Enhancement Start-up For The Anaerobic Sequencing Batch Reactor

The effect of coagulant was analyzed on the start-up for the anaerobic sequencing batch reactor, which was operated at mesophilic conditions(35C) and was fed nonfat dried milk as substrate with minerals and alkalinity. The type of granular sludge formed in this reactor was analyzed in addition.During the laboratory-scale tests, by comparing the overall effects on anaerobic sludge, the most positive coagulant was selected from the three ones. Based on this fact, for the selected one the most positive amounts and way of feeding were decided by similar ways. As a result, among the three coagulants of poly aluminum chloride(PAC), polyacrylamide(PAM) and polyquantemary amine(PQA), PQA had the most positive effect on the anaerobic sludge. It was recommended that the amount of PQA be 1.6~3.2mg/gMLSS and be fed by 10 times, while the way of feeding be once two days.On the basis of the conclusion above, a pilot test on the start-up in the ASBR was operated. Since the day the reactor was fed municipal anaerobic digestion sludge, the average diameter of granular sludge in the reactor fed coagulant was above 0.5mm on day 61. Compared with the control system which was operated at the same way except the feeding of coagulant, it shorted the related time 25 days. On day 86, the average diameter of granular sludge in the reactor fed coagulants was 0.73mm, whereas the control one was 0.55mm. Obviously, the feeding of coagulants enhanced the start-up for the ASBR. Itwas also noted that the activity of seeding sludge, the process of promoting organic loading rate and the configure of reactor exerted great effects on the start-up for the ASBR.As was shown in the electron micrograph of granular sludge, Methanosarcina was the predominant colony in the granules. This type of granular sludge have higher COD removal rate than other types when loaded organics of high concentration. The ways of batch feeding and flexible decanting of ASBR and addition of trace elements could give reasons to the formation of this type of granular sludge.