Overheating disables bugs used in groundwater purification

September 14th, 2009 - 1:33 pm ICT by IANS  

Sydney, Sep 14 (IANS) Overheating disables bugs that help break down groundwater contaminants under the soil, says a new study.
Probing ways of cleaning groundwater, scientists examined how bugs break them down under the soil’s surface.

They found subsurface temperatures associated with microbial degradation can become too high for the microbes’ growth and set back consumption of groundwater contaminants.

This can slow down the purification of the groundwater and even continue the spread of contamination. The new findings mean that researchers now have to rethink the way groundwater remediation systems are designed.

Commonwealth Scientific and Industrial Research Organisation (CSIRO) scientist Colin Johnston, based in Perth, said the researchers were investigating how temperatures below the soil’s surface could be used as an indicator of the microbial degradation process associated with biosparging.

Contaminants are food to the microbes and the oxygen in the air helps the microbes unlock the energy in the food so that they metabolise and grow, consuming more contaminants and stopping the spread of the contamination.

“Observations of diesel fuel contamination showed that at 3.5 metres below the ground surface, temperatures reached as high as 47 degrees Celsius,” Johnston said, according to a CSIRO release.

“This is close to the 52 degrees maximum temperature tolerated by the community of micro-organisms that naturally live in the soil at this depth and within the range where the growth of the community was suppressed.”

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