Selection of Optimal Agricultural Non-Point Source Pollution Prevention and Control Techniques Based on Effect and Cost of Their Pollution Reduction: A Case Study of the Taihu Region

In preventing and controlling agricultural non-point source pollution,it is essential to take into account both pollution reducing effect of a technique and engineering construction-operation costs of the technique. AHP (analytical hierarchy process) coupled with GRAP (grey correlation degree process) was used to select the most suitable ones out of the73 typical technologies for preventing and controlling agricultural (planting,livestock and poultry breeding,aquaculture) non-point source pollution available in the past 20 years in China. A total of 12 were obtained preliminarily in the light of pollutants (TN,TP,NH3-N,COD) reducing effects and construction-operation costs. Results show that for controlling non-point source pollution from farming,the technology of plant-microbe complex for treating field drainage is the best and followed by the technology of ecological buffering ditches; for controlling non-point source pollution from livestock an poultry breeding,the technology of wastewater land filtering system is the best and followed by the technology of artificial wetlands; and for controlling non-point source pollution from aquaculture,the technology of complex filling sequencing batch biofilm reactor is the best and followed by the technology of complex biological-ecological treatment. In light of the actual situation of the Taihu region,the technology of ecological buffering ditches is very suitable for controlling agricultural nonpoint source pollution with field drainage,the technology of wastewater land filtering system is treating wastewater from livestock and poultry breeding in the upper stream of the Taihu Lake Region,and the technology of complex filling sequencing batch biofilm reactor is for treating waste water from aquaculture. The AHP-GRAP method used in the selection is good enough to meet the demand for consideration of both pollution reducing effects and construction-operation costs in comparing and selecting agricultural non-point source pollution control technologies.