Using Aerobic Granule Sludge To Treat Domestic Sewage With Different Operate Patterns

Aerobic granular sludge is viewed as a promising biological wastewatertreatment technology. The application of aerobic granular sludge to the treatment ofthe real-life wastewater has many advantages such as compact reactor structure,higher treatment efficiency, excellent settleability, lower sludge production and thepotential in simultaneous nitrogen and phosphorus removal. However, Theconcentration of COD in China’ domestic wastewater is very low. It needs furtherstudy to use domestic sewage to cultivate granular sludge and achieve high removalof nitrogen an phosphorus. In this study, We cultivated aerobic granular sludge inSBR reactors with domesic sewage using two different operation patterns—singleaerobic stage and anaerobic/oxic pattern and acheive. This study can provide areference for the application of aerobic granule sludge to treat domestic sewage.When used domestic sewage to cultivate granular, there were some particlesformed in the reactor operated with single aerobic stage and they grew very slow.But there were no particles formed in the reactor operated with anaerobic/oxicpattern. When we raised the organic loading rate from0.4kgCOD/（m³·d）to0.66kgCOD/（m³·d）by adding external substrates in influent, the granulationprocess accelerated. Eventually we successfully cultivated naked-eye visiblegranular in both operation patterns. The granulars had a mean size of o.55mmcultivated with single aerobic stage and a mean size of0.45mm cultivated withanaerobic/oxic pattern.When the granular matured in the reactor operated with single aerobic stage,the effluent COD concentration was40⁶0mg/L,NH₄⁺-N was blow4mg/L, TN was20²3mg/L with a average of22.66mg/L, the remove rate of phosphorus was10%²5%. Then we optimized the aeration rate, the remove rate of TN improved.When the aeration rate was0.4L/min，the remove rate of TN was highest, the TNconcentration in effluent was16²0mg/L and reached First class B standard of“Pollutant Discharge Standard of Urban sewage treatment plant”（GB18918-2002）.But the remove rate of phosphorus didn’t improve.When the granular matured in the reactor operated with single aerobic stage,the COD concentration in effluent was40⁶0mg/L,NH₄⁺-N was blow4mg/L, TNwas blow15mg/L with a average concentration of13.26mg/L and remove rate ofabove67%;PO₄^3--P in effluent was blow0.3mg/L and remove rate was above90%. The COD concentration in effluent reached the First class and NH4+-N,_TN and PO43-P reached the First class A standard of "Pollutant Discharge Standard of Urban sewage treatment plant"（GB18918-2002）.When operated with the anaerobic/oxic pattern, to achieve completely aerobic granulation needed only ten more days compared to the single aeration stage under a OLR of0.66kgCOD/（m3-d）. The physical and chemical properties of mature granular achieve with both operate patterns was not notable. But there was obvious differents on the remove rate of pollutants. The remove of TN and PO43-P in the reactor operated with anaerobic/oxic pattern was higher than that in the reactor operated with single aeration stage. So we suggested using aerobic granule sludge to treat domesic sewage with anaerobic/oxic pattern.Based on the operation of the lab scale SBRs in this study, we investigate the application of aerobic granular sludge in practical engineering, including the operation mode, the reactor structure and cultivation and stable operation of aerobic granular.