跨行政区域水污染纠纷的对策探讨——剖析某水域水污染死鱼事故

针对某乡镇企业十分发达地区的跨行政(市县)区域水污染死鱼事故的剖析，本文提出了处理解决跨行政区域水污染纠纷事故的若干对策建议。     

Physicochemical aspects of using natural scavengers in removing methylene blue (basic dye) from solution

Effluent from dyeing and finishing processes is an important source of water pollution. The effectiveness of bentonite, kaolinite and sediment from a local deposit in removing methylene blue as a cationic dye from aqueous solutions has been investigated. The adsorption equilibrium (isotherm) has been determined according to Freundlich and Langmuir equations. The optimum amount is 0.5 g for all adsorbents, and the optimum pH ranges are 2-8 for bentonite and 2-6 for kaolinite and sediment. With respect to kinetic modelling, the adsorption of methylene blue on various adsorbents was fitted to a second-order equation. Also, the thermodynamic parameters were determined. The negative free energy values indicate the feasibility of the process and spontaneous nature of adsorption. The positive ΔH° values indicate the endothermic nature of the process. Thus, Egyptian clay minerals and sediments have a great tendency to remove the dye from solutions.     

南水北调的资源、环境和社会效应

建设南水北调工程，对中国的水资源在地区间进行合理调配，将带动其他资源的合理配置与利用，还可改善环境，是社会发展的需要，又受社会条件制约，一旦突破建成，将促使社会生产力发生新的飞跃并持续发展。     

Towards a smallholder hydrology for equitable and sustainable water management

Situations of water scarcity challenge sustainability and threaten small users' access to water. In response to this problem, there has been a search for a method of hydrological analysis that can better represent the needs of small water users. While this search is rooted in the debate favouring a more participatory and inclusive allocation of the resource, it also requires a new focus on smallholder hydrology that can confront the gaps and biases found in current hydrological practices in many countries. This article looks at past hydrological practices and also at results of recent studies, highlighting the perspective of smallholder irrigators in surface water planning in Zimbabwe, and groundwater planning in India. These case studies show that wider social forces, not always best science, drive hydrological practices. However, new frameworks focusing on the water user can emerge for more equitable and sustainable water management.     

Body fluid analog chlorination: Application to the determination of disinfection byproduct formation kinetics in swimming pool water

Disinfection by-products(DBPs) are formed in swimming pools by the reactions of bather inputs with the disinfectant.Although a wide range of molecules has been identified within DBPs,only few kinetic rates have been reported.This study investigates the kinetics of chlorine consumption,chloroform formation and dichloroacetonitrile formation caused by human releases.Since the flux and main components of human inputs have been determined and formalized through Body Fluid Analogs(BFAs),it is possible to model the DBPs formation kinetics by studying a limited number of precursor molecules.For each parameter the individual contributions of BFA components have been quantified and kinetic rates have been determined,based on reaction mechanisms proposed in the literature.With a molar consumption of 4 mol Cl_2/mol,urea is confirmed as the major chlorine consumer in the BFA because of its high concentration in human releases.The higher reactivity of ammonia is however highlighted.Citric acid is responsible for most of the chloroform produced during BFA chlorination.Chloroform formation is relatively slow with a limiting rate constant determined at 5.50 × 10~(-3) L/mol/sec.L-histidine is the only precursor for dichloroacetonitrile in the BFA.This DBP is rapidly formed and its degradation by hydrolysis and by reaction with hypochlorite shortens its lifetime in the basin.Reaction rates of dichloroacetonitrile formation by L-histidine chlorination have been established based on the latest chlorination mechanisms proposed.Moreover,this study shows that the reactivity toward chlorine differs whether L-histidine is isolated or mixed with BFA components.     

