Strengthening Biosolids solutions track record in the US


Source: Keppel Seghers

Latest project is one of the world’s largest dryer plants.

200 tonnes a day – that is how much sludge Keppel Seghers’ HARDPELLETISER units will treat at the Stickney wastewater treatment plant in Chicago.

Keppel Seghers has just been contracted by the Stickney plant to provide four HARDPELLETISER units as well as supervise their construction and commissioning at a new dryer facility, which will be completed in the third quarter of 2007.

Mr Dirk Eeraerts, GM of Keppel Seghers Inc in USA said, “This will be one of the largest dryer plants in the world and the biggest dryer project for Keppel Seghers so far. It will give us a prominent position in the US biosolids market and is a crucial reference for future biosolids business in the US and the rest of the world.”

The Stickney plant currently serves a population of 5.5 million and is located within a residential area. The plant produces approximately 130,000 dry tonnes of biosolids every year.

Up to now, a large percentage of the biosolids generated by the Stickney plant are air-dried. This treatment process not only requires a huge surface area, it also produces bad odours, which often arose complaints from residents in the neighbourhood.

The Keppel Seghers HARDPELLETISER is an odour-free process that simultaneously dries and pelletises the biosolids, creating a pathogen-free and marketable end product that can be reused as an organic fertiliser.

The product pellets may be applied to agricultural lands, and for the purposes of strip-mined land reclamation, construction of golf courses, and fertilisation of road embankments among many other uses.


The HARDpelletising process is a vertical, multi-stage, indirect convective unit which produces hard, round and dust-free pellets with more than 90% dry solids content in a single and safe operation.

Similar to the pearl formation process in an oyster, biosolids particles grow layer by layer and become hard pellets. This gentle process with efficient heat exchange and gravitation-aided biosolids movements results in low electricity consumption and reduction in operation and maintenance costs.

The Keppel Seghers HARDPELLETISER is available for all kinds of sludge and other biosolids with variable composition and for an evaporation capacity ranging from 50 to 15,000 kg H2O/h.

The HARDpelletising process, with water evaporation, is strictly indirect and no oxygen is allowed into the system. Dust production is prevented through a straightforward and gentle process, and the operating temperatures are kept low. Fire and explosion risks are therefore totally eliminated.

Pellets produced by the HARDPELLETISER are naturally round, hard, dust-free and with a narrow size distribution. The process ensures the stability and pasteurisation of the pellets. The pellets are of high hygienic quality and are easily handled, transported and stored for long periods of time. Hence, they can be used for many applications, ranging from soil improver and fertiliser to green fuel, depending on the sludge characteristics and the local environmental legislation.

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