Preventing fatbergs – and using the material for producing biodiesel
Stephen Williams, Network Protection & Enforcement (Investigations) Southern Water answers questions put to him by Gaynor Hartnell of the RTFA.
- What are fatbergs?
Fatbergs are the result of Fat Oil Grease and food waste being discharged to the sewer from both domestic houses and commercial properties, which then combines with other ‘unflushable’ items (wet wipes, sanitary products etc) to form a solid mass blocking the sewer.
- How / why are they formed?
FOG is formed from the washing up process and is the resultant sludge formed in the emulsification and saponification of those fats, oils, grease and food waste in warm water – in the sewer the FOG settles out and adheres to unflushables, catches on sewer bends and joints – once started the fatberg grows to fill its environment, which could be anything from a 4 inch sewer to a huge chamber……..
- What proportion of sewage blockages does FOG account for?
Approx 25% by itself with a further 40% where it contributes to blockages caused by unflushable items, roots and silt.
(Yearly figures based on Southern Water blockage numbers)
- How much FOG finds its way into the UK’s sewers per year?
Unknown specifically, but in terms of blockages – Southern Water has approx. 20,000 blocks per year, of which 13,500 either are caused by FOG or where FOG is a contributing factor.
- What is the cost of dealing with fatbergs?
Southern Water suffers approximately 20K blockages a year, at a cost of around £15M. Annually in the UK it is estimated as approximately £100 – £120M. But it could be more –there are 12 Water & Sewerage Companies – if all average £15M per year that’s £180M for the UK.
- What is the environmental impact of fatbergs?
Internal floods to properties, floods to roads and open spaces and pollution to watercourses, streams, ponds, lakes and the sea.
- What is currently done with fatbergs?
They are jetted away if small enough in the sewer – and the material will end up in treatment works and their bio-digesters. Large fatbergs such as the one in Whitechapel and Sidmouth are ‘dug out’ and taken for AD/fuel or similar.
- How much biodiesel could be produced if this FOG was captured at source?
Southern Water has 28,000 Food Service and commercial kitchens in its area – if on average each Food Service Establishment (FSE) produced 1 tonne of FOG per year – that would be 28,000 tonnes of FOG yearly.
- What proportion of food service establishments (FSEs) have adequate grease management?
10% or less across the board – however on a survey of revisits following ‘reactive’ intervention by Southern Water 58% of FSE’s had installed some grease management.
- How are FSEs regulated with respect to grease management?
The only ‘direct’ legislation is Building Regs H1 Section 2.21, but this is weak. It uses the word “should” rather than “shall” –
“2.21 Drainage serving kitchens in commercial hot food premises should be fitted with a grease separator complying with BS EN 1825 – 1:2004 and designed in accordance with BS EN 1825 -2:2002 or other effective means of grease removal”
The Water industry Act 1991 allows offences under S111 to be investigated and prosecuted as a criminal offence. The offence is one of causing a blockage rather than not installing grease management. No legislation requires grease management and certainly does not specify function or flow capability or requires a specific level of FOG removal.
- What would be required in terms of legislation / regulation to bring all existing FSEs up to best practice?
Changes in the Water Industry Act 1991 to incorporate the protection of the sewers from FOG by the Water Companies OR New legislation requiring all FSE’s/Commercial kitchens of any description to fit a ‘standardised’ form of grease management – Water Companies would ‘prefer’ removal at source rather than treatment at the time of or after discharge.
- What advantage is there for FSEs in managing their grease properly?
Fewer blockages, floods and pollutions. FSE’s not having to clean their own private drains and possibly a rebate for collecting and returning a good quantity of FOG as happens with UCO.
- How do water companies currently go about protecting their networks from fatbergs?
Network Protection teams across all Water and Sewerage Companies (WaSCs) visit reactively and proactively as many FSE’s/Commercial kitchens as possible to share the message about FOG – but as this is not ‘legislated’ other than Building Regs (which states ‘should’ not ‘shall’) and the grease management industry is completely unregulated, it is a difficult message to offer and difficult one for FSE owner/operators to accept, as historically they have flushed everything and not worried about it because the WaSC’s have just cleaned and not enforced!
Legislation is needed……..
- What sources of information are useful? (e.g. trade associations, reports, websites, individuals willing to be contacted etc)
- NFFF – National Federation of Fish Friers
- Water UK
- SNAP – Sewer Network Abuse Prevention (part of Water UK)
- NCASS – National Catering Association
- BTC – British Takeaway Campaign
- Many of the larger pub groups……. Mitchells & Butlers, Enterprise Inns, Greene King, Martsons, Fullers, Youngs, Harveys, Hall & Woodhouse
Supermarkets – Morrisons, Sainsburys & Asda
- BESA – British Engineering Services Association
- CIBSE – Chartered Institute of Building Service Engineers
- SoPHE – Society of Public Health Engineers
- Cranfield University- Bruce Jefferson
- Isle Utilities – Karyn Georges
- Raffaella Villa – De Montfort University
- Nicky Cunningham – Exeter University
- CIEH – Chartered Institute of Environmental Health.
- ECAS – Environmental Compliance and Services – FOG enforcement for Severn Trent Water and 4 other water companies (part time or projects)
- GCA – Grease Contractors Association – administered by and part of…………
- British Water
- Landlords such as Westfields, Land Securities, Savills, Hammersons…….