低DO协同负荷引发的黏性膨胀和丝状菌膨胀

Activated sludge bulking initiated by cooperation of low DO and sludge loads

为了研究低DO下负荷对污泥膨胀的影响,采用SBR反应器,在DO〈0.5 mg.L-1,pH 7.2~8.0,温度（23±0.5）℃,MLSS 3000~3500 mg.L-1,负荷分别为0.22、0.44、0.66 g COD.（g MLSS）-1.d-1的条件下,研究不同负荷下的SVI变化趋势、污泥膨胀类型、引发原因、耗氧速率、脱氮除磷效果与同步硝化反硝化率。结果显示,低DO下（〈0.5 mg.L-1）,负荷0.22 g COD.（g MLSS）-1.d-1时未发生污泥膨胀,随着负荷升高,污泥沉降性恶化加快。并且不同负荷引发的污泥膨胀类型不同,在负荷0.66 g COD.（g MLSS）-1.d-1时发生黏性膨胀,而负荷0.44 g COD.（g MLSS）-1.d-1时发生丝状菌微膨胀。黏性膨胀时出水氨氮及磷去除效果变差,但丝状菌膨胀时出水水质并没有受到影响,且比吸磷速率更快,出水SS更低。未发生污泥膨胀时同步硝化反硝化率最大,丝状菌膨胀时次之,黏性膨胀时最小。SOUR过高时,很可能伴随着污泥沉降性变差和出水水质恶化。

The SVI,sludge bulking type,SOUR,the denitrification and dephosphorization efficiency,SND rate of activated sludge system were investigated in a sequencing batch reactor（SBR）at low DO loading（0.5 mg·L-1）,pH 7.2—8.0,temperature（23±0.5）℃,MLSS 3000—3500 mg·L-1.The results showed that at low DO levels,the bulking of sludge is not observed at load of 0.22 g COD·（g MLSS）-1·d-1,while the deterioration of SVI accelerates and type of sludge bulking changes with the increase of sludge loads.At 0.66 g COD·（g MLSS）-1·d-1 loading,non-filamentous bulking of activated sludge is observed and the denitrification and dephosphorization efficiency goes down,but at 0.44 g COD·（g MLSS）-1·d-1 filamentous bulking takes place,the denitrification and dephosphorization efficiency keeps well,the rate of phosphorus absorption is faster,and SS in effluent is almost negligible.The SND rate is the maximum at no bulking of activated sludge,medium at having non-filamentous bulking,and minimum at filamentous bulking.If SOUR was over-high it is very possible to droop sludge settleability and to deteriorate water quality in effluent.