Study on the hydrothermal drying technology of sewage sludge

Drying of sewage sludge is an effective way for treatment and utilization of sewage sludge, where reduction of energy consumption is one of the major technical challenges. So we experimentally investigated the possibility of the hydrothermal treatment. We have found that treatment of sewage sludge by saturated steam with the temperature of 190°C and pressure of 20 bar can dramatically improve the dehydration performance of the slurry like product. And the water content can be reduced down to about 55% by a mechanical dehydration. After natural drying 24 h it can be reduced down to about 20%. The final product is almost odorless and can easily be used for the refuse derived fuel (RDF). The sewage sludge product may be used as land-fill, or burned in a boiler or incinerator.