UCC and Queen's are collaborating on efforts to utilise bacteria to help clean up pollution from the Republic's food industry, writes Dick Ahlstrom
Bacterial colonies could soon be pressed into service cleaning up pollution from the Irish food industry. If successful the biological system could replace expensive chemical systems and in the process produce a useful fertiliser.
The work in University College Cork's department of microbiology is led by Dr Alan Dobson and involves a collaboration with colleagues in Queen's University Belfast. It is co- funded by the Environmental Protection Agency and the Department of Agriculture and Food.
The goal is to adapt existing biological waste water clean-up methods for use in the Republic's dairy industry, explains Dr Dobson. In particular the research group is targeting phosphates, nutrients that promote eutrophication of waterways and the runaway growth of algae.
"There are strict legislative controls on the amount of phosphates that can be released after processing," says Dobson. "Typically what companies and municipal authorities would do is add chemicals to precipitate out the phosphate." However this greatly increases the amount of sludge left behind by the process, producing a new waste problem.
Dr Dobson is looking at "biological phosphate removal", the use of colonies of bacteria that happily gobble up as much as 90 per cent of the phosphates in waste water.
"It is a widely accepted technology," he says, and is already in use in the US, Europe and South Africa. "What we are doing is seeing if this removal system can be applied in an Irish context to handle food-industry waste."
Results so far look very promising, he believes. "We have small laboratory-scale bioreactors to mimic the sludge treatment systems."
The sludge is mainly made up of bacteria and the process involves switching from anaerobic to aerobic conditions to encourage phosphate uptake. If the bacteria are held in anaerobic conditions before switching to aerobic, they undergo what is called a "luxury uptake" of phosphate, boosting absorption to between 10 and 20 per cent of normal dry-cell weight.
A large part of the work involves trying to identify the bacteria doing most of the clean-up work in the sludge. There is a complex mix of symbiotic organisms living in the sludge which together make an effective phosphate removal system and Dobson wants to know who lives in the neighbourhood.
Unfortunately the active organisms have proved notoriously difficult to culture, he says, probably because of the interaction between organisms in the sludge. He is using DNA-based techniques including polymerase chain reaction (PCR) analysis to help identify the organisms that live in the sludge.
The researchers are also testing whether it will be possible to use the sludge as feedstock for compost. The organisms grab hold of large amounts of phosphates and if added to any natural compost should boost levels of this important plant nutrient. The team put together a lab system to monitor quality of compost made in this way to see if it is safe and can provide benefit.
The collaboration with Queen's arises from earlier work done in Belfast showing that phosphate-loving bacteria increase their intake when "shocked" by more acidic conditions. The UCC team is trying to apply this to its phosphate uptake system to improve performance and is also helping Queen's to identify the bacteria in its own biological cleanup system.
Dr Dobson's work shows that such a treatment system could be retrofitted to existing systems, sitting close to the top of a wastewater stream and taking out the phosphates before later treatment processes.