Bioassay: A useful tool for evaluating reclaimed water safety

Wastewater reclamation and reuse has been proved to be an effective way to relieve the fresh water crisis. However, toxic contaminants remaining in reclaimed water could lead to potential risk for reuse, and the conventional water quality standards have difficulty guaranteeing the safety of reclaimed water. Bioassays can vividly reflect the integrated biological effects of multiple toxic substances in water as a whole, and could be a powerful tool for evaluating the safety of reclaimed water. Therefore, in this study, the advantages and disadvantages of using bioassays for evaluating the safety of reclaimed water were compared with those of conventional water quality standards. Although bioassays have been widely used to describe the toxic effects of reclaimed water and treatment efficiency of reclamation techniques, a single bioassay cannot reflect the complex toxicity of reclaimed water, and a battery of bioassays involving multiple biological effects or in vitro tests with specific toxicity mechanisms would be recommended. Furthermore, in order to evaluate the safety of reclaimed water based on bioassay results, various methods including potential toxicology, the toxicity unit classification system, and a potential eco-toxic effects probe are summarized as well. Especially, some integrated ranking methods based on a bioassay battery involving multiple toxicity effects are recommended as useful tools for evaluating the safety of reclaimed water, which will benefit the promotion and guarantee the rapid development of the reclamation and reuse of wastewater.     

Revealing the changes of bacterial community from water source to consumers tap: A full-scale investigation in eastern city of China

This study profiled the bacterial community variations of water from four water treatment systems, including coagulation, sedimentation, sand filtration, ozonation-biological activated carbon filtration (O₃-BAC), disinfection, and the tap water after the distribution process in eastern China. The results showed that different water treatment processes affected the bacterial community structure in different ways. The traditional treatment processes, including coagulation, sedimentation and sand filtration, reduced the total bacterial count, while they had little effect on the bacterial community structure in the treated water (before disinfection). Compared to the traditional treatment process, O₃-BAC reduced the relative abundance of Sphingomonas in the finished water. In addition, ozonation may play a role in reducing the relative abundance of Mycobacterium. NaClO and ClO₂ had different effects on the bacterial community in the finished water. The relative abundance of some bacteria (e.g. Flavobacterium, Phreatobacter and Porphyrobacter) increased in the finished water after ClO₂ disinfection. The relative abundance of Mycobacterium and Legionella, which have been widely reported as waterborne opportunistic pathogens, increased after NaClO disinfection. In addition, some microorganisms proliferated and grew in the distribution system, which could lead to turbidity increases in the tap water. Compared to those in the finished water, the relative abundance of Sphingomonas, Hyphomicrobium, Phreatobacter, Rheinheimera, Pseudomonas and Acinetobacter increased in the tap water disinfected with NaClO, while the relative abundance of Mycobacterium increased in the tap water disinfected with ClO₂. Overall, this study provided the detailed variation in the bacterial community in the drinking water system.     

An investigation of changes in water quality throughout the drinking water production/distribution chain using toxicological and fluorescence analyses

Changes in water quality from source water to finished water and tap water at two conventional drinking water treatment plants(DWTPs) were monitored.Beside the routine water quality testing,Caenorhabditis elegans-based toxicity assays and the fluorescence excitation–emission matrices technique were also applied.Both DWTPs supplied drinking water that met government standards.Under current test conditions,both the investigated finished water and tap water samples exhibited stronger lethal,genotoxic and reprotoxic potential than the relative source water sample,and the tap water sample was more lethal but tended to be less genotoxic than the corresponding finished water sample.Meanwhile,the nearly complete removal of tryptophan-like substances and newly generated tyrosine-like substances were observed after the treatment of drinking water,and humic-like substances were identified in the tap water.Based on these findings,toxic pollutants,including genotoxic/reproductive toxicants,are produced in the drinking water treatment and/or distribution processes.Moreover,further studies are needed to clarify the potentially important roles of tyrosine-like and humic-like substances in mediating drinking water toxicity and to identify the potential sources of these contaminants.Additionally,tryptophan-like fluorescence may be adopted as a useful parameter to monitor the treatment performance of DWTPs.Our observations provided insights into the importance of utilizing biotoxicity assays and fluorescence spectroscopy as tools to complement the routine evaluation of drinking water.     

