Application of biostimulation and bioventing system as bioremediation strategy for the treatment of crude oil contaminated soils

Abstract

The purpose of this study was to evaluate the application of biostimulation and bioventing for the treatment of crude oil-contaminated soils. The research needed to check how various industrial biostimulants will perform in the treatment of contaminated soils and whether or not there is a synergetic effect that has to do with the stimulant composition. Soil samples used for this study were collected from South Africa. The soil samples were air-dried for 24 h and subsequently passed through a standard sieve of 2 mm screen. The soil consists of 79.32% sand (2.00–0.02 mm), 14.71% silt (0.02–0.002 mm) and 5.97% clay (< 0.002 mm). A microcosm system containing 1 kg of soil contaminated with crude oil (5% w/w) for biostimulation (BSTc) treatment was amended with varying ratios of municipal wastewater (MWW) and brewery wastewater (BWW) to investigate the possible synergy. The bioventing (BVTc) treatment involves the supply of atmospheric air to the bioreactors through the vadose zone for 30mins flow duration every 48 h intervals at ambient condition for 28 days. The BSTc and BVTc treatments recorded 48–58% and 54–75% total petroleum hydrocarbon (TPH) removal efficiencies, respectively, as the BWW amendment noted appreciable removal compared to MWW, while the control treatment recorded 35%. The result showed that the attempt to boost the TPH removal efficiency using the bioventing with the wastewater amendment was effective, as the presence of enough oxygen in the system resuscitated the activities of the microbial community for enhanced TPH biodegradation. This study inferred that combined bioventing and biostimulation techniques proved to be an effective bioremediation strategy for the treatment of crude oil contaminated soils and could serve as a vital tool towards the mitigation of pollution aftermath faced by communities involved in oil production and/or processing activities.