Study On Municipal Wastewater Treatment Using Biological Aerated Filter With Pre-denitrification

Biological Aerated Filter (BAF) is a recently developed process which is used for the advanced wastewater treatment. A major characteristic of BAF reactors is the use of granular media which integrated solids separation as well as secondary or tertiary biological treatment in one unit. It has the function of filtration, adsorption and biodegradation, etc. The practical operation proves that it has advantages of less land occupied, high treatment efficiency, higher capacity for absorbing shockload, no requirement for secondary settling tanks and the quality of effluent reaches the standard.This paper focuses on the experimental study on the Biological Aerated Filter with pre-denitrification for synthetic municipal wastewater treatment. The paper analyzes the removal efficiency and regularity of the organic matter and nitrogen, and gets the best operating parameters. Also, it will generalize the theory for the advance of the Biological Aerated Filter with pre-denitrification process in wastewater treatment of our country.The experimental results show that the performance of Biological Aerated Filter with pre-denitrification for sewage treatment is excellent. Under the hydraulic load of 1.57m/h~2.52m/h(do not include reflux), the reflux ratio of 200%, air/water ratio of 5:1, the average value of COD, NH4+-N and TN of effluent is 37.98mg/L, 4.91 mg/L and 14.68 mg/L,the average removal percent of COD, NH4+-N and TN is 88.77%, 80.51% and 64.51%. The effluent quality is acceptable and meets the municipal grey water standard. The experimental results also show that most of COD, NH4+-N and TN is reduced in the anoxic zone.The objective of the experiments is to study the influence of hydraulic load, reflux ratio, capacity load, influent temperature and pH. The experimental results show that it will get high pollutants removal efficiency under the hydraulic load of 2.04m/h(do not include reflux), the reflux ratio of 200%, the COD capacity load less than 8 kg/(m3·d).Gas-water backwash is effective for Biological Aerated Filter. The COD of effluent can recover to normal in 5~6 hours. The turbidity can recover to normal in 1~2 hours. The removal of NH4+-N is less affected by backwash process.