Influence of Hydraulic Retention Time on the Treatment of Polluted River Water by an Activated Carbon Rotating Biological Contactor

Abstract

The study combined activated carbon with a rotating biological contactor. The activated carbon adsorption experiments were conducted and the biofilm was formed by using the river water directly. The effects of different hydraulic retention times on the removal of NH4+-N, TP, and permanganate index and on the biofilm properties were investigated at the optimum rotational speed of the disc. Experimental results are as follows. The Freundlich isotherm showed that activated carbon had better adsorption properties for NH4+-N, TP, and permanganate index in water.When the disk speed was 3 r·min-1, the removal efficiency was the best, and the removal rates of NH4+-N, TP and permanganate index were the best at 86.05%, 81.28%, and 77.09%, respectively. In addition, there was a significant linear correlation between the hydraulic retention time and the removal of NH4+-N and TP (R2>0.9), respectively. The removal rates of NH4+-N and TP at different hydraulic retention times were significantly different (P<0.05), but the permanganate index was not (P>0.05).Hydraulic retention time had effects on the biofilm activity, protein and polysaccharide contents,and the three-dimensional fluorescence peaks of S-EPS, LB-EPS, and TB-EPS of the biofilm.