Study On Model And Technology Of Shortcut Denitrifying Phosphorus Removal

Conventional biological nutrient removal technology was widely used due to itslow processing cost and any other advantages. But there are still many deficiencies,such as the contradiction existed in the process of denitrification and phosphorusremoval, the substrate competition, different sludge ages, and so on. Denitrifyingphosphorus removing bacteria (DPB) has a special function of biological nutrientremoval. In anaerobic condition, DPB decompose intracellular polyphosphate topower a life activity and synthesis intracellular material poly light alkanes acid (PHA),stored in a microbe. In anoxic condition, DPB use intracellular material PHA thatproduced in anaerobic phase, and utilize nitrate as an electron acceptor, denitrificationand phosphorus removal at the same time. Compared with traditional biologicalnitrogen removal process, DPB realize denitrification and phosphorus removalsimultaneously, achieve the goal of "one carbon source for two uses", save dosage ofcarbon source, furthermore, Absorption of phosphorus in anoxic condition, can reduceaeration rate, save energy, can also reduce the emission amount of sludge.In this research, study on mechanism and influencing factors of short-cutdenitrifying phosphorus removal was conducted, dynamic of phosphorus release andphosphorus uptake was proposed based on activated sludge dynamic model.Based on the characteristics of short-cut denitrifying phosphorus removal and theadvantages of SBR, batch tests on short-cut denitrifying phosphorus removal wereconducted, high efficient short-cut denitrifying bacteria and short-cut denitrifyingphosphorus removal bacteria were domesticated respectively, then inoculated theminto, completed the starting and optimized operation of short-cut denitrifyingphosphorus removal single sludge system. After the starting, study on CODconcentration, ammonia nitrogen concentration and pH of the system was conducted.Principal results are as follow:(1) Anaerobic phosphorus release dynamic model of short-cut denitrifyingphosphorus removal:Anaerobic phosphorus release is related to carbon source and the ratio of P聚inaccumulating phosphorus in microorganism, the relationship between anaerobicphosphorus release and carbon source C in coincidence with the unified kinetics.(2) Anoxic phosphorus uptake dynamic model of short-cut denitrifying phosphorus removal:Anoxic phosphorus uptake speed is related to the absorbed carbon source, micro-organism concentration, and phosphorus concentration in mixed solution. and therelationship between anoxic phosphorus uptake and phosphorus concentration (P) incoincidence with the unified kinetics.(3) It is shown that phosphorus release activity is a respiratory. When the carbonsource is exhausted, microorganism is still release phosphorus at a low speed. There isa saturated concentration for carbon source, if the concentration higher than this, thephosphorus release speed will reach the maximum, thereafter the phosphorus releasespeed will not change along with the increase of carbon source. The carbon source hasa critical low concentration; lower than this, the phosphorus release speed reduceobviously.(4) In the anoxic phosphorus absorption phase, if the NO2--N concentration issufficient and the TP concentration is very low, microorganism still can absorbphosphorus at a constant speed, it is shown us that can be biological phosphorusremoval can be realizated at a lower concentration(0.5mg/L). The TP concentrationhas effect on phosphorus uptake speed and has a saturated concentration, higher thanthis, phosphorus uptake speed will reach the maximum, and thereafter the phosphorusrelease speed will not change along with the increase of carbon source.(5) Based on the principle of denitrifying phosphorus removal, the carbon andoxygen do not present simultaneously, shortcut nitrification efficiency theory and theadvantages of SBR, a single sludge system that in the coexistence of denitrifyingbacteria and phosphorus removal bacteria was invented. A technical system whichapplicable to the production was established, in which the concentration of NH4+ineffluent is an important control index.(6) The domestication, starting and optimized operation of single sludge systemwas carried out in this research, when the influent COD concentration was100~220mg/L, NH4+concentration was30~40mg/L, TP concentration was4~5mg/L, systemcan obtain good denitrification and phosphorus removal effect, the effluent quality canmeet the first class of A standard. System can handle sewage of low C/N and thelowest C/N was2.5.Controlling the dissolved oxygen with the average level0.5~0.8mg/L, NO2--N accumulation rate reached60%. The average aeration rate was8.5L/h,therefore it saved aeration rate. The hydraulic retention time was40h and the volume ratio of aeration pool was33.75%. The system has characteristics of saving aeration,denitrification with low carbon and significant short-cut denitrifying phosphorusremoval. It is suitable for urban wastewater with low carbon source.There were59figures,42tables and172references in this paper.