Semi-intensive treatment plants for wastewater reuse in irrigation.

Semi-intensive technologies are a middle term between intensive ones (e.g., activated sludge with a retention time of hours) and extensive ones (e.g., stabilization ponds with a retention time of several weeks). The most common semi-intensive configuration used in Israel is made of anaerobic ponds followed by aerated lagoons. These small low-energy units remove about 75-80% of the BOD and are followed by wastewater reservoirs for storage and complementary treatment. The reduction in loading allows a flexible operation of the reservoirs for the removal of other pollutants, while providing storage capacity to cope with the changes in water demand for irrigation during the year. In schemes for wastewater reuse in irrigation, this lay-out has proved to be low-cost, low-energy, flexible, reliable and efficient. Variations of this basic configuration are the use of UASB reactors instead of anaerobic ponds, aerated lagoons in series or low-rate trickling filters instead of aerated lagoons, constructed wetlands or rock-filters for algae removal, etc. Semi-intensive technologies use less energy than intensive ones, and less land than extensive ones. They can remove as much BOD as intensive ones, and as much pathogens and refractory pollutants as extensive ones. They release no or very small amounts of sludge.     

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.     

《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...     

再生水用于绿化灌溉的健康风险评价研究

以北京市某再生水利用工程为例,用健康风险评价的方法,对再生水用于公园绿化灌溉时接触人群的暴露水平和健康风险进行了系统研究,建立了再生水用于公园绿化灌溉的健康风险评价模型,提出了再生水对职业人员和公众的暴露参数,对再生水中氯仿等19种主要污染物的健康风险进行了定量评价.结果表明:职业人群致癌的总危险度为3.91×10-6;非职业人群致癌的总危险度中青年和老年分别为2.12×10-6、1. 27×10-6,均小于可接受健康危险水平10.     

Alternative treatment strategy for tannery water reuse and material recovery.

Most tanneries use conventional systems for treatment of the mixture of all production effluents. Such an approach makes it possible to meet environmental regulations, but because of the high cost of the treatment facilities, its implementation has been scarce, especially in developing countries. With the waste reduction-elimination concept in view, an alternative strategy for water management is proposed based on individual treatment of the effluents from different processing steps to obtain multiquality recycled water for various reuse purposes, materials recovery and complete reuse of treated water. The methodology includes a database generation of tanneries in Mexico, a mass balance and pollution index determination, formulation of water management scenarios and technical-economical evaluation. To replace the traditionally used sulfde oxidation, a sulfide recovering was proposed. Chromium, grease and protein recovery were considered too. The proposed alternative allows a 90% fresh water reduction, the recovery of more than 95% of chromium and sulfide, 90% of grease, 65% of protein and zero discharge of wastewater. Simultaneous implementation of various water saving methods using in-house wastewater treatment techniques for recovering of chemicals and sub-products reduces substantially the cost of water management.     

我国城市污水处理厂污泥产沼气的前景分析

污泥厌氧消化具有稳定污泥和回收能量以及处理后污泥可作农肥的突出优点.我国城市污水处理厂污泥多,污泥厌氧消化的推广空间巨大.污泥厌氧消化推广的主要问题是规模较小、投资高、技术复杂、维修量大等,而沼气利用不理想大大削弱了该工艺的优势.必须降低投资、简化运行和提高沼气利用的效益,加速研究配套政策,才能改变投入高、产出低的现状,才能使污泥厌氧消化成为污泥处理的首选工艺.     

