Water and Effluent Treatment Magazine
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| Sewer netwOrkS Bioremediation combats FOG Yorkshire Water has been trialling bioremediation technology to help tackle the problems caused by fats, oils and grease in sewers. The trials have led to significant improvements and cost savings. Blockages caused by fats, oils and grease (FOG) being disposed of into drains is an ongoing and costly nightmare for water companies to deal with. However, Yorkshire Water has discovered a solution to the problem after trials using ground-breaking bioremediation technology developed by commercial kitchen hygiene solutions expert Mechline. The result has been vast improvements in the sewers and sewage treatment plant performance. Yorkshire Water identified one particular problem site that was causing the nearby sewage pumping station and sewage treatment works to be overwhelmed with fats on a monthly basis. A nearby college catering for 300 residential students three times a day, was using a food waste disposal unit and disposing of all waste food to the sewer and, it had no form of grease interceptor to stop FOG from washing up area, combi ovens and food going straight down the drain. Fran Winter, Network Protection manager at Yorkshire Water, suggested trialing two solutions from UK-based Mechline at the college: Mechline's Waste2O onsite food waste biodigester and the GreasePak drain maintenance system. Both systems use naturally occurring bacteria that produce enzymes to break down FOG into simpler compounds that are compatible with main drains and sewage treatment facilities. F O G cannot reform a f t e r treatment, so drains a n d sewers are free running. Winter first came across Waste2O at a SNAP (Sewer Network Abuse Prevention) group meeting attended by representatives of UK water companies. "It was a totally new solution to Wastewater is the only output 12 | WET News | January 2014 Food being loaded into the Waste2O bio-digester waste aerobically. Unlike composting and anaerobic digestion processes, which produce compost or a compost-like digestate, the low-density liquid digestate from the Waste2O, goes straight to drain quite safely with each unit capable of processing up to 180kgs of waste per day. Running costs are around £1,500 per year, significantly cheaper than food waste disposal units, which also use a considerable The cost of cleaning fats from a pumping station could be in the region of £1,000 the problem of discharging of waste food to drain. We were really struggling to deal with the problem before. We were telling people to decommission their macerators, but had yet to suggest a suitable alternative for them. We could advise people to segregate food waste for collection, but some sites then had issues around bins full of food waste on site, and the lifting of heavy bags of food presenting a health and safety hazard for kitchen staff. Waste2O was a really innovative solution to the problem," she says. In Waste2O, the microorganisms digest food The system uses naturally occurring bacteria to break down FOG amount of fresh water. Waste2O is the only biodigestion system to gain WRc (Water Research Centre) approval. In the case of Waste2O's certification, WRc independently confirmed that the wastewater released from the machine meets with accepted industry norms and is 100% safe for the public sewer systems. At the same time, Mechline's GreasePak drain maintenance system was installed to work together with the Waste2O as an effective means of grease removal. GreasePak can be used on its own or in conjunction with conventional grease traps and is the only system of its kind to achieve the building industry's accreditation through the British Board of Agrément (BBA). Yorkshire Water was rewarded by seeing a significant improvement and cost savings within months, as Winter explains: "When we did a sewer camera review a few months after the installation, the drain system was all clear. I also coordinate all the sewage pumping station cleaning and noticed that we hadn't had to clean the pumping station, which served the college, in a long while. "The cost of cleaning fats from a pumping station could be in the region of £1,000. If we started to re-charge those costs to an organisation that wasn't managing its food waste and drain maintenance correctly then the cost benefits of fitting a system such as the Waste2O would quickly be felt." Winter adds: "Before we installed GreasePak and Waste2O, it would have been 'out of sight, out of mind' for food waste disposal. Staff were literally using the sewer as a bin, which is against Section 111 of the Water Industry Act. They didn't have a clue how much food was being wasted, but now that they collect the food in containers before they add it to Waste2O it has really demonstrated the volume of food waste being generated." Ian Cresswell, Business Development director at Mechline, agrees, saying: "Operators can actually monitor what food isn't getting used and make realtime decisions to improve food usage, from procurement to preparation, to disposal. Waste2O really does help prevent food waste which is top of the government's waste agenda. It also reduces what needs to be collected and transported for offsite processing or landfill, a significant environmental benefit. The Waste2O really is the ultimate on-site food waste solution." ■