外来水量诊断法在污水管网预诊断中的应用

为实现污水管网全覆盖、全收集、全处理目标,全国各地区陆续开展排水管网排查与整治项目。以“长江大保护”为代表的污水提质增效项目指出,在全面开展排查修复工作之前,应对管网进行预诊断。提出了基于外来水量分析的诊断方法,介绍了外来水量预诊断的目的、意义、诊断内容及技术路线,并综合运用水量平衡法、化学质量平衡法和基于流量测量的方法对“长江大保护”项目中的南方某城市排污管网进行了诊断。诊断结果表明：该城市污水系统整体外来水占比约为16%,但局部汇水区域旱天外来水量达到50%以上;该市雨水入流现象严重,约一半以上汇水区域雨水入流量达到30%以上。排污管网预诊断,对管网排查、修复工作具有一定的指导意义。     

基于短期在线监测的污水管网降雨入流入渗分析

以南方某城市典型片区污水管网为例,根据管网拓扑关系制定短期在线监测方案,获取17个监测点为期3个月的有效在线监测数据,对污水管网旱天和雨天的液位和流量数据进行对比分析,定量识别由降雨引起的污水管网入流入渗问题,快速评估降雨入流入渗对污水管网流量变化和运行风险带来的影响,能够为污水管网的修复改造和污水处理的提质增效提供依...     

Continuous measurement of dissolved sulfide in sewer systems

Sulfides are particularly problematic in the sewage industry. Hydrogen sulfide causes corrosion of concrete infrastructure, is dangerous at high concentrations and is foul smelling at low concentrations. Despite the importance of sulfide monitoring there is no commercially available system to quantify sulfide in waste water. In this article we report on our use of an in situ spectrometer to quantify bisulfide in waste water and additional analysis with a pH probe to calculate total dissolved sulfide. Our results show it is possible to use existing commercially available and field proven sensors to measure sulfide to mg/l levels continuously with little operator intervention and no sample preparation.     

Biocides used in building materials and their leaching behavior to sewer systems.

There is increasing concern about diffuse pollution of aquatic systems by biocides used in urban areas. We investigated sources and pathways of biocides significant for the pollution of storm water runoff. Main sources seem to be building envelopes, i.e. facades (paints, plasters) and roof sealing membranes. First results from a defined urban catchment drained by a separated sewer system without any agricultural activities reveal a substantial occurrence. Even after the first flush, concentrations of terbutryn, carbendazim, mecoprop as well as Irgarol 1051 and its metabolite exceeded the Swiss water quality standard of 0.1 microg/L. In laboratory experiments, leaching of mecoprop used as a root protection agent in bitumen sheets for roof waterproofing was determined. The concentrations differed in 16 different sheets two orders of magnitude, depending on the product composition. Using optimized products, it is expected to be the most efficient and sustainable way to reduce the environmental impact. To understand transport dynamics and environmental risk, further storm water events will be analyzed. Based on the ongoing project URBIC, first measures will be proposed to limit the release to surface and ground water.     

Infiltration in sewer systems: comparison of measurement methods.

For 20 years, several methods for the estimation of infiltration have been developed in various countries. These conventional methods are subject to considerable uncertainties due to their underlying assumptions and general principles which are not estimated. Two extended comparative studies of the conventional methods have been made in order to assess the variability in infiltration estimations and associated uncertainties according to the method used. The choice of method is not critical when the objective of a sewer diagnostic study is to define the spatial distribution of infiltration contributions at subcatchment scale. Nevertheless, the methods based on the analysis of the minimum night flow that are generally applied during one dry weather day should be applied during 8 to 10 dry weather days in order to provide estimations with acceptable uncertainties.     

Benchmarking management of sewer systems: more to learn than cost effectiveness.

