Reduce-Retain-Reuse-Restore Technology for the Controlling the Agricultural Non-point Source Pollution in Countryside in China:General Countermeasures and Technologies

After point pollution was effectively controlled,the non-point source pollution was more and more serious and became the focus of water environment pollution control.In this paper,the characteristics of non-point source pollution in countryside was summarized,and the guideline and principle of non-point pollution control was put forward.Then,the strategy for controlling agricultural non-point source pollution,Reduce-Retain-Reuse-Restore theory(4R theory) was proposed and its internal relationship and technology components was explained.Furthermore,under the support of national water control project,4R theory was applied at Longyan country,watersheds of Zhihugang River,Tai Lake region to control the non-point pollution.The practice of the engineers proved that comprehensive non-point pollution control demonstration project achieved the expected design goals,the TN load to river decreased about 47.5%.The water quality of branch Zhujiabang in Longyan country was improved obviously,and the concentration of TN decreased from 6.34～8.83 mg·L-1 to 1.13～3.78 mg·L-1,NH4-N decreased from 2.66～5.33 mg·L-1 to 0.29～1.28 mg·L-1,CODMn decreased from 9.60～15.6 mg·L-1 to 4.52～7.7 mg·L-1,respectively.