A case study about the operational experience and benefits of SEEPEX SAI pumping technology handling dewatered sludge in a VEOLIA advanced anaerobic digestion Thermal Hydrolysis Process at Osberstown STF: PRESENTATION ONLY

McGarian, P.1, and Whitty, A.2, 1SEEPEX UK Ltd, 2Veolia Water Ireland Ltd


With the Smart Air Injection (SAI) technology, SEEPEX offers a high-efficient system solution that combines progressive cavity (PC) pumping with pneumatic dense phase conveying to transport dewatered sludge with 20-40%ds over long distances up to 1,000 meters.
This alternative to conventional technologies has already been applied in several plants across Europe and proven to significantly reduce operational (energy costs, spare parts and downtime) and total investment costs.

The conventional pumping of dewatered sludge over long distances is challenging due to the high viscosity and abrasiveness of the medium. Usually a high discharge pressure is required to overcome the pipe friction losses. Conventional solutions exhibit high power consumption and are vulnerable to wear due to this high discharge pressure. These restrictions are eliminated with the SAI conveying solution, in which sludge plugs are initially compacted in the discharge pipe by means of low-pressure PC pumps and further transported at increased mean velocity by pulsed air injections, i.e. dense phase conveying.
The sludge plugs are coated with a lubricant solution to reduce friction. Further reduction of frictional pressure losses could be obtained by the shear-thinning behavior of both fluids, i.e. sludge and lubricant, whereby the effective viscosity in the pipe boundary layer is considerably reduced for the high-velocity dense phase conveying. As a result, the pressure in the entire pipework can be permanently reduced to a minimum (~ 4 bar).

In a case study of SEEPEX and Veolia at Osberstown Wastewater Treatment Plant, an SAI package system for sludge cake pumping was installed at a brand new plant to handle dewatered sludge with dry solids content of 18-27%ds and a capacity of 4.5m3/h from a belt press to a silo, which feeds the thermal hydrolysis process known as EXCELYS. The package included three pumps, air compressors and control software. The SAI solution has enabled the customer to overcome existing space limitations. The below testimonial confirms the success of the SAI installation to provide an energy efficient and easily maintained process.

“I have worked with sludge cake pumping systems for 17 years, but I have never seen anything like the SAI installation at Osberstown – I am extremely impressed with it!”
“…I would have to say that the SAI installation has fundamentally changed how I would approach sludge cake transfer design / plant layout in future.” Alan Whitty, Principal Mechanical Engineer at Veolia.

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