Thirty-nine municipalities in the Netherlands conducted a pilot study to develop and try out a methodology to compare the quality of their sewerage management. The participants chose a multidimensional benchmarking with an emphasis on the aim of improving the working processes within sewerage management. A second goal was accountability to the stakeholders. The benchmarking methodology was based as well on analysing data within a "balanced-score-card" system as on intensive exchange of knowledge and experiences. The pilot resulted in a state of the art overview of the quality of sewerage management in the Netherlands. However, above all, it resulted in the shocking fact that the work is carried out in many different ways which cannot be explained by technical reasons or local circumstances. To pinpoint best practices and actually implement these improvements the learning process must continue after the analysis and presentation of the data. A start has been made to form regional specialist networks for further discussion and exchange of experiences.     

Integrated operation of sewer system and WWTP by simulation-based control of the WWTP inflow.

In recent years numerical modelling became a standard procedure to optimise urban wastewater systems design and operation by integration. For dynamic control of the wastewater teatment plant (WWTP) inflow, a model-based predictive concept is introduced aiming at improving the receiving water quality. An on-line simulator running parallel to the real WWTP operation reflects the actual state of operation and provides this model information to a prognosis tool which determines the best option for the WWTP inflow. The investigations showed that it is possible to reduce the NH4-N peak concentrations in the receiving water by dynamic WWTP inflow control based on predictive scenario analysis.     

Development and verification of a general approach to describe the efficiency of vortex separators in combined sewer systems.

The water framework directive (CEC, 2000) asks for cost-effective measures for achieving good ecological conditions in receiving waters. Because of low operation costs and good pollutant removal efficiency, vortex separators (VS) are an attractive alternative to traditional stormwater tanks. The German design standard for CSO structures, ATV-A 128 (1992), demands long-term pollution load simulations. Today's simulation software, however, considers the removal processes in CSO structures either very rudimentarily or not at all. The higher pollutant removal efficiency of a structure like a VS cannot be taken into account. This might be one reason why VS are used still comparatively scarcely. A mathematical model describing the removal efficiency could increase the acceptance of VS. Several functions describing the removal efficiency have been derived from model tests or large-scale studies within the last few years. Within this paper, the data from three large-scale studies are used to verify the general applicability of one steady-state and one dynamic approach. The results show that the complex processes involved with CSO facilities and the large error related to monitoring make the validation of models a difficult task. Anyhow, especially the dynamic approach was applicable at all considered facilities.     

Integrated modelling of sewer system and wastewater treatment plant for investigating the impacts of chemical dosing in sewers

Chemicals are often dosed to control the production and accumulation of hydrogen sulfide in sewers. The biological and/or chemical actions of these chemicals have profound impacts on the composition of wastewater entering a WWTP, thereby affecting its performance. In this paper, an integrated modelling methodology for simultaneously investigating the effects of dosing of chemicals in sewer network and N and P removal at the downstream WWTP is reported. The sewer system is modelled using a sewer model (SeweX), and the WWTP is modelled using ASM2d model with some modifications. The importance of integrated modelling in sewer management is also demonstrated.     

Control of sewer systems and wastewater treatment plants using pollutant concentration profiles

On-line measurements of pollutants in the wastewater combined with grey-box modelling are used to estimate the amount of deposits in the sewer system. The pollutant mass flow at the wastewater treatment plant is found to consist of a diurnal profile minus the deposited amount of pollutants. The diurnal profile is found to be a second order harmonic function and the pollutants deposited in the sewer are identified using first order ordinary differential equations.     

城市排水管道开挖与非开挖修复的综合成本分析

排水管道的非开挖修复因工期短、施工对道路交通影响小,近年来在国内开始得到重视与应用。然而,非开挖修复的直接成本较高限制了新技术的推广。对近5年来上海城区完成的10段排水管道修复工程的直接成本进行统计分析,同时对其主要社会成本进行了量化,据此对不同类型修复工程的综合成本进行了分析比较,认为就综合成本而言,非开挖修复优于开挖修复,有必要通过政策调控推进非开挖修复的应用。