Study On The Advanced Phosphorus Removal Technology Based On The Class Ⅲ Criteria In The Environmental Quality Standard For Surface Water

In consideration of centralized wastewater treatment plants (including municipal sewage treatment plants, industrial park wastewater treatment plant, wastewater treatment plant of mixed type) phosphorus removal efficiency is not satisfactory, total phosphorus(TP) of effluent excess emissions easily, well above the receiving waters features standard to induce risk of eutrophication and other problems; based on the class III criteria in the Environmental Quality Standard for Surface Water, we developed technology to advanced removal phosphorus from wastewater treatment plant effluent, that is, by chemical coagulation or oxidation pretreatment+ coagulation, advanced treating the phosphorus to the standards required by the receiving water function area value, which will further improve the water environment and water ecology.1. Distribution characteristics of phosphorus in wastewater treatment plant effluent. This study has selected a urban wastewater treatment plants and a electroplating industrial park wastewater treatment plant to investigated its phosphorus composition. The results show that the urban wastewater treatment plant effluent of total phosphorus Concentration between 0.41-1.39mg/L, the average is 0.94mg/L, in most cases exceed emission standards; Electroplating industrial park Wastewater Treatment Plant effluent of total phosphorus concentrations of water between 1.16-1.21mg/l, exceeds the standards. Different forms of phosphorus in municipal sewage plant effluent distribution are:58.45% dissolvable inorganic phosphate,21.83% other dissolved phosphorus,19.72% floating phosphorus. Different forms of phosphorus in Electroplating industrial park wastewater treatment plant water effluent distribution are:11.21% dissolvable inorganic phosphate,76.72% other dissolved phosphorus(phosphites),12.07% floating phosphorus.2. Conventional coagulant on effluent from urban wastewater treatment plant. The urban wastewater treatment plant effluent content high phosphate, suitable for phosphorus removal by coagulation method. This study used aluminum chloride (AlCl3), ferric chloride (FeCl3), poly aluminum sulfate (PAS), polyaluminium chloride (PAC), calcium hydroxide (Ca (OH) 2) to inspecting different dosage of different coagulant on phosphorus removal effect, when 40mg/L dosage of AlCl3, FeCl3, PAS, PAC, concentrations of total phosphorus in effluent can be achieved wastewater emission standards (0.5mg/L), While the volume of calcium hydroxide in addition 120mg/l could meet the emission standards. In the dosage of aluminum chloride and chloride for 80mg/l, the total phosphorus in effluent up to Ⅲ class of surface water standards (0.2mg/l); when dosage of PAS and PAC for 100mg/L, the total phosphorus in effluent up to III class of surface water standards; And in the experimental dosage of calcium hydroxide, the total phosphorus in effluent could not reach peer emission.3. Synthesis of composite coagulants and the treatment effect on urban wastewater treatment plant water. In order to improve the flocculation efficiency, reduce processing costs, this research study on the preparation of different metal ions molar ratio compound of polysilicate aluminum ferric(PSAF), polysilicic acid with magnesium and ferric (PSAMF), and comparisons with conventional treatment coagulant effects such as ferric chloride and PAC. Results show that, on the treatment of TP content for 0.96 mg/L,CODCr content for 32 mg/L of tail water:when PSAF metal ion ratio on 1:1, more phosphorus was removal; compared with added PSAMF (1:1) or FeCl3, added PSAF (1:1) had a better removal capacity on TP, CODCr and turbidity. when the dosage of PSAF (1:1) on 0.192 mmol/1, the TP and CODCr of tail water can meet surface water Ⅲ class standard.4. Efficacious technologies of phosphorus removal in Plating industrial park sewage plant effluent. Due to the high content of phosphinates in effluent, requiring advanced oxidation pretreatment before coagulation-sedimentation process. First of all, this research study on potassium permanganate oxidation, Fenton, ozone oxidation pretreatment, The results showed that potassium permanganate Oxidation Reaction time is longer, require acidic conditions, and water and manganese ions easily exceeded; Fenton also need to adjust the PH and sludge with high volume; ozone oxidation speed and show good removal effect. Eventually choose O3+PSAF technology, to deal with the actual effluent from plating industrial park wastewater treatment plant, total phosphorus concentrations for 1.16mg/L, phosphinates content for 0.89mg/L,COD content for 76mg/L; When the amount of ozone dosage voted for 24mg/L,PSAF 0.32mmol/L, the concentration of phosphorus in effluent can fall below the Ⅲ class of surface water standards and COD values fall below A-level standards.