Analysis of Different Load Gradients for Acid Production Performance of Activated Sludge in WWTP
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 CODCr/L.After 50 days of stable operation,the acid production rate of the sludge was(606±30)mg CODCr/(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).
国家科技期刊平台
NSTL
万方数据
维普
