New Method for Treating Contaminated Groundwater

Trials are current taking place at Leeds University into new ways to treat contaminated groundwater, helping it to self-clean by introducing basic chemicals like vinegar.

From a health point of view, contaminated water can be extremely harmful and potentially toxic. Groundwater found at waste sites associated with leather or textiles production contains chromium compounds, and connections between these and cancer have been made, as well as with kidney, lungs and liver complications.

The team of researchers at Leeds University is spearheaded by Dr Ian Burke and Dr Doug Stewart, representing the Schools of Earth and Environment, and Civil Engineering, respectively.

Purified Water

They found that when the main component of vinegar, acetic acid, was added in diluted form, bacteria naturally present in the water was encouraged to grow. Consequently, the bacteria purified the water by detoxifying the chromium compounds.

“The original industrial processes changed these chemicals to become soluble, which means they can easily leach into the groundwater and make it unsafe”, Dr Burke explained.

“Our treatment method reconverts the oxidised chromate to a non-soluble state, which means it can be left safely in the ground without risk to the environment. As it is no longer ‘bio-available’ it doesn’t present any risk to the surrounding ecosystem.”

Historical tests on chromate chemicals have been a success in neutral conditions, however this research breaks new ground in that it involves highly alkaline conditions, potentially upping the difficulty factor substantially.

Decontamination Treatment

The preferred way of decontaminating groundwater is through relocating the soil, but this is neither energy efficient nor cheap. The decontamination treatment method being employed by the Leeds team, on the other hand, will not present the need for relocation.

“Highly alkaline chromium-related contaminants were placed in inadequate landfill sites in the UK right up until production stopped in the 1970’s – and in some countries production of large quantities of these chemicals still continues today”, Dr Stewart commented.

“The soluble and toxic by-products from this waste can spread into groundwater, and ultimately into local rivers, and therefore will remain a risk to the environment as long as they are untreated.”

Present regulations within the environmental domain preclude Dr Stewart and Dr Burke’s tests from being replicated in the outside world until 100 per cent proof of their success can be produced.

“From the results we have so far I am certain that we can develop a viable treatment for former industrial sites where chromate compounds are a problem”, Dr Stewart concluded.

“Our next step is to further our understanding of the range of alkalinity over which our system can operate. As society becomes more environmentally-aware, new regulations demand that past mistakes are rectified and carbon footprints are reduced.

“By designing a clean-up method that promotes the growth of naturally occurring bacteria without introducing or engineering new bacteria, we are effectively hitting every environmental target possible.”