Study On Technical Manual For Wastewater Treatment In China's Western Small Cities

Following the China's West Leap Project, the quantity and economic level of many western small cities increase rapidly in recent years. However, construction of wastewater treatment facilities there falls quite behind the need and it has resulted in the continuous deterioration of environmental condition and impaired their sustainable development, forming a reason of poverty. In order to accelerate and regulate the construction of wastewater treatment facilities, it is necessary to enact technical manual for wastewater treatment with respect to the special features and requirements of western small cities. This is part outcomes of the component of the Netherlands Government's Grant Project (MOC-NGGP-2003-3).The characteristics of western small cities and the status of technical manual for wastewater treatment manual in China are investigated firstly and certain characteristics of wastewater treatment techniques in western small cities are discussed and the contents of the guideline are defined.In light of the status and problems of sewer system in western small cities, both of advantages and disadvantages of present sewerage systems are discussed, and related technical problems of different sewer systems is discussed. A new quantitative method to determine interception ratio of intercepted combined sewerage system is proposed, and by using this method, interception ratios in western small cities are pointed out with respect to the type and characteristics of small cities.The potential and possibility of centralized treatment and disposal of municipal wastewater and sewage sludge for adjacent small cities are discussed. It is found that it is unrealistic at present to widely adopt centralized treatment and disposal, however, it will be a development direction in the future because of a lot of advantages in construction, investment as well as operational and maintenance cost and the requirement land should be reserved. The optimum quantity of WWTPs can be determined according to the lowest point of synthetic curve of operational cost and wastewater delivery cost. At present, as the sludge in wastewater treatment plants of western small cities is little, adopting centralized treatment is of high difficulty, but it is a developing direction to built special sewage sludge treatment plant and the possibility of centralized treatment should be considered.