Anaerobic ammonium oxidation (anammox) is an autotrophic denitrification process that has broad application potential for treating coking wastewaters. The present study estimated the effects of thiocyanate (SCN-), a common pollutant in coking wastewaters, on anammox processes and microbial communities in anammox reactors for over two years of continuous exposure. The addition of SCN- (from 50 to 200 mg L-1) showed negative effects on the denitrification performance of the anammox reactors. In SCN--dosed reactors, increased effluent ammonium concentrations indicated the occurrence of SCN--based biodegradation processes. Microbial analysis revealed that the anammox species almost disappeared in the reactor dosed with SCN- at over 100 mg L-1. Instead, an abundance of chemolithoautotrophic bacteria belonging to the Thiobacillus genus demonstrated a linear increase with SCN- addition. The competition between anammox species and SCN--degrading microorganisms was expected to dominate the inhibition effects of SCN- addition on the performance of anammox reactors.
Keywords: Anammox; Microbial community; Thiobacillus; Thiocyanate; Thiocyanate-based denitrification.
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