Selecting suitable seed sludge for anammox enrichment: Role of influent characteristics and reactor operational conditions.

The study investigated the suitability of three different sludge collected from diverse environments for anammox process establishment. Sludge was collected from SBR (S1) treating municipal wastewater, nitrification tank (S2), denitrification tank (S3) treating fertilizer industrial wastewater. The microbial community in the seed sludge was studied. The presence of anammox bacteria was detected only in seed sludge S2 treating high NH ₄ ⁺ -N wastewater. Seed sludge S3 showed high abundance of denitrifiers due to NO ₃ ^- -N and organic carbon rich environments in denitrification tank. The anammox start-up performances of sludge were assessed. S2 achieved start-up within 65 days whereas S1 and S3 showed longer start-up period of 79 and 93 days, respectively. S1, S2, S3 achieved nitrogen removal rate of 148.84 gN m ^-3 day ^-1 , 159.70 gNm ^-3 day ^- 1 and 120.90 gNm ^-3 day ^-1 , respectively. Influent NH ₄ ⁺ -N, NO ₃ ^- -N and organic carbon concentrations governed the abundance of anammox and denitrifying bacteria in seed sludge thereby impacting the anammox start-up.
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