随机分析方法在污水回用风险评价中的应用

随着城市污水回用工程增多,再生回用水的安全性问题日益受到人们的重视,回用水中病原微生物对人体的健康风险是焦点问题之一.对再生水回用造成的人体健康风险评价方法进行了讨论,通过实例介绍了随机分析方法在健康风险评价中的应用.     

基于健康风险评价的饮用水水质安全管理

水质安全是饮用水安全的重中之重，直接关系到人体健康。健康风险评价将环境污染物与人体健康效应联系起来．以致癌风险和危害指数分别反映污染物对人体的致癌危害和非致癌慢性毒害作用的程度，定量评价饮用水水质对人体健康的影响，为饮用水水质安全管理提供更深入的科学依据。依据健康风险评价的结果，能够更加科学合理地指导水源地管理、饮用水处理技术的选择以及水质的分级风险控制。     

南宁市主要饮用水源地水环境健康风险分析

为了解南宁市主要饮用水源水环境质量,分析其对人体健康产生风险水平,对2008—2012年南宁市饮用水源水环境质量进行了分析,并采用美国国家环境保护局(USEPA)推荐的健康风险模型对其所引起的健康风险做了初步评价。结果表明,南宁市主要水源地各污染物环境健康风险水平大小顺序为砷氟化物硝酸盐氨氮铁锰,化学致癌物引起的健康风险水平比非致癌物所致的健康风险水平高4个数量级。水源地水环境健康风险水平主要取决于致癌物质健康风险水平。2008—2012年邕江水源地致癌物质总风险水平较高,空间变化不明显,年际变化呈逐年下降趋势。南宁市主要水源地水环境健康风险水平应受到足够的重视,化学致癌物砷应当作为邕江水源地饮用水源需优先治理的污染物,必须在人们饮用之前将其去除,降低环境健康风险。     

城市再生水利用风险评价指标体系初探

水的再生利用是破解我国水资源短缺问题的重要途径之一,但是再生水利用对人体健康和环境的影响也是生活污水处理必须面对的挑战,从而受到人们普遍关注。根据我国再生水回用途径和天津市纪庄子再生水厂的出水水质情况,构建了再生水利用风险评价指标体系(包括健康风险指标和生态环境风险指标),并对纪庄子再生水厂的出水与景观用水和地表水分别进行了风险评价,得出再生水用在不同用途时存在的不同环境风险。     

城市供水水源地南湾水库水质健康风险评价

根据信阳市供水水源地南湾水库水质实测资料,应用关国环保局推荐的健康风险评价模型进行分析与评价。结果表明：基因毒物质由饮水途径所致健康危害的个人年均风险Cr6＋〉As,致癌物Cr6＋和As对人体健康危害的个人年均风险均未超过国际辐射防护委员会（ICRP）推荐的最大可接受风险水平（5×10-5．a-1）。非致癌物的个人年均风险为F-〉Hg〉NH3-N〉CN-〉酚,五者风险水平在10^-9～10^-12之间,均低于ICRP标准4—7个数量级。化学致癌物对人体健康危害的个人年均风险远远超过非致癌物的年风险。饮用水源各类污染物所致健康危害的个人年总风险为6．03E一05,超过国际辐射防护委员会（ICRP）推荐的最大可接受值5×10^-5．a-1,及瑞典环保局、荷兰建设和环境部推荐的最大可接受水平1×10^-3.a-1。     

常规工艺再生水效果及其回用健康风险评价

对常规处理工艺再生城市污水的效果进行了试验研究,初步讨论评价了再生水中化学污染物对人体的健康风险。研究结果表明,常规处理工艺对城市污水再生效果较好,可以有效去除有机物和浊度物质,对大肠菌群去除率集中在99.9％～99.99％之间,混凝沉淀去除Cu,Fe,Mn,Pb效果较好,对Ni,As,Cd的去除效果较差。对再生水风险评价结果显示,常规处理再生水的健康风险主要来自致癌物质,终生致癌风险在10~(-5)数量级,而非致癌物健康危害风险在10~(-9)数量级。     

