A microbial consortium and Pseudomonas strain (PPO1) were used in studying biodegradation of benzene, toluene, and p‐xylene under aeorbic conditions. Studies involved removal of each compound individually as well as in mixture with the others. Both cultures exhibited a qualitatively similar behavior toward each compound. Both the pure culture and the consortium grew on benzene following Monod kinetics, on toluene following inhibitory (Andrews) kinetics, whereas neither could grow on P‐xylene. Benzene and toluene mixtures were removed under cross‐inhibitory (competitive inhibition) kinetics. In the presence of benzene and/or toluene, p‐xylene was cometabolically utilized by both cultures, but was not completely mineralized. Metabolic intermediates of p‐xylene accumulated in the medium and were identified. Benzene and toluene were completely mineralized. Cometabolic removal of p‐xylene reduced the yields on both benzene and toluene. Except for cometabolism, kinetic constants were determined from data analysis and are compared with values published recently by other researchers. © 1994 John Wiley & Sons, Inc.

This work presents recent developments of algal bioreactors used for CO₂ removal and the factors affecting the reactor performance. The main focus of the study is on light intensity and photoperiods. The role of algae in CO₂ removal, types of algal species used in bioreactors and conventional types of bioreactors including tubular bioreactor, vertical airlift reactor, bubble column reactor, flat panel or plate reactor, stirred tank reactor and specific type bioreactors such as hollow fibre membrane and disk photobioreactors etc. are discussed in details with respect to utilization of light. The effects of light intensity, light incident, photoinhibition, light provision arrangements and photoperiod on the performance of algal bioreactors for CO₂ removal are also discussed. Efficient operation of algal photobioreactors cannot be achieved without the improvement in the utilization of incident light intensity and photoperiods. The readers may find this article has a much broader significance as algae is not only limited to removal or sequestration of CO₂ but also it is used in a number of commercial applications including in energy (biofuel), nutritional and food sectors.