不同负荷梯度对污水厂活性污泥的产酸性能分析

Analysis of Different Load Gradients for Acid Production Performance of Activated Sludge in WWTP

活性污泥发酵产酸有利于实现污泥资源化利用。文中以污水厂活性污泥为研究对象,在污水厂现场采用半连续碱性发酵方法,探究了先低梯度再高梯度长周期提负荷过程中污泥的产酸性能。结果表明:低梯度提负荷运行阶段,第112 d污泥的酸化率达到最大值,且乙酸占比为71.67%,游离氨(FA)质量浓度为(208±39)mg/L,低于250 mg/L,对微生物无抑制性。在高梯度提负荷阶段,第192 d污泥的水解率提高至41%,丁酸与戊酸的占比增加,FA质量浓度逐渐升高至450 mg/L时产酸性能下降。低梯度的优势菌Guggenheimella(24.88%)演变为高梯度的unclassified_Clostridiales(37.08%)。此外,当负荷为3250 mg TSS/(L·d)时,挥发性脂肪酸(VFAs)达到最大值(3339 mg COD_(Cr)/L)。经过50 d的稳定运行,污泥的产酸率为(606±30)mg COD_(Cr)/(g VSS)。合适的负荷梯度有助于污泥中有机物在碱性条件下(pH值=10.0±0.05)长期稳定连续生成VFAs。

Activated sludge fermentation to produce acid is beneficial to sludge resource utilization.The acid production performance of activated sludge was investigated under the operation condition of first low gradient and then high gradient increasing load in WWTP by the semi-continuous alkaline fermentation method.Results showed that the sludge acidification efficiency reached the maximum on the 112th day for the low gradient increasing load stage,and acetic acid of acetic acid was 71.67%.Additionally,the concentration of free ammonia(FA)was(208±39)mg/L.It was less than 250 mg/L,implying that and there was no inhibition on microorganisms.While for the high gradient increasing load stage,the hydrolysis efficiency of sludge increased to 41%on 192 d,and the proportion of butyric acid and valeric acid gradually increased.The volatile fatty acids(VFAs)concentration started to decline until the FA reaches 450 mg/L.The dominant bacterium was Guggenheimella(24.88%)with low gradient stage,which evolved into unclassified_Clostridiales(37.08%)under high gradient stage.Furthermore,when the load was 3250 mg TSS/(L·d),the VFAs reached a maximum of 3339 mg COD_(Cr)/L.After 50 days of stable operation,the acid production rate of the sludge was(606±30)mg COD_(Cr)/(g VSS).The appropriate load gradient is conducive to the long-term stable and continuous formation of VFAs by organic matter in sludge under alkaline conditions(pH value=10.0±0.05).