The role of biofilms in water reclamation and reuse.

Biofilms play a major role in many water reclamation and reuse technologies. Normally, wherever there is water, a support surface and nutrients available, a biofilm will form. In some cases, this may result in problems for the water treatment system, due to biofouling or the growth of pathogenic or other unwanted microbes, but more frequently, the biofilm serves a very useful purpose by biodegrading organic contaminants in the water or by converting unwanted inorganic materials into harmless ones. Biofilms are commonly found associated with membrane reactors and filtration systems used in water reclamation and reuse systems, and are often a critical component. They are also found in soils where they may impact water injection or removal systems, or in situ bioremediation. Knowledge of the way biofilms form, how they grow and how to control them is critical for effective design and operation of many water reclamation facilities. This paper explores the modes of formation and growth of biofilms, modern methods for exploring the structure and function of biofilms, and how to control their growth. This paper also presents details on our development of microelectrode sensor arrays for continuous soil pore water quality monitoring.     

Pharmaceutical rejection by membranes for wastewater reclamation and reuse.

Various membranes, which have different materials and nominal molecular weight cut-offs (MWCO), were compared in terms of rejection of ibuprofen and removal of effluent organic matter (EfOM) from membrane bioreactor (MBR), because pharmaceutical compounds contain a potential risk and EfOM is the precursor of carcinogenic disinfection by-products when reusing for drinking water source. To provide equivalent comparison with respect to hydrodynamic condition, mass transfer parameter, J0/k ratio, was used. A tight-UF membrane with a molecular weight cut off of 8,000 daltons exhibited 25 approximately 95% removal efficiencies of ibuprofen with a molecular weight of 206 with and without presence of EfOM(MBR). EfOM(MBR) caused the reduction of ibuprofen removal efficiency for UF membrane. Rejection of EfOM(MBR) by UF and NF membranes ranged 29 approximately 47% and 69 approximately 86%, respectively. UF membrane could successfully remove ibuprofen at lower J0/k ratio range (< or = 1) in organic free water but could not efficiently reject ibuprofen with a relatively hydrophilic EfOM(MBR) (SUVA < or = 3).     

Helminth eggs removal by microscreening for water reclamation and reuse.

Irrigation with reclaimed water is becoming a practical alternative to conventional irrigation in semi-arid areas of the Mediterranean like Spain, but it requires a reliable treatment process to provide a safe water supply. Helminth eggs are one of the main concerns for the safe use of reclaimed water, as they can survive adverse environmental conditions and they are highly infective. Spanish water quality criteria and International guidelines set a limit of 0.1 eggs/l for water uses with unrestricted human exposure. Two microscreening processes have been tested to determine their potential for helminth eggs removal, after a conventional physic-chemical reclamation process. Hydrotech Drum and Discfilters, provided with 10 microm pore size filter cloth, were tested to determine their efficiency for helminth eggs straining. An experimental test was conducted using 20 microm spherical latex particles, as surrogates for helminth eggs, to test the removal efficiency of a small full-scale drumfilter. In a subsequent laboratory test, actual Trichuris suis eggs were strained using a 10 microm pore size filter cloth from a discfilter. Results from both tests indicate that drum and discfilters are able to achieve 99% removal efficiency for spherical latex particles and a complete removal for helminth eggs in reclaimed water.     

The water reclamation and reuse project of El Prat de Llobregat, Barcelona, Spain.

Water reclamation and reuse have become essential components of water resources management in the Metropolitan Area of Barcelona, by helping to develop additional water resources in the lower Llobregat River, one of its main sources of water supply. By generating a reliable flow of 300,000 m3/day of high quality reclaimed water, the options available for integrated water resources management have widely expanded to allow in-stream river water substitution, restoration of natural wetland areas, agricultural irrigation, and supply to a seawater intrusion barrier. Those management options have been possible thanks to the implementation of an extensive water distribution system that allows distribution of reclaimed water to a point 15 km upstream of the reclamation facility, and to a seawater intrusion barrier within a few kilometres of the plant. The cost of producing reclaimed water using a physico-chemical process (0.05 euro/m3) and the investment required for such a facility (0.21 euro/m3 annual capacity) are very close to those of similar large scale projects in Spain. However, higher degrees of treatment, such as demineralization for agricultural irrigation and for injection into a seawater intrusion barrier, result in considerable increases of both water reclamation cost and investment costs.     

