Study On A Process Of Denitrifying Phosphorus Removal With The Single Sludge System

The standard of wastewater discharge is controlled more strictly with severepollution getting worse and worse which makes the nitrogen and phosphorus removaltechnology aiming for pollution control will be the study focus in the wastewatertreatment area. For now, A2/O process is used in most sewage treatmentprocess.However，it is difficult to improve further the removal efficiencies of A2/Oprocess because of its high sludge reflux ratio, uneven organic load. Aiming at thosequestions, we design a process named anaerobic and aerobic parallel flow end withanoxic activated sludge process, and also carried some experiments in the laboratoryto validate the feasibility of this process in removing the nitrogen and phosphprus inthe wastewater.To investigate external factors on the process that C/N, influent flow ratedistribution ratio, recycling sludge ratio were selected as the main influentialparameters and carried out the comparative experiments for ever single parameterrespectively. The experiment validates that:(1) when the carbon-nitrogen ratio ofinfluent was equal to10, nitrate could be best used, total phosphorus uptaken werebest;(2) As the influent flow rate distribution ratios=1:2:2:1, distribution of organicload was more uniform, so the pollution removal efficiencies were better;(3)Asrecycling sludge ratio was equal to0.6,there are high sludge concentration in thesystem which is good for improving pollution removal efficiencies. Under thecondition that the flow was10liters per hour, and other parameters are: C/N is equalto10, influent flow rate distribution ratio is equal to1:2:2:1, recycling sludge ratio isequal to0.6, the process will reach the best removal efficiencies. The average removalrate of COD, NH4+-N, TN and TP are respectively84.1%,82.5%,81.4%and86.1%.As the influent concentration of COD, NH4+-N, TN and TP are respectively301mg/L,30.34mg/L,33.6mg/L and8.1mg/L, and the concentrations of these four targets in theoutflow are48.1mg/L,5.32mg/L,6.25mg/L and1.12mg/L, among which theconcentration of COD and TN are better than the standard provided by the first levelstandard A of the pollutant discharge standards of the urban wastewater treatmentplant(GB18918-2002) and the concentration of NH4+-N in the outflow also achievethe first level B standard.