Treatment of gaseous volatile organic compounds using a rotating biological filter.

Rotating biological filter (RBF), which provides higher oxygen mass transfer has been developed for treating gaseous volatile organic compounds (VOCs) such as BTEX (Benzene, toluene, ethylbenzene and xylene) at higher concentrations. The screening of enriched cultures has been done initially to enhance the performance of RBF for treating xylene, toluene and xylene, and BTEX at various loading rates. The removal efficiency of BTEX was maximum (82%), higher than toluene and xylene (79%), and xylene (72%). The presence of xylene enhanced the removal of toluene in the mixture. In the BTEX, toluene was found to be highly biodegradable followed by ethylbenzene, benzene and xylene. The RBF also removed nutrients from wastewater along with VOCs. The stability study of RBF showed that supply of nutrient media influenced the RBF performance more. Further, the predominant strain identified in the mixed culture was Enterobacter cloacae SP4001, responsible for biodegradation of BTEX.

Process optimization and analysis of product inhibition kinetics of crude glycerol fermentation for 1,3-Dihydroxyacetone production.

In present study, statistical optimization of biodiesel-derived crude glycerol fermentation to DHA by immobilized G. oxydans cells over polyurethane foam is reported. Effect of DHA (product) inhibition on crude glycerol fermentation was analyzed using conventional biokinetic models and new model that accounts for both substrate and product inhibition. Optimum values of fermentation parameters were: pH=4.7, temperature=31°C, initial substrate concentration=20g/L. At optimum conditions, DHA yield was 89% (17.83g/L). Effect of product inhibition on fermentation was trivial for DHA concentrations ≤30g/L. At higher concentrations (≥50g/L), kinetics and yield of fermentation showed marked reduction with sharp drop in Vmax and KS values. Inhibition effect was more pronounced for immobilized cells due to restricted transport of fermentation mixture across polyurethane foam. Retention of fermentation mixture in immobilized matrix resulted in higher localized DHA concentration that possibly enhanced inhibition effect.