Hi, I know you've just fixed and simplified the original mod, but perhaps you would be interested in making it even better?
Regardless, I'll just throw some ideas I think would make the experience better and more fun imo.

1: Research placement and requirements
Issue:
Now the research is kind of confusing, considering the toxic incinerator is unlocked early with red/green science, but to get the heatpipes that require it to work you need to unlock nulear power considerable later in the game with red/green/blue science.

Possible solution:
Split the research into different categories:
- Pollution Collection (red/green): Pollution Collector, Blue Xenomass, Red Xenomass
- Pollution Processing (red/green): Toxic Sludge, Toxic Waste Treatment, Fill Toxic Sludge barrel, Empty Toxic Sludge barrel
- Pollution Warfare (red/green/military): Toxic Dump , Toxic Turret, HEV Suit
- Pollution Solution (red/green/blue): Toxic Incinerator, Low-heat Exchanger -- Either locked behind nuclear power, or make the heatpipes unlock with this recipe too.

2: Collecting pollution have a cost
Issue:
Now it's free ¯_(ツ)_/¯

Solution:
Have it cost power, or something else to collect.
a: Electricity -- At least it should need a fan sucking the gas out of the air.
c: Electricity + coal -- Coal is needed to filter the air and capture the pollution?

Addition: If possible.
- Hand held sludge weapon -- would also require a new ammo type. Purple skinned flamethrower and ammo maybe?

Anyway, thanks for maintaining this mod and Happy New Year! :)

2: Collecting pollution have a cost

definitely should cost at least energy.

otherwise it is s great mod. Sadly red xenomass is a bit scarce. The mod settings for a higher drop rate from the nests don't seem to work too.

The mod could definitely be better, and I do welcome suggestions. I just don't know a lot about modding yet.

1: The research is indeed whack, but it's been like this since the original mod. I'll try to have a look at the tree sometime soon.

2: I agree that it should have some kind of cost, at least in terms of electrical, but there's a con associated with doing that.
Currently the collector is based on the storage tank, which you may have already guessed from the ingame sprite. However, storage tanks cannot consume energy or process items (the coal you mentioned, for example). I would also like to make the fan animate, but storage tanks also don't support that.

Why not switch to an assembling machine or something similar? Because the storage tank does one thing that no other entity in factorio does. Its window at the front shows the amount of fluid that's inside it, and it updates based on how full it is.

It's definitely possible to have both, other mods do it, albeit in a "cheaty" way. They spawn and overlay multiple entities, but I've yet to figure out how to do that.

Yes I've seen other mods to that with multiple entities.
So for example use the steam turbine mixed with a chemical plant if you manage to figure that out.

I know nothing about modding or the alike, and i understand it might be too much work to make it look good.

Why not switch to an assembling machine or something similar? Because the storage tank does one thing that no other entity in factorio does. Its window at the front shows the amount of fluid that's inside it, and it updates based on how full it is.

Well you could just add a second step here.
Have a machine do the collecting and require a normal storage tank to be connected to store the pollution gas.