ABSTRACT:
The feasibility of using less hazardous inducer compounds to maintain the ability of an enrichment culture to degrade a hazardous compound was investigated. Bench‐scale (5 L) batch enricherreactors (ERs) maintaining enrichment cultures were used to bioaugment bench‐scale continuous‐flow activated sludge reactors treating 1‐naphthylamine (1NA). Potential inducer compounds tested were 1‐acetatenaphthalene, 1‐naphthoic acid, 1‐naphthalene‐sulfonic acid, and gentisic acid. In batch experiments, subcultures of the original enrichment culture that had been grown on potential inducer compounds for a period of 3 months without 1NA, maintained the ability to degrade 1NA but at reduced rates compared to a control maintained on 1NA. In continuous‐flow experiments, separate 13.7‐L reactors received daily inoculations of 2–4% by mass of INA‐enrichment culture, or 3% by mass of the subcultures maintained on inducer compounds. Target compound breakthrough from augmented reactors was significantly reduced (relative to an acclimated control) following a step‐increase from 1 to 5 mg 1NA/ L, and reintroduction of 5 mg 1NA/L after its absence from the waste stream for 9 days (two separate experiments). A modest reduction of breakthrough was also observed following a 10 mg 1NA/L spike (a separate experiment).