[fuoqi]

The problem is with trying to "recycle" garbage plastic. Plastic is mostly carbon, oxygen, and hydrogen. Properly burning it using high-temperature (900+°C) pyrolysis converts most of plastic into water and carbon dioxide. There are some issues with sulfides and nitrogen oxides, but scrubbing those is a familiar problem for the industry. Remaining ash is relatively inert and can be used as a filler in various applications. Releasing carbon dioxide is not great, but it's much safer biologically than polluting environment and oceans with microplastics and total volume is relatively small compared to other emission sources.

[Retric]

I don’t see how sending plastics to a dump is going to result in ocean micro plastics. Environmentally you’re inefficiently generating energy from trash and reducing landfill size from bring trash vs failing to sequester the carbon in the trash and releasing some air pollution. I doubt pyrolysis is a net gain.

Properly constructed and operated landfills are a small source of methane, but otherwise quite benign.

[fuoqi]

"Properly constructed and operated landfills" which prevent leakage of microplastics and toxic decomposition products into air and waterways are far from being cheap, especially on longer time frames and with involved volumes (more than 80M metric tonnes per year just in US!). Usually, you either end up with slack maintenance, resulting in eventual pollution of the environment, or you export this waste into third world countries with significant amount of such "exports" ending in oceans.

And plastic does not stay inert in landfills forever either, it slowly decomposes, releasing products into environment (methane and carbon dioxide being most benign of those). Effectively, you get slower, less controlled and more dangerous (biologically speaking) "burning" which will be done for many generations instead of burning the stuff right away in controlled conditions.

[Retric]

Dumps are the ultimate expression of surface area vs volume.

A single 2200 acre landfill can handle 5 million metric tons per year for ~250 years. 80M metric tons isn’t a particularly big issue from an environmental or cost issue it’s all a question of collection and transportation to disposal sites not long term storage.

[pixl97]

>I don’t see how sending plastics to a dump is going to result in ocean micro plastics

Because that tends to only happen in a few, what we consider, first world nations. A huge portion of the world does not have sanitary waste collection system, and therefore produces huge amounts of plastic waste that get into rivers and the ocean.

Of even in places with waste collection, an (un)healthy amount of plastics never make it to the trash. Blow off/run off from trash cans is one example. Another is direct environmental loss into the environment. For example washing your clothes releases massive amounts of plastics, unless you happen to buy only natural materials.

Plastic is both a wonder material, and a wonder mess. Using it in things like medical device sanitation is a net benefit for humankind, using it everywhere appears to have higher costs than expected.

[Retric]

An incinerator isn’t going to solve the lack of a waste collection system. It’s a completely orthogonal issue.

[mrkeen]

> Properly burning it using high-temperature (900+°C) pyrolysis converts most of plastic into water and carbon dioxide.

I'm a little confused. Isn't pyrolysis what the company said they were doing?

Do they know what pyrolysis is, and are simply lying about doing it, or is pyrolysis a myth?

[fuoqi]

It's not a myth, it's a basic chemistry and physics. Increase temperature enough and chemical bonds start breaking, transforming complex molecules into simpler ones. Go far enough and you will get bare ionized atoms, i.e. plasma.

But there are different forms of pyrolysis. In my understanding, the company uses lower temperatures to transform plastic into "synthetic oil" (i.e. mix of hydrocarbons instead of long polymer chains), which in theory could be used to synthesize new plastic. Only small part of plastic gets transformed into gas and burned. But this "oil" is much harder to work with than oil pumped from ground, so instead of recycling it fully, some of it gets discarded into environment, resulting in toxic hazard.