unit desalinates the diverse streams, and the high-quality permeate is reused for the production of boiler make-up. Different treatment by-products such as RO brines or IX regeneration wastes are safely disposed of into a sea outfall. The WRP also encompasses a common sludge handling facility that deals with the hazardous material from various treatment units. The technologies presented are interlinked to other chapters, thereby providing comprehensive explanations of the treatment system presented.

This chapter describes the water treatment system at the Dangote refinery and petrochemical complex in the Lekki Free Zone near Lagos, Nigeria. The project is still under construction with mechanical completion and startup planned for the end of 2022. The raw water for diverse petrochemical processing steps will be drawn from the adjacent Lekki Lagoon and then treated, thus providing the entire complex with a high-quality supply. Treatment will include a sequential batch reactor and diverse filtration technologies, and seasonal fluctuations are to be taken into account. The effluent treatment plant will also deal with various refinery effluents. The system is to be based on effluent categorization and subsequent targeted handling, which will ensure efficient and cost-effective treatment. The wastewater will be divided into oily wastewater (oily used water), contaminated rainwater, sanitary wastewater (sanitary used water), cooling tower and boiler blowdown, each of which are to be decontaminated in individual treatment lines. Furthermore, complex effluents such as spent caustics and phenolic sour water will be handled separately. In the case of spent caustics, the core technology will consist of high-pressure, wet air oxidation, which offers a high level of sulfide and COD removal. By contrast, in order to remove excess cyanide, phenolic sour water will first be stripped and then subjected to an oxidation process. The effluents from the treatment plant are to be further decontaminated in a water reclamation plant comprised of an ultrafiltration treatment system, a two-stage, two-pass reverse osmosis unit, a downstream degasser tower, and final polishing in a mixed bed ion exchanger. The treated effluent will be of a high quality and thus suitable for reuse as boiler feed water. The water treatment system will include units for handling both sludge and, most importantly, rejects. As a result, the hazardousness of highly contaminated treatment by-products will be reduced and permit safe disposal.

Coal gasification plant is having the process of producing syngas, a mixture consisting primarily of carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2), methane (CH4), and water vapor (H2O) from coal and water, air, and/or oxygen (Jindal Steel & Power, Coal gasification process and information on the JSPL Angul plant. https://www.jindalsteelpower.com/odisha.html. Accessed 17 Dec 2021, 2020). Coal gasification plant scheme. (© WABAG) During a coal gasification process, high volumes of used waters containing organic and/or inorganic compounds are generated. The specific characteristics of waste water from coal gasification plant water are directly related to the operation of gasification plant.In Angul, waste water from coal gasification plant after treating in BIO-ETP (by others) and from cooling tower blowdown is being recycled for cooling tower makeup after treating in tertiary effluent treatment plant which is designed and constructed by Wabag.

The Ujams Water Reclamation Plant (WRP) treats industrial used water that is mainly discharged by an abattoir, a brewery, and a tannery located in the city of Windhoek’s northern industrial area. The purpose of the plant is to clean and reclaim industrial effluents for further reuse for the augmentation of the Klein-Windhoek River and other applications such as dust control during road construction. Potential future reuse applications include urban irrigation and reutilization in industry. The project is a public-private partnership between the city of Windhoek and Ujams Wastewater Treatment Company Ltd. (UWTC) and subject to a BOOT business model (design, build, own, operate, transfer) is being operated for a period of 21 years up to 2035.In order to handle the complex range of contaminants in the feed water, WABAG prepared an innovative treatment concept using the in-company-developed MICROPUR® fine sieving pretreatment process in combination with a membrane bioreactor (MBR), UV disinfection, sludge treatment, and exhaust air treatment. The plant, which has a capacity of 5175 m3/d, was officially inaugurated in October 2014 by the mayor of Windhoek and has been in full operation ever since.The key facts relating to the Ujams water reclamation facility are that (i) the plant represents Namibia’s first industrial water recycling and wastewater membrane bioreactor, (ii) the plant is being operated using a public-private partnership business model (BOOT), (iii) the plant is able to purify effluents from differing production facilities and manage extreme variations in terms of inflow loads and used water characteristics, and (iv) the plant is characterized by a smart, compact, and flexible process design and plant layout.In 2015, Ujams Water Reclamation Plant received the Global Water Intelligence (GWI) Distinction Award in the “Industrial Water Project of the Year” category.

