Study Of Start-up Of ANAMMOX Reactor And Its Sludge Granulation In ASBR

The nitrogen from wastewater is of huge danger to aquatic ecological system and safe drinkable water source. Conventional biological nitrogen-removal process has some disadvantages, such as high oxygen consumption, addition of external carbon source and the resulting huge costs of investment and operation. Recently, the cost-effective ANAMMOX (anaerobic ammonia oxidation) has been gaining more attention to solve the N-removal problem from wastewater. In this research, the start-up performance of ANAMMOX process (Anaerobic sequencing batch reactor, ASBR) for the treatment of actual municipal wastewater and its corresponding sludge granulation were investigated under different inocula, which aimed to obtain an optimized inoculating method for the quickening start-up of ANAMMOX reactor.seven different mixed sludges, i.e., river sediment and anaerobic digested sludge(Rl), river sediment and anaerobic granular sludge(R2), river sediment and aerobic activate sludge(R3), anaerobic granular sludge and aerobic activate sludge(R4), anaerobic digested sludge and aerobic activate sludge(R5), anaerobic granular sludge, river sediment and aerobic activate sludge(R6), anaerobic digested sludge, river sediment and aerobic activate sludge(R7), were used as inocula to start up anaerobic ammonia oxidation reactors in ASBR,respectively. After 180-228d operation, anaerobic ammonia oxidation processes were obtained successfully in the above-mentioned seven reactors. The average ammonia-removal efficiencies at the steady operation in seven reactors were 92.97%,95.24%,91.07%,97.03%,94.18%, 97.35% and 93.17%, respectively. It was found that the ANAMMOX reactor inoculated with mixed sludge including anaerobic digested sludge, river sediment and aerobic activate sludge could achieve the start-up more rapidly than that of other kinds of inocula, and its total inorganic nitrogen removal efficiency were the best (89.01%).It was obvious that the carriers have a certain influence on the start-up of ANAMMOX reactor and sludge granulation. The results showed that the inoculation of mixed sludge including anaerobic digested sludge and aerobic activate sludge(R8), anaerobic digested sludge,river sediment and aerobic activate sludge(R12) under pumice carrier could obtain anaerobic anmmonia oxidation successfully after 99d and 87d operation, respectively. At the steady phase of operations, the average removal efficiencies of NH4+-N in two reactors were 93.76% and 94.11%. The running stability of R8 and R12 reactors which obtained granular sludge was better than that of R9 and R13 reactors. Inoculated with mixed sludge including anaerobic granular sludge, river sediment and aerobic activate sludge, under pumice carrier(R10),under carborundum wires carrier(R11),no carrier(R6), anaerobic ammonia oxidation processes were obtained successfully after 132d,123d and 135d operation, and obtained granular sludge respectively. It indicated that anaerobic granular sludge itself could serve as the carrier of ammonia oxidation reactor.This paper investigated the start-up of ANAMMOX reactor under different kinds of sources and carriers, explored the efficient ANAMMOX granular sludge cultivation methods in treating wastewater with low-carbon source, which was of great significance for engineering application of this process in biological nitrogen removal of municipal wastewater.