Good morning Mastodon!
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Waste gases coming out of the kiln are mostly carbon dioxide from the combustion of all those carbon-based plastics that didn't make it to recycling and organic materials. They shared this interesting slide of what residual waste is actually made up of, after doing an extensive and probably deeply unpleasant survey separating out and weighing the contents of those bags. A depressing amount could have been composted or recycled
@afewbugs HHW = hazardous household waste
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Everything that doesn't burn up in the kiln comes out of the bottom and gets turned into aggregate. I hope you like boxes of rocks Mastodon.
Ferrous metals get pulled out by an electromagnet. Non ferrous metals melt into these weird modern art type sculptures that clog up the pipes and are the reason the plant has to be periodically shut down for maintenance to remove them. So I guess the moral is don't put metal in your non recyclable waste, but if you're going to only put ferrous metal?
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@afewbugs HHW = hazardous household waste
@tops thanks, edited!
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Everything that doesn't burn up in the kiln comes out of the bottom and gets turned into aggregate. I hope you like boxes of rocks Mastodon.
@afewbugs we *love* #BoxesOfRocks
srsly this is the most joyful pic so far (after Ashley with his fancy chair)
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Everything that doesn't burn up in the kiln comes out of the bottom and gets turned into aggregate. I hope you like boxes of rocks Mastodon.
@afewbugs fascinating thread, thanks! (I've visited the one at Ferrybridge, but didn't get a tour)
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Waste is then collected from the pit using this giant claw and dropped into the hopper feeding the kiln
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Within the carbon dioxide are various toxic gases, which are neutralised chemically, and heavy metals and other particulates which are extracted by filter to produce fly ash. This is then neutralised by this company to produce building aggregates: https://oco.co.uk
You can see emissions data for the plant here: https://www.viridor.co.uk/exeter-emissions-data/
@afewbugs oh we were just talking about fly ash! Vitally important for concrete's longevity.
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So the Exeter energy-from-waste facility, along with another one in Plymouth, opened for operation in 2015. Before that Devon recycled 55% of its waste and sent the remaining 45% to landfill. Now it recycles 56% (not a massive improvement in that time!), sends 43% to EFW and only 1% goes to landfill.
Managing closed landfill is still a massive logistical and financial operation for Devon County Council, which has responsibility for 58 of them, some of which date from before 1950 when records began so they don't even know what's in them. I didn't realise how much ongoing maintenance they need, but methane has to be flared off periodically and leachate has to be cleaned up before it can contaminate waterways.
@afewbugs it hadn’t occurred to me how much better incineration would be than landfill.
On the face of it, burning everything sounds bad, but I suppose it must actually be easier to manage the pollutants from that, as well as obviously producing energy from it.
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When we visited the world's biggest claw machine was operated by an extremely tolerant bloke called Ashley, who very good naturedly answered all our questions while trying to get on with his job. A couple of people told him he had the coolest job in the world, to which he replied that it had been for the first six hours or so but after that it got a bit boring.
@afewbugs
Omg this is all so great, it gives me childlike wonder looking at the photos
I reckon I'd have really loved this as a kid tbh -
@afewbugs
Omg this is all so great, it gives me childlike wonder looking at the photos I reckon I'd have really loved this as a kid tbh@afewbugs
It has a FURNACE. It has a SPECIAL CONTROL CHAIR FOR GIANT CRANE. It has a CONTROL ROOM omg -
The Marsh Barton facility isn't actually owned by the council, it has a contract with company Viridor which it pays to operate it. This is all utterly insane and probably Margaret Thatcher's fault.
@afewbugs
It's probably a PFI scheme from the Blair days, which of course was Thatcher's fault. -
@afewbugs
It has a FURNACE. It has a SPECIAL CONTROL CHAIR FOR GIANT CRANE. It has a CONTROL ROOM omg@afewbugs
The control room doesn't look as much like Thunderbirds as I'd have liked, but still! -
Ferrous metals get pulled out by an electromagnet. Non ferrous metals melt into these weird modern art type sculptures that clog up the pipes and are the reason the plant has to be periodically shut down for maintenance to remove them. So I guess the moral is don't put metal in your non recyclable waste, but if you're going to only put ferrous metal?
