Proceedings of the 5th International Symposium on Water Pollution and Treatment—ISWPT 2022, Bangkok, Thailand

The use of metal coagulants in water treatment generates huge amounts of sludge. Effective management to mitigate the challenges associated with the increasing amount of WTS remains a significant concern. This paper provides an overview of the beneficial reuses of water treatment sludge (WTS) as coagulant and adsorbent. Recent advancements in coagulant and adsorbent synthesizing techniques are discussed. Recovered coagulant (RC) and adsorbent have been successfully removed several pollutants in both water and wastewater, reducing the need for new coagulant production and disposal of sludge. Coagulant and adsorbent from sludge have potential to be utilized in both water and wastewater treatment processes and, hence promoting sustainability. Sulfuric acid is commonly used to recover contaminated coagulant. Calcination, activation, or impregnation have been studied in adsorbent production. Recovered coagulant/adsorbent could be as effective as or even better than fresh coagulants/adsorbent.

The pine sawdust biochar (BC) prepared by pyrolysis at 400 °C for 2 h was modified with different amounts of hydrochloric acid, among which 5H-BC modified by 5 mol·L⁻¹ hydrochloric acid had the best oil adsorption efficiency in seawater. Petroleum degrading bacteria (PDB) were immobilized on 5H-BC, and the optimum conditions for immobilization were: inoculating 10% (v/v) PDB suspension, and fixing for 4 h at the speed of 180 r·min⁻¹ on the shaking table. 5H-BC and 5H-BC-PDB were added to the simulated oil-polluted seawater. It was found that 5H-BC could quickly transfer the oil in seawater to BC phase through adsorption, but the total oil removal efficiency of 5H-BC-PDB was 23.5% higher than that of 5H-BC. High-throughput analysis of BC phase showed that 5H-BC-PDB contained more Acinetobacter and Pseudomonas, which indicated that BC immobilized with PDB was not only beneficial to the emulsification of oil, but also to the biodegradation of residual PAHs.

The objective of this work is to study the evolution of marls from the Tigzirt landslide, which represents one of the active and spectacular landslides that the Wilaya of Tizi-Ouzou (Algeria) has experienced in recent years; under the effect of environmental conditions and the quality of the percolating water (polluted and unpolluted water). The alteration of rocks subjected to chemical attacks or wet/dry cycles can have a negative impact on the stability of slopes. An experimental study composed of plasticity tests (Atterberg limits), shear tests and odometer tests and was carried out on materials having undergone wetting–drying cycles initially soaked in water containing nitrates and sulfates. The results of the shear tests showed a decrease in the mechanical characteristics of the marl in contact with water containing the salts compared to those of the marl only. The analyses of the odometer tests show that the salts tend to nullify the swelling pressure.

Danjiangkou Reservoir is the water source for the Middle Route of South-to-North Water Transfer Project, as well as an important drinking water source of Hubei Province. In 2021, Danjiangkou Reservoir has a good safety guarantee situation on the whole. However, there exists some problems such as imperfect water source protection and management mechanism, hidden danger of water quality and inadequate funding investment mechanism. In specific, the hidden dangers of water quality include imperfect isolation facilities, water resource management information system, environmental pollution prevention and control measures and difficult management of water-level fluctuation zone. In this paper, suggestions for water source safety guarantee construction of Danjiangkou Reservoir future are proposed: (1) improve the supervision and management mechanism and the protection and management mechanism of drinking water source, strictly enforce the daily management, supervision and inspection of the water source; (2) strengthen the supervision of water quality risks, carry out the construction of ecological isolation zones of water sources, improve the management system of water-level-fall zones and strengthen the construction of information systems and traffic protection facilities; (3) establish a long-term and stable fund guarantee mechanism, a sound investment and financing system, a special transfer payment mechanism for water source of the middle route of the South-to-North Water Diversion Project and a green development fund for Danjiangkou Reservoir water source area; (4) promote the construction of emergency standby water sources.

Water inrush has become a significant disaster in the karst tunnel construction. The University City tunnel crosses the Zhongliang Mountain where karst strata are well developed in the Chongqing city, southwest China. This study simulated the groundwater seepage field in the natural and construction conditions by visual Modflow software. Groundwater flows from north to south in natural condition. With the tunnel excavation face as the center, a falling funnel with a large influence range is formed, and the excavated tunnel becomes the local discharge datum. Then, the groundwater flow direction from north to south has changed to the tunnel as the center of the confluence, and the groundwater level in the anticlinal core area has further decreased. The volume of water inrush was estimated. The simulation results are similar to the actual tunnel water influx results obtained from the calculation. Our goal is aimed to simulate the changes in hydrogeological conditions after the tunnel construction and predict the amount of water surge in the tunnel. The achievements of our study would provide a vital reference for groundwater management and protection in the karst tunnel construction.