Water reuse for urban landscape irrigation: aspersion and health related regulations.

The Mediterranean seaside resort of Le Grau du Roi includes 40 hectares of landscaped areas spray irrigated with river water supplied through a separate network. Wastewater collected from several municipalities is treated in an activated sludge wastewater treatment plant (WWTP) and polished in waste stabilization ponds (WSPs). Planned substitution of treated wastewater for river water is hindered by spray irrigation prohibition within a 100 m distance from houses and recreational areas. WWTP and WSP effluents were monitored for pathogens with a particular attention to Legionella in Spring and Summer 2006. Helminth eggs, salmonellae and enteroviruses were never detected neither in WWTP effluent nor in the ponds. Legionella spp content was slightly higher or of the order of magnitude of river water contents. Regarding Legionella pneumophila contents, WSP effluent did not significantly differ from the river water. E.coli and enterococci contents in WSP effluents complied with the "excellent quality" criteria of the European Directive for coastal bathing waters. Therefore, substituting WSP effluents to river water is unlikely to alter health risks related to spray irrigation and, in this case, the buffer zone required by the French water reuse guidelines appears being short of support.     

城市污水再生利用的定位与发展方向

1 城市污水再生利用的定位 城市污水再生利用是一个高度复杂的系统工程,涉及政策导向、目标定位、用水途径、水质要求、技术选择、安全保障、经济效益、公众宣传、价格差异、付费原则等多个层面.     

《水回用导则再生水厂水质管理》国家标准解读

面对再生水厂运营管理和水质保障需求,为适应再生水标准化工作需要,国家市场监督管理总局和国家标准化管理委员会于2021年首次发布了《水回用导则再生水厂水质管理》国家标准.该标准是《水回用导则》系列国家标准之一.针对目前再生水厂的水质管理缺乏统一标准,全流程水质风险识别与过程管控不健全等问题,该标准规定了再生水厂水质管理的...     

An integrated wastewater reuse concept combining natural reclamation techniques, membrane filtration and metal oxide adsorption.

In a Sino-German research project, a sustainable water reclamation concept was developed for different applications of municipal water reuse at the Olympic Green 2008 in Beijing, China. Results from pilot-scale experiments in Beijing and Berlin show that selective nutrient removal by adsorption onto granular ferric hydroxide (GFH) after a membrane bioreactor (MBR) can maintain a total phosphorus concentration of <0.03 microg L(-1) P, thus preventing eutrophication of artificial lakes. Operation time of GFH adsorption columns can be extended by regeneration using sodium hydroxide solution. A subsequent ultrafiltration (UF) membrane after bank filtration creates an additional barrier for pathogens and allows for further urban reuse applications such as toilet flushing. Short term bank / bio-filtration prior to UF is shown to effectively remove biopolymers and reduce membrane fouling.     

The role of physical-chemical treatment in wastewater reclamation and reuse

Amid the heightened public health concerns for emerging microorganisms such as cryptosporidium and enteropathogenic E. coli in the water environment, there have been many instances where optimization of chemical coagulation-flocculation processes and filtration of wastewater was not achieved in practice, resulting in waste of coagulant chemicals and breach of the multiple barriers to pathogen removal and inactivation; thus, unnecessarily endangering public health. In addition, lack of information on the optimization of these processes has hampered the establishment of alternative and more cost-effective wastewater reclamation methods for tertiary and advanced wastewater treatment.Thus, the purpose of this paper is to evaluate the basic factors affecting the optimization of chemical coagulation-flocculation and filtration processes in municipal wastewater reclamation and reuse, based on the theoretical developments and practical applications. Reference is also made to the wastewater treatment processes and operations that can produce reclaimed water with an extremely small probability of enteric virus contamination.     

《水回用导则污水再生处理技术与工艺评价方法》国家标准解读

面对污水再生处理技术与工艺应用评价需求,为满足标准化工作需要,国家市场监督管理总局和国家标准化管理委员会于2021年首次发布了《水回用导则污水再生处理技术与工艺评价方法》国家标准.该标准针对目前污水再生处理技术与工艺评价存在的评价指标体系不健全、评价方法不统一、与不同水源水质和再生水水质要求之间的关系不清晰等突出问题,...     

Aspects of municipal wastewater reclamation and reuse for future water resource shortages in Taiwan.

