| At present eutrophication caused by phosphorus pollution becomes so serious that water bloom and red tide occur repeatedly, which endangers heavily the living surrounding of human. The biological reduction of phosphate to phosphine can be used to develop a new biotechnology for anaerobic phosphate removal from wastewater. Financially supported by the National Natural Science Foundation of China (No.50278084), the research on dephosphorization conditions and dephosphorization characteristics of phosphate reducer was carried out and the effect of phosphine on anaerobic microbial ecology was investigated. The main achievements were as follows:By determining total P contents in the culture both at the beginning and at the end of batch cultivation, the phosphate reduction activities of cow manure, swine manure, chicken manure and two kinds of anaerobic activated sludge were compared and the swine manure was found to be the best inoculum. Based on the result the swine manure was mixed with two kinds of anaerobic activated sludge at the mass ratio of 3:1:1 and the mixture was then used as seeding sludge to test the optimal conditions for anaerobic phosphorus removal. The results showed that the optimal carbon and nitrogen sources were glucose and peptone, respectively. The optimal initial pH value was 6.5 and the optimal temperature was 35℃. Under the optimal conditions the maximal phosphate removal efficiency was achieved during the four-day cultivation. No obvious effects on the anaerobic phosphorus removal were found when molybdenum and other trace elements as well as reducing agent sulfide were added into the culture media.The anaerobic removal of three kinds of inorganic phosphorus compound was tested. When glucose was electron donor and the ratio of glucose to phosphorus compound was 1:1, the removal efficiencies of phosphate, phosphiteand hypophosphite ranged from 1.99% to 6.28%, from 2.06% to 6.26% and from 3.05% to 8.28%, respectively, at concentrations of 50-400 mgP/L. Phosphine content was determined in the headspace of culture grown on phosphate, phosphite and hypophosphite, separately, and the phosphine accumulation was discovered to be the highest with hypophosphite. The results indicated that the reduction of hypophosphite to phosphine was carried out most easily among three kinds of phosphorus compound. At the same amount of electron donor the removal efficiency of hypophosphite was 1.23 and 1.15 times as large as that of phosphite and phosphate, respectively, and the removal efficiency of phosphite was close to that of phosphate. The dehydrogenase activity increased with the increase of phosphite and phosphate content in the culture, respectively. The change of dehydrogenase activity had the same trend as that of the hypophosphite removal efficiencies at different P levels. The results showed that the dehydrogenase had a certain correlation with anaerobic P conversion.The effects of phosphine as an end product of phosphate reduction on growth and activity of anaerobic bacterial populations were investigated by using batch experiment. The results showed that high phosphine levels had an adverse effect on methane production, sulfate reduction and denitrification. Compared with that in the controls without phosphine the maximum methane content in the culture with phosphine decreased 37% and the half life of sulfate reduction in that lengthened for 62% with glucose as substrate. The half inhibitory concentrations of phosphine to methane formation and sulfate reduction were 895.8 mL/m3 and 583.8 mL/m3, separately. However, with acetate as substrate, the maximum methane content in the culture with phosphine decreased 22% and the half life of sulfate reduction in that lengthened for 19%, compared to that in the controls. The half inhibitory concentration of phosphine to methane formation from acetate was 940.0 mL/m3. The phosphine concentrations of 971 mL/m3 and 500 mL/m3 were found to inhibit the NO3"-N transformation at a concentration of 70 mg/L. The 971... |
PDF Full Text Request