Toxin-eating bioreactor finishes trials

A toxin-eating bioreactor designed to improve the disposal process of metalworking fluids has successfully completed trials at BAE Systems’ Brough facility.

A toxin-eating bioreactor designed to improve the disposal process of metalworking fluids (MWFs) has successfully completed trials at BAE Systems‘ Brough facility.

The bacterial treatment, known as microcycle technology, turns toxic MWFs into grey water for safe disposal in the sewerage system. MWFs are used to provide lubrication and cooling during the shaping of metals. However, they also contain a high number of dangerous chemicals and compounds that have, up until now, made its disposal a lengthy and expensive process.

Developed by Microbial Solutions, the technology has been designed to combat the problems associated with current MWF disposal methods by improving efficiency and environmental impact. The system works by treating MWFs in a bioreactor with a high-surface-area matrix that carries a selection of bacterial cultures. The MWFs are then mixed by bubbling air through the reactor. Microbial Solutions claims that within 10 days, the bacteria can reduce the pollution load of MWFs by up to 98 per cent.

Prof Will Pope, chief executive of Microbial Solutions, said: ‘What is clever about the system is the specific mix of bacteria. The bugs were individually found in a huge research-and-development project that trawled metalworking corrosion all over the world. They were then put together in a consortium whereby collectively they could metabolise the whole metal-working fluid molecule.’

The company hopes that microcycle technology will soon replace existing treatment processes, such as ultrafiltration and vacuum evaporation.

Pope said: ‘These systems are expensive, they use a lot of power, have very high capital costs and don’t remove the toxins. Our microbial culture metabolises the whole lot.’ He added: ‘There are also peripheral benefits. Most sites do not house the existing technologies because they do not have enough waste going through to have high- capital-cost equipment. So they tanker it to a central disposal site. Our technology avoids this as it is a scalable system with low capital costs — you can run the whole thing off a 13A socket.’

In light of increasing industrial pressure to reduce the pollution and toxicity of waste fluids, BAE has been trialling the system at its Brough facility in Yorkshire.

The site has used the five-tonne reactor for more than nine months and is currently in discussions with Microbial Solutions to extend the plant to a total capacity of 25 tonnes. This new bioreactor is hoped to process the facility’s entire waste MWF, which is estimated to be around 0.5 million litres per year.

Speaking about the trial, Andy Southwick, BAE Estates team leader at Brough, said: ‘We are pleased with the results. However, taking it from a laboratory experiment, which was in a 25-litre tank, and putting a 5,000-litre tank on site presented a few challenges for Microbial Solutions. For instance, there were some problems in generating the biofilm as the bacteria were not sticking to the matrix. By trialling different types of matrix to see how one worked better than the other, Southwick’s team came up with a modified design that has since proved very efficient.

‘Some days you can put a metalworking fluid in there and you can see a dramatic change from the cloudy coolant that goes in, to seeing it look more like water. On average it takes around 10 days, but temperature is a big factor in how well the bacteria work. In winter, the air is a little cooler and the metalworking fluid colder so the process does not take as long.’

Southwick is hoping to replace the site’s current vacuum evaporation technology with microcycle technology in the near future. ‘The benefit of using the bioreactor is that it does not really use that much energy compared to the vacuum evaporator. While our existing process is quicker, I’m hoping the microcycle technology will allow us to constantly process our metalworking fluid so there will be the fluid going in at one end and, at the same rate, treated water coming out the other end,’ he said.

BAE is expected to install a full-size working system at the Brough site in the next six months. This will be used as a demonstrator for the rest of the company and, if successful, may be rolled out to a further six sites in the company’s air and land systems divisions.

Ellie Zolfagharifard