Biodegradability testing of a petroleum refinery wastewater by respirometry

A study was undertaken to evaluate aerobic biodegradation of a petroleum refinery wastewater (before and after API separator) using an automatic laboratory respirometer. Seed activated sludge was acclimated with a small quantity of wastewater under study, in fill and draw type reactors. Relatively high initial substrate to seed biomass ratios of 20 and 15 were used to encourage growth conditions. Each wastewater sample was diluted to five concentrations and oxygen uptake data was recorded till the beginning of the endogenous phase. Oxygen uptake data were analyzed using Monod and Haldane kinetics. Results showed that the refinery wastewater was inhibitory and kinetic data only followed the Haldane equation.