Experimental Study On Filler Modification And Treatment Of Contaminated River Water By Biological Aerated Filter

Experimental study on biological aerated filter processing of contaminated river water was conducted in this project, in order to provide reference for practical engineering application in contaminated river water treatment by BARPollutants removal of the five different filler was studied, indicating that the removal rate of CODcr were all greater than87%. The NH3-N removal rate of pall ring was only69.4%, while ceramsite and biological suspended packing were respectively up to84.2%and83.9%. Generally considering, ceramsite was chosen to be the filler of BAF.Throughout the ceramsite BAF start-up operation stage, the removal rate of CODCr, NH3-N and TP were90.36%,89.51%and38.06%, respectively. The tests were carried out under different HRT, air/water ratio and filler layer height, indicating that the best HRT was6h, the best air/water ratio was3:1, and that the pollutants were mainly removed in the bottom30cm of filler layer.Study on processing the actual river water showed that the effluent CODCr reached surface water quality requirements of class Ⅰ, and the effluent NH3-N and TP respectively reached surface water quality requirements of class Ⅱ and V.The phosphorus adsorption process of modified ceramsite was simulated well by pseudo-first-order reaction kinetics equation and Langmuir adsorption isotherm equation, and the process of intra-particle diffusion was the control step. In addition, the phosphorus adsorption of modified ceramsite was better at pH7. And the phosphorus dynamic adsorption process of modified ceramsite was simulated well by the logistic model, which showed that the breakthrough time was310min and the breakthrough concentration was0.189mg/L. According to the related characterization tests, the specific surface area of modified ceramsite increased, and the iron oxide adhered on the surface was in the form of α-FeOOH.During the modified ceramsite BAF start-up phase, the average removal rate of CODCr, NH3-N and TP were88%,82%and81.17%, respectively. As to the processing of actual river water, the average removal rate of CODCr, NH3-N and TP were86.46%,87.45%and77.34%respectively, which showed that the effluent CODCr reached surface water quality requirements of class Ⅰ and the effluent NH3-N and TP reached surface water quality requirements of class Ⅱ. In all, the removal of TP by the BAF increased greatly. Furthermore, the iron oxide adhered on the surface of modified ceramsite wouldn’t dissolute in the river water. Conversely, the modified ceramsite BAF could remove the total iron in the river water partly.