Polycyclic Aromatic Hydrocarbon and Culturable Bacterial Profile of Produced Water Effluent Collected from a Flow Station Waste Pit Located in Edo State, Nigeria

This study was aimed at monitoring the quality of produced water from a flow station waste pit located in Ologbo in Edo State of Nigeria, in order to ascertain the levels of compliance to environmental standards. Samples were analyzed for physicochemical, polycyclic aromatic hydrocarbons and microbiological qualities adopting standard analytical procedures. The results of the study revealed that with the exception of the level of total dissolved solids (TDS) recorded in February 2017, the other physical parameters were found to be in consonance with the Department of Petroleum Resources (DPR) standard. Results showed that the levels of benzo(a)pyrene, benzo(a) anthracene, chrysene, dibenzo(a,h)anthracene, benzo(b) fluoranthene, benzo(k) fluoranthene, indeno(1,2,3-cd)pyrene and benzo(ghi)perylene were higher than the stipulated Department of Petroleum Resources standard. The concentrations of the heavy metals ranged between 0.41 – 1.49 mg/Lfor iron, 0.011 - 0.087 mg/L for manganese, 0.00 – 0.38 mg/Lfor zinc, 0.0 – 0.052 mg/Lfor copper, 0.0 – 0.028 mg/L for chromium, 0.0 – 0.092 mg/L for cadmium, 0.0 – 0.009 mg/L for nickel, 0.0 – 0.032 mg/L for lead, and 0.0 – 0.008 mg/L for vanadium. Pseudomonas spp. had the highest percentage frequency of occurrence (28.6 %), followed by Bacillus spp. (26.8 %) and the bacterial isolates with the least percentage frequency were Staphylococcus and Micrococcus spp. (13.4 %). This study revealed that the quality of produced water from the waste pit does not completely conform to the prescribed environmental standards and thus will require proper effluent treatment and monitoring to improve its quality prior to its discharge into the receiving environment.