截流式合流制排水管网设计新思路

提出了一种以溢流井为分界线,将截流式合流制排水管网分解为一系列小型完全合流制排水管网的设计新思路,并以管网关联矩阵和节点连接特性矩阵为基础,以节点平衡原理和节点递归算法为核心,实现完全合流制排水管网的流量计算和水力计算.该方法能有效减小管网计算模型的规模,降低程序设计难度,提高程序的实用性.     

Possibility of sewage and combined sewer overflow reuse with biological aerated filters.

The secondary effluent from municipal plants in Korea generally represents higher BOD with lower SS. Therefore, more soluble forms of organics and NH4-N need to be removed to improve its effluent for reuse. In this study reuse possibility of secondary effluent and CSO (combined sewer overflow) using BAF (biological aerated filter) was evaluated. The tertiary application with 1.2 h EBCT, SS, BOD and COD showed stable concentrations less than 1.3, 1.3 and 6.2 mg/L, respectively. Nitrogen could be nitrified even at 7 degrees suggesting BAF can be used for a water reuse method as well as an effective add-on facility in cold regions. However, BAF was not stable with CSO application at increased flow rates suggesting CSO must be equalised prior to application. Disinfection was necessary even during normal weather conditions.     

合流制溢流控制指标与标准制定研究

合流制溢流(combined sewer overflow,CSO)控制是城市水环境质量改善的关键一环,相关指标及标准制定尚显薄弱.基于技术的排放控制指标主要包括溢流频次、溢流体积控制率、污染物排放浓度限值、CSO效率及稀释度等,因这些指标缺乏对CSO水质水量控制效果的综合评价,进而提出雨季CSO污染负荷占比的指标;基...     

银川市某高密度城区合流制溢流污染特性研究

针对合流制管网系统溢流污染严重且易造成受纳水体出现黑臭现象等问题,以银川市第一污水处理厂片区为例,基于雨洪管理模型(SWMM),在短历时设计降雨和典型年长历时降雨条件下,模拟分析了研究区域溢流排口溢流量及溢流污染物负荷对不同降雨条件的响应关系及其对受纳水体水质的影响。结果表明：雨天合流制管网系统的溢流量及溢流污染负荷量较大,且无论是短历时还是长历时降雨条件下,均具有随着降雨量的增加而增大的特点;厂前溢流污染浓度大,超过受纳水体自净能力,短期内水体水质处于黑臭状态。本研究对银川市黑臭水体治理及溢流污染防治方案的制订具有重要的参考价值。     

Influence of characteristics on combined sewer performance

Elements of combined sewer systems are among others sub-catchments, junctions, conduits and weirs with or without storage units. The spatial distribution and attributes of all these elements influence both system characteristics and sewer performance. Until today, little work has been done to analyse the influence of such characteristics in a case unspecific approach. In this study, 250 virtual combined sewer systems are analysed by defining groups of systems, which are representative for their different characteristics. The set was created with a further development of the case study generator (CSG), a tool for automatic generation of branched sewer systems. Combined sewer overflow and flooding is evaluated using performance indicators based on hydrodynamic simulations. The analysis of system characteristics, like those presented in this paper, helps researchers to understand coherences and aids practitioners in designing combined sewers. For instance, it was found that characteristics that have a positive influence on emission reduction frequently have a negative influence on flooding avoidance and vice versa.     

合流制溢流污染控制系统决策

合流制溢流(CSO)污染控制以削减溢流进入受纳水体的污染物总量为目标。由于合流制排水系统的复杂性以及污染物传输、溢流过程的随机性和多变性,CSO污染控制涉及一系列错综复杂的理论与工程实际问题,因而需要进行科学的系统决策,以降低投资、提高效益。首先分析我国城市CSO污染控制存在的主要问题;再从解析合流制及其溢流污染控制系统的组成关系入手,从宏观、系统的角度分析CSO污染的产生与传输过程,构建CSO污染控制系统,并对几个主要子系统进行分析;最后提出CSO污染的系统控制原理,探讨子系统的合理衔接、匹配和控制方案的优化选择问题,为我国城市CSO污染控制提供一个清晰的思路。     

Probabilistic modelling of combined sewer overflow using the First Order Reliability Method.

This paper presents a new and alternative method (in the context of urban drainage) for probabilistic hydrodynamical analysis of drainage systems in general and especially prediction of combined sewer overflow. Using a probabilistic shell it is possible to implement both input and parameter uncertainties on an application of the commercial urban drainage model MOUSE combined with the probabilistic First Order Reliability Method (FORM). Applying statistical characteristics on several years of rainfall, it is possible to derive a parameterization of the rainfall input and the failure probability and return period of combined sewer overflow to receiving waters can be found.     

