Effect of Air-Water Ratio on Reclaimed Water Treatment in a Biological Aerated Filter

Water reuse is a feasible strategy to solve the problems of cost control and water-saving emission reduction in thermal power enterprises. The effect of air-water ratio on the pollutants removal was investigated using biological aerated filter (BAF) technology in the Xianren Island thermoelectric unit of Huaneng in Yingkou. The effect of backwashing air-water ratio on the recovery capacity of pollutant removal and operation time was also investigated. Results show that the removal efficiencies of COD, NH₄⁺-N and NO₃^--N were 61.1%, 81.2% and 48.6%, respectively, when the ratio of air-water was 4:1 in the BAF, and the overall removal achieved a good overall removal performance with the ratio of air-water of 4:1. Moreover, the BAF had a good SS removal when the ratio of backwashing air-water was 4:1. The BAF was able to recover the COD removal ability, where the removal efficiency of COD was 60.3% within 4 h. The NH₄⁺-N and NO₃^--N removal ability was also recovered in 5 h with a removal efficiency of 82.2% and 50.0%, respectively. The operation time could last 25 h. BAF has showed an excellent capacity prolonging the operation time and reducing the frequency of backwashing when the ratio of backwashing air-water was 4:1.