Industrial Wastewater Treatment

Freshwater resources are limited and are becoming increasingly polluted due to the rapid urbanization and industrialization. Water pollution is a preeminent pervasive problem affecting the lives of more than 785 millions people globally, both in terms of quality as well as scarcity. Due to boom in industrialization, several toxins and chemicals such as inorganic particles, harmful hydrocarbon, organic matter, and heavy metals etc. are discharged into freshwater bodies thereby making it unsuitable for domestic and drinking purposes. Therefore, it is imperative to design and perform wastewater treatment processes for the production of freshwater. Various technologies have been explored for this purpose including electrochemical oxidation, advanced oxidation process, advanced biological treatment employing algae, bacteria and fungi and membrane-based filtration techniques. Among these, membrane technology is the most suitable strategy applied for wastewater treatment and has gained considerable attention due to its exciting features such as high separation performance, smaller footprint area, cost-effectiveness, low energy requirement, convenience in operation and high efficiency. In this chapter, we will initially discuss membrane technologies applied for the treatment of wastewater. Then, we will describe various types of synthetic membranes, membrane processes and membrane modules being used in wastewater purification. Afterward, an insight into the membrane operation that includes membrane performance, membrane selectivity, separation mechanism, concentration polarization and membrane fouling will be discussed. Finally, different membrane cleaning processes such as physical, chemical, biological and physicochemical cleaning methods will be discussed.

Water is required for sustaining life. It is also used in anthropogenic activities such as agriculture, washing, and industries. Emerging technologies to decontaminate wastewater spent filter backwash water (SFBW) and waste sludge have been widely investigated in wastewater treatment plants. Most of the industries produce spent filter backwash water (SFBW). SFBW utilization is important due to the feasible heavy metals recycle, microorganisms and predecessor for disinfection outcomes. Modernization in coagulation and membrane techniques, particularly in Ultrafiltration and micro- treatment, provides an appropriate method for SFBW to assure the water quality needed for reuse. The main advantages of Ultrafiltration (UF) are less land consumption and reliable water quality. It can remove microorganisms from the water completely, improving the biological quality of water. The suspended particles, viruses and colloidal substances in water are purified using this method. As the primary purification technology of urban drinking water, Ultrafiltration is an alternative to recycling industrial wastewater and sewage drains. Compared with the conventional water treatment process, the EC and UF process has higher efficiency, better effects of treatment and low energy consumption. It is important to further investigate ultrafiltration technology to improve the quality of water, protect water resources, and balance the ecological environment.

Advanced wastewater treatment and reclamation is a sustainable strategy to address the issues related to emerging contaminants (ECs) present in aqueous solutions. Conventional treatment methods are found to remove ECs only partially. Low-pressure membrane separation processes have received extensive attention from researchers worldwide due to their simplicity, eco-friendliness, continuous separation, easy scaling up, the possibility of hybrid processing, low fabrication, and operating costs. However, these processes are limited due to low membrane lifetime, low selectivity, flux decline, linear up-scaling, and fouling. Heterogeneous photocatalytic systems using TiO₂ photocatalyst had been intensively investigated and found to be efficient, economical and environmentally friendly, and sustainable for the degradation of ECs from aqueous solutions owing to the various advantages it possesses including (i) an increase in photocatalytic potential, (ii) stability (chemical and thermal), (iii) energy efficiency, (iv) cost-effectiveness, and (v) non-toxicity. However, these systems have the drawbacks of catalyst separation after treatment and incomplete mineralization. Photocatalysis (PCO) has been integrated with low-pressure membrane systems to address this issue. This chapter provides an overview of ultrafiltration (UF) integrated photocatalytic oxidation (PCO) systems in aqueous solutions, especially for the removal of emerging contaminants (ECs). The mechanisms, merits, and demerits of UF separation, PCO process, and integrated ultrafiltration-photocatalytic oxidation (UF-PCO) processes are discussed in detail. The key influencing factors/operating variables on the performance of UF-PCO systems such as; photocatalyst loading, structure, and properties of photocatalyst, light wavelength, light intensity, initial concentration of pollutant, pH of feedwater, temperature, aeration, inorganic ions, membrane material, membrane pore size, transmembrane pressure (TMP), membrane packing density, and cross-flow velocity (CFV) are discussed elaborately. Furthermore, the removal of ECs had been explored with respect to its characteristics and the same of the membrane. A discussion on the economic aspects of UF-PCO systems in water and wastewater treatment is also included.

