The Research On Changing Characteristics Of Microbe Population In Activated Sludge

In this dissertation, by using the method of SBR in the lab condition, the domestic sewage was direct aerated in testing equipment. The activated sludge was cultivated step by step by controlling the environment conditions. During the process of cultivating activated sludge, the laws of change and biodegradation characteristics of microorganism population were emPH atically analyzed according to the experiment PHenomenon. Observed and analyzed large amount of zoogloeas which appeared during the process of cultivating. The influences of load on main microbe by changing the load were studied.The results showed that: 1. The activated sludge was cultivated successfully in lab by controlling the environment conditions. The microbe evolved from low-grade to high-grade during the process of cultivating. 2. During the process of cultivating, the effluent quality indexes changed with the change of main microbial community. At the early stage of cultivating, the free cells were the main microbe. The effluent effect was not good. The removal rate of COD is 40%, of BOD is 26.6%. The sludge settleability was not good enough in Aeration Tank, the value of SV₃₀ is 1.3%.At the medium stage of cultivating, the swimming type of ciliates were the main microbe. The structue of sludge is compacter than at the early stage of cultivating. The effluent effect was improving. The removal rate of COD is 60%, of BOD is 64.5%. The sludge's SV30 in Aeration Tank is 5%. At the late stage of cultivating, the Vorticella like protozoan appeared and became the dominant population. It marked the maturity of the activated sludge. The value MLSS achieved 1949.6mg/L. A large amount of branched zoogloeas made the flocs of activated sludge bigger. The removal rate of COD achieved 74%, of BOD achieved 74.2%. The sludge's SV₃₀ in Aeration Tank is 15%. The efficiency of sewage treatment is good.3. During the process of cultivating activated sludge, Branched zoogloeas appeared. The removal rate of COD increased remarkably. Branched zoogloea possesses stronger tolerance for water quality and shock loading ,which can enhance the reversibility of injured activated sludge.4. Observed the influences of changing organic load on main microbe, the results showed that high load can cause the nematode mass rearing, made the sludge abnormal and the effluent quality bad. Branched zoogloea possesses stronger tolerance for water quality and shock loading, so did not change.