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Eggs turning food waste into a biogas and natural fertiliser

A FASCINATION with a type of bacteria that can live without the need for air is a niche area of interest, to say the least.

But for Kieran Coffey, a Clonakilty-based engineer, it has been the foundation of a lifetime’s body of work culminating in his invention, MyGug.

Every year in Ireland, a million tonnes of food is wasted. Some food waste is composted, usually, at the domestic level, some is taken away in a brown-bin scheme, and the rest will end up in landfill, where it slowly breaks down, releasing methane gas, recognised in recent years as a more potent greenhouse gas than carbon dioxide.

Food waste from brown bins is transported by trucks to large processing plants called Anaerobic Digesters. The waste is broken down quickly in sealed tanks, producing two useable waste by-products: biogas and liquid fertiliser.

Ostensibly, this is a good thing — closing the loop on waste — but the problem is, says Kieran, that the transportation of waste and the large operations required to turn it into useable by-products is often fraught with complications and has the potential to produce a bigger carbon footprint than it aims to take out of the chain.

The solution? Move this process as close to the source of waste as possible.

To this end, Kieran, originally of Newbridge in County Kildare, has created MyGug to help businesses and, eventually, homes to take control of their food waste and reap the benefits of doing so for themselves: free, clean cooking biogas and a nutrient-rich liquid fertiliser, perfect for growing vegetables with.

Kieran studied mechanical engineering in DIT followed by a Masters in Environmental Technology.

He has been working in water and wastewater treatment for 25 years, the last ten with Cork County Council. But solving the problem of food waste in as productive a way as possible has proved itself to be his lifelong passion.

Anaerobic Digestion, or AD, is the process by which bacteria that can survive without air decomposes organic material.

“I’ve been interested in AD since college. For my final year project, I developed a lab-scale Anaerobic Digester and it has always been in the back of my head. I think AD is an amazing process and not utilised enough, and I kept thinking: Why aren’t more people in Western Europe and the U.S using this technology?” asked Kieran.

“In China, there’s estimated to be 30 million ADs. They’re very basic, underground structures, usually in rural settings. People dispose all their waste into these units, get biogas out for cooking and liquid digestate for growing more vegetables. It’s a fully circular system with absolutely no waste.

“The focus in Europe tends to be on big digesters, this includes Ireland. All the infrastructure is based around collecting and bringing to a central location: that’s the way AD has operated for a long time, and it’s hard to steer something so huge onto a new course.”

In 2017, Kieran decided the time was right to put what he knew into developing MyGug as a viable alternative to the problem of food waste.

“I applied for an SEAI grant to further develop the concept of MyGug. I’ve been involved in process design for large scale wastewater treatment plants, anything from 500 people to 60,000 people, and in Process Design you can miniaturise anything.

“Ultimately I’m a designer, an inventor and a fixer and not everything I needed to build MyGug could be got off the shelf, so I had to adapt aspects of the design to make it work for the kind of scale I needed MyGug to be used for. I used my knowledge of Process Design and Automation Design and came up with the concept of the egg-shaped tank.”

Yes, MyGug is egg-shaped, but why is this an important design feature?

“The egg shape has been used for a long time in wastewater treatment plants, since the 1930s. For AD to work most efficiently, there must be good mixing. An egg has no corners, no area within that will allow solids to settle. Stir it, and all the contents of the egg are going to mix well — there are no ‘Dead Zones’.”

The egg shape is based on a new field of scientific study known as biomimicry, or biomimetics, where nature is emulated to solve complex human problems. The egg shape is structurally very strong so, in terms of environmentalism, says Kieran, fewer materials are utilised in its fabrication.

“I’m fascinated by the egg shape; it really captures people. They are attracted to the shape and they like it, they ask what it is: people are very curious, which wouldn’t be the case with any normal tank.”

So, what is MyGug and how does it work?

MyGug is an Anaerobic Digester scaled in size for small to medium-sized businesses and soon available for domestic use too.

What makes it different to composting is that any kind of food waste can go into it: milk, yogurt, leftover scraps, beer, wine; vegetable matter, meat, and fish — raw and cooked; sauces, oils, grease. Every kind of food waste produced in a kitchen can go into the digester.

“MyGug is a tank of anaerobic bacteria, bacteria that operates in the absence of air, and feeds on organic material. Waste food is fed through a sink macerator, mixed with water to create a slurry, and gradually fed into the egg-shaped tank where the bacteria breaks it down and converts it into biogas for cooking and a nutrient-rich fertiliser used to grow more food.

“The bacteria like warm conditions, so the egg is insulated and kept warm to around 37 degrees Celsius, or body temperature.

“As the bacteria get to work, they break down the organic material into constituent parts that each type of bacteria has a role for.”

Right now, MyGug is only available for commercial use, although a domestic version — the Mini Gug — should be available within the next six months.

“MyGug is a complete system, everything comes with it: sink and maceration unit, egg tank, gasbag, fertiliser tank, heating, and monitoring system. For commercial customers, MyGug is available in three different sizes: 5, 10, and 25-tonne food waste capacity per year. The largest is suited to a medium-sized hotel business. For the domestic customer, MyGug Mini has the capacity to create up to two hours of cooking time from the biogas produced.”

Any new technology needs people who are willing to reach farther than most and be the early adopters. Rebecca Scott, the owner of Rebecca’s Kitchen and Farm Shop in Kilbrittain, saw the potential of MyGug and is the first commercial business to have the system installed.

“Rebecca and her father, Guy, are really happy with the system. It really sorts out an issue for them by having a quick and easy way to get rid of food waste. MyGug deals with it all, and they’re getting close to the equivalent of one yellow cylinder of gas a week.

What’s the future vision for MyGug?

“I hope to see thousands of people, business, and domestic users, using this technology because it makes complete sense. The problem with food waste is that the farther away it is from where it is created, the more likely it is to become contaminated, and if there is any kind of contamination the liquid digestate cannot be used on land. The more difficulties, the more emissions created.

“The ideal is treating food waste as close to source as possible: the user then also has the benefit of biogas and liquid digestate.”

How does it feel to see an idea that you’ve been thinking about, designing, and developing your entire professional life come to life and gain traction?

“It feels very satisfying, I have to say. Things are always moving slower than you’d like them to, but I think Rebecca’s Kitchen& Farm Shop has been a real turning point. Now people are starting to understand what can be done on a small scale when the process is automated,” said Kieran.

“There are huge benefits for treating locally too: the liquid digestate provides fertiliser and nutrients for growing more food, and local food production, enabling people to produce their own food locally, is an excellent way of reducing carbon footprint.

“I’m hoping to get more units installed and show the benefits of micro-scale anaerobic digestion. MyGug is like a bin that doesn’t fill, a gas canister that doesn’t empty, and provides an unlimited supply of liquid bio-fertiliser to grow more food.

“MyGug is a fully circular and sustainable technology and I hope more people can use it.”

Reposted from EchoLive


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