Ray Taylor, chief technical officer at Next Filtration, explains the advantages of using bioaugmentation to deal with sewer blockages, and says stress exo- proteins are finding favour over the use of bacteria and enzyme alternatives


dding selected strains/mixed cultures to wastewater (bioaugmentation) has

become one way of dealing with tens of thousands of blockages in UK sewer networks every year – of which almost three quarters are caused by FOG (Fats Oils, Grease). If you are going to try bioaugmentation,

should you choose a bacteria, an enzyme or a product consisting of proteins? Ray Taylor, chief technical officer (CTO)

at Next Filtration, says there has been some scepticism about using Enzymes: “It’s true that enzymes are a catalyst that break up FOG,” he said, “but smaller molecules of fat can congeal further down the sewer - or their impact reduced by dilution – hence the perception that what at first appeared to have resolved the problem, has reappeared later. Over the years, albeit with good intentions, there has been plenty of dabbling, but faced with such chronic FOG problems, and regulator penalties, we are at last seeing some commitment to conduct thorough studies that show how bioaugmentation can bring benefits; not just in one area known for blockages, but at the point of source, and then much further along the network and into the treatment works.” He added: “Enzymes have also been

introduced to enhance the effect of proteins, but in turn this can enhance surfactants that already take a very long time to degrade. Enzymes have a very different effect on fat compared with bacteria; breaking up long chain triglycerides and liquefying the fat, oil and grease in wastewater, but without actually digesting it.” Taylor says that arguably, the use of bacteria has earned a better reputation, but mixed results haven’t helped the reputation of bioaugmentation. However,


there are now new products that aren’t dormant and that have a much higher bacteria count. “I’ve seen the frustration first-hand,”

Taylor continued, “that by the time certain bacteria are alive and kicking, the water has already travelled through the sewer network. The disgruntlement has then been fuelled by being told that there needs to be more time for the bacteria to acclimatize or recover from bacteriocides – and for more to be added – so of course this keeps adding to costs, and unpopularity if results are still inconclusive.”

LIMITED LIFESPAN The same has been said about extruded enzymes but even more so due to their limited life of just minutes to days. Unlike bacteria, they can’t repair themselves or reproduce when they become damaged. When applied correctly, some bacteria can make a positive difference, but Taylor says he does not buy the sales talk that their impact can be controlled. He said: “For me, for all the good bacteria can do in breaking down organic matter into simple compounds, they will inevitably take their own path. This potential lack of control then begs the

It is important to address FOG problems at source, not just the one area known for blockages, and also much further along the network and into the treatment works

crucial question as to what effect those independent bacteria will have on a treatment works?” An alternative to bacteria and enzymes

comes in the form of proteins released from heat Stressed Fermentation plus non-phenolic synthetic surfactants, which in trials have reduced effluent ammonia by 50% and phosphates by 60%. These small proteins are released by

living yeast in response to a mild heat shock; HSP Heat-Shock Proteins known as stress exo-proteins. These can be easily applied at source or at any stage to bring process improvements all through the system, rather than just in one particular trouble-spot known for getting regularly clogged up.

A counter-argument or concern at the

Ray Taylor is CTO at Next Filtration

‘Faced with such chronic FOG problems, and regulator penalties, we are at last seeing some commitment to conduct thorough studies that show how bioaugmentation can bring benefits’ - Ray Taylor

moment is that finding that winning bioaugmentation formula will remove the now valuable resource of FOG from the system – but Taylor says he recently worked with a water company and a food outlet where a win-win-win scenario was possible for all parties. “The blockage problem at the food outlet was an historic one,” he said. “A build-up of FOG, blockages, overflows, general unpleasantness and a great deal of money to put it right – only to see the same old problem inevitably come back. The water company worked hard on its relationship with the food outlet, who eventually bought a highly effective grease trap. They now keep the grease as biofuel for their vehicles – and by the water company adding a protein to the wastewater, the build-up of FOG has been eliminated.” The point here is that the local problem has been addressed at source, rather than always just focusing on the pumping station, which is now in better shape than for many a year. The protein mix has successfully contributed to getting more air into the water and bringing COD levels down. This in turn is better news for the treatment plant, which still receives its sludge load that can be treated anaerobically for green energy - offsetting the direct biodiesel route from pumping station reclamation. This aspect of treatment proves that you

don’t necessarily need to jet first or close an asset down to add solvent and then pay for disposal. Call-outs and maintenance costs can be reduced, screens are kept FOG-free and there is also less energy required to run network and treatment pumps. Furthermore, Surplus Activated Sludge (SAS) is reduced (typically by around 15%) – and the quality of final effluent also increases. The numerous benefits are ready and waiting.

Next Filtration


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