Chennai, the capital city of Tamil Nadu, is a very water-stressed, highly industrialized conurbation with a population of more than 11 million. Owing to its water problems, reclamation and reuse require urgent expansion. Accordingly, following the start-up of the Koyambedu and Kodungaiyur water reclamation plants in Q3 of 2019, the total reclaimed water supply to industry amounts to approximately 126,000 m3/d, which represents roughly 17% of the total quantity of sewage (municipal used water) generated. This percentage is set to increase substantially as it is now mandatory for all industries in Chennai to use treated, municipal secondary effluents. In this chapter, the process design and operational results of the Koyambedu water reclamation plant are presented and discussed. It is a 45,000 m3/d multi-barrier system, which via a 60-km-long pipeline provides high-grade water (ultrafiltration [UF] and reverse osmosis [RO] are the core process steps) to various industries such as the large automotive production facilities at Irungattukottai, Sriperumbudur, and Oragadam southwest of Chennai. The process consists of pretreatment with chlorine dioxide dosing (for pre-disinfection and pre-oxidation in the equalization tank) and dual media (sand and hydro-anthracite) rapid gravity filtration (for the removal of turbidity and biodegradable substances), basket strainers (200 μm) as a protective measure for ultrafiltration (UF), pressure-driven UF for the removal of residual turbidity and colloidal matter, cartridge filtration (5 μm), reverse osmosis (with brackish water membranes), and ozone (O3) disinfection of the RO permeate. The major design parameters/contractual standards consist of the total dissolved solids and silica concentrations in the source water amounting to 1500 mg/L and 40 mg/L, respectively (secondary effluent from the Koyambedu Sewage Treatment Plant), and 70 mg/L and 5 mg/L, respectively, in the RO permeate (reclaimed product water). The typical actual reclaimed water values for total dissolved solids and silica are 40 and 0.5 mg/L, respectively. The operational results show that every contractual standard is met at all times.

Water reuse is being increasingly identified and considered as a sustainable water management strategy in China. This chapter provides an overview of current status, policies and standards, and experiences of water reuse across the country. Currently, with the promotion and enactment of water reuse–related policies and targets, there are rapid development in associated facilities and infrastructures and reclaimed water has been applied for many fit-for-purpose applications. At provincial levels, it is identified that water stress and economic conditions are key influencing factors for the evolution and progress of wastewater treatment and reuse.Notably centralized systems are the dominant forms of water reuse in urban areas of China. Particularly, the fit-for-purpose water reuse with multiple applications is considered to be feasible that can meet end users which require varied water quality levels. Besides, water eco-nexus cycle system that addresses environmental and cascading functions can further amplify the significance of reclaimed water in urban water systems. Some case studies are presented to illustrate the practical application of these centralized patterns. The summarized information can provide references for other water scarcity cities and regions for water system planning, design, and management.