污水循环再生处理中痕量壬基酚积累规律研究

采用实验室小试和数值模拟方法,研究了污水循环再生处理过程中痕量环境激素壬基酚(NP)的积累浓缩规律,建立了基于实验室污水循环再生处理系统的壬基酚积累模型,为污水安全健康回用提供理论依据.研究结果表明,当污水回用率R、去除率η一定时,污水反复循环回用会造成再生水中壬基酚的累积,累积趋势随回用率R增加而增大;提高壬基酚的去除率,可降低再生水中污染物的浓缩累积趋势.以目前城市污水再生处理系统所能达到NP去除率和出水浓度,利用循环积累水质模型计算出最大回用率为42%,循环浓缩累积系数δ为1.067.该模型可用于指导实际污水再生处理与循环回用系统的设计、运行和管理.     

《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,...     

地下水污染健康风险评价方法

为了探讨构建适合我国国情的地下水污染健康风险评价体系,在综合分析国内外有关地下水污染风险评价的研究方法的基础上,初步探索建立了一套地下水污染健康风险评价方法。该评价方法包括危害识别、剂量-效应分析、暴露评价及风险表征4个步骤,对每一步骤进行了详细的探讨,提出了危害识别与判定方法及原则,毒性因子查询、暴露量和风险计算等方法,以及有关建立我国地下水污染健康风险评价体系方面的一些建议。     

甘南州饮用水消毒副产物水平及健康风险评价

调查了甘南州居民生活饮用水中消毒副产物的种类和分布水平，并对其健康风险进行评价。采集甘南藏族自治州四所水厂的出厂水及相对应的管网末梢水经理化分析，测得8项指标达标率为100%。季节变化对DBPs的含量影响不明显，通过DBPs致癌风险及非致癌风险分析，6种DBPs通过饮用水暴露对成人和儿童造成的致癌风险R<10-4且非致癌风险HI<1，表明该区域饮用水中消毒副产物危害程度尚不会危及人类健康。     

Reusing Urban Wastewater—An Alternative and a Reliable Water Resource

ABSTRACT

Fundamental concepts of reusing urban wastewater as an alternative and a reliable source of water supply are discussed, along with the categories for water reuse, planning methodologies, wastewater reclamation technologies, and economics. The rational basis for integration of urban reclaimed water into water resources planning is proposed and the safe use of reclaimed water is evaluated. Special attention is paid to tertiary or advanced wastewater treatment systems that are capable of producing essentially pathogen-free effluent for a variety of uses such as irrigation of urban landscape, flushing of toilets served by dual plumbing systems in large commercial buildings, and groundwater recharge for eventual potable reuse. The motivating factors for wastewater reclamation and reuse are summarized and the costs of water reclamation projects are discussed with several examples. The integration of this alternative water supply into water resources planning is proposed and the safe use of reclaimed water is emphasized.     

Emerging contaminants and treatment options in water recycling for indirect potable use.

Solutions to global water stress problems are urgently needed yet must be sustainable, economical and safe. The utilisation of alternative water sources like reclaimed municipal wastewater is one of the most obvious and promising options in integrated water resources management. Among the various beneficial uses of reclaimed wastewater Aquifer Recharge (AR) receives growing attention because it features advantages such as additional natural treatment, storage capacity to buffer seasonal variations of supply and demand as well as mixing with natural water bodies which promotes the acceptance of further uses, particularly indirect potable use. Major concerns about the safety of this exploitation route of an alternative water source are connected to microbial and chemical contaminants occurring in wastewater, among which are emerging trace organics like endocrine disrupters and pharmaceuticals. This paper reviews the current international debate about the relevance of emerging contaminants and technical mitigation options in water recycling for indirect potable use.     

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.     

