Aerobic Granulation in Hydrocarbon-Rich Wastewater Treatment

Abstract

Petroleum industry alone is regulating a major part of the world economy. Everyday million litres of hydrocarbon-rich wastewater is generated from oil refineries, which is one of the major drawbacks of oil industries. Oily wastewater is carcinogenic for humans and animals, and oils can cause ground seepage and can reduce oxygen solubility in water which further affects the marine ecosystems. Among the treatment processes, biological techniques are more suitable to provide eco-friendly results.The current research trends in hydrocarbon-rich wastewater treatment suggest aerobic granulation as one of the modern biological remedies for oily wastewater. Aerobic granules are densely packed microbial aggregates containing millions of different bacteria. They offer cost-effective and simultaneous degradation of carbon, nitrogen, phosphorus and hydrocarbons in a single reactor system. This technology has been successfully employed in treating petrochemical, coal gasification and palm oil meal effluents. About 1–3.5 mm-sized aerobic granules containing extracellular polymeric substances of 200–300 mg/g volatile suspended solids with 30–70 m/h settling velocity provided almost 90% chemical oxygen demand and 70–90% oil removal while treating 5.6–320 mg/L of hydrocarbon containing wastewater. Above 5 g/L of granule biomass and below 50 mL/g sludge volume index indicated granule stability and compactness throughout oil removal process. This chapter focuses on the mechanisms, effecting factors, characteristics and characterization techniques of aerobic granulation with its detailed application in hydrocarbon-rich wastewater treatment.KeywordsHydrocarbon-rich wastewaterPoor biodegradabilityAerobic granular reactorGranulation mechanismCharacterizationParametersFactorsOil degradation