When we talk about resource management and recycling, we generally think of processing material such as metal, plastic and glass. This is very important, but a big part of ensuring effective waste handling, is to also consider the ground beneath our feet, says John Irwin of waste management specialist CDEnviro.
If you think about land remediation in this country, then it’s hard not to think of the Environmental Protection Agency (EPA) Superfund program, which is responsible for cleaning up some of the nation’s most contaminated land developments.
The Superfund may sound a bit like something out of the worlds of DC or Marvel comics but, in truth, there is a link between land remediation and the fictional superheroes. The Superfund program steps in to benefit communities that would otherwise live in blighted environments, threatened by dark forces — in this case contamination in the brownfield sites — in much the same way that Batman cleans up Gotham.
However, for every Superman there’s a Kryptonite and so it is with land remediation. While there are systems and solutions to deal with most material in brownfield sites, until now it was rare, if not impossible, to find something that could deal with everything in one go. The combination of heavy metals and hard rocks, for instance, was enough to stop remediation attempts in their tracks; or at the very least send costs and timescales rocketing.
The idea of equipment that could deal with heavy metals, waste products from construction and demolition, and large rocks and stones at the same time may sound like something from a comic book.
Systems to treat multiple waste streams and types of contaminants simultaneously have now been developed and tested in the market, meaning land remediation just got a whole lot easier — good news for the economy and the environment.
The sorting and screening equipment now available is advanced enough to take on land remediation and many other tough recycling challenges.
The Kryptonite of land remediation — hard rock and heavy metals – have previously proved problematic as they offer two much varied challenges. Hard rock can be large, abrasive and tough to process and therefore takes its toll on the machinery used to process it — even the toughest of heavy duty excavator mounted breakers can only take so much.
The force provided by these machines is also no help in dealing with the many heavy metals, including lead, chromium and zinc, which may be present on the soil or hidden away within it. These need a more scientific approach.
The new systems are able to combine the science and engineering approaches and bridge the gap so that there is finally a realistic, efficient solution for brownfield remediation.
The systems use a combination of material scrubbing and recovery processes for the heavy metals, as well as more robust processes to break up the hard rocks.
Many treatment options use chemicals like surfactants, but new systems can now remove hydrocarbons from the surface of the contaminants and then isolate and remove them from the washing water afterwards without the need for chemicals. This saves on operating costs and potential environmental issues.
The systems don’t just cleanse the soil and produce waste that still needs to be dealt with. The treated material is cleansed and sorted so that it can be reused and recycled — the outputs include aggregate, organic material and water.
Brownfields aren’t all brown
Although the term brownfield is used as a universal label for urban sites that have been used for industry, commercial or residential purposes and need revitalizing, each site is different due to its location, usage and other factors. The systems used to remediate them therefore need to be flexible — there is no ‘one size fits all’ option.
Once the likely contaminants on a site, space available and the degree of modularity/portability required have been assessed, screening and scrubbing machinery can be selected that is suitable to process the land. Often a modular approach will be preferred as this can be transported and adapted easily to meet the needs of different sites.
Why recycle the land?
We’re hardly short of land in the U.S., so some people would ask why is it necessary to go to the time and expense to reuse land. However, unused brownfield sites are a wasted resource that could be used for new businesses, housing, public works facilities, transportation, or other infrastructure — all within established communities meaning a ready-made supply of employees, customers and users. Redeveloping sites within existing populations can also boost sustainability as travel requirements are reduced when compared to using new Greenfield options.
Without treatment, brownfield sites reduce property prices and even threaten the health and well-being of local workers and residents because of the contaminants that can be present. Human health can be affected either through direct contact with pollutants in the land or affected water or by ingestion through the food chain. The risk of inhaling poisonous substances such as anthrax spores, small pox and noxious gases is also a concern. Simply put, we cannot expect to use the soil around us as a garbage bin and not be affected by the consequences.
Time to grab your cape
In our everyday lives, those of us who work in the waste industry may be overlooked, or even looked down on — like so many superhero alter egos. However, the exciting innovations and solutions being developed in the industry mean that we can change the world from the ground up.
For more information on environmental remediation, visit www.cdenviro.com.