Sludge - Kings Lynn WwTW
The work at Kings Lynn Wastewater Treatment Works (WwTW) was carried out as a joint venture between Imtech’s subsidiary business, Imtech Process and Galliford Try for Anglian Water.
The project was awarded as an NEC Target Cost Option C and included 19,000 tonnes of DS, enhanced treated sludge digestion plant and sludge screens. The scheme also required sludge belt thickeners, two mesophillic anaerobic digesters and jet mixing systems on the digester.
The enhanced process was designed for hydrolysis (42°) and pasteurisation (55°) and three sludge centrifuge dewaterers were required, and the polyprep system (liquid for belts/powder for centrifuges) was installed.
Two combined heat and power (CHP) engines, each producing one megawatt were installed, and water jackets on CHP engines were specified to provide heat for the hydrolysis stage.
A waste gas boiler generating steam for pasteurisation stage of the Monsal process was also chosen. This decision was taken as using steam rather than water eliminates vivienite and prevents heat exchanger blinding.
One bubble-type gas holder with a 2000m3 capacity was specified, with a low level waste gas burner.
A sludge opex optimisation plan was developed and Imtech Process also provided a full MCC, ICA, Scada package, installed enhanced sludge digestion to provide six log kill on e-coli levels and reduce sludge production by 20%.