Material Balance Analysis Of Bio-flocculation And Two-stage Biological Aerated Filter Process

So far,there is still lack of effective and comprehensive methods for evaluating wastewater treatment systems.Taking a bio-flocculatipn and two-stage biological aerated filter process as an example,in this work an approach was established for material balance analysis.According to the operation data of the bio-flocculatipn and two-stage biological aerated filter process,the material balance of carbon and nitrogen is analyzed,and provided the effective way to improve the process.The removal of COD in biofloculation system mainly depends on adsorption oxidation of flocculation tank,the removal effect is relatively good,but most TN discharges outside of system with outlet water,so the subsequent BAF process is needed for further treatment of TN.The balance rate of COD of postposition denitrification BAF is 87.65%,the quality of COD in the effluent of postposition denitrification BAF,the quality of oxidized COD in C/N and the quality of COD consumed by denitrification in DN account for 40.7%,46.5% and 0.45%respectively of total COD in the influent.The most COD in system was consumed as the carbon source of denitrification in DN tank.The quantity of TN discharging with outlet water in postposition denitrification BAF accounts for 81.8% of the quantity of TN in influent,most TN entering the system discharges with outlet water,so the removal effect of TN in this system is not ideal.Wherein,the removal mass of TN in C/N tank accounts for 13.6% of total quantity of TN in influent,the quantity of TN consumed by denitrification in DN tank accounts for 1% of total quantity of TN in influent,and TN balance rate of postposition denitrification BAF system is 96.4%.The COD balance rate in preposition denitrification BAF system is 100.2%,and in addition to system test error,sludge in filter tank probably absorbs some COD.The COD quality of the effluent in in preposition denitrification BAF system,the COD quality consumed by denitrification in DN as well as the COD quantity removed in C/N tank account for 17.4%,23.8% and 59.0% respectively of total COD in influent,which clearly shows that this system has better removal effect than postposition denitrification BAF system,COD in the influent is removed mainly by the metabolism of aerobe in tank.Quantity of TN discharging with outlet water in postposition denitrification BAF accounts for 39.5% of TN quantity ininfluent,the proportion of nitrogen entering system discharging with system outlet water is small.The quantity of TN consumed by denitrification in DN tank accounts for 31.9% of total TN in influent,The removal mass of TN in C/N tank accounts for 17.6% of total TN in influent,and TN balance rate of preposition denitrification BAF system is 89.0%.The quantity of COD,TN and NH₄⁺-N removed by biofloculation system within one hour is 9266 mg,144mg and 160 mg respectively;the quantity of COD,TN and NH₄⁺-N removed by postposition BAF system within one hour is 2867 mg,203mg and 458.5mg respectively;the quantity of COD,TN and NH₄⁺-N removed by preposition BAF system within one hour is7350 mg,1052.5mg and 896.5mg respectively,synthesizing the removal proportion of COD,TN and NH₄⁺-in reaction area and according to the test research,the conclusion can be achieved the removal effect of preposition BAF system is much better than postposition BAF system.