Experiment About The Advanced Treatment Of Municiple Wastewater By Biological Aerated Filter

The whole world is facing water risk now, and China is also meeting the serious scarcity of water resource. To resolve this problem, we need to do more than reasonble resource distribution, but also finding new resource by effective wastwater treatment, so we can use the water circuly.A wastewater plant in Beijing planting to treat their secondary water deeply, and transfer the treated water to another factory, who is lacking of water for manufactring. The study is working on this advanced treatment by biological aerated filter. A continous two stage of bilolgical aerated filter was used. By changing the filter rate and air/water ratio, the different treatment effects were studied, which were very important to future alteration of the plant.In the start-up of bilolgical aerated filter part, ceramsite and volcanic rock were used as filter materials to incubate biofilm in a compound inoculation way. The COD of the inflow various from 25.04 to 58.7mg/L, while the variation of NH₃-N is 0.64².92mg/L. The filtering rate is 1m/h and the air-water raito is 4:1. The average removal percents of COD and NH₃-N are 30% and 55%, separately. The experiment demonstrates the start-up of BAF in this situation is capable; COD and NH₃-N of the inflow shouldn't be too low; appropriate filter materal and air quantity are key factors for BAF running.In the continous two stage part, ceramsite was chosen as filter material. Filter rate and air/water ratio were the two key factors to control the experiment. The a/w ratio was set to 2, and filter rate were 1,2,3,4m/h separately. The out of NH₃-N were basically under 0.3mg/L, and the average is 0.21mg/L. It shows that the BAF has a shock resistant in a low content of organic matter, high a/w ratio situation. The removal proportion depands on the inflow NH₃-N content. And under different filter rate, the removal of COD is stable, which is aways good and has a shock resistant ability. It is also found that a long HRT is good for remove COD. The removal of turbidity behaves similar, the remove effect goes bad as the fiter ratio goes high.At the same filer ratio, the various treatment effects under the different air/water ratio were also studied in this paper. Set the filer ratio at 3m/h, change the a/w to 2:1,1:1 and zero. It is demonstrates that a/w ratio has a significant influence to the removal of NH₃-N. A slightly high a/w ratio cause a good remove effect, so the outlet of NH₃-N are all under 0.2mg/L. Without air, even the DO in water is high, the removal of NH₃-N drops obviously. But the influence on COD removal was not that obvious. The removal was mainly in O1 stage. Especially under a low content of organic matter situation, the first stage use almost all of the organic matter, the removal of COD in second stage is basically impossible.