Nanofibrous membranes created by electrospinning are nanotechnology-based technologies for developing new separating membranes, electrospun nanofibrous membranes (ENM). These can be used because of their particular characteristics to make multifunctional water treatment materials. On the other hand, its extremely porous construction with large pores reduces the capacity of NaCl to desalinize dissolved salts. As a result, it is only suited as a prefilter before delicate reverse osmosis operations to separate large/microparticles from MF applications. These membranes can be enlarged to provide water treatment by changing them to take out more intricate colloidal solutions, including oil/water suspensions, requiring an organic solution to be rejected. When an ENM surface has been changed and crosslinked with thin, selective coating layers, a combination membrane with smaller pores can be produced that can be used in UF separation. A nonporous composite membrane can be generated by adding an interfacial polymerizing layer which can be employed for nanofiltration and reverse osmosis applications. The current research on electrospun polymer membranes is covered in this chapter, emphasising progress, issues and prospective improvements in water treatment applications.

Pollution resulting from industrial wastewater imposes a significant threat to human life and the environment. Adsorption is recognized as a suitable tool to overcome the water contamination problem of industrial origin. Nevertheless, high costs of commercial adsorbents like activated carbon led to eco-friendly low-cost natural biosorbents such as plants, microbes (e.g. bacteria, fungi, microalgae), biomaterials (e.g. chitosan, chitin), agricultural wastes, etc. The present chapter covers biosorption as a useful technique for industrial wastewater treatment. Different types of biosorbents and mechanisms of the biosorption process are initially explained. Afterwards, regeneration of biosorbent achieved by desorption is explained, followed by a cost estimation of biosorbents for wastewater treatment. Finally, probable challenges for industrial implementation of biosorption for wastewater treatment and prospects are explained.

The elixir of life is water which drives the entire natural process that occurs on our planet. Such an exotic gift by nature undergoes severe damage due to reckless activity by a human. Majorly water sources got polluted by ejection of industrial contaminated wastewater, domestic household wastewater and sewage wastes. Industrial wastewater is introduced in large volumes into the water sources, in turn producing intense health hazards on living beings and the environment. The contaminants from industries include toxic chemicals, heavy metals, metal dust, dyes, radioactive substances etc. At present, people across the globe are so much concerned about protecting and restoring water sources. Conventional industrial wastewater treatments like filtration, adsorption, flotation, ion exchange, coagulation and chemical precipitation are effectively adopted to remove the pollutants. However, these techniques are not sufficient in the case of the removal of hazardous heavy metals and microorganisms. In this scenario, advancement in nanoscience and nanotechnology has opened a new avenue to remove these toxic chemicals from waste water has gained importance and drawn attention with an eagle eye among researchers. Nanomaterials have been attracted due to their excellent physicochemical and flexible characteristics providing significant results with 100% efficiency. Nanomaterials in the form of nano-photocatalyst, nano adsorbents and nano membranes are widely committed. Nano metals, nano metallic oxides, nano metal sulfides, hybrid nanostructures (metal & metal oxides), magnetic nanoparticles, carbon nanotubes, graphene oxide, silica, nano polymers etc., have been utilized for removing contaminants in wastewater. This chapter expresses in detail the capacity of these nanoparticles to provide a sustainable approach in the industrial wastewater treatment process.

Overcoming the present global water quality and safety concern is a real challenge for the actual and future generations, and the green synthesis of nanomaterials has become a rising investigation point to support this goal due to its non-toxic and cost-effective aspects when compared with the conventional synthesised nanomaterials techniques, namely physical and chemical method. The nanomaterials green synthesis approach is classified as a bottom-top methodology. The nanoparticle formation occurs through a bio reduction mechanism of biological materials in the atoms/molecules level to nuclei and after towards a nanoscale particle ranging between (1–100 nm). The secondary metabolites present in leaf, peel and fruit extracts are responsible for the presence of bioactive compounds (alkaloids, lipids, terpenes, phenolic compounds), which have strong antioxidant activity and act as stabilising agents, being able to reduce metal ions. The application of metallic green nanoparticles (silver, gold, iron, copper) has been reported to efficiently remove emerging pollutants (heavy metals, dyes, etc.) from industrial wastewater by adsorption and photocatalytic treatment technologies. The great prospect of plant-mediated nanoparticles has been extensively explored; however, the scientific community should keep addressing all the efforts to guarantee the safety criteria for human health and ecosystems focusing on a sustainable decision.

