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Low temperature anaerobic digestion

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An Irish start-up using a pioneering system of low-temperature anaerobic digestion is set to start transforming the way wastewater is treated.

“Where there’s muck there is brass” has always been more of a saying than a statement of fact. But that is now changing with industrial producers and water companies actually saving hard currency by investing in an innovative form of anaerobic digestion (AD) that could transform wastewater treatment across the industrial and municipal sectors.

Some of these are putting their faith in NVP Energy, an Irish start-up spun out of the National University of Ireland, Galway. It claims to offer a revolution in wastewater treatment by using innovative AD technology that reduces the amount of wastewater pollutants requiring treatment while producing a high quality methane-based biogas by-product.

Offsite manufacturing

Low operating costs and rapid installation, using prefabricated, offsite manufacturing have enabled NVP to sell its technology to a brewer with the promise of a return on its investment within three years.

For the brewing, dairy and meat processing industries, wastewater treatment is a major consideration. A typical brewer, for example, produces 2,000m3 of wastewater every day – and, if it has no wastewater treatment facilities on site, faces substantial trade effluent charges from the local water company.

But treatment technologies are, traditionally, capital intensive and have high ongoing operational costs. And it has been hard to find a system which provided an acceptable payback period to warrant the initial investment.

Enter NVP and its module – an expanded granular sludge bed reactor that covers granules with a new kind of microbial coating. This kick starts the anaerobic digestion of the organic components in the wastewater process at temperatures below 20˚C – a compelling development.

Low temperature

“The unique aspect of the technology is that it is able to work at temperatures as low as 4˚C and upwards,” says NVP managing director Michael Murray. “Other systems only work at 30˚C to 35˚C and require energy to drive them. Our system takes mid- to low-strength wastewater from production lines and turns it into an energy source.”

The system, Murray explains, will consequently be able to remove  90%  of chemical oxygen demand (COD) in the water and 50% all the suspended solids with minimal energy input.

This level of COD reduction will cut the client’s annual trade effluent charges by over 60% because, although the water coming out of NVP’s technology still needs further treatment, it is much cleaner – and therefore cheaper for the water company to treat.

On top of that, as an added bonus, the process produces high quality methane biogas, which will be used to generate heat, reducing the site’s energy consumption footprint.

Three year ROI

The low operating costs mean that a typical customer should see a return on investment within those three years. One such customer is brewer Heineken. It is installing NVP plant at its brewery in Hereford  in two stages, with stage one now undergoing commissioning. In this first stage, one NVP Energy module, capable of handling up to 500m3 of wastewater a day has been installed, alongside a 1,530m3 balancing tank which will receive all effluent discharges from site operations.

If commissioning is successful and the biogas produced is suitable for combustion in the on-site boilers, three more modules will be installed in a rolling programme throughout 2019.

NVP managing director Michael Murray is confident and expects his firm to grow rapidly, built on a technology that is now proven and building a reputation largely through positive feedback from clients.

The company was formed in 2013 and spent the following three years scaling up the technology to meet industrial standards.

The firm installed its first commercial-scale installation at an operational site in County Armagh, Northern Ireland, at a meat processing site operated by Irish food processor ABP Group in April 2016.

Solid performance

ABP sustainability manager John Durkan, who oversaw the commissioning by NVP Energy of the flagship sludgeless wastewater treatment plant, says its plant delivered solid, reliable performance right from the outset.

“ABP is always on the look out to support and enable innovative and technology-driven projects that will solve problems, so this project ticked all our boxes,” he says. “It’s carbon neutral, sustainable, odourless, cutting edge technology, low cost of treatment, no sludge production with clean wastewater discharge. On top of that, it delivers high quality methane gas for use on site.”

The treatment plant at Lurgan processes the entire flow of wastewater produced on site, turning the waste chemicals into biogas, ideally suited for heat and electricity generation – enough to offset ABP Foods’ gas usage on site by 40%.

This commission was followed by one for Arrabawn Dairies Group which has been operating for 18 months.

Food, drink and water

The company targets the food and drink and municipal water sectors because they tend  to produce low-strength wastewater with lower organic content than the waste streams produced by other sectors such as agriculture. These low-strength wastewaters are ideally suited to NVP’s energy-positive process.

The focus is now firmly on the water utilities clients, with the firm currently installing a module for Welsh water company Dwr Cymru.

“This is for one of its sites in Wales and will also be operational by the end of the year,” says Murray. “That will help us get into the municipal wastewater treatment market. That’s a market that has been slow to adopt new technologies. It uses traditional AD, which is highly energy-intensive. Our technology is attractive as it significantly reduces energy costs.

These projects mark important milestones for NVP. “We had two projects back in 2017 – Arrabawn and ABP – and we have now added a number of other blue-chip companies to our pipeline. We are deploying first-of-its-kind technology in these key market segments.

“We received patent approval in the United States in September of last year and European patent approval just recently. That means that we can move into these two key markets with patented technology. Our strategy will be to market and deploy systems ourselves on a turnkey basis in the UK and Ireland and to work with partners in the US, European Union and other more distant markets.”

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