| Most scholars'research at home and abroad on anaerobic phosphorus releasing mechanism are in an external carbon source conditions, but no plus carbon source circumstance of phosphorus releasing mechanism is likely to nature's most widespread phosphorus releasing mechinism, which is of great significance on excess sludge, heavy metal, radioactive elements, the synthesis of PHB, the landfill' phosphorus pollution, eutrophication and so on..Taking the phosphate-rich sludge as the research object in an A/O sewage treatment process, which is aquathermolysisde in no plus carbon source conditions of pH, nitrate concentrations, VFAs (scfa), chitosan bacteria, glycogen influence on sludge phosphorus releasing in a self-made organic glass tube. In order to discuss the factors and mechanism affecting phosphate release, a series of indicators of sludge properties such as TCOD, SCOD, TSS, VSS and poly-β-hydroxybutyrate content (PHB) weremonitored. The results indicated that:1. The pH of anaerobic phosphorus releasing is a very important restrict factor, low pH lead intracellular phosphorus enrichment to hydrolysis, the dissloution P-concentration in acidic condition is significantly higher than the alkaline, but anaerobice phosphorus mass increase as the pH rise,and high pH leads phosphate deposits. When pH is greater or equal 7.5, the GAOs is not influence on PAOs, which is dominance in the system..2. nitrate concentrations inhibit the releasing of phosphorus, when nitrate concentrations is higher than 100mg/L, the inhibition is obviously, when is less than 50 mg/L, the inhibitory effect is not obvious.So the nitrate concentrations should be strictly controlled below 50 mg/L.3. Lots of volatile fatty acids(VFAs)are produced during the course of digestion.which are ethyl, butyrate,propionic acids, the ethyl acid is the most one while the propionic is at least. And the total production reach peak about 24hours, which can be further speculateed that the process is over about 24hours.4. When the microorganisms in glycogen burn out, the absorption of VFAs break and the PHB will no synthesis, and the process of releasing phosphorus end. glycogen is a restricted factor for releasing phosphorus process of sludge.5. the concentration of P-PO43- increased throughout the course of the study and was negatively correlated with the concentrations of VSS and TCOD, but positively correlated with the concentrations of SCOD, PHB, and NH4+-N.According tometrology relationships, although the phosphate releasemechanics are different, thePHB content in the phosphate-rich excess sludge changes in ways similar to the PHB in activated sludge. Therefore themechanism of phosphate release from phosphate-rich excess sludgemay be similar to that of activated sludge.6. The interruption of anaerobic VFAs and phosphorus-release would be occurred when the glycogen in the phosphorus-accumulating-organisms was exhausted. The mean ratioof△mP/△mPHB is 0.475,△mGLY/△mPHB is 0.512,△mP/△mP-ploy is 0.298 respectivel, which is Accord with theoretical of 0.48,0.50,0.31.7. According to the production of volatile fatty acid,it can be seen that which is higher than 0.12gSCOD/gMLSS, so the nutrient-supplye is enough to composite PHB.8. No plus carbon sources of phosphorus-richs ludge is winnable to finish the process of anaerobic fermentation and phosphorus releasing.In addition, among the sludge phosphorus releasing behavior,except microbial activite,which still have adsorption, desorption, precipitation, biological death disintegration such as complicated physical and chemical behavior, the specific mechanism is also need further research..
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