Over the past few decades, the urge for fresh and pure water has been rising each day. The need of the hour is to develop such viable technologies which are economical, have greater efficacy and lower carbon footprint over conventional methods. The current chapter features modern research studies related to the application of nanocellulose and its composites for the treatment of wastewater. Cellulose in the form of nanocrystal and nanofibrils are used effectively for the purpose of water purification owing to their unique properties. Nanocelluloses are bio-degradable, non-toxic materials used sustainably as nanofiller due to their remarkable mechanical properties, larger surface area, controllable surface chemistry and high aspect ratio. The chapter discusses the effectiveness of these materials for the removal of water pollutants through adsorption, catalytic degradation, photocatalysis, and flocculation. The mechanisms involved in the action of these processes are also discussed. Moreover, the limitations of these nanocellulose-based materials, along with the opportunities and the future prospects for wastewater treatment, have been discussed in detail.

Polluted water is the outcome of human deeds, which become a problem due to its toxicity and hazardous effects on aquatic life. Recent advancements in material science have developed various strategies and applications of Nanocomposites based on clay minerals and polymers in the environmental remediation of wastewater. Nanocomposites are made up of clay minerals, and polymers have shown improvement in properties of compatibility and degradability, high surface area, amplified active sites, and high clay minerals’ adsorption capacity, which makes Nanocomposites very important striking. This chapter focuses on applications of different composite clay materials to eliminate wastewater pollutants. Modified polymers and clay minerals’ structural and physicochemical properties have also been discussed in detail. The key direction of this chapter is the discussion of the various clay polymer composites, together with their synthesis and use in the adsorption of contaminants. The key focus of this chapter is the discussion of different synthesis methods of clay-polymer composites and their use in wastewater treatment. The discussion highlights the potential future aspects in the development of nanocomposite sound polymers.

Several advanced techniques for water treatment depend on materials and chemicals that can pose a secondary pollution risk if not removed, such as nanoparticles, catalysts, and disinfectants. The removal of these compounds requires the use of additional unit operations, making the water treatment process more expensive or even non-scalable. Immobilizing active materials in polymeric composites is an effective way to address these concerns. Such hybrid materials possess a combination of properties that are not normally found in a single constituent, combining the thermal and chemical stabilities of inorganic materials with the processability and flexibility of organic compounds while avoiding dangerous chemicals leech into the treated water. Given that water producers are required to provide high-quality drinking water, polymeric composites have been broadly employed to abate several pollutants. In this context, several nanometric materials have been integrated into polymeric matrices to form state-of-the-art water treatment composites, finding application in microbiological treatment, adsorption and photocatalysis. Due to their chemical flexibility, high surface area, optimal mechanical properties, and cost-effectiveness, such composites have great potential in water purification. The possibilities for tuning polymeric networks are virtually endless, which allows for relatively simple control of functionality (chemical modification, surface modification) and nanomorphology (porosity, structure) of the composites, and fine-tuning of these materials for specific applications and contaminants. In this chapter, we provide an up-to-date review of the importance of polymeric composites in removing several pollutants from water. The main techniques and materials employed in preparing nanocomposites for water treatment, along with their target contaminants, will be addressed, as well as a discussion on their economic feasibility and comparison with well-established techniques.

The textile industry is considered a major pollutant source among all the industrial units because this industry intensively uses a variety of chemicals for the pre-treatment and processing of fibres, wool etc. The wastewater generated from textile processing plants has a complex chemical composition and abnormally elevated physical characteristics. Various chemicals such as organic dyes, bleaching agents, fixing agents etc., are used to upgrade the characteristics of the finished textile materials. A number of methods such as adsorption, coagulation, electro-Fenton oxidation, membrane separation and biological degradation are followed to eliminate the undesirable components from the outlet stream. The success of the treatment process depends on understanding the underlying mechanism of mass transfer by diffusion, the kinetics of pollutant removal and hydrodynamics of mixing. Modeling represents a process by mathematical equations, which comprises the variables affecting the process performance. The model equation shows the relationship between the input and response variables in a process. Model of a process helps to simulate the conditions and understand the robust behavior of systems. The optimisation is a mathematical approach to identify the best condition for a process. The objective of optimisation is to minimise the operating cost or maximise process efficiency. In the wastewater treatment domain, modelling and optimisation are helpful to understand the pollutant removal rate, demarcate the major variables affecting the process efficiency and identify the range of operating conditions. Textile wastes have high salinity, prohibitive total dissolved solids and residual organic dye compounds. The important models developed for a treatment plant are the mass transfer, kinetic, adsorption, and process models. The mass transfer model gives an insight into the rate of diffusion of pollutants in an aqueous medium. A kinetic model explains the rate at which undesirable compounds are removed from wastewater and elucidates the effects of temperature on the process. The process models are used to realise the important variables affecting the process efficacy. The process model explains the interactive effect and linear effect of variables on the response variable. The modelling tools used in textile treatment plants are response surface method (RSM) and Artificial Neural Networking (ANN). RSM is the most widely used method to develop the model equations and optimise the process. The second order quadratic models developed by the RSM method interpret the effects of parameters on the response variables. RSM utilises the experimental design method to develop the complete model expression for the operation with the least number of experiments. Irrespective of treatment strategies for textile wastewater such as coagulation, adsorption, electrochemical oxidation, bio-degradation, ozonation, photolytic degradation and membrane filtration, the RSM is used as a versatile method for building the model and process analysis. The quality of the model equations is tested by statistical tools such as ANOVA table, fit statistics table, 2-D contour graph and 3-D response surface plot.

