Hydrocarbons such as fuels, oil, grease, solvents, lubricants and coolants are recognised as the common types of contaminants in industrial applications. Contaminated soils have been identified as top of the four main priority waste streams in several countries. In Australia, a Townsville site, historically used by Queensland Rail as a maintenance depot, was contaminated with diesel, oil and grease from the maintenance of trains and rolling stock.
The soil contained high levels of hydrocarbons along with heavy metals. The site was scheduled for redevelopment and needed to be urgently decontaminated before construction could proceed.
Typically, standard bioremediation of hydrocarbon contaminated soil takes around 18 months to naturally breakdown. Due to pressures from the developer this timeframe needed to be dramatically reduced. Virotec was contracted to remediate the construction site using ViroSoil Technology.
ViroSoil Technology utilises Rapid Sequestro-Degredation (RSD), an advanced form of bioremediation, and typically reduces the time taken to destroy hydrocarbons in soil by up to 50% of conventional land-farming or bioremediation methods.
However, unlike standard methods, including the more costly thermal desorption methods, RSD permanently binds heavy metals while destroying hydrocarbons in soil. To assist and enhance the natural processes and significantly increase the rate of degradation of the contaminant, an inoculum of naturally occurring petrophillic microbes is required to rapidly proliferate.
ViroSoil Technology using RSD was used to treat approximately 50,000 tonnes of contaminated soil from the site. The soil was heaped into piles which were aerated using an excavator and irrigated on a regular basis to provide the enzymes and microbes with optimal growth conditions. This enabled a more rapid breakdown of the hydrocarbons into more inert compounds, namely carbon dioxide, water and benign organic elements.
The results show that RSD is an economically and environmentally sound solution to treating hydrocarbons in contaminated soils. After treatment with RSD the contaminants in the soil were all lowered significantly below the prescribed treatment target limits. This treatment provided a fast and effective result and construction was able to resume.
ViroSoil Technology absorbs and bioremediates hydrocarbons, absorbs between 6-10 times its own weight, utilises a naturally derived product from a totally renewable source, is completely safe to handle and apply, leaves surfaces dry and residue free, reduces the amount and hazardous nature of waste, does not release hydrocarbons under compaction, does not leach, and offers multiple treatment and disposal options.