Two sludge drying and pelletising installations will replace multiple hearth incinerators in two wastewater treatment plants in Atlanta, Georgia, USA. Seghers Keppel Technology Group of Willebroek, Belgium, will provide the engineering and supply of core equipment, including its HARDpelletiser units.
Both plants have full secondary treatment, anaerobic digesters and centrifuges for mechanical dewatering of the sludge. One plant with a capacity of 4.5 tonnes of water per hour will be installed in the Utoy facility (165,000 m3/d). The second unit will be installed in the Clayton facility (380,000 m3/d). This dryer has a capacity of 6.7 tonnes of water per hour. USFilter will construct the plant and operate and maintain it as part of a design, build and operate (DBO) contract.
The project will convert sewage sludge produced at plant into high quality pellets with potential commercial value to help the city reduce incineration plant emissions. The pelletised product is ranked "Class A" according to the US Environmental Protection Agency 503 regulations, and will be available for direct application as fertiliser and soil conditioner.
Pellets produced by Seghers HARDpelletiser process are used as a slow release fertiliser and soil improver on agriculture and grassland or in forestry and soil reclamation projects. The high heating value of the pellets make them useful as fuel for co-incineration in coal power stations, cement kilns, feedstock in gasification plants or support fuel for incineration.
