Study on the Treatment Effect of the Oily Wastewater by the Biological Soil Aquifer Treatment System

Abstract

Soil aquifer treatment with physical, chemical and biological functions for oily wastewater treatment was put forward and strain identification, best growth conditions was studied in this paper, including temperature, pH, diesel oil content and inorganic salt concentrations. Firstly, the oily wastewater treatment effect and the influence factors of the SAT was investigated. Then, the oil degradation bacteria were domesticated, screened and purified and its degradation characteristics were studied and build a biological SAT(bioSAT). Thirdly, the oily wastewater was treated by the bioSAT and the effect was investigated. At last, to confirm the optimal treatment conditions. The research results showed that: 5 bacteria strains were identified as following: Enterococcus faecalis-L1, Lysiniibacillus-L2, Bacillus sp-L3, Rhodococcus equi-L4 and Ochrobactrum-L5. Based on their ability to degrade oil, L-2 and L-4 were selected and their growth conditions majorized. Optimum bacteria growth was recorded at 2% substrate (diesel) concentration, pH 7-8, temperature range between 25°C and 30°C and inorganic salt concentration range from 1 g/L to 3 g/L for the bacteria strains L2 and L4. The equilibrium concentration was reached on the 30th day, and the highest removal rates of 84.63% and 99.23% were reached on the 36th day.