季节冻土区梯形混凝土渠道冬季停水与过水运行方式对温度场的影响研究

针对西北地区输水明渠易发生冻胀破坏的问题,依据热传导和水分迁移理论建立冻结期渠基土温度场,以分析渠道内过水对温度场分布的影响为目标,以新疆玛纳斯河四级水电站引水渠为典型案例,应用有限元软件进行温度场的模拟,并将结果与相关文献中的数据及破坏类型进行比对,验证模拟的合理性。结果表明:渠道内是否过水对渠道的温度场有显著的影响,主要是其温度场的分层发生变化且其温度线也出现了强烈波动。经实地观察发现,输水明渠渠基土体易产生较大的冻胀变形导致衬砌板胀裂、隆起及滑塌等破坏十分严重的位置与模拟中温度场发生变化的位置基本一致,且满足误差要求。用冻结期渠基土温度场变化来预测输水明渠发生冻胀破坏的准确位置具有很大的参考价值。     

Energy requirements for waste water treatment

The actual mathematical models describing global climate closely link the detected increase in global temperature to anthropogenic activity. The only energy source we can rely on in a long perspective is solar irradiation which is in the order of 10,000 kW/inhabitant. The actual primary power consumption (mainly based on fossil resources) in the developed countries is in the range of 5 to 10 kW/inhabitant. The total power contained in our nutrition is in the range of 0.11 kW/inhabitant. The organic pollution of domestic waste water corresponds to approximately 0.018 kW/inhabitant. The nutrients contained in the waste water can also be converted into energy equivalents replacing market fertiliser production. This energy equivalent is in the range of 0.009 kW/inhabitant. Hence waste water will never be a relevant source of energy as long as our primary energy consumption is in the range of several kW/inhabitant. The annual mean primary power demand of conventional municipal waste water treatment with nutrient removal is in the range of 0.003-0.015 kW/inhabitant. In principle it is already possible to reduce this value for external energy supply to zero. Such plants should be connected to an electrical grid in order to keep investment costs low. Peak energy demand will be supported from the grid and surplus electric energy from the plant can be is fed to the grid. Zero 'carbon footprint' will not be affected by this solution. Energy minimisation must never negatively affect treatment efficiency because water quality conservation is more important for sustainable development than the possible reduction in energy demand. This argument is strongly supported by economical considerations as the fixed costs for waste water infrastructure are dominant.     

Benchmarking of municipal waste water treatment plants (an Austrian project).

An Austrian research project focused on the development of process indicators for treatment plants with different process and operation modes. The whole treatment scheme was subdivided into four processes, i.e. mechanical pretreatment (Process 1), mechanical-biological waste water treatment (Process 2), sludge thickening and stabilisation (Process 3) and further sludge treatment and disposal (Process 4). In order to get comparable process indicators it was necessary to subdivide the sample of 76 individual treatment plants all over Austria into five groups according to their mean organic load (COD) in the influent. The specific total yearly costs, the yearly operating costs and the yearly capital costs of the four processes have been related to the yearly average of the measured organic load expressed in COD (110 g COD/pe/d). The specific investment costs for the whole treatment plant and for Process 2 have been related to a calculated standard design capacity of the mechanical-biological part of the treatment plant expressed in COD. The capital costs of processes 1, 3 and 4 have been related to the design capacity of the treatment plant. For each group (related to the size of the plant) a benchmark band has been defined for the total yearly costs, the total yearly operational costs and the total yearly capital costs. For the operational costs of the Processes 1 to 4 one benchmark ([see symbol in text] per pe/year) has been defined for each group. In addition a theoretical cost reduction potential has been calculated. The cost efficiency in regard to water protection and some special sub-processes such as aeration and sludge dewatering has been analysed.     

Risk management in waste water treatment.

With the continuous restructuring of the water market due to liberalisation, privatisation and internationalisation processes, the requirements on waste water disposal companies have grown. Increasing competition requires a target-oriented and clearly structured procedure. At the same time it is necessary to meet the environment-relevant legal requirements and to design the processes to be environment-oriented. The implementation of risk management and the integration of such a management instrument in an existing system in addition to the use of modern technologies and procedures can help to make the operation of the waste water treatment safer and consequently strengthen market position. The risk management process consists of three phases, risk identification, risk analysis/risk assessment and risk handling, which are based on each other, as well as of the risk managing. To achieve an identification of the risks as complete as possible, a subdivision of the kind of risks (e.g. legal, financial, market, operational) is suggested. One possibility to assess risks is the portfolio method which offers clear representation. It allows a division of the risks into classes showing which areas need handling. The determination of the appropriate measures to handle a risk (e.g. avoidance, reduction, shift) is included in the concluding third phase. Different strategies can be applied here. On the one hand, the cause-oriented strategy, aiming at preventive measures which aim to reduce the probability of occurrence of a risk (e.g. creation of redundancy, systems with low susceptibility to malfunction). On the other hand, the effect-oriented strategy, aiming to minimise the level of damage in case of an undesired occurrence (e.g. use of alarm systems, insurance cover).     

