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Why not have a rotating chamber with multiple filters inside on the exhaust, that when full of particulates it just rotates to the next filter? NO more wasting fuel to heat up the temps to burn it away.
Or, perhaps a tank of water (or high temp fluid so it wouldn't evaporate) that sprays across the exhaust stream to capture the soot in the water (like falling rain cleaning the particulates out of the air), where is can then be filtered with a replaceable spin-on filter.
Or, perhaps a centrifugal canister than flings the particulates to the bottom of the canister, similar to a carpenter's shop vac collector for dust.
I think there are better ideas out there that yes would be more expensive, but waste less fuel.