Study On Pb Immobilization By Accumulated Phosphorus Sludge

The lead is a wide distribution elements in the nature, The lead caused the environment pollution through natural phenomenon and human activities, lead can enter the body through different channels, and accumulate in the body. The lead have great harm to human body, and human began to pay more attention to lead pollution treatment. According to the domestic and foreign present on lead pollution research progress, this table research the phosphorus sludge fixed lead pollution effect and long term stability.The experimental research results are as follows:1.After the training, the polyphosphate accumulation bacteria activated sludge has strong anaerobic release phosphorus ability. When the pH is less than6.5, the chemically dissolved phosphorus are likely to is dominant, and the pH is more litter, the content of chemical phosphorus is more higher, and when the pH greater than6.5, the phosphorus are likely to the microbial released. In appropriate pH range, the polyphosphate accumulation bacteria activated sludge release phosphorus content increased with pH value rise, but too high pH value against anaerobic release phosphorus. The nitrates in high concentrations can inhibit anaerobic sludge phosphorus enrichment release phosphorus.2. The polyphosphate accumulation bacteria activated sludge has good removal effect used to react with the lead nitrate and the lead acetate, The removing rate reached99%, and the remove effect of lead acetate is better than lead nitrate. The sludge to remove lead ion in the solution by ion exchange methods when experiment starting, Along with the experiment, the sludge remove lead ions in the solution is mainly sludge release phosphate and sulfur with lead ion occurred inorganic precipitation reaction, the sludge also through the enzyme reaction lead ions into the cells accumulations. At the end of the reaction, the lead in the residual sludge was stable and presented as the leads combinated by organic and sulfide and the residual lead, accounted for more than95%, The other form of lead was less, the lead in residual sludge was largely made up of phosphate lead. 3. The polyphosphate accumulation bacteria activated sludge release phosphorus less at anaerobic conditions, in strong acid environment, the sludge release phosphorus amount more than pH neutral environment. The sludge adsorption ability of Pb2+is very strong, it can completed adsorption processes within15minutes. It’s ability of removing Pb2+in waster is falling at strong acidic environment conditions.4. Because of the bacteria breeding gradually in A2O process and in the course of cultivation, so the bacteria concentration distribution in the sludge, and the size is more one hundred to hundreds of nanometer, the collection is mainly the organic polymer cemented by microbial secretion. The main components of lead deposits is phosphorus ore or phosphorus ore, and galena is very small. The formation of phosphoric acid lead including two stages of fast adsorption early and absorption of phosphate nano precipitation. After the lead adsorbented on the cell surface, it reacted with phosphate released by phosphorus accumulating bacteria on the cell surface. Or the lead reacted with poly phosphate generate lead phosphate precipitation, when it diffuses into the vacuole. therefore, the lead phosphate primary distributed in cell surface or internal. The release of phosphorus mainly comes from the bacteria release phosphorus, some may come from heavy metal toxic induced the cells to break down and release phosphorus.5. The lead phosphate precipitate is nanometer organic polymer secreted by a microorganism. In the sequential extraction of organic matter or sulfide, the nanometer lead phosphate is likely to dissolved quickly, The nano phosphate crystal fully exposed to extract solution with the dissolution of the organic matter, the phosphate lead of nanometer scale is likely to occur rapid dissolved under the factors such as the activity of nano itself, organic solvent and low pH value, the nanometer phosphate lead is likely to dissolved quickly, and more than40%of the phosphate lead was lost in step extraction organics or sulfide extraction.