Research Of Nitrogen And Phosphorous Depth Removal From Sewage By Processing With Screened Strains And Algae

Uneven distribution of water resources in different regions and seasons are themain reasons of the water resources shortages of our country. This situation is muchmore serious when the water pollution getting worse. The reuse of reclaimed water isan effective solution for the water crisis, for example,70%of the scenic environmentof Beijing is reclaimed water. However, the extra nitrogen and phosphorus in thereclaimed water can easily caused water eutrophication due to its excessive discharge.Therefore, the deeply removal of nitrogen and phosphorus are required in reclaimedwater, for the secondary effluent in most of waste water treatment plants in ourcountry couldn’t reach the standards of reclaimed water quality for scenicenvironment.The main prupose of this paper was to establish a process of deeply removalnitrogen and phosphorus from reclaimed water. A high efficient screening method waspropsed, the identifications of the screened strains by biochemical and molecularbiology were carried out and the proper cultivations were also determined. Theeffluent of the SBR-Algae reactor treating system could reach the quality standards ofsurface water V level.A high efficient screening method was proposed to screen polyphosphateaccumulating organisms (PAOs) based on the anaerobic/aerobic cultivation. Theresults showed this method had higher PAOs screening rate of93%than thoseobtained from the traditional screening methods (15%).15strains were screened outand8identified as Raoultella.sp.,5identified as Pseudomonas sp., except2Bacillussp.,. The phosphate removal rate of B8could reach95%. Testing experiments showedthat the polyacid and polysaccharide carbon sources were not suitable for B8whileFe2+, Ca2+, Mg2+and Co2+could enhance the phosphate removal rate. The growthkinetic model indicated that the maximum growth ratio was obtained at40℃. Thephosphate removal rate increased from52%to73.3%after adding B8into activatedsludge.SBR-Algae reactor treating system was established and the HRT of SBR toAlgae reactor was1:3.93%of the COD,93%of the ammonia and75%of thephosphorus were removed by SBR while the22%of phosphorus were removed byAlgal reactor. The phosphorus concentration of the effluent below0.1mg/L and theNTU could reach0~1.The maximum uptake capacities of PO43--P reached0.25g/(m2.d) by algae, whilethat of NH4+-N reached1.0g/(m2.d). Energy spectrum analysis indicated themineralization of Ca2+, Mg2+, P by algae which useful to the nutrient removal.