Research On In-situ Biofilm Technology In Organic Polluted Rive Way Treatment

As economy developed rapidly, the organic pollutions in the champaign rivers system increases a lot. The disadvantages of champaign rivers are: poor water fluidity, self-cleaning ability and low concentration of dissolved oxygen. The polluted characteristics of the organic pollutions in the champaign river system were researched in the paper. Furthermore, through simulate experimentation in the laboratory, we get the optimized valid parameters of the in-situ biofilm technology.The homeostasis that the pollutants transferred between sediment phase and water phase were ascertained by the research on the static release-adsorb state of pollutants (including organic compounds, ammonia, phosphate ). The sediment would adsorb pollutants when the concentrations of pollutants in the river are high; by contrary, if the concentrations of pollutants in the river are lower than the sediment, the sediment would release these pollutants and result in the endogenesis pollution. In the experiment, the concentration of NH4+-N of the polluted sediment is more than 3.5g/kg, and the PO43- and dissolved-COD is about 0.65g/kg and 13.5-15.5g/kg。By the mixing effect of aeration, dissolved-pollutants in the re-suspended sediment transfer between water phase and sediment phase easily. The release and adsorption of pollutants by the sediment occurred in 2h as the water and sediment were mixed. Then, it would reach a homeostasis. The maximum quantities of NH4+-N,PO43-,COD released from the polluted sediment would be 0.2475g/kg,0.2065g/kg,9.1g/kg, respectively and the maximum quantities of NH4+-N,PO43-,COD adsorbed would be 0.6913g/kg,0.3168g/kg,2.3g/kg , respectively.The Dissolved Oxygen (DO) in the water was consumed quickly, what means the existence of aerobe in the sediment. The Sediment Oxygen Demand curves indicates that: manpower oxygen-supply must be introduced to insure the concentration of DO in the water is more than 3mg/L to meet the demand of living aerobe in the sediment.Through aeration, we found that NH4+-N in the water was almost translated into NO3--N completely, which illuminate that there is amount of aerobe that have strong biological activity in the sediment. Compared with the treatment efficiency of biofilm composed of microorganism from activated sludge, sediment native microorganism can remove more than 90% of NH4+-N in the water (fill rate of L-J mixed filler is 50%, treatment time is 60h, the ratio between gas and water is 17:1). It can reach a great disposal effect by the direct use of sediment native microorganism in case of the risks brought in by the use of adventitious microorganism.Simulated experimental research on in-situ biofilm technology in organic polluted riverway treatment shows that L-J combination filler is the best. Take into account of the ammonia removal efficiency and economy, fill rate of 50%-75%, the aeration rate of 0.008m3/h, the ratio between gas and water of 14:1 are preferred. The removal rate of COD and ammonia can reach 80% and 90%, respectively. Intermittent aeration is available to remove 30% of TN in the water. In-situ biofilm technology in organic polluted riverway treatment can not only improve the polluted water of the riverway, but also amend the polluted sediment in some extent. And the better the effect of water restore is, the better the effect of sediment restore is.