Monsal has been awarded the contract to supply the advanced digestion technology for Southern Water at Goddards Green and for Anglian Water at Cambridge sludge treatment centre, two of the UK leading water utilities. 

These are the first project of its type to be awarded in AMP4 (Asset Management Plan 4) and demonstrates the shift in this investment cycle from traditional single stage digestion to more robust multi stage biological processes in the UK.  

Both advanced digestion facilities will incorporate the patented United Utilities Hydrolysis process. Monsal are the development partner and exclusive licensee for the process in the UK. Integration of pre-treatment technology which optimise hydrolysis and acidification reactions are gaining favour with UK water utilities. 3 of the 10 water utilities have now committed to investment in this technology with Monsal with additional projects under development later this year. 

The plug flow reactor configuration is unique and ensures optimal conditions for pathogen reduction and hydrolysis reactions prior to anaerobic digestion.  The pioneering work in developing the process was acknowledged in 2004 by receiving runner up award in the IChemE water prize and winning the 2005 Utility awards technology prize in 2005. 

Integration of advanced digestion technology at Cambridge in Anglian Water will confer the following strategic benefits: 

·         Security – facilitate recycling of product

·         Quality - guarantee enhanced standard 99.9999% pathogen kill

·         Energy - more biogas, positive energy balance,  integration with CHP

·         Stabilisation - Improved product stabilisation, reduced odour

·         Quantity - less product for disposal 

The site at Goddards Green in Southern Water is a high rate digestion facility and is designed to treat a maximum sludge throughput of 350m³/d at 8% DS or 10,220 TDS per annum with an average of 285 m³/d at 7% DS. Goddards Green operates 2 digesters nominally 1900 m³ each, and under average operational conditions the digester will operate at 4.0 kgVS/m³.day (13 days retention) rising to a peak organic loading of 4.8 kgVS/m³.day (11 days retention). Monsal installed the original digester heating system in 1999 which utilises its concentric tube heat exchangers which have successfully operated with thick sludge (up to 8%DS) for over 6 years at Goddards Green. 

Advanced Digestion technology is now committed at the following UK sites: 

Hydrolysis technology has now been operating highly effectively at the Macclesfield and Bromborough sites for a number of years with an average VS% reduction of 59% for both sites. The process can be adapted to meet treated or enhanced sludge quality and can run in two operation al modes. The UK standards of treated and enhanced are similar to Class B and A respectively. The success of these full scale plants and a change in market conditions has led to an increase in uptake of the technology with other UK water utilities. 

Goddards Green advanced digestion facility is scheduled for completion in June 2007. Cambridge advanced digestion facility is scheduled for completion in May 2007.

Figure 1 – Goddard’s Green site overview  

For further information contact: 

Aidan Cumiskey