This chapter describes the reclamation of water from drought-proof, municipal effluent sources, and the reuse of the reclaimed water in the Beijing Olympic Park. The main drivers for water reuse have been water stress, water eco-system destruction, loss of surface water bodies, and the intention to improve the urban landscape for the 2008 Summer Olympic Games and beyond.In order to alleviate its water crisis, during recent years the city of Beijing has supported the development of water reclamation and reuse. The “dragon-shaped” water system in the Beijing Olympic Park is a successful example of recreational water landscapes using reclaimed water over a period of more than ten years. Artificial water landscapes usually face the risks of quality deterioration and water algal blooms, and therefore, maintaining proper water quality is extremely important.Since 2008, five reclamation plants at QingHe and BeiXiaoHe with a total capacity of 650,000 m3/d have supplied water to the Olympic Park for irrigation, toilet flushing, recreational reuse (such as make-up water for fountains), and the replenishment of the “dragon-shaped” water system. All five of these facilities employ membrane filtration (membrane bioreactors and tertiary ultrafiltration) as a core technology, but differing post-treatment systems (such as reverse osmosis, ozonation, and disinfection). The details of the reclamation plants and the membrane units are described.A constructed wetland and a series of ponds further polish the reclaimed water, which is blended into the landscaped water system in order to control the risk of algal blooms and maintain the good quality of the landscaped lake waters. Algal blooms may occur in scenic water created by reclaimed water in summer, even if nitrogen and phosphorus concentrations are very low. Consequently, it is necessary to setup the ecological purification processes and maintain the scenic water quality. Over 90% of the Beijing population accept water reclamation and reuse for noncontact recreational landscaping purposes, but demonstrated low levels of acceptance with regard to other reuse fields, for example, car washes, agricultural irrigation, and residential toilet flushing based on questionnaires (Chen and Jiao, Environ Sci (in Chinese) 33(12):4133–4140, 2012).The employment of reclaimed water can provide both notable economic and environmental benefits. In the case of water landscape system in the Beijing Olympic Park, as compared to the use of tap water, some CNY 9.38 million p.a. (EUR 113,800 p.a.) (i.e., saved costs of buying tapwater instead of using reclaimed water) were saved in the years between 2008 and 2014. It can therefore be stated that this successful project has contributed significantly to an improvement in the economic, environmental, and social sustainability of the capital city of Beijing.

Antibiotic resistance is one of the most pressing global health threats of our time. The rise of antibiotic-resistant bacteria is largely attributed to the overuse and misuse of antibiotics in human medicine, agriculture, and animal husbandry – in short within the One Health concept. These resistant bacteria can contaminate water sources, posing a significant challenge for water reuse associated risks. As water scarcity becomes more prevalent due to increasing global demand and climate change, the reuse of wastewater for various purposes, including agricultural irrigation and potable uses, has been promoted as a sustainable solution. However, when wastewater contains antibiotic-resistant bacteria or antibiotic residues, its reuse can inadvertently spread these contaminants into the environment, further perpetuating the resistance problem. The linkage between antibiotic resistance and water reuse calls for improved wastewater treatment technologies. The information concerning antibiotics and antibiotic resistance in the context of water treatment is very heterogenous and difficult to access. This is why the DSWAP (detoxification systems for water and air pollutants) as a comprehensive strategy aims to gather, consolidate, and provide information on the efficiency of various water treatment technologies designed to remove pollutants from wastewater designated for water reuse.

Long-term experience in Windhoek (55 years) shows that treated, domestic used water (secondary effluent) can be both safely and cost-efficiently utilized for direct potable reuse (DPR). The advanced water reclamation process employed is resilient and produces purified water of a quality that constantly meets all the required drinking water standards. In addition, non-regulated (emerging) constituents such as micro-pollutants, antibiotic-resistant bacteria, and genes are removed to below the limit of detection. Bioassays in combination with chemical footprint analysis provide a further indication regarding the safety of the purified (reclaimed) water, which accounts for approximately 25% of the drinking water supply. Consequently, this source is an essential part of integrated water resource management in Windhoek and has contributed substantially to the city’s social, economic, and environmental development. A multiple barrier approach ensures the highest possible safety levels, which are consistently achieved. Three differing barrier types are employed with non-treatment, treatment, and operational functions. The non-treatment barriers consist of comprehensive source control, the strict separation of domestic and industrial effluents, and the blending of the reclaimed water with treated dam and ground water. The main treatment barriers are comprised by the Gammams Sewage Treatment Works (a nutrient removal plant) and the New Goreangab Water Reclamation Plant, an advanced multiple barrier purification system, which is based on ozonation and biological activated carbon filtration (a “non-reverse osmosis process”). One example of an operational barrier is the dosing of powdered activated carbon in the case of inadequate source water quality.The public acceptance of direct potable reuse is mainly driven by the lack of other affordable alternatives and the fact that since DPR commenced 55 years ago, no health problems related to reclaimed water have been experienced. Other contributory factors are an open information policy, excellent public education practices, and consumer confidence in both the quality management and the advanced water treatment technology used, which after more than 20 years of operation in the current facility remains unchanged.