A major development of recent years has been the arrival of new treatment systems for dealing with waste from road sweepings, municipal wastewater and utilities. One of the companies involved in maximising the recovery of such materials for reuse is CDEnviro. In this article the company’s Peter Craven outlines the potential opportunities here, and his belief that regulators are not doing enought to support this kind of activity.
WITH increasing pressure on landfill space across Europe, legislative measures such as the Waste Framework Directive and the Landfill Directive have attempted to foster a greater drive to explore the recovery of materials previously sent to landfill.
Attitudes to materials recovery have since become more carrot than stick, you might say, with a growing recognition that businesses have an opportunity to make themselves more efficient and eliminate unnecessary waste disposal costs.
All kinds of materials also have the potential to be a valuable resource, with the availability of suitable processing techniques. This holds true even for things like sewer grit, road sweepings and gulley waste.
CDEnviro, for example, has installed recycling systems for sewer grit at a number of sewerage treatment works in the UK. These plants are processing sewer grit from the inlet works and in some instances are also acting as a central recycling facility for imported wet waste captured at other smaller treatment plants. As sewer grit is more than 90% mineral material there is significant potential for this material to be cleaned and dewatered and made suitable for further use. The treatment process involves a variety of processing phases including attrition, high frequency screening, dewatering and stockpiling.
The ability of the system to produce a clean, dry grit and recycled aggregate product has been recognised by the major water utility companies. Some of these firms have in turn carried out considerable market research with local construction contractors, to establish whether there is a commercial application for this material. The response from the latter has been extremely positive with the general feeling being that contractors would be more than happy to use this material if all the required certifications were in place.
A similar situation applies in relation to road sweepings and gulley waste. Research has shown that this is a valuable resource, and opportunities exist to recover its 90% mineral content.
Typically 50% of this waste material is sand, grit and small stones, with another 40% composed of a larger mineral fraction which has potential for use as a recycled aggregate.
An accurate picture of the volumes of this waste being generated in the UK is difficult to establish – figures are hard to come by – but each Local Authority in the UK sweeps roughly 20,000 to 25,000 tonnes of waste from the highways every year with a further 4,000 tonnes coming from road gulleys. With 27 county councils in the UK responsibility for waste disposal, we can estimate that between 648,000 tonnes and 783,000 tonnes of this material could be treated every year. Efficient recovery of the 90% mineral fraction equates to somewhere between 583,000 and 705,000 tonnes of recycled grit and aggregates every year in the UK alone.
At present approximately 2 million tonnes of road grit is spread on the roads every winter in the UK so even at a conservative estimate we are in a position to reduce the pressure on the virgin materials currently used for this by 25%.
The opportunity in the UK is replicable across the EU member states, with there being the potential to reintroduce several million tonnes of recycled road sweepings and gulley waste into local construction applications if all the required certifications are in place.
It is here that the system appears to break down. At present the Environment Agency in the UK has issued a “Guidance on low risk waste activities” document which deals with both sewer grit and road sweepings. Currently this guidance only allows these recycled materials to be used in a very limited number of applications, a restriction that is stifling the development of this industry.
In the absence of certification to allow a more widespread use of these recycled materials an opportunity will be missed. Both equipment manufacturers and the industry as a whole have demonstrated a commitment to tackling waste reduction and maximising the value of the recycled products. Unfortunately, the EA has not shown the sense of urgency that is required if we are to fully exploit the opportunity presented by sewer grit, road sweepings and gulley waste.