The Water Resources Agency (WRA), Ministry of Economic Affairs (MOEA) has predicted that the annual water demand in Taiwan will reach approximately 20 billion m3 by 2021. However, the present water supply is only 18 billion m3 per year. This means that an additional 2 billion m3 have to be developed in the next 17 years. The reuse of treated wastewater effluent from municipal wastewater treatment plants could be one target for the development of new water resources. The responsible government departments already have plans to construct public sewerage systems in order to improve the quality of life of the populace and protect the environment. The treated wastewater effluent from such municipal wastewater treatment plants could be a very stable and readily available secondary type of water resource, different from the traditional types of water resources. The major areas where reclaimed municipal wastewater can be used to replace traditional fresh water resources include agricultural and landscape irrigation, street cleaning, toilet flushing, secondary industrial reuse and environmental uses. However, necessary wastewater reclamation and reuse systems have not yet been established. The requirements for their establishment include water reuse guidelines and criteria, the elimination of health risks ensuring safe use, the determination of the wastewater treatment level appropriate for the reuse category, as well as the development and application of management systems reuse. An integrated system for water reuse would be of great benefit to us all by providing more efficient ways to utilise the water resources.     

Performance of a combined eco-system of ponds and constructed wetlands for wastewater reclamation and reuse.

An on-site study on the operational performance of a combined eco-system of ponds and SF constructed wetland for municipal wastewater treatment and reclamation/reuse in Donging City, Shandong, China was carried out from January 2001 through October 2003. The removal efficiencies for various main parameters were: TSS 84.8 +/- 7.3%, BOD5 87.2 +/- 5.3%, CODCr 70.2 +/- 18.6%, TP 52.3 +/- 23.1%, and NH(3)-N 54.8 +/- 23.9% with effluent concentration of TSS 9.12 +/- 5.12 mg/l, BOD5 6.44 +/- 4.58 mg/l, CODCr, 42.8 +/- 6.7 mg/l, TP 0.94 +/- 0.27 mg/l and NH(3)-N 7.95 +/- 2.36 mg/l. In addition, the removal efficiencies for faecal coliforms and total bacteria were > 99.97% and > 99.998% respectively, which well meet Chinese National standards for effluent quality of municipal wastewater treatment plants. The composition of TSS was closely related to CODCr and BOD5 variations, and nitrification-denitrification is the major mechanism of nitrogen removal both in ponds and in wetlands. In addition, sedimentation also played an important role in the removal of TSS, nitrogen, phosphorus and BOD5. The removal efficiencies of various parameters, the number of species and biomass of biological community in the system increased gradually with the ecological maturation.     

城市公共用水的节水和污水再生利用潜力分析

城市公共用水的管理与需求控制是城市水资源可持续利用的必然要求.基于终端用水分析原理,建立了公共用水部门节水与污水再生利用综合评估模型(MWUM模型).在此基础上,以北京市为例,分析了其公共用水潜力的结构、技术与经济特征.北京市公共各行业用水结构基本保持稳定,机关用水所占比重较大;节水率较大的宾馆和院校的单位节水成本最小,是城市公共节水的重点领域;污水再生利用的单位成本与节水成本具有可比性,节水与再生水利用应统筹考虑.     

对《污水再生利用工程设计规范》中氨氮指标的建议

通过对城市污水处理厂二级出水回用于电厂循环冷却补充水的氨氮指标分析以及与其他相关排放标准的比较,考虑到工业循环水系统冷却塔的处理效果,建议调整《污水再生利用工程设计规范》(GB50335—2002)中的氨氮指标值,以便使污水处理厂出水可作为电厂的循环冷却补充水,实现在满足电厂使用需要的前提下降低工程综合成本的目的。     

Characterization of bacterial biofilm communities in tertiary treatment processes for wastewater reclamation and reuse

