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USW researchers make sewage waste breakthrough

25 Jun 2023 4 minute read
Tractor spraying fertiliser

Researchers at the University of South Wales (USW) have made a breakthrough in how sewage waste could be used to revolutionise the development of large-scale farm fertilisers.

A team led by Dr Christian Laycock, associate professor in sustainable chemistry at USW, has been experimenting with the products leftover from a process called anaerobic digestion (AD).

The University’s Sustainable Environment Research Centre (SERC) has been carrying out ground breaking research into AD for a number of years.

AD breaks down human, animal, or food waste to produce biogas – which can be used as an alternative to fossil-based gases – and biofertilizer. The process happens in large, sealed, oxygen-free tanks, and uses special microbes to process the waste, separating out useful gases and nutrients.

Until now, the ‘slurry’ – known as digestate – left over once the AD process has finished has been difficult to develop further, despite having a high nutrient content which enables it to be used as a fertiliser – because its large liquid content means it is easily washed away, while transporting the substance can be costly.

But the breakthrough made by the USW team has resolved many of the challenges posed by the residue.

Pollution

“One of the problems with using digestate as a fertiliser is that it doesn’t have much ability to retain the nutrients that it contains, and those nutrients very easily leach out into soils and groundwater and cause nutrient pollution,” Dr Laycock said.

“This nutrient pollution can cause serious problems in rivers and lakes, where algae can develop and effectively choke-off the oxygen supply to animal life and other plants which depend on healthy water to survive.

“We’ve developed a method of enhancing the digestate by adding substances which are easily used by organisms. This process is beneficial for three reasons – firstly, the proprietary additives contain nutrients which are helpful for crops in their own right, and, secondly, they improve the soil conditioning properties of digestate.

“The third reason, which is the most important, is that the bio-available substrates turn the digestate from a liquid into a gel, which means the nutrients are released about seven times more slowly than from a digestate or mineral fertiliser.

“In turn, this means that more of the nutrients go into the crops, rather than getting washed away quickly and causing nutrient pollution and soil degradation.

“With more of the nutrients going into crops, the crop yields are also increased, with up to double the crop yield observed in trials carried out at USW when compared to using mineral fertiliser.”

More studies

Despite the promising results from the early research, Dr Laycock said that more studies are needed to determine the possible benefits of the new fertiliser.

“There’s obviously huge potential benefits from the process, with AD producing low-carbon energy in the form of biogas and the leftover digestate able to support agriculture as a fertiliser,” he said.

“The challenges we now face are finding efficient ways to get the fertiliser on to land, understanding the long-term impact it has on the environment, and then commercialising the material for widespread application.

“Once we have more understanding of those issues and how they can be addressed, the obvious benefits of this process will make it very hard to ignore.”

The research has been carried out with funding from the European Regional Development Fund and European Social Fund, as part of the FLEXISApp project and Knowledge Exchange Skills Scholarship (KESS2), which is a pan-Wales higher-level skills initiative, supporting doctoral, MPhil, and research Masters degree qualifications in all Welsh universities.


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Cathy Jones
Cathy Jones
9 months ago

Very promising indeed. This is EXACTLY the kind of research we need to be helping fund and creating space for in Cymru…

Padi Phillips
Padi Phillips
9 months ago
Reply to  Cathy Jones

It is indeed what is needed, and many more such research schemes. Sadly the funding came from the EU, which is unlikely to be a source for any such future research projects – unless Cymru becomes independent and negotiates a better relationship with the EU. I don’t somehow see the UK Shared Prosperity Fund coughing up the cash, as Cymru isn’t supposed to be an innovator, just a handy playground for tourists and goodlifers taking advantage of OPD in our small country.

Mab Meirion
Mab Meirion
9 months ago

Follow the smell and the money, good old EU…

hdavies15
hdavies15
9 months ago
Reply to  Mab Meirion

Cash from cach ? Mewn baw mae bwyd mewn misoedd !

hdavies15
hdavies15
9 months ago

Excellent work. Don’t let the big chemical conglomerates get hold of it otherwise it will get priced at extortionate levels. A bright marketing/business mind should be able to create localised distribution channels so that the product can be sold to farms and horticulture within a fairly small radius. Potential for all round win-win.

Mab Meirion
Mab Meirion
9 months ago
Reply to  hdavies15

I remember several years ago North Korea was castigated in the Tabloids for doing the very same…

Tatws Bryn would not dream of doing such a thing…I hope !

hdavies15
hdavies15
9 months ago
Reply to  Mab Meirion

Old fashioned “dom” matured in a corner of the farmyard was the best, with dash of horse manure matured for a year or two for some crops.

Mab Meirion
Mab Meirion
9 months ago
Reply to  hdavies15

In school I was considered too bright to do gardening but not bright enough (or something) to be included in the 8% who were put forward for Uni (thank the lord for Coleg Harlech, since denied to many hundreds of others but that is another story) I regret that I never passed the green fingers exam and have an entirely wild garden, my friends the bees are content but an odd tomato would have been nice…

Mab Meirion
Mab Meirion
9 months ago
Reply to  Mab Meirion

Streaming: ABCD you had no real choice where they put you except if you had passed the 11plus AB if not CD, for those to young to know…

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