Defra - Department for Environment, Food and Rural Affairs.

Science Search

Science and Research Projects

Return to Science Search homepage   Return to Project List

Biorecycling: Resource Recovery and Reduction of Oily Hazardous Wastes via Biosurfactant Washing and Remediation - WR0203

This study will apply soil-washing technologies to other oily industrial wastes to enable recycling of uncontaminated primary resources, or recovery of secondary resources. Use of biosurfactants, artificially concentrated solutions of natural microbial secretions, will ensure that any residues in washed solids are fully biodegradable, and that the liquid eluates are amenable to bioremediation after separation of useful oil.

Bacteria secrete biosurfactants to enable them to digest hydrocarbons which are immiscible in water. Chemical extractions of concentrated solutions of microbial biosurfactants are now widely available as commercial products for environmental applications (e.g. Mulligan, 2005). Numerous previous studies have demonstrated that surfactant addition enhances the recovery of non-aqueous phase liquids (NAPLS) during soil washing and can promote biodegradation (Mulligan et al., 2001). Biosurfactants have also been shown to extract non-exchangeable heavy metals. Biosurfactant washing has recently been shown to achieve 95% removal of oil from sorbents used to treat spills (Wei et al., 2004).

The biological degradation of hydrocarbons relies mainly on aerobic activity by micro-organisms, especially bacteria. By using biosurfactant for soil washing the possibility of bioremediation as a treatment mechanism is not hampered by surfactant toxicity. Moreover, temperature, aeration and nutrient addition can be optimised for oily liquids in a bioreactor to achieve more rapid degradation. Any residual oil and surfactants in the washed soils are then more readily biodegradable by composting. This approach could be used to expand ex-situ bioremediation to a range of contaminated soils, including petrol station soils or associated groundwater plumes. Sustainable treatment methods for this key UK contamination issue are currently limited to natural attenuation or costly and difficult in-situ bioremediation methods.

The primary objective is to evaluate the use of biosurfactant soil-washing as a process-based treatment of particulate wastes, as a precursor to oil recovery or enhanced bioremediation, and as a mechanism of resource recovery or waste minimization. The specific objectives required to achieve this are as follows:

(1) To review the “state-of-the-art” of soil washing technology, identify commercially available biosurfactant products, candidate waste streams, and obstacles to implementation, using international scientific and technical publications.

(2) To identify and sample 10 suitable oily waste streams of significant volume, economic or environmental significance

(3) To optimise experimental biosurfactant washing conditions, including surfactant: water: waste ratios, agitation, temperature, timing, reagents, and other physical, chemical or mechanical factors.

(4) To develop effective physio-chemical separation of oil and aqueous phases, allowing recovery of oil and recycling of biosurfactant solution.

(5) To investigate usage rate, lifetime and cost of biosurfactant solutions.

(6) To assess the enhanced aerobic degradation of oil in eluates using liquid bioreactor experiments, and in washed solids using conventional composting techniques.

(7) To evaluate the in-cycle biosurfactant enhancing potential of appropriate bacterial strains.

Project Documents
• FRP - Final Report : WR0203 Final Report_SID5   (647k)
Time-Scale and Cost
From: 2005

To: 2007

Cost: £263,312
Contractor / Funded Organisations
University - Teesside
incl. processing and reprocessing              
Cleaning Systems              
Environmental Protection              
Hazardous Waste              
Pollution - Prevention and Control              
Pollution Prevention and Control              
Products and Processes              
Sorting systems              
Systems for Resource Recovery              
Waste Management              
Fields of Study
Waste Management