On the subject of Things Not To Put In Your Bin, it sounds obvious but things that will explode is a big one. Explosions can damage the specialist heat proof lining of the kiln, forcing it to be shut down for maintenance or even requiring it to be replaced, and explosions can also force gases through the filtration system faster than it can deal with them causing air pollution. People are apparently throwing away gas cylinders, which is crazy because domestic cooking and heating gas cannisters can be returned for a deposit. Empty camping gas cannisters can be returned to any outdoor shop selling gas cannisters.
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On the subject of Things Not To Put In Your Bin, it sounds obvious but things that will explode is a big one. Explosions can damage the specialist heat proof lining of the kiln, forcing it to be shut down for maintenance or even requiring it to be replaced, and explosions can also force gases through the filtration system faster than it can deal with them causing air pollution. People are apparently throwing away gas cylinders, which is crazy because domestic cooking and heating gas cannisters can be returned for a deposit. Empty camping gas cannisters can be returned to any outdoor shop selling gas cannisters.
@afewbugs round here (even in middle of town!) you can literally leave out any metal item that you no longer want on the pavement and someone will haul it off for the scrap metal value..
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On the subject of Things Not To Put In Your Bin, it sounds obvious but things that will explode is a big one. Explosions can damage the specialist heat proof lining of the kiln, forcing it to be shut down for maintenance or even requiring it to be replaced, and explosions can also force gases through the filtration system faster than it can deal with them causing air pollution. People are apparently throwing away gas cylinders, which is crazy because domestic cooking and heating gas cannisters can be returned for a deposit. Empty camping gas cannisters can be returned to any outdoor shop selling gas cannisters.
But the worst one is batteries. Most people now (hopefully!) know you shouldn't put batteries in your domestic waste, but only recognise batteries as the little AA cylinders rather than recognising batteries as being in little household things like toothbrushes, hearing aids, ear pods or vibrators where they're sealed in and invisible. Vapes are a huge one, and although single use vapes have been banned vapes with a recharge port at a similar price point are still being treated as single use disposable items. These cause a lot of fires in waste collection lorries when they're compacted, but also fires at waste management plants which want the fire in one place only, the kiln. So remove batteries from small electronic devices for disposal if you can, and if you can't dispose of the whole device in the battery recycling bin that every shop selling batteries should by law have available.
So basically stick your broken sex toys in the clear plastic battery bin in Sainsburys
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On the subject of Things Not To Put In Your Bin, it sounds obvious but things that will explode is a big one. Explosions can damage the specialist heat proof lining of the kiln, forcing it to be shut down for maintenance or even requiring it to be replaced, and explosions can also force gases through the filtration system faster than it can deal with them causing air pollution. People are apparently throwing away gas cylinders, which is crazy because domestic cooking and heating gas cannisters can be returned for a deposit. Empty camping gas cannisters can be returned to any outdoor shop selling gas cannisters.
@afewbugs And no doubt e-waste batteries, especially the rechargeable Lithium based ones
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On the subject of Things Not To Put In Your Bin, it sounds obvious but things that will explode is a big one. Explosions can damage the specialist heat proof lining of the kiln, forcing it to be shut down for maintenance or even requiring it to be replaced, and explosions can also force gases through the filtration system faster than it can deal with them causing air pollution. People are apparently throwing away gas cylinders, which is crazy because domestic cooking and heating gas cannisters can be returned for a deposit. Empty camping gas cannisters can be returned to any outdoor shop selling gas cannisters.
@afewbugs
That is a disposable SIP canister - for welding usually but some of us use them for other shenanigans. The gas in them isn't flammable - it's usually CO2, Argon or a mix but they're meant to go in your can recycling bin not general waste because they can still have pressure in them which is bad. -
@afewbugs round here (even in middle of town!) you can literally leave out any metal item that you no longer want on the pavement and someone will haul it off for the scrap metal value..
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@afewbugs it hadn’t occurred to me how much better incineration would be than landfill.
On the face of it, burning everything sounds bad, but I suppose it must actually be easier to manage the pollutants from that, as well as obviously producing energy from it.
@benjamineskola @afewbugs yeah, me too, my brain always went "burning stuff bad" but this thread has been fascinating. Thst they can even recycle the ash into aggregates is neat.
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@afewbugs
That is a disposable SIP canister - for welding usually but some of us use them for other shenanigans. The gas in them isn't flammable - it's usually CO2, Argon or a mix but they're meant to go in your can recycling bin not general waste because they can still have pressure in them which is bad.@jamesb I'm guessing it just expanded in the heat then and exploded from the pressure
