DO及曝气方式对磷酸盐还原除磷工艺的影响

摘要

以超高盐(7％NaCl)高磷榨菜废水为研究对象,考察了DO以及曝气方式对磷酸盐还原除磷工艺的影响.试验结果表明,DO主要通过影响生物膜内微环境的分布,导致除磷效能随DO的降低而降低.只有当DO高于5.5 mg/L时,才能构建出适合磷酸盐还原菌生长的特殊区域(ORP＞-150 mV).同时曝气量的不同,还会影响生物膜内的传质过程,进而影响微生物基质降解和膜内微生物种群分布.同DO水平下,微孔曝气较穿孔曝气有利于膜内的对流传质过程以及各菌种间的协同作用.DO过高(DO＞6.0 mg/L)或曝气搅动过大(穿孔曝气方式)会导致生物膜脱落,造成出水COD升高.因此,好氧磷酸盐还原除磷工艺宜采用微孔曝气方式,并将DO控制在6.0 mg/L.%The high-phosphorus pickled mustard tuber wastewater containing hypersaline (7% NaCl) has been studied. The effects of dissolved oxygen (DO) and aeration mode on the process of phosphorus removal by phosphate reduction is investigated. The results show that DO mainly affects the distribution of micro-environment inside biofilm, and then results in the decrease of phosphorus removal efficiency with the decrease of DO. The particular zone (ORP>-150 mV) suitable for the growth of phosphate reduction bacteria can be constructed only when DO is more than 5.5 mg/L. Besides, different aeration rate has effect on the mass transfer process and has further effect on the substrate degradation of micro-organism and the distribution of microbe species inside the biofilm. In contrast with perforated aeration,micro-porous aeration is propitious to convective mass transfer process and the synergy between the strains,under the same level of DO. DO being too high (DO>6.0 mg/L) or aerate agitation being too strong (perforated aeration mode) can result in biofilm detachment,and then lead to the rise of effluent COD. Therefore, phosphorus removal process of aerobic phosphate reduction should adopt micro-porous aeration mode, and DO should be controlled at about 6.0 mg/L.