Study On The Effect Of Heavy Metals With Phosphate Accumulating Bacteria In Wastewater

In this paper, the effect of heavy metals on the ability of phosphate accumulating bacteria purifying municipal sewage was studied by adding 4 kinds of solutions containing different contents of Cu²⁺, Zn²⁺, Cr⁶⁺, and Cd²⁺ to sewage. The results showed that the lower the concentration of every kind of heavy metals were helpful to phosphate accumulating bacteria, and the higher the concentration of heavy metals in municipal sewage, the more serious the poisoning. At high concentration of heavy metals in municipal sewage, the removal rate of PO₄^3--P and CODcr was gradually reduced with the increase of heavy metals'concentration. In addition, each heavy metal had its own extent of effect on the ability of phosphate accumulating bacteria. Among 4 heavy metals, Cd²⁺, Cr⁶⁺ and Cu²⁺ had more toxicity to phosphate accumulating bacteria; however, Zn²⁺ had weaker toxicity than others. The tolerance of phosphate accumulating bacteria to heavy metals was listed as follows: Cd²⁺ 0.50 mg/L, Cr6+ 1.00 mg/L, Cu²⁺1.00 mg/L, Zn²⁺ 3.00 mg/L.The effect of heavy metal copper on the ability of phosphate accumulating bacteria purifying municipal sewage was studied in stage research. And also the system to contain in heavy metal copper sanitary sewage month time change in processing was analyzed. The result indicated that, micro concentration of heavy metal copper was helpful to phosphate accumulating bacteria. At high concentration of heavy metals in municipal sewage, the removal rate of PO43--P was gradually reduced with the increase of heavy metal's concentration.At low concentration of metal Cu²⁺, the removal rate of CODcr basically wasn't reduced.The tolerance of the phosphate accumulating bacteria system to four kind of different heavy metals (copper, zinc, lead, cadmium) was studied. The results showed that the low dose heavy metal Cu²⁺, Zn²⁺, Pb²⁺, the Cd²⁺ all have their own extents of effect on the ability of phosphate accumulating bacteria. Along with the dosage unceasing increase, the system can have the resistance mechanism to the heavy metal, and restores gradually normally eliminates the phosphorus rate. At the dosage heavy metal of Cu²⁺, Zn²⁺, Pb²⁺, Cd²⁺ in the experiment, the influence to the system which degrades the COD ability produces to be very small. The tolerance of phosphate accumulating bacteria to heavy metals was listed as follows: Cu²⁺>Cd²⁺>Pb²⁺>Zn²⁺. The tolerance of the phosphate accumulating bacteria system to heavy metals can be greatly improved through the suitable domestication. Under the heavy metal ion function, microorganism's community structure can change, including protozoon's microorganism suppresses. Compared to the domesticated microorganism in active sludge processing including the heavy metal ion waste water, the domesticated active sludge system had huge superiority, therefore domesticated microorganism processing has huge potential to be used in the active sludge treatment plant to contain the metallic ion waste water.