The Study Of Processes In The Guangrao Wastewater Treatment Plant

The submerged biofilm process and the modified A²/O process are the commonwastewater treatment processes; the paper takes the submerged biofilm process andthe modified A²/O process of the Guangrao Wastewater Treatment Plant as the objectof study, and analyzes the removal efficiency. First, focused on the main pollutants（carbon, nitrogen and phosphorus） removal effect and the concentration changes alongthe processes, and the best operation parameters of two processes are confirmed; Then,according to the material balance of carbon, nitrogen and phosphorus, pollutiondegradation dynamics equations of two processes are set up and the degradationparameter K are confirmed; Finally, the nitrobacteria of aerobic ponds are counted,the aerobic pond nitrification principle are analyses. The conclusions are as follows:（1） the effluent concentrations of the submerged biofilm process: COD51.8mg/L, TN20.49mg/L, TP0.80mg/L, the average removal rate respectively are73.8%,54.0%,69.1%; the effluent concentrations of the modified A²/O process: COD52.6mg/L, TN17.8mg/L, TP0.81mg/L, the average removal rate respectively are73.7%,64.2%,68.7%. Processing performance is stability, the effluent indexes can reach Ι-B criteriaspecified in the Discharge Standard of Pollutants for Municipal Wastewater TreatmentPlant （GB18918-2002）. Organic matter and nitrogen of the submerged biofilm processare mainly removed in anaerobic pond, and phosphorus mainly in aerobic pond;Organic matter and nitrogen of the modified A²/O process are mainly removed inpre-anoxic pond and anoxic pond, and phosphorus mainly in aerobic pond.（2） The submerged biofilm process and the modified A²/O process are in the stableoperations of the different conditions, hydraulic loading capacity, COD load, C/N, C/Pand temperature on the effect of process efficiency are studied and the best operationparameters are confirmed: hydraulic loading capacity, the submerged biofilm process 14-19m³/m²·d, the modified A²/O process6.0-7.7m³/m²·d; COD load the submergedbiofilm process1.10-1.54kg/m³·d, the modified A²/O process0.4-0.8kg/m³·d; C/N4.3-4.8; C/P70-90; temperature20-28℃.（3） According to the specific transformation way of carbon, nitrogen and phosphorus,the system material balance formulas are established, based on the material balanceequations, the degradation dynamics equations of carbon, nitrogen and phosphorus ofthe submerged biofilm process and the modified A²/O process are established,according to the experimental date, the pollutant removal rate constant K arecalculated.（4） Through to the NH3-N and NOx-N concentration changes in the aerobic ponds ofthe submerged biofilm process and the modified A²/O process, the Denitrificationprinciples are summarized. Using the count method of MPN, the nitrobacteria ofaerobic ponds are counted; the result is consistent with the conclusion through thechemical index: the nitrobacteria reacts nitrosation and nitration, the nitrite bacteriachanges NH3-N into NO₂^--N, the nitrobacteria changes NO₂^--N into NO₃^--N. Thenitrification of the modified A²/O process is better than the submerged biofilmprocess.