Integrated Management of Non-conventional Water Resources in Anhydrous Islands

Anhydrous islands are dependent either on non-conventional water resources, such as desalinated seawater or reclaimed water from wastewater, or on water importation from the mainland. The latter option is often expensive and non-sustainable. Desalinated water can be used for potable and non-potable water applications, while reclaimed water can be used for non-potable water applications. Thus all water needs can be satisfied by an optimal blend of desalinated and reclaimed water. It is important to calculate the optimal capacities and locations of seawater desalination plants, wastewater treatment plants and water reclamation plants, and to estimate the water/wastewater conveyance system, in order to minimise water production and distribution costs. Mathematical modelling and optimisation techniques can be employed for calculating the optimum scenario: the satisfaction of all water needs at minimum cost. In this article, we have estimated the water demands taking into account water quality for the anhydrous Greek island of Syros, in the Aegean Sea. Syros has been subdivided into 6 regions, taking into account geographical and population distribution criteria. All water needs are to be satisfied by desalinated seawater and reclaimed water. A mixed-integer linear programming algorithm is used here to calculate the optimal scenario (location and capacities of desalination plants and wastewater treatment and water reclamation plants, as well as the desalinated water, reclaimed water and wastewater conveyance infrastructure needed) by minimising the annualised total cost including capital and operating costs.     

Urban and agricultural competition for water,and water reuse

Competition for water can be resolved by construction of more facilities for storing water in wet years for use in dry years, by weather modification, watershed management, urban and agricultural water conservation, reuse of sewage effluent and other wastewater, desalination of saline water, water banking and transfer of water rights or other changes in water use. Reuse of wastewater requires treatment so that the water meets the quality requirements for the intended reuse. Groundwater recharge and recovery can play an important role in the treatment and storage of wastewater for reuse—agricultural, urban, and industrial, as well as potable. Often, water shortages are only shortages of cheap and abundant water, and competition problems can be resolved by good planning and management if the public is willing to pay the price and to accept changes in water use.     

生物慢滤池用于污水深度处理的实验研究

利用生物慢滤池对人工模拟污水和西安市某污水处理厂的二级出水进行了深度净化处理实验,通过分析进出水中氮、磷含量和高锰酸盐指数及上层水和出水中的叶绿素a含量等指标,考察了生物慢滤池的净化效果。结果表明:生物慢滤池对人工模拟污水的处理效果较好,总氮、氨氮、总磷和高锰酸盐指数的去除率分别为66.4%、40.2%、66.4%和73.3%;深度净化污水厂二级出水,总氮、氨氮、总磷和高锰酸盐指数的去除率分别为35.1%、21.0%、30.2%和12.6%,去除率略低于人工模拟实验;生物慢滤池对叶绿素a有很好的截留效果,去除率分别为93.4%和66.4%;生物慢滤池处理后的再生水水质达到《城市污水再生利用景观环境用水水质》要求,可回用于城市景观水体,作为城市景观水体的补充水源,避免水体富营养化的发生。     

Interbasin water transfers at the US–Mexico border city of Nogales,Sonora: implications for aquifers and water security

Nogales, Sonora, on the US–Mexico border, employs interbasin water and wastewater transfers to address water scarcity in the context of a rising population, a warming climate, and cross-border institutional asymmetries. A unique feature of its geography and border context is Nogales's export of wastewater both north to the US and, starting with the August 2012 commissioning of a strategically positioned wastewater treatment plant, south to the Alisos basin, which is its principal drinking-water source. Thus, when the new plant is fully operational, it will result in indirect potable reuse of effluent via recharge of the source-water aquifer. This paper finds that such strategies contribute to increased water scarcity in Nogales, and to detrimental health, livelihood and environmental impacts in the source basin, thus raising questions about interbasin transfers as a principal water management strategy.     

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.     

MBR处理工艺主要设备选型及常见问题探讨

随着城市对再生水利用量的需求加大,提高污水处理厂出水水质已成为必然趋势。在用地有限的条件下,MBR工艺在污水处理厂新建及升级改造工程中广泛应用。介绍了MBR工艺的类型及其主要配套设备,重点针对配套设备的结构型式及其在运行中出现的常见问题进行分析,并针对设备选型提出建议。