Study On Automatic Control Of Chemical Biological Flocculation-Suspended Medium Bioreactor Process

Many problems now facing Waste Water Treatment Plants (WWTP) are: high capital investment, expensive operating cost and poor phosphorous removal. So in this paper, the pilot-scale experiments of the process of Chemical Biological Flocculation & Suspended Packing Bed (CBF-SPB) used for municipal sewage treatment was studied to solve the above problems. The features of Chemical Biological Flocculation and laws of pollutants removal were examined in depth. In accordance with the experimental data, nitrification kinetic model of Suspended Packing Bed was established, which explored the characteristics of Suspended Packing Bed theoretically. The pilot-scale facility was provided with automatic control system, which was composed of two subsystems—the chemical flocculant dosage control system and Suspended Packing Bed nitrification control system.The pilot-scale experiments of Chemical Biological Flocculation showed that the process start time was very short, and the effluent concentration of COD_Cr, NH₃-N, TP, SS might all meet the standard-Pollutants Discharge Standard of Municipal Sewage Treatment Plant (GB18918-2002) when the chemical flocculant dosage was 70mg/L, HRT was 35min, and three aeration rate was 6.0m³/h, 3.5 m³/h, 0.8 m³/h respectively. Under the same process conditions, the removal rate of COD_Cr, TP and SS of Chemical Biological Flocculation were 25%, 12% and 10% higher than that of traditional Chemical Enhanced Primary Treatment. Six hours after chemical flocculation addition ceased, the TP removal rate was maintained at about 50%. As there was phenomenon of flocculant enrichment in return sludge, it was favourable to improve the remove efficiency of pollutants and keep the stable running state.The analysis on sludge biological phase in flocculation tank by molecular biology techniques indicated that sludge abundance was very high and populations were stable. Suspended particles and heavy metals could be removed efficiently by Chemical Biological Flocculation.The pilot-scale experiments of Suspended Packing Bed demonstrate that it had the capacity of fast membrane formation, and the biomass over the packing surface amounted to 2.2g/m2 after 20-25 days operation. The optimal operating conditions...