Study On The Start-up Style Of ABR Treating Low-strength Wastewater And Meanism Of Granule Sludge

Two anaerobic baffled reactors (ABR) which have different start-up methods were used to study the granulation of sludge.The anaerobic sludge in the ABRs was taken from a wastewater treatment plant.By comparing the diameter and the feature of granular sludge forming,the effects of two methods which include changing feed CODcr and HRT were analyzed.Result of the study indicated:(1) It took 90d's to complete the start-up by the form of enlarging the feed concentration gradually at constant hydraulic retention time(HRT). Up to 80% of the CODcr was removed and the system operation was stable,but the structure of granular sludge was loose. On the other hand, it took 49d's to complete 80% CODcr removal, with higher degree of granulation, by the form of reducing the HRT at constant CODcr concentration.(2) Both the patterns of start-up were capable of enhancing granule formation.The shape of granular sludge is irregular as globular and spheroidicity,and particle diameter is 1-2mm.The granule sludge in the compartments of ABRs was compact and smooth on its surface with the Methanosaeta sp. as its priority microbes.(3) The first chamber has important effect to remove COD.The remove rate of COD in the first chamber is up to 60% in the two ABRs. 50% of the the total VFA comes from the first chamber,70%~80% of the total VFA is produced in the first two chambers.(4) I.e.bacillus,filamentous and few cocci were observed in different compartment of ABR during the study.The activity of sludge of different compartments increased along the reactor.