Experiment And Research On The Combination Of Biological Filter And Oxidation Pond To Rural Sewage Treatment

With the rapid development of rural areas in China,great changes have taken place in the production and lifestyle of rural residents.The resulting rural water environmental pollution problem is increasingly prominent.Many untreated sewage is discharged directly into the water nearby,causing serious pollution to the ecological environment.In this paper,a combined rural sewage treatment system of"biological filter tank-oxidation pond"was constructed,and the operation of biological-ecological combined process was studied.Two kinds of composite filter materials,natural zeolite and volcanic rock,were determined by the filter material optimization test.At the same time,several kinds of wetland plants were transplanted into the oxidation pond system,and the nitrogen and phosphorus indexes in sewage were continuously degraded to realize the utilization of resources.Taking temperature as the main factor,the removal effect of the combined system on each pollution index was studied by monitoring the water quality of continuous inlet and outlet of biological filter and oxidation pond from July to December 2019.The main conclusions are as follows:1. According to the filter material optimization test,the adsorption effect of natural zeolite on ammonia nitrogen is obviously better than that of the other two kinds of filter materials（volcanic rock and maifan stone）.The adsorption effect of the three kinds of filter materials on phosphorus is not ideal,so it needs to be combined with biological phosphorus removal method to enhance the removal effect.The adsorption performance of ammonia nitrogen and phosphorus by the combined filter material is better than that of the single filter material.2. According to the membrane hanging startup test of the biological filter,the membrane hanging startup was carried out by adjusting the filtration rate and setting a certain gradient of inlet flow.After 28 days,the membrane hanging was successful,the microbial species and biofilm concentration kept increasing,and the removal rates of COD_Mn,NH₄⁺-N and TN all increased steadily.3. During the operation of the biological filter system,the removal effect of COD_Mnis not affected by the temperature,the removal effect of NH₄⁺-N and TN is more affected by the temperature,and the removal effect of TP is less affected by the temperature.4. During the operation of the oxidation pond system,the effluent concentration of COD_Mnin pond 1,pond 2 and pond 3 varied in the range of 10.23-19.86mg/L,12.75-24.53mg/L and 10.56-21.02mg/L,respectively.The effluent concentration of COD_Mnin summer and winter sections changed little.The effluent concentration of NH₄⁺-N in pond 1,pond 2and pond 3 varied in the range of 1.31-3.91mg/L,1.45-4.23mg/L and1.92-5.18mg/L,respectively.The effluent concentration of TN in pond 1,pond 2 and pond 3 varied in the range of 4.42-9.83mg/L,4.58-9.94mg/L and 5.97-12.03mg/L,respectively.TP effluent concentrations in pond 1,pond 2,and pond 3 varied in the range of 0.31-0.52mg/L,0.32-0.54mg/L,and 0.30-0.52mg/L,respectively.Except for A few times in December when the effluent could not reach the discharge standard of grade A standard,it could be reached in other time periods.The results of this paper show that the removal effects of COD_Mn,NH₄⁺-N,TN and TP are good through the design of bio-ecological combined sewage treatment system.It is a sewage treatment technology suitable for rural areas.