Simultaneous biodegradation of pyridine, indole, and ammonium along with phenol and thiocyanate by aerobic granular sludge

Abstract

Aerobic granular sludge potential for concurrent biodegradation of two nitrogenous heterocyclic compounds (NHCs), i.e., pyridine and indole, and ammonia nitrogen along with phenol and thiocyanate was investigated in three sequencing batch reactors (SBRs) (R1, R2, and R3). Pyridine and indole were provided, respectively, in R1 and R2, whereas R3 was operated with a mixture of equimolar concentrations of pyridine and indole. Three concentrations of NHCs (1.0, 2.5, and 5.0 mM) were investigated to observe the impact on aerobic granules. Pyridine did not exhibit any adverse effect on the granular characteristics (volatile suspended solids of 6.00 ± 0.08 g L-1 and sludge volume index of 37.98 ± 0.84 mL gTSS-1) up to a concentration of 5.0 mM (402.93 ± 6.29 mg L-1) (R1) with around 74% and >98% removal for pyridine and other pollutants (phenol, thiocyanate, and ammonia nitrogen), respectively. However, indole had a substantial adverse impact on the granular characteristics and other contaminants removal with a concentration of more than 1.0 mM (120.65 ± 4.84 mg L-1) (R2). The current research work provides an experimental treatment methodology for the wastewater in which pyridine, indole, ammonium, phenol, and thiocyanate coexist.