The Study On Nitrogen And Phosphorus Removal Of New Single-tank At Low Temperature

This article is one part of the technology report of the demonstrated wastewater treatment projects in Kangding. This project is one of the construction ministry demonstrated wastewater treatment projects in western towns. Through this study we can supply the design and operation of Kangding sewage treatment plant and the other sewage treatment plants in cold area with technical advice, and we can avoid making mistakes in the work.Because of the circumstances of KangDing and the run requirement of the wastewater treatment plant, the study focus on: (1) The impact on the influence of low temperature to nitrogen removal and phosphorus removal; (2) Finding out the most efficient treatment group from all groups when temperature is at 5~7℃; (3) Writing down some phenomenon and analyzing it; (4) Treating the effluent with constructed rapid infiltration pond basising on the most efficient group when temperature is at 5~7℃, and studing the change of water quality of effluent.The experimental results indicated that the clearance of CODCr and TP go down slowly when temperature decrease. Although temperature has impact on clearance of CODCr and TP, it is litter than the impact on nitrogen removal. The nitrogen removal rate is reduced by 12%~15% when temperature decrease from 22℃to 6℃, at the same time, the TP removal rate is reduced from 65% to 50%,by 15% or so.The reason of the reduce of TP removal rate is: the releasing rate of Phosphorus of anaerobic area is reduced to a certain extent and SS of effluent increased when temperature is decreased.The experiment shows that the influence of the low temperature to NH4+-N and TN removal is more. The removal rates of NH4+-N and TN are reduced by 68% and 56% separately when temperature is decreased from 22℃to 6℃.13℃is a turning point of NH4+-N removal rate. NH4+-N removal rate is above 78% still when temperature is at 13℃, but this rate goes down rapidly when temperature continues being reduced from 13℃. The NH4+-N removal rate is about 22% only when temperature is at 6℃, reduced by 56% than the rate of 13℃.At the same time, the TN removal rate cann,t reach the standard of effluent quality of sewage treatment plant(GB18918-2002). Heat preservation must be took into accunt when we design the sewage treatment plant of KangDing. The tempreture of mixed liquor in reactor should be guaranteed...