Preparation of solar-enhanced AlZnO@carbon nano-substrates for remediation of textile wastewaters

Photoactive aluminum doped ZnO(AlZnO) was synthesized by sol-gel method.After that,AlZnO photocatalyst was deposited on five carbon-based materials(CBMs) using ultrasonic route followed by solid-state mixing using ball mill.The CBMs used were poly aniline(PANI),carbon nitride(CN),carbon nanotubes(CNT),graphene(G),and carbon nanofibers(CNF).The crystal phases,elemental compositions,morphological,and optical properties of the AlZnO@CBMs composites were investigated.Experimental results revealed that two of AlZnO@CBMs composites exhibited superior bleaching efficiency(100% removal) and photocatalytic stability(three cycles) for 50 μmol/L Methylene Blue(MB) contaminated water after 60 min irradiation in visible light at pH 6.5,0.7% H_2O_2,and 5 g/L inorganic salts.Under optimum conditions,AlZnO@CBMs nanocomposites were employed for the treatment of mixed dyestuffs composed of MB,Methyl Orange(MO),Astrazone Blue FRR(BB 69),and Rhodamine B(RhB) dyes under dark,ultraviolet,visible,and direct sunlight.For mixed dyestuffs,the AlZnO@G achieved the highest dye sorption capacity(60.91 μmol dye stuffs/g) with kinetic rate 8.22 × 10~(-3) min~(-1) in 90 min via multi-layer physisorption(Freundlich isotherm) on graphene sheet.In additions,AlZnO@CN offered the highest photo-kinetic rate(K_(photo)) of～54.1 × 10~(-3) min~(-1)(93.8% after 60 min) under direct sunlight.Furthermore,the selective radical trapping experiment confirmed that the holes and oxidative superoxide radicals are crucial on dyes photodegradation pathway.Owing to their superior performance,AlZnO@G and AlZnO@CN nanocomposites can offer an effective in-situ solar-assisted adsorption/photocatalytic remediation of textile wastewater effluents.     

On-going nitrification in chloraminated drinking water distribution system (DWDS) is conditioned by hydraulics and disinfection strategies

Within the drinking water distribution system (DWDS) using chloramine as disinfectant, nitrification caused by nitrifying bacteria is increasingly becoming a concern as it poses a great challenge for maintaining water quality. To investigate efficient control strategies, operational conditions including hydraulic regimes and disinfectant scenarios were controlled within a flow cell experimental facility. Two test phases were conducted to investigate the effects on the extent of nitrification of three flow rates (Q = 2, 6, and 10 L/min) and four disinfection scenarios (total Cl₂=1 mg/L, Cl₂/NH₃-N=3:1; total Cl₂=1 mg/L, Cl₂/NH₃-N=5:1; total Cl₂=5 mg/L, Cl₂/NH₃-N=3:1; and total Cl₂=5 mg/L, Cl₂/NH₃-N=5:1). Physico-chemical parameters and nitrification indicators were monitored during the tests. The characteristics of biofilm extracellular polymetric substance (EPS) were evaluated after the experiment. The main results from the study indicate that nitrification is affected by hydraulic conditions and the process tends to be severe when the fluid flow transforms from laminar to turbulent (2300<Re<4000). Increasing disinfectant concentration and optimizing Cl₂/NH₃-N mass ratio were found to inhibit nitrification to some extend when the system was running at turbulent condition (Q = 10 L/min, Re = 5535). EPS extracted from biofilm that was established at the flow rate of 6 L/min had greater carbohydrate/protein ratio. Furthermore, several nitrification indicators were evaluated for their prediction efficiency and the results suggest that the change of nitrite, together with total organic carbon (TOC) and turbidity can indicate nitrification potential efficiently.