曝气深度对好氧颗粒污泥稳定性的影响

摘要

探索了浅层曝气原理与气提式序批反应器(SBAR)及好氧颗粒污泥(AGS)技术联用的可行性.逐步提高曝气头在水面下的位置(130~30cm),发现曝气深度对SBAR内流场环境有重要影响,表现为曝气量的不断增大(400~500L/h)、而溶解氧(DO,8.00~5.88mg/L)及循环速度(27.25~11.39cm/s)均不断减小.AGS在曝气深度≥70cm期间能较好地维持其稳定性.期间AGS的污泥体积指数(SVI)在16.19~43.13mL/g、胞外聚合物(EPS)为181.65~262.46mg/gMLSS、颗粒化率为80%~88%及污泥比耗氧速率(SOUR)在42.42~49.54mgO2/(gMLVSS·h) ,对化学需氧量(COD)、总无机氮(TIN)及总磷(TP)的去除率分别在87%、94%及86%以上.然而,当曝气深度≤50cm后,由于水力剪切力被大大削弱及氧的传质阻力明显增加,造成了颗粒化率及EPS迅速减小至46%及111.65mg/gMLSS,对COD、TIN及TP去除率最终下降至43%、70%及47%,并出现了明显的解体,最终导致了系统的异常.与底部曝气的序批式反应器(SBR)相比,基于浅层曝气原理的SBAR内的流场更加均匀,并具有降低AGS反应器曝气能耗的潜力.%Principle of shallow aeration was applied to aerobic granular sludge(AGS) technology in a sequencing batch airlift reactor(SBAR),and its feasibility was explored. Location of aerator under water surface was gradually decreased(130—30cm). It was found that aeration depth had an important influence on the flow field of the SBAR,which characterized by increase of aeration rate(400—500L/h)and decrease of dissolved oxygen(DO,8.00—5.88mg/L)and circulation velocity (27.25—11.39cm/s). Stability of AGS could be maintained when the aeration depth was more than 70cm. During these periods,sludge volume index(SVI)was between 16.19mL/g and 43.13mL/g, extracellular polymeric substance(EPS)was between 181.65mg/gMLSS and 262.46mg/gMLSS, granulation rate was between 80% and 88% and specific oxygen uptake rate(SOUR)was between 42.42mgO2/(gMLVSS·h) and 49.54mgO2/(gMLVSS·h),and removal rates of COD,total inorganic nitrogen(TIN)and total phosphorus(TP)were over 87%,94% and 86% respectively. However, when the aeration depth was less than 50cm,the granulation rate and the EPS rapidly decreased to 46% and 111.65mg/gMLSS,and the removal rates of COD,TIN,and TP eventually reduced to 43%,70% and 47%. The reason included greatly decrease of hydraulic shear force and significantly increase of oxygen mass transfer resistance in the SBAR. Additionally,obvious disintegration of AGS was observed,which eventually led to instability of the system. Compared with bottom aeration of sequencing batch reactor(SBR),the flow field of SBAR based on the principle of inka aeration was more uniform,which had the potential to reduce aeration energy consumption of AGS reactor.