Grey water characterisation and its impact on the selection and operation of technologies for urban reuse.

Characterisation of grey water reveals a source water that is similar in organic strength to a low-medium strength municipal sewage influent but with physical and biodegradability characteristics similar to a tertiary treated effluent. The characteristics of the water suggest biological processes are the most suitable unit processes for treating grey water. The highly variable nature of the source requires that selected technologies must be inherently robust in their operation. One potential area of concern is the high COD/BOD ratio and nutrient deficiency in terms of both macro and micro nutrients which grey water exhibits potentially retard the efficacy of biological processes.     

Hybrid membrane systems for secondary effluent polishing for unrestricted reuse for agricultural irrigation.

Field experiments are in progress for secondary wastewater upgrading for unrestricted utilization for agricultural irrigation. The integrative approach of secondary effluent polishing is based on using a hybrid UltraFiltration (UF) and Reverse Osmosis (RO) membrane pilot system with a capacity of around 1 m3/hr. The UF effluent is used to feed the RO membranes. The RO permeate is subsequently applied for vegetable irrigation. Field results indicate the importance of the UF component in the removal of the organic matter and the pathogens that are still contained in the secondary effluent. Under specific conditions, when the dissolved solids content is relatively low, regarding sanitary and health aspects, the UF effluent can be applied for unrestricted irrigation. During the RO stage most nutrients are removed, allowing application of the effluent without jeopardizing the soil fertility and the aquifers. Preliminary economic assessment indicates that the extra cost for effluent polishing via the UF stage only is in the range of 5 to 15 US cents/m3. The extra cost for the RO stage is also assessed at 10 to 25 US cents/m3. The additional cost depends to a large extent on the quality of the incoming raw secondary effluent and local requirements of the command region.     

多级提水灌区水资源管理决策支持系统建设

多级提水灌区水资源调度决策信息具有信息量大、结构复杂、完备性差的特点。提出将决策支持系统(DSS)引入灌区水资源规划、管理、决策工作中,进行水资源信息的动态管理,建立多级提水灌区水资源管理决策支持系统的总体功能结构、数据库结构及模型库;给出系统的实现思路及其软硬件环境。     

Upgrading of waste water treatment plants by cloth-filtration using an improved type of filter-cloth

In order to reach in the effluents of wastewater treatment plants values for phosphorous below 0,5 mg P/l and for the suspended solids below 5 mg SS/l, a filtration stage is necessary in almost all instances. Apart from conventional deep-bed porous media filters (gravity filters), cloth filtration systems offer a viable alternative because of the low head loss, and their low price. The use of pile fabrics instead of conventional needle felt solves the crucial problem of cloth filtration: the considerable increase of cloth resistance due to the irreversible soiling. Cloth filtration plants equipped with this filter media allow for considerably higher hydraulic strains and for higher surface loads with a separation performance on the same level as reached by conventional systems. If the problem of clogging is solved as well, it should be possible to use pile fabrics with even finer filaments on a pile of micro-fibres, which would further increase the effluent quality.     

