Biohydrogen production from synthetic oily wastewater in an upflow anaerobic sludge blanket reactor

Abstract

In this research, an upflow anaerobic sludge blanket (UASB) reactor, with a 16-liter working volume, was constructed from borosilicate glass for treating oily wastewater simulated from distilled palm oil and water, and for producing biohydrogen. A mixed bacterial culture was used as degrading microorganisms at an optimum temperature of 37°C and uncontrolled pH. Polyethylene sorbitan monoleate, or Tween 80, a nonionic surfactant, was used to enhance oil solubilization, and thus the biodegradation, as well as the biohydrogen production. The enhanced oil solubilization was first studied with various surfactant concentrations. At the optimum surfactant concentration, the effect of oil loading rate was then investigated. The percent oil removal (measured as COD and oil content in % v/v), biogas production rate, and hydrogen content in the produced gas were the main parameters observed in this study. In the solubilization study, the optimum surfactant concentration was found to be 0.10% w/v (which is equivalent to weight ratio of oil to surfactant of 18.8:1). The effect of COD loading rate was also determined and it was found that a 20 kg COD/m3d loading was the optimum COD loading rate. Under this optimal condition, 68.9% of COD removal and 89.9% of oil removal were achieved. Moreover, the biogas was composed of 81.8% CO2, 28.1% CH4, and 10.1% H2 with the specific production rate of 1.37, 0.62, and 0.22 (l/d)/reactor volume, respectively.