The Remove Characteristics Of Zinc And Lead In Wastewater By Biological Phosphorus Removal Granular Sludge

In recent years, with the development and utilization of heavy metal, heavy metal wastewater increases day by day, and the heavy metal pollution has caused great threat to our environment and health. So the treatment of heavy metal wastewater has been taken more seriously. At present, the main treatment methods of heavy metal wastewater include chemical deposition, ion exchange, solvent extraction and so on. But these exist many problems such as high cost, poor treatment effect and secondary pollution.Biological adsorption method has been widely used in heavy metal wastewater treatment for reducing operating costs and the secondary pollution. Biological adsorption method has many advantages such as wide source, low investment, low operating cost, high adsorption efficiency,and strong regeneration ability. And now the sewage plant exists large amount of excess sludge, which is not easy to deal with, and the excess sludge is a kind of biomass waste, Making use of the excess sludge is a kind of good method for treating containing zinc and lead heavy metal wastewater, and achieved the aim of waste control by waste. But the excess sludge settleability is poor, not easy to separate defects after adsorption of heavy metals, so we need to improve the residual sludge settleability and granularity, Because granular sludge has good settling and biomass, so making use of biological phosphorus removal granular sludge removing the Zn²⁺ and Pb²⁺ in wastewater can not only improve the removal rate, and the problem of large amount of excess sludge of Sewage plant is resolved.In the alternating anaerobic/aerobic running of SBR reactor, the syetem is coexistence of granular sludge and floc sludge, which has advantages of excellent performance of nitrogen and phosphorus removal. Adopting EUB338 all bacteria probe（green） and PAOmix probe（red） FISH staining analysis was carried out on the granular sludge, the granular sludge in phosphorus accumulating all bacteria in the majority In the stability of the system. the settleability of sludge is good and the SVI is 52.2 m L/g, sludge concentration is 6830 mg/L, sludge average particle size is 565 μm. The content of Extracellular Polymeric Substances（EPS） in granular sludge was 212.72 mg/g-MLSS, the content of extracellular polysaccharide and extracellular protein was 62.16 mg/g-MLSS, 176.15 mg/g-MLSS. In addition, in a cycle, biological phosphorus removal system of COD removal rate reached 80.3%, PO43--P removal rate reached 98.4%, TN removal rate reached 77.5%.The research studied the effect of the initial concentration of Zn²⁺,sludge concentration, p H, temperature, reaction time and coexisting ions on the removal of Zn²⁺ by biological phosphorus removal granular sludge.The result showed that the maximum adsorption capacity of Zn²⁺ in 100 mg/L Zn（NO3）2 solution by biological phosphorus removal granular sludge was 29.55 mg.g-1, the average adsorption capacity was 17.54 mg.g-1 and the best conditions were p H=5,T=25 ℃ ³5 ℃ Mlss=1000 mg/L.The removal process of Zn²⁺ is is divided into fast adsorption, slow adsorption,and adsorption equilibrium three process, in accordance with pseudo two order kinetics equation.The content of Ca2+,K+, Mg2+and TP in solution,showed that the Ca2+,K+, Mg2+ occurred ion exchange with Zn²⁺ involved in the removal of Zn²⁺. After Determining the content of Zn²⁺ in the Solution, the extracellular polymer substance and the cell. It was found that the removal of Zn²⁺ also included the role of extracellular polymeric substance and intracellular phosphate accumulating organisms（PAOs）, The proportion of Zn²⁺ in the cell was 33.52%. Combined with the Fourier transform analysis of Zinc in the sludge, the main functional groups participating in the removal of Zn²⁺ were found, including Carbon chain, carboxyl, primary alcohols, polysaccharides, phosphoric acid and sulfuric acid groups.The research studied the initial concentration of Pb²⁺, sludge concentration, p H, temperature, reaction time and coexisting ions on effect of removal of Pb²⁺ by biological phosphorus removal granular sludge.The result showed that the optimal removal rate of Pb²⁺ in 100 mg/L Pb（NO3）2 solution by biological phosphorus removal granular sludge was 98.97%,and the best conditions were p H=5. Within the scope of temperature is 25℃ 40℃, adsorption capacity of Pb²⁺ keep at around 99.17 mg/g, When the sludge concentration is 1000 mg/L, the removal rate of Pb²⁺ is 98.54%.The removal process of Pb²⁺ is a first removal process（0¹5 min）, after the slow removal（15⁶0 min）, the final balance of the process（60²40 min）, in accordance with pseudo two order kinetics equation. Besides,the adsorption process of Pb²⁺ was analyzed by the adsorption thermodynamics and adsorption kinetics, the maximum adsorption capacity of Pb（NO3）2 was 199.45 mg.g-1, and the average adsorption capacity was 99.01 mg.g-1 The content of Ca2+,K+, Mg2+and TP in solution,showed that the Ca2+,K+, Mg2+ occurred ion exchange with Pb²⁺ involved in the removal of Pb²⁺. After Determining the content of Pb²⁺ in the Solution, the extracellular polymer substance and the cell. The mechanism of Pb²⁺ removal by biological phosphorus removal granular sludge was related to the interaction of Pb²⁺ and polyphosphates inside the cell of phosphorus accumulating organisms（PAOs）, The proportion of Pb²⁺ in the cell was 80.65%. Combined with the Fourier transform analysis of lead in the sludge, the main functional groups participating in the removal of Pb²⁺were found, including carboxyl group, III（protein peptide amide）, phosphoryl, phosphate group and sulfate group.