鸭儿湖污染治理研究

鸭儿湖污染是通过氧化塘系统控制的。氧化塘系统,由四个串联氧化塘组成,总面积为2800亩,塘深3米,当废水量为7万吨/天时停留时间为80天。并利用净化后的废水培育鱼种(鱼种塘),通过菌—藻—浮游动物—鱼的相互作用,以鱼种形式回收部分营养元素。以解决在氧化塘沿岸的东西排灌渠12.8公里两岸人民的灌溉水和饮用水的污染问题。从1976年底氧化塘初步建成,四年运转结果表明:COD、有机磷、对硝基酚、对硫磷、马拉硫磷、乐果和六六六处理效果分别为77.3、82.5、99.3、98.7、98.4、92.9和86.2%。每天实际废水负荷为8万吨。1977年以来水生态系逐渐得到恢复,至1979年鱼的畸型率下降到0.1%。鱼体内(背肌)六六六残留从15—30毫克/公斤下降到0.155毫克/公斤,农作物中六六六的残留1979年比氧化塘建立之前降低了2.7—9.4倍。  

STUDIES ON THE POLLUTION CONTROL OF THE YA-ER LAKE

Ya-Er Lake is located in the west part of E-Cheng county, Hubei Province. In the past it covered about 6000 ha (now 2000 ha) and was one of the main fish production district in the province. Since 1962 the lake was polluted by wastewater of a chemical plant which manufactured parathion, malathion, dimethaote and BHC. The aquatic ecosystem was ruined. About forty percent of fish population were of abnormal form. After the ecological surveys carried out in 1972—1974, the pollution control of Ya-Er Lake was studied. The research works included: survey of the self-purification of pesticides of the lake, simulation experiment on the processes that would occur in the oxidation ponds, and the biological degradation of pesticides in aquatic environment, etc.The pollution control system of Ya-Er Lake consists of the following parts: 1. Oxidation ponds system. At one end of the lake, four oxidation ponds, connected in series, were constructed. The total area is about 187 ha and 3 m in depth. The retention time of wastewater is about 80 days when the amount of the effluent is 7×104 tons per day. The effluent from the pond system is then discharged into another pond for culturing fingerling fish. Therefore the nutritive elements contained in the effluent can be utilized by the fish and the eutrophication process is retarded in the receiving water body. 2. Sewer pipelines, 5.9 km long, between the chemical plant and oxidation ponds. 3. Two outfall canals (12.8 km long) which run along either side of the oxidation ponds collect and drain the rainwater into the lake. They are also used as water sources for farming. The above facilities were nearly completed in 1976. The operating experience for four years showed that the syatem was quite successful in district pollution control. The oxidation pond system can effectively reduce the organic wastes. The average removal efficiences for COD, organic phosphate, pnitrophenol, parathion, malathion, dimethaote and BHC are 77.3, 82.5, 99.3, 98.7, 98.4, 92.9 and 86.2 percent, respectivly. The daily waste-water load was 8×104 tons. Biological survey showed that the biotic community in the Ya-Er Lake ecosystem has been recovering since 1977. The rate of abnormal type of fish decreased to 0.1 percent in 1979. The BHC residues in fish decreased from 15—30 mg/kg to 0.55mg/kg (in skeletal muscle). The BHC residues of farm products in 1979 were 2.7mg—9.4 fold less than those before the construction of the oxidation ponds system.