Grey water characterization and treatment for reuse in an arid environment

Grey water from a university facilities building in Cairo, Egypt was analysed for basic wastewater parameters. Mean concentrations were calculated based on grab samples over a 16-month period. Values for chemical oxygen demand (COD) and nutrients exceeded values reported in a number of other studies of grey water, while coliform counts were also high. A submerged membrane bioreactor (SMBR) system using a hollow fibre ultrafiltration membrane was used to treat the grey water with the aim of producing effluent that meets reuse guidelines for agriculture. A test run for 50 days at constant transmembrane pressure resulted in very good removal for key parameters including COD, total suspended solids (TSS), colour, turbidity, ammonia nitrogen, anionic surfactants, and coliform bacteria. High standard deviations were observed for COD and coliform concentrations for both monthly grab samples and influent values from the 50-day SMBR experiment. SMBR effluent meets international and local guidelines for at least restricted irrigation, particularly as pertains to COD, TSS, and faecal coliforms which were reduced to mean treated values of 50 mg/L, 0 mg/L (i.e., not detected), and <50 cfu/100 mL, respectively.     

我国工业污水集中处理厂运行及水质特征分析

以我国工业污水集中处理厂的实际运行和监测数据为基础,分析了我国工业污水集中处理厂的设计处理能力、污水处理量、水力负荷率及使用的主要处理工艺等,研究了COD、BOD5、NH3-N、TN、TP的进出水水质特征以及与去除效率的相关关系.结果 表明,我国工业污水集中处理厂以1万～5万m3/d的规模为主,平均水力负荷率较低,为4...     

砂石加工系统废水处理新工艺探讨

在水利水电工程建设中, 砂石骨料生产过程会产生大量的废水, 其主污染物为悬浮物(SS),根据<水电工程施工组织设计规范>(DL/T5397-2007)的要求:砂石加工过程中产生的废水应处理达标后才能循环使用或排放.中国传统的处理工艺经过多年实践,发现存在处理能力不稳定、出水效果差、运行人员劳动强度大等缺点.新工艺以高效旋流污水净化器为核心处理设施, 在同一罐体内快速完成对高浓度悬浮物废水的多级净化, 使水质达到排放要求,同时在废渣脱水中采用了真空带式过滤机,并对废渣脱水工艺进行了有益的探索.     

Performance improvement of hybrid membrane bioreactor with PAC addition for water reuse.

A study was carried out on a hybrid (AS-SBF) membrane bioreactor (HMBR) for the municipal wastewater reclamation and reuse at Chengfengzhuang WWTP in Daqing City, Heilongjiang Province. It was found that the effects of DO and water temperature on performance of the HMBR was significant. Under the conditions of water temperature in range of 10-14 degrees C, pH of 6.6- 7.0, DO of 4-6 mg/l and HRT of 7 h, the HMBR exhibited removal efficiencies for CODcr, BOD5, NH3-N and TN of 96.7%, 98.9%, 93.7% and 60.5% respectively. The turbidity of effluent from HMBR was below 1 NTU. The effluent of HMBR meets the standard of wastewater reclamation for oil exploitation. PAC was added into the bioreactor at the second operating stage, in order to further research parameters variation. The flux was improved by 53.2%, compared to the membrane without PAC-addition, due to formation of a PAC pre-coat layer on the membrane surface, with lots of advantages such as larger granules, higher porosity, non-compressibility, higher filterability and easy removal, compared with pure biomass layer. In addition, the performance of HMBR was further improved, due to adsorption and degradation of SMPs, the average removal of CODcr and TN was further improved by 5.1% and 13.5% respectively. Biomass in the HMBR was quantitatively measured, of which the biofilm played a major role in pollutants removal.     

江东灌区水资源评价及节水途径

本文通过对江东灌区水资源利用状况调查和远期水资源需求预测,进行了水资源供需平衡分析。分析认为:江东灌区地表水资源严重不足,必须采取有效措施,探索节水途径,促进灌区可持续发展。本文从6个方面对节水途径做了简要分析和探讨。     

膜生物反应器在污水厂中水回用中的应用

介绍了平板膜一生物反应器中水回用工程在污水厂中的应用。实践证明,该工艺与以前的中水回用工艺相比,具有出水水质好、运行稳定和操作维护简单等优点。经济分析表明,中水的吨运行费用为0.57元,吨水总成本为1.05元。