FLUID HANDLING A COMPLETE SOLUTION
SEEPEX
SEEPEX back mixing technology increases sludge throughput
SEEPEX engineered solution encompassing progressive cavity pumps for dewatered sludge back mixing has increased sludge throughput at Anglian Water ’ s Cotton Valley cake import facility by 50 %, enabling the site to generate more biogas , and delivering significant savings in logistics and cake storage costs .
Anglian Water is the largest water company in England and Wales by geographic area , supplying water and recycling services to over six million domestic customers , processing over 142,000 tonnes of dry solid sewage sludge in 2020-21 to generate 115GWh of bioenergy .
The Cotton Valley Sludge Treatment Centre ( STC ) is one of Anglian Water ’ s ten main STCs where sludge is dewatered and treated anaerobically to produce bioenergy . In 2008 an advanced digestion Thermal Hydrolysis Process ( THP ) was commissioned to speed up the anaerobic digestion process . As part of an upgrade a sludge handling facility was designed to handle approx . 160 tonne a day of imported dewatered sludge from satellite works .
LONG STANDING PROBLEMATIC APPLICATION
Progressive cavity ( PC ) pumps ( not SEEPEX ) were installed to back mix the dewatered sludge and pump it into the THP . The two pumps were costing overall circa £ 100K per annum due to rotors and stators change every 3-6 months . Their inability to transfer no more than 3.5m3 / h ( bottleneck and limiting gas production ) meant the site was not able to meet the design criteria limiting the amount of imported raw cake being handled to only 120 tonne per day . Additionally , prior to maintenance , the silo had to be emptied to allow the pumps to be worked on , but also cake imports from satellite sites had to be diverted whilst work was carried out resulting in substantial logistical costs .
SEEPEX was invited to survey the site based on their vast experience in pumping and mixing dewatered sludge within Anglian Water ’ s water recycling treatment sites and sludge treatment centres . Leigh Thornley , Engineer for SEEPEX , says : “ We took pride in Anglian Water coming to SEEPEX with the opportunity to resolve a long standing problematic application .”
CUSTOM-MADE
SEEPEX was asked for a complete turnkey package which included the removal of the existing pumps which were installed under a 7m high silo . The new pumps required custom made hoppers which were 5m long to fit under the existing silo , and being able to handle 5.5m3 / hr of 16 % DS sludge which had been back mixed within the pump from 25 % DS and transfer this approx . 60m . Part of the SEEPEX solution was to offer standardisation of pump size with other sludge treatment centres within Anglian Water resulting in commonality of spare parts .
PRODUCTIVITY INCREASED
SEEPEX supplied and installed two custommade pumps from their BTES range with a dimensionally identical hopper to fit within the same footprint of the original pumps whilst delivering over 55 % increased throughput capacity from 3.5m3 / hr to 5.5m3 / hr .
SEEPEX BTES range pumps are designed to fit under silos , have custom made hoppers to suit the application and additionally incorporate an isolation devise to enable maintenance of the pumps to take place whilst sludge is left in the silo .
Pumps from SEEPEX BTES range handle highly viscous to semisolid products from silos .
60 PECM Issue 50