A^2O工艺中反硝化除磷及过量曝气对生物除磷的影响

Anoxic biological phosphorus removal and effect of excessive aeration on biological phosphorus removal in A^2 O process

如何有效提高城市污水厂除磷效率一直是研究的热点,而反硝化除磷菌可以在碳源不足的条件下,通过“一碳两用”的方式同时实现反硝化脱氮和吸磷作用,是一种新型高效的技术.试验以啤酒废水为研究对象,验证了厌氧-缺氧-好氧(A2O)工艺中反硝化除磷现象的存在及其对系统脱氮除磷的影响.试验结果表明,A2O系统稳定运行时,反硝化聚磷菌在缺氧区可利用在厌氧段储存的PHB大量吸磷,同时氮也得到去除,计算表明缺氧除磷量可占厌氧总释磷量的71.3%,另外可节约曝气能耗25%.无论系统进水COD浓度从200mg.L-1变化为400mg.L-1,COD、总氮和总磷去除率总能保持较高水平,平均出水总氮和总磷浓度分别小于10mg.L-1和0.30mg.L-1.另外发现,过量曝气对系统除磷具有明显的影响,导致除磷效率降低,甚至会产生不吸磷现象,系统需要经过约一个污泥龄时间才能恢复其吸磷能力,所以应加强系统曝气的控制.

A pilot-scale nutrient removal activated sludge system, based on the A^2O configuration, was used to treat brewery wastewater. In the experiment, the existence of denitrifying phosphorus removing bacteria （DPB） and the contribution of DPB to phosphorus removal was observed. The tests showed the average total amount of anoxic P uptake accounted for 70 % of the total amount of P uptake of the system at steady state, oxygen requirement could be decreased significantly （about 25%）. Denitrifying phosphate removal resolved the competition for organic substrates between Poly-P organisms and denitrifiers under lower organic loading. Effluent total-P concentration could achieve less than 0. 30 mg · L^-1 and average effluent total-N was less than 10 mg· L^-1. It is clearly demonstrated that the phosphorus uptake almost stopped in an over-aerated system, the released phosphorus could not be taken up fully again. Consequently, incomplete phosphorus uptake led to temporary reduction of biological phosphorous removal efficiency. It took about the time of one sludge age to eliminate that disturbance.