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Pembrokeshire has awoken to the disaster of human and animal sewage damaging our waterways. But what of our other waste streams?

Jamie Ashe reports

We arrived at our second recycling facility to a jollier vibe, more farmer biologist than James Bond. Stormy down anaerobic digestion ( AD) plant near Bridgend is where all our food waste goes and some commercial waste. Lorries dump their load into a concrete pit about 7m X 10m with a second one in case the first needs maintenance. A tanker with liquid waste from a cheese factory arrived while we waited. A hydraulic ram pushed the waste to a conveyor and up it went and was dropped into a huge blender which chopped up the little bags of food waste we put in our caddies, and added liquid – water or wey from the tanker of dairy waste.

A centrifuge then spun the wet food waste, flinging it through holes on the sides. The plastic bags we line our bins with did not pass the holes, they were compressed removing moisture and then spat out into a pile. The bags would go off to the Cardiff energy to waste place down the road. So in fact it doesn’t matter if you use biodegradable or plastic bags for putting food waste in as it all gets burnt for energy.

Out of the sides of the centrifuge poured a gloopy chopped up food soup. We were taken round to see it flowing down the pipe, it was brown puke colour and you could see lumps in it. A couple of our group held their noses because of the smell. I slightly gagged at the ‘ puke of wales’ flowing past. The building had overhead air extractors sending smelly air through a container of wood chip seeded with bacteria which broke down the smells, as a result there was no smell outside.

The gloupy soup was then pumped into huge tanks, each about the floor area of an olympic swimming pool and 17m high. Here it would undergo anaerobic digestion

and gas would collect in large domes above it. The domes would rise and fall depending on how much gas had collected.

There were 3 of these giant silos and gas could be pumped between them to equalize storage or one could be emptied in case of maintenance. Lightning had hit one producing a large flame but it could be isolated by closing valves so no gas from the other tanks caught fire.

After a final extraction chamber the gas was ‘ scrubbed’ by spraying water which removed sulphur which could damage the gas engine. Engines in shipping containers burnt the gas powering a shaft to turn a generator. The energy output was 3 mW in total.

The by- product of the process is a liquid fertilizer pumped into 2 lagoons on an adjacent farm. A tenant farmer uses it to fertilize 4500 acres of land owned by the AD plant. He grows a variety of food crops but also a small area of maize to feed the AD plant if there is a shortage in food waste for a few days and maize also helps reduce the acidity of the food waste.

The AD reservoirs where essentially large stomachs and needed the right bacteria to digest the food. The manager told us that each huge ‘ stomach’ had developed different taste and did well with different feedstock. One did really well when fed bread. These huge round silos with green domes on top suddenly appeared like sentient beings with personal preferences!

The site produces waste heat, enough to heat a housing estate via a district heating system. If it was in Germany or Sweden this would have happened but for some reason not in Britain. I suggested heated green houses growing tomatoes etc. Another idea was a large domed ‘ world’ containing heated swimming pools and tropical plants. I often thought our Bluestone swimming pool, instead of being in the National Park and heated with good land used to growing miscanthus and willow should have been near Milford Haven power station which is sending all its waste heat into the Estuary.

But at stormy down AD plant as i stood around the pit of food waste bags and breathed in the pungent air the saying “where there’s muck there’s money” came to mind. The constant output of 3000kw would be worth at least 13.6p per kwh which would be an income of £ 10,000 per day or £ 3.6million per year. On top of this would be the gate fees for collecting the waste which would be even more.

If Pembrokeshire residents could compost their own food waste it would save the council a lot of money in staff time, fuel costs and gate fees to get rid of it. A third of our council tax bill goes on recycling and environment. The more we compost at home the better, but food waste could create gas close to home if it it was easier for farmers to receive domestic waste. The cost and barriers to a licence make this impossible so instead it is driven all the way to Bridgend. Or it could simply be composted locally with heat and soil fertility for our use.

Not long ago food waste was just thrown in with all the rubbish which went to landfill causing rats and polluting leachate. The stormy down AD plant technology came from Germany they even have a guy called Wolfgang who comes over to tell them how to be more efficient. It was 2019 that Cris Tomos as cabinet member brought in our household separation system, placing Pembrokeshire as the lead recycling county in Wales and Wales became second best in Europe.

There is great scope for export of AD and waste to energy technology and expertise and general waste management systems around the world. Just as the technology matures and becomes available we are seeing massive species loss and climate change catastrophes gathering pace. It feels like we are in a last minute effort to save the planet from destruction.

I feel privileged to live through these times and see recycling really take off in Wales. As the place where the industrial revolution started it feels right that it is the place which leads the way in tackling the huge global environmental problems that industrialisation has caused.