Bioremediation of Offshore Oily Drilling Fluids

Abstract

The use of bio-treatment technology to dispose of oily waste mud has many advantages: it is relatively inexpensive (only 30–50% of the expense of conventional chemical or physical processing technologies), has a low impact on the environment with no secondary pollution, and utilizes local control and entails simple operations. After the collection, isolation, purification, cultivation, and domestication of petroleum degrading bacterial, three strains were obtained that effectively degrade petroleum hydrocarbons. The growth of the bacterial strains and the consequent crude oil degradation were found to be at the greatest rates using the following biochemical processing conditions. The strains were grown in ammonium nitrate and a small quantity of yeast powder at a temperature of 50°C and pH of 6.0. The strain quantity was 2% and the rotating speed of the shaker was 180 rpm. The biochemical disposal process and laboratory-scale simulation of processing devices of oily waste mud were also designed. The oil content of disposed oily waste mud was generally less than 2 mg/L, and the degradability of the waste was over 98%. This percentage meets the requirement of the national wastewater discharge standards in China’s offshore oil exploration and development fields.