| In this paper, the technology of the anaerobic suspended packed bed combined with biological aerated filter (BAF) was used in the rural domestic sewage treatment. A lot of theoretical research and engineering practice show that, BAF technology is a cost-effective treatment method, and it can overcome some shortcomings of the conventional activated sludge, such as a large occupancy area, high investment in infrastructure and sludge bulking. Anaerobic suspended packing bed can effectively play the role of pretreatment. When it is combined with the BAF, it can reduce the concentration of influent suspended solids and the number of BAF backwash, making much less cost. In this paper, sewage was treated, research of anaerobic suspended packed bed, the hanging membrane of BAF and treatment effect was made, and the best operating parameters was obtained by studying the performance treatment parameters of the anaerobic suspended packed bed and BAF. Through experimental results, we got the following conclusions:(1) We used the starting mode of the hanging membrane, "immersion packing, and continuous feeding", on the suspended anaerobic packed bed and biological aerated filter. When the water contained Chemical Oxygen Demand (CODCr) from 120mg.L-1 to 400mg.L-1, Hydraulic Retention Time (HRT) was 4 hour and pH ranged from 7 to 8, the CODCr removal rate of the anaerobic suspended packed bed was more than 12.5%. When the average concentration of ammonia nitrogen and CODCr was 234.2mg.L-1 and 56.2mg.L-1 separately, the average removal rate of biological aerated filter was 54.5% and 77.7%.(2) Anaerobic suspended packed bed has certain removal effect of CODCr and SS. The average removal rate was 26.2% and 89.6% separately. The treatment rate of ammonia nitrogen and Total Phosphorus (TP) were less effective, 2.6% and 4.5% separately. Effluent from anaerobic suspended packed bed received BAF further processing, indicating that BAF had some removal effects on such major pollutants as CODCr, ammonia, TP and SS. And the average removal rate was 67.6 %, 93.2%, 22.8% and 61.5% separately. (3) When HRT were 4h, 3h and 2h separately, the average removal rate of the CODCr by the anaerobic suspended packed bed was 35.6%, 24.3% and 18.8%. The average removal rate of ammonia nitrogen were -2.2%, -0.25%, 10.1%, the average TP removal rates were 11.1%, -1.3% , 3.8%, and the average removal rate of the SS were 92.5%, 87.5% and 88.6%; when pH is from 5 to 6, 6 to 7 and 7 to 8 , the average removal rate of the CODCr were 29.1%, 18.8% and 23.0%. The average removal rate of ammonia nitrogen were -5.0%, 5.3% , -1.9%, the average TP removal rates were 6.4%, 4.5%, -1.8%, and the average removal rate of the SS were 90.1%, 88.6% and 87.2%.(4) When HRT was 4h, 3h and 2h, the average removal rate of the CODCr by BAF were 70.8%,71.8% and 60.0%. The average removal rate of ammonia nitrogen were 92.6%, 95.35, 91.3%, the average TP removal rates were 16.8%, 17.5%, 11.1%, and the average removal rate of the SS were 60.0%, 63.8% and 53.5%.When HRT was 3h, and the ratio of gas to water were respectively 20:1, 10:1 and 5:1, the average removal rate of the CODCr were 72.6%, 57.5% and 63.3%. The average removal rate of ammonia nitrogen were 96.0%, 84.4%, 66.9%, the average TP removal rates were 17.10%, 2.3%, 42.7%, and the average removal rate of TN were 15.2%, 12.6% and 13.8%.(5) Backwash way of biological aerated filter was joint air and water backwashing. Air and water impact strength were controlled from 8L.m-2.S-1 to 10L.m-2.S-1, and 2L.m-2.S-1 to 4L.m-2.S-1separately. Anti- washing time was 5min, and recovery time of processing power was about 6 hours.(6) The removal efficiency of CODCr and TN increased more obviously after the BAF device was modified. When the gas-water ratio was 10:1, reflux ratio was 1:1, the temperature was low (December 2009), and rate of inflow were 0.24 L.h-1, 0.36 L.h-1 separately, the average removal rates were 88.3% and 42.6%.(7) When the ratio of air to water was 10:1, HRT was 3h, and the temperature was high (June 2009), we made a research on the CODCr and ammonia concentration change along the height of the packing bed .The results showed that: CODCr degradation occured mainly in the height of 40cm in the packing layer, in which CODCr removal rate reached 60.1%, making up 76.8% of the total removal rate; ammonia degradation mainly occurred in the filler layer of the height from 20cm to 60cm, in which ammonia nitrogen removal rate reached 60.3%, making up 65.5% of the total removal rate.(8) The removal mechanism of pollutants was discussed. The denitrification performance of BAF needs the further research.Through the result of the experiment we can conclude the BAF can denitrificated better. |
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