合流制排水系统雨季污染物溢流的截流与调蓄控制研究

截流式合流制排水系统是我国主要的排水体制之一。以昆明市主城区明通河合流制排水系统为背景,研究了雨季产污及迁移规律及削减入湖污染物的措施,并进行了工程示范。示范研究结果表明,在CODCr截留率小于80%、截流倍数n0=1~3、调蓄量2~20 mm(以不透水地面计),提高截流倍数或调蓄量均可显著提高污染物截留率。截流倍数与调蓄量可表述为截留系数的函数,截流倍数增加1等效于调蓄量增加8 mm,截留系数为CODCr截留比率的幂函数。     

Micropollutants in stormwater runoff and combined sewer overflow in the Copenhagen area, Denmark

Stormwater runoff contains a broad range of micropollutants. In Europe a number of these substances are regulated through the Water Framework Directive, which establishes Environmental Quality Standards (EQSs) for surface waters. Knowledge about discharge of these substances through stormwater runoff and combined sewer overflows (CSOs) is essential to ensure compliance with the EQSs. Results from a screening campaign including more than 50 substances at four stormwater discharge locations and one CSO in Copenhagen are reported here. Heavy metal concentrations were detected at levels similar to earlier findings, e.g., with copper found at concentrations up to 13 times greater than the Danish standard for surface waters. The concentration of polyaromatic hydrocarbons (PAHs) exceeded the EQSs by factors up to 500 times for stormwater and 2,000 times for the CSO. Glyphosate was found in all samples whilst diuron, isoproturon, terbutylazine and MCPA were found only in some of the samples. Diethylhexylphthalate (DEHP) was also found at all five locations in concentrations exceeding the EQS. The results give a valuable background for designing further monitoring programmes focusing on the chemical status of surface waters in urban areas.     

Effectiveness of combined sewer overflow treatment for dissolved oxygen improvement in the Chicago waterways.

An Use Attainability Analysis (UAA) has been initiated to evaluate what water-quality standards can be achieved in the Chicago Waterway System (CWS). There are nearly 200 combined sewer overflow (CSO) locations discharging to the CWS by gravity. Three CSO pumping stations also drain approximately 140 km2. Because of the dynamic nature of the CWS the DUFLOW model that is capable of simulating hydraulics and water-quality processes under unsteady-flow conditions was used to evaluate the effectiveness of water-quality improvement techniques identified by the UAA including CSO treatment. Several CSO treatment levels were applied at gravity flow CSOs to evaluate improvement in dissolved oxygen (DO). The results show that pollutant removal at CSOs improves DO to a certain degree, but it still was not sufficient to bring DO concentrations to 5 mg/L or higher for 90% of the time during wet weather at most locations on the CWS. Flow from the pumping stations results in substantial stress on DO since a huge amount of un-treated water with a high pollution load is discharged into the CWS in a short period of time at a certain location. The simulation results indicate that CSO treatment does not effectively improve DO during wet-weather periods on the CWS.     

区域特征参数及降雨等级差异性对合流制系统溢流影响模拟研究

针对地形坡度、土壤渗透性能、不透水面积率、年径流总量控制率、截流倍数、截流井上游管段设计重现期六类合流制区域特征参数及降雨因素对合流制溢流总量及溢流频次的影响,利用S WMM模型模拟研究了合流制区域特征参数对溢流结果的影响权重、合流制区域特征参数组合正交方案的差异性及降雨因素与引入的溢流比概念的响应关系.结果表明,合流...     

Impact of sewage treatment plants and combined sewer overflow basins on the microbiological quality of surface water.

In a small river catchment, microbiological quality of different sewage treatment plants under regular conditions and in case of heavy rainfall, when combined sewage overflow basins (CSOs) are activated, was examined regarding microbial indicators and pathogens. In the watercourse, no self-cleaning effects could be observed. Small compact treatment plants discharge treated wastewater with a poor microbiological quality compared to river water quality and the quality of treated wastewater of larger plants. During storm water events, concentrations of microorganisms downstream of sewer overflows were approximately two logs higher than during dry weather conditions. Concentrations of parasites decreased slowly during the overflow, in parallel to filterable matter and particle-bound substances. The annual load of microorganisms originating from CSOs significantly exceeds the load from treated effluent of the sewage plants. Thus, an improved hygienic quality of the water course could be achieved by preventing overflows and by enhancing sewage treatment plants.     

Series of surveys for enteric viruses and indicator organisms in Tokyo Bay after an event of combined sewer overflow.

Combined sewer overflows (CSOs) have been recognised as one of the serious sources of pollution to the water environment during rain events, although field surveys to investigate the effect of their magnitude and duration on receiving waters have been very limited. The fates of enteric viruses (norovirus G1, G2, enteroviruses) and coliforms were determined in the wastewater treatment plant on a fine day and on a rainy day. Not all microorganisms were reduced in the primary treatment, but were reduced in the secondary treatment. Occurrences of enteric viruses and levels of coliforms were surveyed in the receiving coastal area after a CSO event, with the profiles of the enteric viruses in the coastal seawater being almost at the same positive ratio for 4 d after the CSO event.     

