Modelling sewer sediment deposition, erosion, and transport processes to predict acute influent and reduce combined sewer overflows and CO2 emissions

摘要

Understanding of solids deposition, erosion, and transport processes in sewer systems hasnimproved considerably in the past decade. This has provided guidance for controlling sewer solidsnand associated acute pollutants to protect the environment and improve the operation ofnwastewater systems. Although measures to decrease combined sewer overflow (CSO) events havenreduced the amount of discharged pollution, overflows continue to occur during rainy weather inncombined sewer systems. The solution lies in the amount of water allotted to various processes innan effluent treatment system, in impact evaluation of water quality and prediction technology, and innstressing the importance of developing a control technology. Extremely contaminated inflow hasnbeen a serious research subject, especially in connection with the influence of rainy weather onnnitrogen and organic matter removal efficiency in wastewater treatment plants (WWTP). An intensiveninvestigation of an extremely polluted inflow load to WWTP during rainy weather was conducted innthe city of Matsuyama, the region used for the present research on total suspended solid (TSS)nconcentration. Since the inflow during rainy weather can be as much as 400 times that in drynweather, almost all sewers are unsettled and overflowing when a rain event is more than moderate.nAnother concern is the energy consumed by wastewater treatment; this problem has becomenimportant from the viewpoint of reducing CO2 emissions and overall costs. Therefore, whilenestablishing a prediction technology for the inflow water quality characteristics of a sewage disposalnplant is an important priority, the development of a management/control method for an effluentntreatment system that minimises energy consumption and CO2 emissions due to water disposal isnalso a pressing research topic with regards to the quality of treated water. The procedure to improvenwater quality must make use of not only water quality and biotic criteria, but also modelling systemsnto enable the user to link the effect of changes in urban sewage systems with specific quality, energynconsumption, CO emission, and ecological improvements of the receiving water.