Among various industry wastewater, oily industry wastewater, cause extensive pollution to water and soil. This wastewater contains oily substances include phenols, petroleum hydrocarbons and polyaromatic hydrocarbons, which are toxic and can inhibit the growth of plants and animals. To human beings, they also bring mutagenic and carcinogenic risks. Hence, there is high priority need to develop a efficient technology to treat oily industry wastewater. This research study aims to optimize the operating parameters in the ozonation and UV-chlorination process to remove chemical oxygen demand (COD) from oily wastewater using response surface methodology (RSM). Three factors three levels Box-Behnken response surface design (BBD) is used for optimization and mathematical model development. pH, ozonation time and retention time are selected as process variables in the ozonation process. pH, UV irradiation and chlorine dose are selected as process variables in the UV-chlorination process. Significant quadratic polynomial modes are obtained with a high coefficient determination value (R² = 0.90 for COD). Numerical optimization is employed to achieve optimum conditions, resulting in >85% COD removal in both ozonation and UV-chlorination processes.

In this study, a TiO₂ immobilized on kaolin was synthesized by the sol_–gel route. The surface morphology, chemical and phase composition of the kaolin, synthesized TiO₂ nanoparticles, and their nanocomposites were investigated using high-resolution scanning electron microscopy (HRSEM), RAMAN spectroscopy, high-resolution transmission electron microscopy (HRTEM) coupled with energy dispersive spectroscopy (EDX) and selected area electron diffraction (SAED). The influence of operational parameters such as irradiation time and catalyst dosage were evaluated. The influence of irradiation light on the degradation of chemical oxygen demand (COD) and total organic carbon (TOC) in tannery wastewater was found to be highest in 90 min, which follows a linear removal efficiency. It was evident that the photocatalytic degradation rate initially increases with catalyst loading and then decreases at high values. Almost complete decolourization was obtained upon 90 min of sunlight irradiation in the presence of kaolin/TiO₂ catalyst. The satisfactory stability in recyclability of photocatalyst indicates colour, COD and TOC abatement in tannery wastewater treatment. It is clear that photocatalysis has good potential to degrade organic pollutants. Thus, there is a need to determine the degradability performance on a commercial scale.

Freshwater scarcity is a global problem that pertains to the ever-increasing population, contamination of freshwater by wastewater generated from different anthropogenic sources as well as misuse of freshwater for secondary (non-potable) applications. Later two issues could be addressed through the appropriate implementation of Microbial Technology in an eco-friendly way. The application will involve proper selection of the wastewater sources (for microbial isolation), their pollutant identification, selection of tailor made bacterial consortium/ isolates for treatment of the wastewater and converting the waste into reusable by-product. This is the current trend used for pilot scale wastewater treatment using biofilm bioreactors. This article talks about the few successful case studies implemented for different types of wastewater treatment (municipal/Agricultural runoff, petrochemical, tannery/mining industry and milk processing plant wastewater) in biofilm reactors that could run for years after being installed in the pilot scale. The processes are faster, sludge free and, in most cases, ensure complete reuse of treated water, hence preventing wastage of freshwater for non-potable applications. Biofilm based system makes them resistant to external perturbation, stable with enhanced efficiency. Through this approach, eco-friendly processes of wastewater treatment could be made self-sustainable.