Correlation of combined sewer overflow reduction due to real-time control and resulting effect on the oxygen concentration in the river

Real-time control of the sewer system is a frequently applied measure for the abatement of pollution caused by urban runoff in the receiving water. Although the goal is an improvement of the water quality the actual aim of real-time control is usually formulated as the reduction/avoidance of combined sewer overflow. However, testing a virtual drainage system by means of a three-month rain series, hardly any correlation between the combined sewer overflow reduction and the resulting effect on the oxygen concentration in the river has been found. The efficiency of real-time control for pollution abatement by means of artificial performance criteria has to be doubted.     

Advanced real time control of a combined sewer system

The research project ‘Real Time Control of a Combined Sewer System by Radar estimates of Precipitation’ seeks to improve the water quality of a stream by reducing quantitative and qualitative discharges of combined sewage overflow (CSO). The complex monitoring and simulation system that has been set up for control purposes is described. Two advanced real time control (ARTC) strategies have been developed. First a pollution based real time control (PBRTC) strategy, and second a water quality based real time control (WQBRTC) strategy. The PBRTC strategy is already implemented, the WQBRTC strategy will be implemented during the course of the project. For the PBRTC an off-line analysis is presented to show the effectiveness of the strategy.     

Hydraulic performance of sewer pipes with deposited sediments.

This paper investigates in-sewer sediment deposit behaviour and its influence on the hydraulic performance of sewer pipes. This evaluation is based on experimental results regarding the mobility of non-cohesive and partly cohesive deposits in a partially full circular pipe. The focus of these tests is on the development of bed forms and friction characteristics. In particular, it is investigated to what extent the bed forms from the non-cohesive and (partly) cohesive sediments affect a sewer's discharge capacity. Based on the laboratory study results and on the existing criteria for sewer design, a generic assessment of a sewer's hydraulic performance is made. The relative discharge factor for a pipe with sediment deposit is analysed in terms of the thickness and roughness of the deposit.     

浅谈粉碎型格栅在排水泵站中的应用

粉碎型格栅在北美、欧洲、日本有十余年的应用实践,近年来在我国上海、杭州、广州等城市污水中途泵站中也有应用.介绍了粉碎型格栅的结构、工作原理及对固体物的粉碎效果.通过与传统机械格栅比较,分析了粉碎型格栅的特点、使用优势,并提出使用粉碎型格栅应注意的事项.     

Numerical simulation of domestic wastewater sewer performance

The hydraulics of municipal sewers were considered with respect to flow rate fluctuations that sometimes cause accumulation and sometimes cause scouring of the sediments. The minimal slopes that would ensure self‐cleaning conditions once a day and the required capacity for the yearly maximum peak flows were calculated. The range of fluctuations in shear stresses along the sewer walls and in the wastewater table were observed and compared for sewers of different diameters. From these computations a simple design rule for predicting minimal slopes was developed.     

Solids separation efficiency of combined sewer overflows.

The removal of sewer solids at combined sewer overflow locations depends on the flow patterns inside the overflow structure on the one hand and on the sediment characteristics on the other hand. Flow conditions can be described by the residence time distribution; sewer sediments can be characterised by their settling velocity distribution. The combination of both distributions leads to a dimensionless efficiency curve, which gives the removal efficiency as a function of the Hazen number. For field conditions this efficiency curve is mainly influenced by the settling velocity distribution of the sewer sediments and, as a consequence, nearly identical efficiency curves are found for different types of prototype CSO structure. For design purposes, a methodology using return frequency analysis is proposed.     

Size fractionation of COD in urban wastewater from a combined sewer system.

The objective of this work was to determine the partitioning of the pollutant load in urban wastewater in order to improve the conventional sewage treatment. In addition to settling tests, physical fractionation of COD in the degritted influent of Roma-Nord sewage treatment plant was performed via sequential filtration through sieves and membrane filters of the following pore size: 150-100-50-25-1-0.2 microm, and 100 kD (about 0.02 microm). Biodegradability studies were also performed on the different size fractions. Size fractionation showed that COD in Roma-Nord sewage is predominantly associated with settleable and supracolloidal (> 1 microm) particles, each size range including about 40% of total COD. Biodegradability tests indicated that the large fraction of COD associated with supracolloidal particles, which are not removed in the primary treatment, is characterised by slow degradability. This suggests that removal of these particles prior to biological treatment may greatly improve the overall treatment scheme. Preliminary pilot plant coagulation tests with lime at pH 9 showed that lime-enhanced primary treatment may increase COD removal efficiencies from typical 30-35% up to 65-70%, by inducing almost complete removal of the COD fraction associated with supracolloidal particles.