Study On Building The Phosphate Reduction System Of Hypersaline & High Phosphate Wastewater

In general, the high phosphorus treatment technics were mainly absorb, chemical and biological technics. The absorption has disadvantages of anti-jamming in sorbent, loss in dissolve and difficulty in regeneration, etc, while the chemical phosphorus removal technic was problematic in high running cost, huge chemical sludge produce, difficult disposition, etc. And, there is disadvantage of mass in discharge of rich-phosphorus sludge in the PAO biological phosphorus removal technique. In recent years, with the aggravation of nitrogen and phosphorus pollution and eutrophication of water environment, as well as the improvement in discharge standards of nitrogen and phosphorus, it is urgent affairs to exploit a highly efficient phosphorus technic. This thesis, focusing on hypersaline and high phosphorus wastewater, studied the newly phosphorus removal technique based on phosphate bio-reduction to achieve high efficiency and low cost in phosphorus removal and decrease in discharge of surplus sludge.Aiming to build the phosphate bio-reduction in reactor, the thesis systemically researched on the effect of organic loading, temperature and influent pH value on building the phosphate bio-reduction. During orthogonal experiment, the integration influence of each factor was discussed, and the quantitative orthogonal regress equation in anaerobic was found. By comparing some building manners of phosphate bio-reduction, and adopting startup manner of aerobic first and anaerobic subsequently, it succeeds in building the phosphate bio-reduction system in biological reactor for the first time, and gained the manner of building system and the key control parameters. Besides, quickly building of halophilic system was achieved in this thesis. The main conclusions are as follows:â‘ When adopting direct anaerobic startup, the salinity shift manners, organic loading and temperature had more impact on the removal of COD, but minor impact on the removal of phosphate. With the temperature of 30℃, organic loading of 1.0kgCOD/m³Â·d, the salinity shift manner adopted 2.0% initial salinity (NaCl calculated, take the same as follows); when the removal rate of COD achieved 70% in some salinity, and then upgraded 0.5% salinity each time until the goal salinity, the time of reactor complete startup was 127d, the removal rate of COD achieved 70%; however, under the same condition, the removal of phosphate was low, the top removal rate was about 15%. The predominance bacterium was halophilic bacillus in the reactor.â‘¡When adopting startup manner of aerobic first and anaerobic subsequently, the salinity shift manners had no prominent impact on the removal of COD and phosphate in the condition of aerobic. The organic loading had minor impact on the removal of COD. When the organic loading was 0.5kgCOD/m³Â·d and 1.0kgCOD/m³Â·d, the removal rate of COD all achieved more then 90%; but the organic loading has marked impact on the removal of phosphate. When the loading was 1.0kgCOD/m³Â·d, the removal rate of phosphate was rather higher, keeping about 40%. This way, the predominance bacterium was halophilic bacillus in the reactor. During the aerobic startup, the reactor didn't discharge the surplus sludge, and the sludge age of it was rather long, which was a long sludge age system.â‘¢After the stabilization of reactor anaerobic running which aerobic startup first, the organic loading and temperature had the rather prominent impact on the removal of COD and phosphate, but the influence of influent pH value was minor. The integration influence of organic loading, temperature and influent pH value to build the phosphate bio-reduction by orthogonal experiments was studied. The main results indicated that the organic loading has marked prominent impact on the removal of COD and phosphate, temperature second, and the influence of influent pH value is no prominence. Besides, the thesis achieved the regress equation between Nv, t and effluent COD and the regress equation between Nv, pH, t and effluent phosphate, which were COD=8122.5+1378NV-241.8t+322(NV-1.5)(t-27.5) and PO₄^3--P=122.87+5.64NV- 1.13t-6.73pH, respectively. When the temperature is 30℃, organic loading is1.0kgCOD/m³Â·d and influent pH value is 7.1, the removal rate of COD and phosphate were rather higher with 73.73% and 44.88% respectively, which preliminarily built the phosphate bio-reduction system.â‘£Through the study of the influence of oxygen condition on phosphate bio-reduction system, conclusions were drawn as follows: the concentration of NO3--N could accelerate the phosphate bio-reduction process; the removal rate of phosphate in aerobic condition was higher than that in anaerobic condition, the removal rate of phosphate was 42.43%, which was higher than 25.61% in anaerobic condition.The contents of this thesis were strong in pertinency, and the results were important in practicality value, which could provide theory and technic support in exploiting the new biological phosphorus technic based on phosphate reduction, and the thesis has considerable cutting-edge, which was a reformable technic to the biological phosphorus removal technics in existence. And, the research has an important realistic significance.