Sweeper plant on the road to recovery

A plant that can treat - and reuse - both liquid and solid waste from road sweepings has just opened for business in the northeast. Dean Stiles reports

A treatment plant that has just opened in Birtley, County Dur-ham, is set to recover and reuse 1M litres of water and 1,000 tonnes of solid waste a month from road sweepings taken from construction sites.

The facility, which has been two years in planning and construction, is operated by Admec Municipal Services – a northeast specialist in road cleansing and pressure jetting. Admec believes it will be the first road sweeping company in the UK able to offer construction companies an in-house road sweeping service with treatment and recovery. It is also the first sweeper company to apply to the Environment Agency for a waste treatment licence

Admec designed and built the plant using tried-and-tested technology from other industries. In operation, sweepers reverse up a ramp and discharge the sweepings into a raised tank. Lamella filter plates aid the process of separating water and solids, allowing the water to be drawn off for reuse in the sweepers.

The solids settle to the bottom of the tank and are scrapped with an integral blade and removed for recovery and treatment. About half of Admec’s 2.5-acre site is used to harvest rainwater and there are also plans to use a wind-powered turbine to reduce running costs.

Quality trials

“We’ve done various trials to ensure that we would get the relevant quality of water reclaimed from the process,” says John Halliwell, Admec’s operations director. “Essentially, we are converting the material from liquid waste – which has obviously got various problems in terms of disposal – separating the water and solids and looking for outlets for the solids.”

“From a road-sweeping business, or the point of view of anyone operating sweepers, the saving potential of our process comes from not throwing away the water and reusing it, making them sustainable in terms of water usage,” he adds.

The traditional disposal method of discharging sweepings on-site is becoming increasingly unacceptable, while liquid and untreated waste can no longer be discharged direct to landfill. Like other sweeper companies, Admec uses specialists to treat the arisings that are then usually disposed to landfill.

Rising landfill costs will soon make this prohibitively expensive, but Halliwell believes there is the potential to reuse the arisings – for example, the solid waste could go to construction sites for use as backfill or aggregate.

“Once treated, the solids can go to landfill, but what we are concentrating on is reuse of the solids. We have already had some initial discussions with people who are interested in the solid elements – and we can reuse all the water,” explains Halliwell.

He adds: “There are considerable benefits in environmental terms and in the cost terms of being able to routinely reuse the arisings, converting them into useful product for the construction industry.”

The service has special relevance for construction companies that need to comply with the requirements for site waste management plans. All construction projects in England estimated at between £300,000 and £500,000 in value must now have a site waste management plan to demonstrate compliance with their duty of care. The plan details the types of waste removed from the site, who is handling the waste, and where it is going.

Catering for councils

However, while most of Admec’s customers come from the construction industry, the company is actively looking to target local authorities with this new facility.

“The business plan for the new plant is not to keep the solution to ourselves, but to enable other people to set up using it. And it’s not just relevant to construction companies. We would be very pleased to hear enquiries from local authorities,” says Halliwell.

“Most of our work is done on construction sites where we clean up so that no contamination ends up on main roads. Basically, you get a cocktail of roughly 50% water and 50% solids, depending on the weather. What we do is make that product safe, separating it into water and solids so that we can reuse the water in the sweepers or get it clean enough to discharged into the sewer under our consent to discharge.”

Halliwell adds that for local authority applications, Admec may need to do some more development work looking at particular contaminant issues in the solids, but is confident the process has relevance for the public sector, due to its ability to divert waste from landfill.

Dean Stiles is a freelance journalist

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