Removal of Lead and Oil Hydrocarbon from Oil Refining-Contaminated Wastewater Using Pseudomonas spp

Abstract

The main objective of this study is to investigate the potentiality of using three bacterial species {Pseudomonas florescence (PF), Pseudomonas paucimobilis (PP) and Pseudomonas sp. (PQ)} for the removal of lead and crude oil from oil-contaminated wastewater of an oil refining company, Alexandria, Egypt before discharging into open environments. Bacterial candidates were employed in a batch mode as free-living individuals or mixture. Bioremediation assays were run with three different oily wastewater/bacteria ratios (1:1, 1:2 and 2:1). At each batch, residual concentration (RC) of the selected parameters (Pb+², oil content, BOD and COD) were determined and their removal efficiencies (RE %) were calculated. Results revealed high removal efficiency for Pb (90.97% from initial concentrations 307.9 mg/l) and oil (56.8 and 68.8% from initial oil concentrations 25 and 500 mg/l respectively) from physically treated oil refinery wastewater. In addition, partial removal of COD (30.98% from 720 mg/l) and BOD (18.98% from 590 mg/l) was achieved. Pseudomonas florescence (PF) was the most active reaching the highest removal of most of the tested parameters and wastewater/bacteria ratio of 1:2 was the most convenient while the ratio 2:1 was the least suitable and was inhibitory in most cases for the contaminants removal. Results highly recommend using Pseudomonas spp especially Pseudomonas florescence (PF) as efficient, low cost remediation method in oil refineries and similar industries where metallic and organic contaminants are included. It is also suggested treating wastewater using fixed Pseudomonas florescence in a continuous system, which can greatly enhance bacterial performance for biodegradation of organic and accumulation of inorganic contaminants.

Key Words: Accumulation, Biodegradation, Industrial Wastewater, Lead, Organic Matter, Petroleum Oil, Pseudomonas spp.