The concern with wastewater reuse as a sustainable water resource in urban areas has been growing. For the reclamation and distribution of wastewater, biofilm development deserves careful attention from the point of view of its promotion (e.g. biofiltration) and inhibition (e.g. clogging and hygiene problems). As the first step to control biofilm development, bacterial biofilm communities in tertiary treatment processes were characterized by using molecular biological methods. The result of clone library analysis showed that Nitrospirae-related (nitrite-oxydizing bacteria) and Acidobacteria-related (probably oligotrophic bacteria) groups were dominant. The ratio of the Nitrospirae-related group to the Acidobacteria-related group was associated with ammonia load, whereas other operational conditions (process, media, temperature, salt) did not clearly affect the phylum-level community or the dominant sequence of nitrifying bacteria. The result of real-time PCR also indicated that high ammonia load promotes the proliferation of nitrite- and ammonia-oxidizing bacteria. Regarding water supply systems, some researchers also have suggested the dominance of Nitrospirae- and Acidobacteria-related groups in biofilm formed on water distribution pipes. In tertiary wastewater treatment, therefore, it is concluded that oligotrophic and autotrophic bacteria are the dominant groups in biofilm samples because assimilable organic carbon is too poor to proliferate various heterotrophic bacteria.     

污水再生利用工程运行状况评价指标体系的构建与应用

构建污水再生利用工程评价指标体系并对其运行状况进行综合评价。根据集中式和分散式污水再生利用工程的不同特征,在分析其主要影响因素的基础上,分别构建了由水量、水质、技术、经济、管理5个方面量度,13个单项指标组成的污水再生利用工程运行状况评价指标体系,采用BP神经网络综合评价法,选取西安市现有集中与分散式污水再生利用典型工程分别进行评价。评价结果与污水再生利用工程实际状况吻合,表明所构建的评价指标体系合理可行,能为污水再生利用系统的规划和管理提供有效依据。     

武钢中水回用处理工程

武钢中水回用处理工程处理规模19.2万m3/d,工艺流程为:调节池-前混合反应池-高密度沉淀池-后混合反应池-V型滤池-接触池-清水池.总结整理了调试、运行中出现的问题和解决方法,实际运行结果表明,出水水质指标均优于设计值.     

Centralised urban wastewater reuse: what is the public attitude?

Public support is crucial for successful implementation of wastewater reuse projects. This paper analyses the findings of a questionnaire-type survey (256 participants) conducted to determine the attitude of Israeli urban public towards possible urban reuse options. The paper summarises the support/objection to 13 reuse options and the correlation between support and environmental awareness and perceptions. Results show that a high proportion of the participants supported options perceived as low-contact, such as irrigation of public parks (96%), sidewalk landscaping (95%) and use in the construction industry (94%), while higher-contact reuse options found less support (e.g. commercial launderettes, 60%). No correlation was found between biographical characteristics and support (education, gender, income, age). Based on the results, public campaigns in Israel should focus on disseminating information regarding wastewater treatment technologies, discuss health related issues, highlight the positive economic impact of water reuse and generate a positive public opinion, as these factors tend to influence individuals to support reuse projects.     

Water policy in Spain: seeking a balance between transfers,desalination and wastewater reuse

Decision-making in water resources management is a perennial source of political debate. When a basin suffers from a structural water shortage the possible solutions are either a transfer from another basin or the use of other unconventional resources such as those obtained through desalination or water reuse. Politics and territorial interests have given rise to undesired fluctuations in Spain’s water policy, in particular with regard to transferring water from one basin to another. However, conflicts have not prevented water management in Spain from being one of the most advanced in the world, even with its unfavourable geographical context.     

Feasibility of a constructed wetland and wastewater stabilisation pond system as a sewage reclamation system for agricultural reuse in a decentralised rural area.

The performance of a constructed wetland (CW) and wastewater stabilisation pond (WSP) system for sewage reclamation and paddy rice irrigation in a decentralised rural area was examined using a feasibility study. The CW was satisfactory for sewage treatment, with good removal efficiency even in the winter period, but the effluent concentration was relatively high in the winter period owing to the high influent concentration. The CW effluent was further treated in a WSP and the WSP effluent was considered safe for crop irrigation with respect to sewage-borne pathogens. Reclaimed water irrigation did not adversely affect the yield of rice; on the contrary, it resulted in an approximately 50% greater yield than in controls. The chemical characteristics of the soil did not change significantly during the experimental period of irrigation with reclaimed water. In the winter, CW effluent could be stored and treated in a WSP until the spring; the water could then be discharged or reused for supplemental irrigation during the typical Korean spring drought. Overall, sewage treatment and agronomic reuse using a CW-WSP system could be a practical integrated sewage management measure for protecting receiving water bodies and overcoming water shortages in decentralised rural areas.