The biosolids granulator (photo) is a dry-on-demand system for the treatment of sewage sludge from municipal and industrial wastewater-treatment plants. It combines existing centrifuge-based dewatering with proven drying technology. This process, said to be unique in the world in this form, uses the dewatered solids ejected directly from the rotating centrifuge bowl. This is then immediately heat-treated and solidified by the primary direct-heat input stream. The solid particles are then further dried by the secondary hot airstream in the main drying chamber. The result is an improved dried granule with up to 50% dry solids and a consistent pathogen count below 100,000 cfu/g. These process results can be achieved using either low-temperature (75–90°C) waste heat available on site, heat generated from a fuel source or a combination of both. — GEA Group, Düsseldorf, Germany
A biosolids granulator for the treatment of sewage
| By Mary Page Bailey and Gerald Ondrey