Biodegradation of p-toluenesulphonic acid by comamonas testosteroni in an aerobic counter-current structured packing biofilm reactor

p-Toluenesulphonic acid degradation by Comamonas testosteroni was studied in a continuously operated fixed-bed biofilm reactor. Static mixer elements (Sulzer Chemtech, Switzerland) were used as a support matrix for biofilm formation. Degradation of p-toluenesulfonate was investigated at several aeration (0.5–4 L min−1) and dilution (0.15–0.4 h−1) rates under septic conditions. The maximum observed pollutant degradation rate was 198 mg of C L−1 h−1. In spite of nonsterile conditions, a very limited range of microbial species was present in the reactor. The system was operated for over 3 months and Comamonas testosteroni used as inoculum was largely present in the biofilm (about 60% of the total microbial population) during the whole cultivation period. Two other aerobic bacterial strains detected in the biofilm were not able to degrade p-toluenesulphonic acid. High biomass attachment was observed on polypropylene static mixers. Immobilised biomass reached the level of 10.4 g of dry weight per m2 of the support and 23% of its structure was active biomass.