The mechanical biological treatment plant in Langhurstwood Road is operated by Biffa as part of a long-term contract with West Sussex County Council.
The facility reduces the amount of non-recycled black bag household waste that is sent to landfill and is designed to divert more than 75 per cent of incoming material into a resource.
The plant has reduced landfill waste from around 30 per cent in 2018/19 to just under nine per cent, according to Horsham District Council as Toni Bradnum, its cabinet member for recycling and waste, visited recently.
This comes as the plant is due to be modified so it can start processing food waste when separate collections are rolled out across West Sussex.
Cllr Bradnum said: “From our perspective here in Horsham, this plant is fantastic and the reduction to landfill waste that has been achieved is an exceptional achievement.
"Full of high-tech equipment separating everything we throw in our household waste bins, from paper bags to food waste and virtually all of life's rubbish. Even street sweepings are re-used.
“It's a staggering volume they deal with, and the fact that most is now diverted from landfill is very encouraging.”
The facility includes the mechanical recovery of material to produce refuse-derived fuel which is taken to an energy from waste facility. Any biodegradable material treated within the AD plant generates electricity.
Mechanical and biological treatment is not a single technology, but rather a combination of sorting and treatment technologies.