Antibiotics have been detected in natural environment in many regions of the world, and their potential disadvantageous influences on organisms in the environment have attracted widespread attention. The sewage treatment plants don’t completely take out antibiotics before tailwater release into the environment. The antibiotic contamination could promote the development of antibiotic resistance genes and drug resistant bacteria and bring irreversible damage to the natural ecosystem and human health. Because of the widespread use and discharge of antibiotics, lakes have become important repositories of antibiotics. With the rapid industrialization and urbanization of the Yangtze River Economic Belt, the Yangtze River basin has already become one of the regions with the maximum antibiotic emissions in China. This review briefly addresses the current situation of antibiotic contamination in the Yangtze River basin and typical lakes in the middle and lower reaches and evaluates the main types of pollution and ecological risks of antibiotics in typical lakes during the dry season.

Drinking water is indispensable among the most available resources of human beings. At present, there is the behavior of “development first, treatment later” for water sources, and there are many problems in the management of water quality, water quantity and carbon pollution prevention and control of drinking water sources. The drinking water source of Qiuci Reservoir is one of the most important centralized drinking water sources in Hezhou city. The carbon pollution problem of the water source source is related to the drinking water safety of Hezhou city residents and the sustainable development of the city. This paper takes the turtle stone reservoir water source as the main research object, by discusses the current situation of carbon pollution control, from the government management, enterprise participation and survival and development of the reservoir residents management department, talent construction, capital investment, and according to the corresponding countermeasures, to improve the local turtle stone reservoir drinking water source carbon pollution control management to provide some reference.

This paper provides a comprehensive analysis of greenhouse gas (GHG) emissions associated with a wastewater treatment plant in Jiaxing, China. The study calculated scope 1–3 GHG emissions for all stages of the wastewater treatment system. The study evaluated the sources of GHG emissions and identified opportunities for reducing emissions in the wastewater treatment plant. The results show that the carbon emissions of each stage vary based on the power consumption and the associated emission factors. The study recommends the use of renewable energy sources, energy-efficient technologies, and green supply chain management practices to reduce carbon emissions. The study highlights the significance of considering indirect emissions such as scope 2 and scope 3 emissions to provide a more comprehensive estimate of a facility’s carbon footprint. The findings align with previous studies that have emphasized the importance of reducing energy consumption and adopting sustainable practices to improve the sustainability of wastewater treatment plants.

Based on the water footprint theory, a regional water use evaluation index system was constructed to analyze the temporal change of water footprint in Shandong Province from 2011 to 2020, and the LMDI model was used to explore the degree of influence of the driving factors such as population, economy and technology on the change of water footprint. The results show that the total water footprint of Shandong Province first fluctuates and then decreases. The degree of dependence on water resources is high, and the economic benefit value of water footprint has increased significantly year by year. The water resource stress index and water resource load index are high, the water resources system in Shandong Province is overloaded, the development and utilization of water resources are high, and the potential for redevelopment and utilization is very small. Economic effects have a greater impact on the water footprint than technological effects, and technological effects are greater than population effects.

By combing the literature on water resources property rights and water rights confirmation, we summarize the experience and shortcomings in the construction of China's water rights system and put forward corresponding suggestions on China's agricultural water rights confirmation through the current situation, influencing factors and the experience of confirmation of rights in foreign countries with high efficiency in water use. Agricultural water rights should be confirmed according to the actual local situation, promote the policy of confirming agricultural water resources rights to households, strengthen the maintenance and renewal of old water conservancy facilities, improve the system of confirming and registering agricultural water rights, optimize the allocation of agricultural water rights, promote agricultural water conservation, and improve the efficiency of water resources utilization.

Lebanon is a country known for its abundance of water resources (natural and artificial). Numerous ports and tourist beaches exist along its coastline with the Mediterranean Sea. This positioning provides high resources, which are essential for the Lebanese economy. Solid wastes polluted almost all rivers and lakes for several reasons: Most of them are related to bad sewage systems, industrial wastes, and even from the Flora distributed along the rivers. Unfortunately, today, the Lebanese water pollution problem has become severe. Worse than the 2015 garbage crisis, which remains unsolved so far, Lebanese beaches are covered by solid wastes, besides that rivers and lakes are polluted with poisonous substances. It becomes urgent to find a solution for the accumulated solid wastes in the waterways and in the coastal regions. To maintain the environmental system, several researchers, around the world, designed and produced different machines to collect aquatic solid wastes, and to check their physical characteristics. Such machines are expensive referring to the bad economic crisis that occurred in Lebanon and the surrounding countries. The aim of this study is to produce a new vessel machine that has a navigation ability to reach the polluted zone in the waterways, collect the floating solid waste, and transport it to the shore to evacuate them. This new vessel still has the same quality and performance already existing in the international market, while reducing the cost of manufacturing, operation, and maintenance.

