Residents living near an incinerator have made new complaints about foul smells, two months after it re-opened.
The HLC centre at Crymlyn Burrows started trials in January
Trials at the £35m recycling and energy centre at Crymlyn Burrows near Neath started in January, 18 months after it was closed by a fire.
The Environment Agency has traced the smell to the plant and is working with the operator to eradicate it.
The company said recent smells were "very mild indeed" but campaigners want the facility shut down for good.
The plant was given the go-ahead to start operating in May 2002 despite a number of protests.
Last week its operator, HLC Waste Management Services Limited, was fined £4,000 and ordered to pay £4,000 costs after admitting breaching operating conditions which allowed odours to escape from the site prior to a major fire there in August 2003.
Since the blaze, the plant has been partly refurbished and partly re-built and a new senior management team appointed.
It began trials in January but people living nearby say since then the smells have returned.
Mike Ryan, who lives in Crymlyn Burrows and founded the Stop The Incinerator Campaign, said: "We've had terrible smells of rotting garbage coming into the village.
"It's been like shoving your head in wheelie bin - you could not open the windows or doors.
Mr Ryan said the smell from the plant was like rotting garbage
"It's obvious to me our objections at the start have been proved right.
"My quality of life and all the residents' quality of life has gone."
The Environment Agency confirmed it had received fresh complaints about the plant since it re-opened.
A spokesman said it had not taken any enforcement action but was working with HLC to resolve the problem.
When fully operational the plant would be capable of processing all domestic and non-hazardous commercial waste generated in the counties of Neath Port Talbot and Bridgend.
Seventy-five percent would be recycled, composted or burnt to produce power for the plant with the rest going to landfill.
A company spokesman said it was hoped the plant would be operating fully in the near future.
He said liaison meetings are held regularly with residents to give them a chance to discuss concerns and added he was aware of complaints by Mr Ryan and others.
But he said odours had emanated from the plant a few weeks ago but were 'very mild indeed' and the plant was operating strictly to Environment Agengy rules.
He added: "The trials have been very successful to date."