Dax Airscience has adapted an infection control product used in the healthcare sector to remove odours from many types of waste sites. Andrea Lockerbie sees one in action
Odour is the bane of many a waste and recycling site operator. Sites often struggle with controlling odours, creating an issue for neighbours and employees and drawing the attention of regulators.
So an invitation to ‘sniff and see for myself’ the impact of Dax Airscience’s AirSteril system, which uses ultraviolet light and controlled ozone technology, was met with curiosity.
The location was Powerday’s MRF at Willesden Junction in London. Having been to and smelt waste and recycling facility over the years, including the Powerday site a few years back, I can confirm that, standing in the middle of the main hall, where incoming waste was being moved only metres away, I could not smell anything.
Paul Anderson, Dax Airscience managing director, previously worked for a company that sold fogging systems. In his previous role, he explains, it was difficult to get on top on the odour complaints and control them, no matter what neutralising system was being used.
But he had heard about AirSteril, which was a company successful in the arena of washrooms, hospitals and care homes, with its product for infection and bacteria control. Crucially, another attribute of the unit was that it neutralised odours.
Anderson explains: “I went to AirSteril and showed them what the problem was with volatile organic compounds and waste. They came back to me and said the technology would work but the units they had would not be robust enough because they were designed for clean environments, hospitals and so on.”
On the proviso that the AirSteril units probably would not last more than six months in a harsh waste environment, they were trialled for four months in a Viridor facility.
Anderson says: “At the end of the four months, Viridor was so pleased that it bought the units, despite knowing they would not last. The company said it would be cheaper to replace them every six months than to run the fogging system it had been using.”
Having then confirmed that the technology worked, Dax AirScience was formed as a separate company and it went back to the drawing board to make some radical changes so that the units were fit for the waste sector. The original units were horizontal, which meant that they filled with dust, so they became vertical to eliminate this.
The internal fans, which acted as another dust trap, were also taken away and it was found that, without them, the units would work by thermal convection. The heat of the lamp causes air to rise inside the tube and draws air in through the bottom.
By removing the fans, the units were also found to be more effective because they allowed air to pass through the chamber more slowly, which improved the unit’s ability to treat it.
Once the redesign was finished, Dax AirScience replaced the first set of units sold to Viridor, and went on to install them at two more of the company’s sites, including a 3,000sq m one. It then installed units at the anaerobic digestion (AD) plant on Langage Farm in Dorset, and also at Powerday’s 5,000 sq m Willesden Junction MRF and refuse-derived fuel (RDF) processing facility.
It has since installed the units at other waste sites including Seneca’s 12,000sq m facility in Wembley, the largest to date.
The one type of plant Anderson says the units do not work in is in-vessel composting (IVC) plants: “We tried compost sites but IVC was too aggressive – too much steam and heat involved”. But he adds it is suited to waste transfer sites, AD plants, MRFs, EfW plants and RDF facilities.
Anderson is confident that Dax AirScience is the only company using this technology in the waste and recycling sector in the world – and it offers a solution where others have failed.
He cites one case, where, after a week of his units being fitted, odour sampling through the independent Odournet laboratory found a 66% reduction in odours, despite the site in question putting three times the amount of waste into the building than had been agreed for the trial.
One of the advantages of the AirSteril units is that they have no moving parts; only a bulb has to be replaced every four to six months and cleaning can be done at the same time. A two-year warranty comes with the units and, if a maintenance contract is taken out, the units are covered for the life of that contract.
As the units use ozone in an enclosed environment, they have also been tested by the Health and Safety Executive, which is satisfied that they will not breach ozone limits. But, to be certain, the systems are fitted with alarms, set 50% below the ozone limit, to enable shut down if needed.
Powerday founder and chairman Mick Crossan explains that his Willesden Junction site previously had a dust suppression system in place, with blowers and fans introducing water and different neutralisers.
As the site had been receiving odour complaints – Crossan says it has since found that most of them can be attributed to a handful of local residents – the Environment Agency (EA) was doing regular odour patrols. But once the AirSteril system was put in, the EA officers were unable to get an odour reading from the site.
The facility operates more or less seven days a week for 20 hours a day, so Crossan says the company “has a duty of care to all the people who work here”. As soon as the units were installed, there was a noticeable difference. As well as odours, the units also kill bacteria and viruses in the air – their original purpose in sectors such as healthcare.
Crossan was initially sold on the units after he was given a small one to test at his first meeting. He says: “At home we had a double incontinent 18-year-old dog, and I didn’t want to put her down. But the smell in the morning in the utility room was awful and my wife couldn’t put up with it.
“I was given one of these little machines and I put it in the utility room. My wife went back 10 minutes later and the smell was gone. So that is when I said if it worked for that purpose, let’s see how we go with putting these new systems in.”
Crossan adds that the cost of installing the units will work out better than its previous system in the long run, although there was considerable outlay to retrofit the facility. Anderson calculates that, after installation, the cost per unit – which will do 100sq m – is about £24 in electricity and one or two lamp changes.
Dax AirScience has just launched a new model of AirSteril in which the entire inside is coated in titanium dioxide, a catalyst for one of the reactions needed, to give a better reaction and output.
The company has been in discussions with the EA for two years about getting the product approved as Best Available Technique, and now needs to find a site to test and prove the odour levels before and after the technology has been installed. It hopes to be approved by the end of the year.
It is also looking at creating portable units for vehicles, to decontaminate trailers after they have transported waste.
Having initially targeted the UK waste market, the company’s next moves are in the Republic of Ireland and Europe towards the end of the year.
Crossan explains: “For every waste company, if they are taking in odourous material, the biggest issue is complaints about odour.”
Powerday also plans to use the units at its new site, under construction in Enfield, north London. Crossan adds: “It just worked for us. It definitely made a difference – not just the odours, but on working conditions.”