In order to resourcefully utilize the sludge generated every year, guarantee the backfilling quality of pipes and trenches of polluted water, and accelerate the construction progress, as well as reduce the cement usage amount to lower the engineering costs, the experiment was carried out to prepare the early strength sludge fluidized soil by replacing sulphoaluminate cement with slag in equal amount. Through exploring the influence of different sludge moisture contents and slag replacement rates on the fluidity and filling ability of fluidized soil, and analyzing the influence of different sludge moisture contents, slag replacement rates and periods on the compressive strength of fluidized dynamic soil, it is inferred that the fluidity of the fluidized soil increases linearly with the increase of the moisture content of sludge and remains basically unchanged with the changes of the slag replacement rate. The compressive strength decreases linearly with the increase of sludge moisture content and slag replacement rate, and increases with the increase of period. The filling rate of fluidized soil can reach over 97%, which can solve the backfilling quality problem of pipes and trenches of polluted water better.

Pharmaceutical wastewater is one of the most difficult industrial wastewaters to treat. The environmental protection department must supervise the enterprises to choose the appropriate wastewater treatment process and strengthen the management of wastewater treatment at the organizational and operational level. This paper designs the evaluation index system of sewage treatment supervision by consulting data, enterprise research, collecting expert opinions, and other work, and uses analytic hierarchy process (AHP) to calculate the weight of each index to fully reflect the value status of each index in the system. This paper first constructed a hierarchical structure model of the evaluation index system of pharmaceutical enterprises’ sewage treatment supervision, and then took China Medical City, a national pharmaceutical park in Taizhou, Jiangsu Province, as a case study. Experts and scholars who have participated in environmental protection work of the park for a long time as well as management personnel of HSE department are invited to conduct pair-wise comparison and score for the final weight calculation of indicators. From the weight results, it is found that input cost and pollutant reduction are the indicators with the highest weight. Therefore, in the future, the park needs to improve its pollution reduction ability on the basis of cost consideration.

The degradation of pharmaceutical with high concentrations of N,N-dimethylformamide (DMF) mainly includes chemical oxidation and physical adsorption. However, these methods have low efficiencies and high expensive. Hence, this study combined the high-temperature acid digestion, iron-carbon micro-electrolysis, and coagulation reaction, which was used to degrade the pharmaceutical wastewater with a high concentration of dimethylformamide. These results showed that the organic nitrogen of wastewater was mostly converted to ammonia nitrogen as the high-temperature acidolysis reaction. The ammonification rate of DMF wastewater increased with the increase of acidity and reaction time. The ammonification rate of DMF wastewater reached more than 80% as the high-temperature acidolysis reaction, the degradation rate of chemical oxygen demand (COD) reached 30%, and the removal rate of total nitrogen was 15%. After pretreatment, iron-carbon micro-electrolysis in combination with coagulation reaction further increased the COD degradation (about 25%). The removal rate increased with the increase of dosage. This method had a noticeable effect on the ammonification, COD degradation, and biochemical enhancement of high-concentration DMF pharmaceutical wastewater in pharmaceutical plants.

Yan’an is located in the loess hilly-gully area and belongs to a typical mountainous strip city with very scarce water resources. The current reclaimed water supply is less than 1.3% of the total urban water supply. There are three sewage treatment plants in the central city, the sewage collection pipeline network has been built for 238.16 km, and the reclaimed water pipeline is about 28 km. In the utilization of urban sewage water in Yan’an, there are problems such as imperfect sewage collection and reuse pipe network, unsmooth management system, unsound policy system, and insufficient funds. The sewage water utilization potential in Yan’an which predicted by index analysis is 44,900 m³/d in 2025 and 68,600 m³/d in 2030. Engineering countermeasures for the construction of sewage treatment facilities and pipe networks, with non-engineering countermeasures for the mechanisms, systems, funds, water prices, operation modes, professionals, propaganda, and demonstration are proposed, which has reference significance for similar cities to use sewage water.

