As the Environment Agency begins to review its Quality Protocol’s (QPs), it is time, according to one technology provider, to raise the bar much higher on PAS 110 regulations on the physical contamination in digestate.
Gemidan, which recently opened its third pre-treatment facility, believes that whilst PAS 110 has served a worthy purpose, the waste industry isn’t challenging itself enough, citing competition over food waste feedstock and a lack of Government incentives. Gemidan also claim that long-awaited regulation on local authority food waste collection will dramatically increase the amount of feedstock available for AD operators.
“It is heartening to see the media give so much airtime to the huge problem of plastics polluting the sea, which has rightly brought about huge concern from the public”, said Tony Pickess from Gemidan. “But what about plastics polluting the land and then ending up in our streams and rivers? Are we really happy continuing with the practice of spreading poor quality digestate on to farmland?”
He added: “It’s become all too easy now for companies to say ‘we’ve got PAS 110 so that’s all we need to do’, but it doesn’t take an environmental scientist to work out that fragments of plastic, as well as glass and metal, pollutes the soil and may well end up back up in our food chain”.
Pickess also pointed to the traditional, highly aggressive hammer mills used at recycling plants that he says create micro as well as macro plastics that then ironically, creates the burden of trying to remove them – inevitably resulting in ‘grit and plastic’ preventing most anaerobic digesters from producing as much gas as they should.
He compares this to Gemidan’s new facility that has been independently tested to prove that its much gentler, lower maintenance pre-treatment technology produces a food waste substrate that is virtually 100% free from non-organic contamination. For AD plants receiving this vastly superior substrate (in terms of purity as well as reduced organic matter particle size), gas generation is much faster, with the added benefits of less wear and tear on equipment throughout the process – and no digestate treatment required.
He continued: “In addition to preventing plastics and other contaminants from polluting farmland, this has far-reaching bottom-line gains though enhanced gate fee revenues from increased digester throughput.
“We also need to look much more closely at how contamination is being measured exclusively by weight in regard to PAS 110 with plastics being so light. In Denmark this issue is very effectively addressed by having a regulatory limit based on ‘total surface area’ of plastic in waste derived substrates. Addressing this issue in the UK would result in farmers having far more confidence in the quality of digestate-based fertiliser. End-of-waste classification achieved from tougher and more meaningful contamination requirements would have more environmental credibility and be justified in requiring less in the way of regulation.
“Hopefully the Environment Agency’s review of its Quality Protocol’s (QPs) can steer the industry towards better practice – and in the meantime, there is always room for a company to seize the initiative by setting their own standards with regard to contamination, just as so many businesses have responded to growing public pressure by changing their policy about the use of plastic”.
