Study On Purification For Livestock Waste Water By Immobilized Microcystis Aeruginosa

Microcystis aeruginosa as a kind of dominant specie on algal bloom from China was chosen for experimental material in this dissertation, SA and PVA as the immobilized carrier were experimented for immobilized Microcystis aeruginosa respectively. The author adopted orthogonal experiment to determine the optimum condition of using SA/PVA to imbed and immobilize Microcystis aeruginosa. By means of experimental simulation wastewater, this dissertation made in-depth research on the efficiency of SA/PVA removing N,P in different kinds of involved factors. Also, the optimum imbedding condition of immobilizing Microcystis aeruginosa was adopted to dispose the wastewater from livestock farm, and this dissertation investigated the growth of immobilized Microcystis aeruginosa and the efficiency of SA/PVA removing N and P in the practical wastewater.This orthogonal experiment was indexed by balling, mechanical strength, transferring time and the ability to purify NH4+-N/TP; and factors influencing the above indexes were investigated, including the concentration of imbedding agent, the concentration of cross-linker, the time of cross linkage, the imbedding proportion and so on. Consequently, the optimum imbedding condition based on SA gelatin balls was obtained, i.e., the concentration of imbedding agent:3% SA; the concentration of cross-linker:5% CaCl2;the time of cross linkage:2h; the imbedding proportion:1:1(VSA:VAlga); and also the optimum imbedding condition based on PVA gelatin balls was obtained, i.e., the concentration of imbedding agent:10% PVA-0.5% SA; the concentration of cross-linker:mixture solvent of saturated boric acid and 2% CaCl2; the time of cross linkage:12h; the imbedding proportion: 1:2(VPVA-SA:VAlga)-Under the above conditions, immobilized Microcystis aeruginosa had better performance on biological activity, mechanical strength and transfer.By means of experimental simulation wastewater, this dissertation made in-depth research on the efficiency of SA and PVA removing N,P in different kinds of involved factors. The results indicated that the configuration, i.e., illumination:2500lux-3000lux; temperature:25℃; pH:8, was best fit for immobilized Microcystis aeruginosa removing N,P in the simulation wastewater; and the configuration, i.e., high density gelatin(5×106); the proportion of gelatin balls to wastewater:10%-14%; the proportion of N/P in the wastewater:5:1-10:1, was better for removing N,P in experimental simulation wastewater.By means of immobilizing Microcystis aeruginosa on SA/PVA and purifying different concentration of wastewater from livestock farm, the author studied on the removal rate for TN, NH4+-N, TP, PO43-P and COD, the growth of Microcystis aeruginosa in the purifying process and the change of Chlorophyll a content. Meanwhile the author drawed a parallel between immobilized and non-immobilized Microcystis aeruginosa, and studied on the influence on pH from immobilized gelatin cells and their leakage. The results indicated that after six days of purification for wastewater, immobilized Microcystis aeruginosa had better effect on removing N,P than suspended algae obviously; for different concentration wastewater from livestock farm, the average removal rate of SA to each involved component was higher than PVA; Compared with suspended algae, the amount of immobilized algae and the content of Chlorophyll a were higher; In the later period of experiment, the amount of algae and the content of Chlorophyll a about PVA were higher than S A; pH had been increasing in the early days, leveled off and reached 9 finally; At the beginning, the leakage of SA gelatin cells kept greater than PVA gelatin cells, and finally the leakage of SA gelatin cells almost reached the double of PVA, which showed that immobilized algae by PVA had higher strength.