Huangjinxia Reservoir is a crucial source project in the Hanjiwei River diversion project. After the completion and operation of the reservoir, the water level reaches of the reservoir will rise, change the original water flow structure, greatly increase the submerged area of the original basin, and reduce the self-purification capacity of the water body. Under the existing pollution load conditions, the MIKE21 model is used to predict and calculate the concentrations of chemical oxygen demand, total phosphorus, and total nitrogen in the water body of the reservoir. The calculation results show that after the construction of Huangjinxia Reservoir, the concentrations of chemical oxygen demand and total nitrogen in the river reach the Class III water quality target requirements of the state, and the concentration of total phosphorus reaches the Class II water quality target requirements of the state. The overall water quality in the region is good. The possibility of water eutrophication is not high in the initial stage of reservoir construction and operation. However, due to the complex topography of some river channels (Jinshui River, Youshui River, etc.) and reservoir bay, poor water quality, poor water exchange performance, and the phenomenon of stem and leaf loss and death of flooded plants, the concentration of pollutants in some areas exceeds the standard. The long-term retention of pollutants does not rule out the possibility of water eutrophication. The water quality can be purified, and local water eutrophication can be controlled through rational use of the corresponding aquatic biological control technology.

The residual circulation in the Bouregreg Estuary (Morocco) was modeled using a simple model to reduce degrees of freedom and modeling effort. The Moroccan Estuary’s residual circulation profile has never been studied to our knowledge. Direct current measurements were used to determine residual currents using Hansen and Rattray’s analytical solution. According to MacCreary and Geyer, Reynolds-averaged equations in hydrostatic form and Boussinesq approximations are used to determine water salinity and momentum along channels. Besides momentum advection and Coriolis forces, only gradients along the channel were considered. An analytical solution combining Hansen and Rattray’s classical theory with Geyer and MacCready’s analysis of residual flow was used to model a fixed station in a river using residue flow, temperature, and salinity flow. The residual flow of Bouregreg Estuary was well described by a simplified model approach that was in agreement with observed data. Observation data was used to calibrate Hansen and Rattray flows. The residual circulation model can be used to predict chemical pollution in estuaries.

Rural revitalization is the only way for Chinese dream of great national renewal, good living environment and perfect infrastructure are the material basis for rural revitalization, and rural sewage treatment is one of the key points to improve rural human settlements. This paper takes the rural sewage treatment of Xiuzhou District as an example summarizes the problems in the process of rural domestic sewage treatment, such as the difficulty of centralized collection, the instability of water quantity, the difficulty in terminal treatment caused by rain and sewage confluence, and the poor operation and maintenance. From the rural domestic sewage treatment in Xiuzhou District to the problems existing in the national rural domestic sewage treatment, puts forward some thoughts and optimization suggestions on rural domestic sewage treatment in the future from the aspects of planning, design, operation and maintenance, monitoring, etc., with a view to playing a certain reference role in the planning and design of rural sewage treatment in the future.

The green development of reservoirs is a long-term, dynamic and systematic project, an important measure to build rivers and lakes that benefit people’s happiness. In order to understand the water pollution situation in rural areas of China. In this paper, the safety problems of reservoirs in rural areas of Youyang are studied and analyzed. The water quality of reservoirs is measured according to the national ‘surface water environmental quality standard’. The Xiaoba secondary reservoir safety evaluation in Youyang County uses a single-factor evaluation method. The evaluation results show that the comprehensive qualitative evaluation index of the water quality of Xiaoba secondary reservoir in Youyang County is P_j = 0.37, and the water quality grade is excellent. Based on the evaluation results, the corresponding protection measures for the water quality of Youyang County reservoir are put forward, which provides a new idea for the standardized construction of the comprehensive management system for the safe operation of Youyang County reservoir.

River and lake water environment governance and enhancement have become the focus of high-quality development. The premise of accurate pollution control is to precisely trace the source. Targeting the outstanding problems of rivers, implementing “one river, one policy,” strengthening supervision and management, and enhancing the pertinence and operability are the important tasks that need to be solved at this stage of river water environment improvement and remediation. The Zhoucheng River is located in the third-tier protection zone of the Taihu Lake Basin, and its water environmental protection is the focus of its renovation. In order to systematically carry out the Zhoucheng River water environment renovation to meet the standards, the Zhoucheng River water environment pollution comprehensive traceability, classifying and establishing a long-term mechanism as the main task, based on the investigation and analysis of the current state of the water environment quality to clarify the Zhoucheng River pollution status and causes, and further propose water quality management measures to meet the standards in a targeted manner. Through comprehensive evaluation of water quality, identification of main pollution factors and evaluation of main water quality indexes, etc., know that the water quality of the main stream of Zhoucheng River gradually deteriorates from upstream to downstream, and its main pollution factor is ammonia nitrogen, followed by total phosphorus and finally permanganate index. Besides, the main polluted section of the main stream of Zhoucheng River is located in the upstream section and the middle and downstream (Zhoucheng Settlement section).