Starting Test Of Micropore Aeration Variable-speed Oxidation Ditch In A Pilot-scale And Study On Influence Factors About Phosphorus Removal

Oxidation ditch is one of the widely used biological treatment process in WWPTThe traditional oxidation ditch using surface aeration has some disadvantages, such aslow mass transfer efficiency,being prone to sludge settling and bulking, low nitrogenand phosphorus removal rate. Microporous aeration oxidation ditch uses bottomaeration instand of surface aeration, improving oxygenating efficiency, which has beenwidely used in the upgrading of the wastewater treatment plant. In order to furtherimprove oxygenating efficiency and oxygen utilization of micropore aeration oxidationditch, a new type of oxidation ditch has been devised. Compared to traditional oxidationditch, the technology innovation of micropore aeration variable-speed oxidation ditch isused in the new ditch type and the special combination of oxygenating and liquid flow.Through the study of start-up and running of micropore aeration variable-speedoxidation ditch, exploring the factors affecting nitrogen and phosphorus removal, wecan draw the main following conclusions:（1） The system start-up successfully in a low-temperature. During the start-up of thesystem, the removal rare for COD, NH₄⁺-N and TN averaged respectively over90%,90%,65%, TP removal rate increased from33.52%of the startup to more than90%ofthe final. The water quality indicators could meet the water level A standard except TP。In addition, the time of the sludge cultivation and domestication extending makes itdifficult to start-up in low temperatures.（2） Plot system has no sludge settling at flow rate of0.15m/s, DO at0.8-1.5mg/L,Under the condition of low temperature, low dissolved oxygen and low flow rate, the system achieves a successful start-up and a high pollutant removal, which implies thatmicropore aeration variable-speed oxidation ditch has great application potential withlow consumption and high efficiency.（3）Reactor has stronger capability resisting shock load and high removal of nitrogen,phosphorus and organic matter. Average effluent concentration of COD、NH₄⁺-N、TN、TP are40.64mg/L,1.72mg/L,10.94mg/L,0.56mg/L respectively in the stable operationphase. The water quality indicators could meet the water level A standard （theattainment rate over80%）.（4） In the process of system operation,AUR, NUR increased with rising temperature,while, the effluent ammonia concentration decreased with the increasing AUR, NUR;When effluent ammonia nitrogen is low, NUR is more than AUR, when effluentammonia nitrogen is high, AUR is more than NUR.（5） By the study on factors of phosphorus removal, we can conclude as follow:1)Test water, NaAC and glucose as carbon source, Phosphorus release rate of testwater close to NaAC, and bigger than glucose. phosphorus uptake rate: Test water＞NaAC＞glucose.2)At the temperature of12℃,16℃,20℃and25℃, Phosphorus uptake andphosphorus release rate increase with rising temperature.3)COD concentration effect on the phosphorus uptake rate in aerobic section: noCOD, aerobic phosphorus uptake rate is higher, when COD exist, aerobic phosphorusuptake rate is sluggish, and the higher COD concentration, the lower rate.4)When Oxygen, nitrate and nitrite are used as electron acceptor in phosphorusuptake stage, phosphorus uptake rate: oxygen＞nitrate＞nitrite.There is a good linearrelationship between nitrate and nitrite consumption and P uptake, P uptake are0.96,0.49mgP/mgN respectively.