Today, water scarcity affects human activities and ecosystems in many countries worldwide, leading to emerging new technologies to supply water from unconventional resources or enhance the recycling and reuse of available wastewaters. While, these emerging technologies might have environmental impacts, which are big challenges for sustainable development. Analyzing environmental impacts can help find the best and most sustainable choices that have the least negative impacts on ecosystems, resources, and human health. Life Cycle Assessment (LCA) is a tool to analyze and assess the environmental impacts for sustainability studies. LCA is essential in policymaking for developing desalination projects, especially in restricted areas like the Persian Gulf. An LCA study involves a total inventory and impacts of the energy and materials required across the industry value chain of the product, process, or service. This chapter is discussed the sustainability concept and takes a look at the technologies used in industrial wastewater treatment and desalination from a sustainability point of view. The general contaminants of industrial wastewater and saline water are presented. In addition, the LCA concept, framework, approaches, and Life cycle Inventory (LCI) methodology are explained. Various impacts of conventional and emerging industrial wastewater treatment and desalination technologies are presented to compare the technologies. Furthermore, prospects and challenges are discussed as a summary for the water engineering community.

Emerging industrial and human activities are depleting water and other environmental resources due to the massive production of synthetic complexes. Compounds present in sewage are resistant to degradation and have various toxicological properties, which generate various environmental issues. Many conventional methods based on physical, chemical and biological principles are applied to treat sewage. Currently, a combination of different conventional methods is in practice for effective treatment. The photoelectrochemical technique is a combination of light and electrical energy used in the treatment of sewage. In this technique, different types of metals and semiconductor types of photocatalyst are utilized to treat sewage due to its stability, efficiency and remediation performance. In the modified photocatalytic reactor, solar or artificial energy is applied for the oxidation of hazardous compounds which generate hydrogen. The modified photocatalyst has been employed in recent times for efficient treatment and refining hydrogen production. Recently, diverse photocatalytic reactors are designed for a large-scale treatment perspective. Photoelectrochemical reactors have an eco-friendly approach and are less harmful to the environment. Thus, recently researchers are focusing more on this technique from a treatment perspective.

Water remains at the centre of human survival on the planet earth. Water availability and its consumption pattern in the world have drastically changed over the past few decades. The rising population and changes in the standard of living have put stress on the water bodies, and major countries around the globe are on the verge of facing serious water scarcity. Earth has an abundance of water but is not in usable form. It demands technologies that can provide fresh water for the people but must be economical, sustainable and less energy-intensive. Desalination is the solution, but the conventional techniques are energy-intensive processes and not eco-friendly. Solar energy has come out as a sustainable and greener energy source for carrying out desalination. Solar energy for desalination has been widely explored in recent times. Another major problem with developing countries is handling water-borne diseases, which lead to major health issues and fatalities. Solar energy comes to the rescue here, and its application for the disinfection of water will cater to the need for safe water, improving community health and providing a sustainable solution. The chapter presents a review on the application of solar energy in two broader domains of water treatment; (a) water desalination and (b) water disinfection. The chapter discusses the different types of solar integrated desalination technologies with their uniqueness and limitations. Recent developments for the most common desalination technologies of multi-stage flash (MSF), vapour compression (VC), multi-effect distillation (MED), and reverse osmosis (RO), and electro-dialysis (ED) are discussed. Solar energy-based technologies will prove to be an alternative to the current technologies in water treatment and disinfection, the price will remain the concern, but this will be overcome with the efforts and technological improvement in the field. Solar energy and its utilization in the water treatment process make its way as the potential solution for all safe and clean drinking water.

The water industry accounts for about 30–40% of the total energy demand of the municipalities worldwide. This may vary from one facility to another based on the source, water quality, water storage, distance from the source, elevation, facility's age, and type of treatment techniques employed. Water abstraction and distribution are the highest energy consumption units among conventional water treatment facilities. Advanced treatment technologies, especially desalination (membrane and thermal) and disinfection technologies (ozone and ultraviolet), are the most energy consuming processes over the conventional treatment technologies. Various energy optimization measures such as the use of gravity for water transfer and distribution (where possible), selection of most energy and treatment efficient technologies, upgrading the treatment system and equipment (especially pumps), renewable energy generation at the facility, water conservation and restoration or protection of the potable water sources etc. can be employed to minimize the energy demand of the water treatment facilities. Application of these measures is challenging due to lack of adequate knowledge by the operational staff, lack of public awareness, investment cost involved, changes in future water treatment regulation with a growing population, pollutant load in the potable water bodies, etc. The current chapter discusses the possible energy intensive factors of the drinking water facilities with possible energy optimization measures and their limitations.