Study On The Treatment Of Municipal Sewage In Land Aerobic Biological Filtration System

In recent years, with the development of economy and the continuous improvement of people’s living standards, the contradiction between serious water pollution problems and people’s demand for water resources become increasingly evident. Wastewater land treatment system which have the points of sewage harmless and resource, was widely used in the area of rural sewage treatment. But with the continuous improvement of the requirements in the sewage treatment, traditional sewage land treatment efficiency has been unable to treat the growing demand for wastewater discharge and treatment. So the concept of “rising flow water + land aerobic+ land biological filtration” was raised in this experiment, to explore the effect of the system on the treatment of urban domestic sewage and its operational characteristics. Provide data support for its application in practical engineering.In this experiment, we build a research model in Qingdao Haibohe sewage treatment plant. Firstly, the experiment explored the effect of temperature on the starting of the system under the condition of low temperature and medium temperature. The experimental results show that under the condition of low temperature(5 ~ 8℃), the starting time of the system is about 30 days, and the starting time is about 20 days in the medium temperature(19 ~ 12℃). The biological phase of the system was observed, and the color of the biofilm decreased gradually with the decrease of water flow direction. Microbial species along the flow direction become diverse, microbial community structure from low level to high transformation, to ensure the stable operation of the reactor.By adjusting the operating parameters, the effects of temperature, coagulation pretreatment, COD volume load and aeration rate on the removal efficiency of the system were pointed out. The experimental results show that the removal effect of the system is best when the water temperature is 28 ~ 30℃, COD volume load is 0.14 ~ 0.21 kg COD/(m3·d)and aeration quantity is 1.8m3/h. Under these conditions, the removal rate of COD was about 92%, the effluent COD was stable at 50mg/L, the removal rate of NH4+-N was about 95%, and the effluent NH4+-N was stable at 5mg/L Raw water coagulation pretreatment can significantly prolong the system’s back washing cycle, improve the removal effect of TP. With 10 days running, the reactor required back washing with gas rat 1.2 L/(m2·s), water rate 1.0 L/(m2·s)and back washing time 9min. Under these conditions, the system recovered rapidly and performed the best.In the experiment, the effect of coagulant on dewatering performance of sludge was studied. The optimal dosage of CPAM, FeCl3, PAC, PFS were 150mg/L, 900 mg/L, 1200 mg/L, 500 mg/L, respectively. Under the conditions of their best dosage, the treatment effect of PAC is the best. Then the experiment studied the effect of combined coagulant on the dewatering performance of sludge and the best dosage are obtained as follows: the dosage of FeCl3, CPAM were 1500mg/L and 120mg/L respectively, the sludge pH was 7; the dosage of PAC, CPAM were 1500mg/L and 150mg/L respectively, the sludge pH was 8; the dosage of PFS, CPAM were 390mg/L and 180mg/L respectively, the sludge pH was 7.