曝气量对家庭生活污水处理净化槽的水质影响

Influence of Different Aeration Rates on Domestic Sewage Treatment in Purifying Tank Connecting Multiple Septic Tanks

为了满足农村多用户化粪池联用处理要求,对单独净化槽进行了改造。将原有的两级厌氧一级好氧工艺改为一级厌氧两级好氧工艺,提高净化过程的生物处理能力。针对这种新型净化槽,调查了不同曝气量下的生活污水净化能力,分别测定了各区出水水质COD、BOD5、NH3-N和浊度的变化情况。实验表明,一级好氧和二级好氧中的溶解氧随着曝气量的不断增加表现出先快速增加,然后缓慢增加,最后又快速增加的特点。在曝气量均为1.8L·min-1时,一级和二级好氧区溶解氧分别为2.4mg·L-1和3.1mg·L-1,出水COD、BOD5、NH3-N和浊度分别为23、13、7.6 mg·L-1和9NTU。若再增加曝气量,出水水质变化将趋缓,因二级好氧区生物降解的底物浓度较低,已成为主要的控制因素,所以基于能耗的考虑,曝气量的优化就变得更为重要。

One purifying tank for one septic tank is difficult to be implemented in rural area in China, owing to the cost. So it is necessary to develop one purifying tank for multiple septic tanks. In this study, an individual purifying tank was reformed to meet the treatment require- ments for multiple septic tanks. The original process of two-stage anaerobic and one-stage aerobic digestion was changed into one-stage anaerobic and two-stage aerobic digestion. The ability of biological treatment for purification process was improved. For the new tank, sewage purifying capacity under different aeration intensities was investigated, and chemical oxygen demand（ COD ）, five-day biochemical oxygen demand（BODs）, NH3-N and turbidity of effluent from different zones were measured. As aeration rates increased, the dissolved oxy- gen（ DO ） in the first aerobic and second aerobic zones increased rapidly at the beginning, then slowly, and finally rapidly again. The DO was 2.4 mg· L^-1 and 3.1 mg· L^-l in the first and second aerobic zones respectively, at the aeration rate of 1.8 L·min^-1. The values of COD, BODs, NH3-N and turbidity of the effluent were 23 mg·L^-1, 13 mg· L^-1, 7.6 mg·L^-1 and 9 NTU, respectively. However, further increasing aeration did not improve water quality much. The biodegradable substrates in the second aerobic zone were a major controlling factor due to low con- centration. Therefore, the optimization of aerobic rates would be important for treating domestic sewage in purifying tank.