One of the obvious challenges of running Dogs Trust rehoming centres is the need to dispose of a significant quantity of hazardous waste. All locations not connected to mains drainage have to be served by reliable on site treatment systems and on completion of the latest installation at Salisbury a total of five WPL systems will be in operation around the UK.
The charity cares for some 16,000 dogs a year at 18 rehoming centres and in 2006 several centres were issued with improvement notices by the Environment Agency due to failure of existing package treatment plants to meet the required standard of treated effluent discharge. The Trust initially approached specialist wastewater contractor Warwick-based Soma Services for help.
Graham Hyde, Soma’s Technical Sales Director, said, “Soma was asked to look at on-going performance problems as well as supply of new equipment. Management of the sites, in particular the use of disinfectants, was reviewed, along with plant-sizing.”
The need for more effective routine maintenance was identified in the review, along with the need to up-rate equipment at several locations. WPL, Hampshire-based solutions provider in packaged sewage treatment plants, agreed to partner Soma Services in managing this difficult waste stream in five locations.
Drawing on Soma’s operational experience, WPL designed and manufactured a modular High Performance Aerated Filter - HiPAF - treatment plant with a Robust Aerobic Digestion System – RADS - to treat the hazardous waste. HiPAF is most appropriate for commercial and domestic applications where the site is not connected to mains drainage and is well-suited to difficult situations such as the treatment of dog and other animal waste.
This compact plant contains primary settlement, biological treatment and final settlement modules housed in glass-reinforced plastic tanks which can be installed above or below ground.
Introduction of RADS has significantly reduced desludging costs at Dogs Trust centres as the process reduces sludge volume requiring tankerage off site. These benefits are compounded by the recatagorisation of the aerobically treated sludge as domestic waste rather than dog waste - previously the dog waste had to be booked into the main sewage treatment works as a special load at a higher cost.
The first site to be supplied with a WPL system was Dogs Trust Shrewsbury Rehoming Centre near Telford in 2010. Since then, systems have been commissioned in Loughborough, Ballymena and Ilfracombe. The Salisbury installation will be completed in the next couple of months. Graham Hyde said, “Soma has been involved with the drainage design from the early development stages of all the new and redeveloped centres and operates as a specialist sub-contractor on these developments. Recent moves towards rolling out RADS technology at other sites served by package sewage treatment systems will not only ensure optimum performance, but will provide significant savings in tankerage costs.”
Simon Kimber, Sales & Marketing Director, WPL, said, “We’re very impressed with the work that Dogs Trust does and are pleased to supply our specialist treatment systems to ensure compliance with environmental legislation. The waste generated by this type of establishment is very difficult to treat and it is a testament to the combined process expertise of WPL and our partner on this project, Soma Services, that we have developed a robust solution.”
Paul Wass, Project Surveyor for Dogs Trust said, “We are very happy with the work that Soma Services and WPL have done for us over the past eight years and in particular the development of the RADS system. This has made a significant difference to the amount of desludging that we have to have carried out on our installed systems and has dramatically reduced the associated costs.”