Processing Magazine

Thermal drying system set to reduce Italian plant''s sludge production 75 percent

April 4, 2012

The Italian company Multiservizi will install a sludge belt dryer from Siemens Automation at its plant in the city of Jesi, Ancona. Once the dryer becomes operational in 2012, it will allow the plant to reduce the amount of biosolids produced annually by roughly 75 percent. The belt dryer evaporation capacity is 2000 kg/hr.


Multiservizi is a publicly owned Italian company that operates water and wastewater treatment plants for 45 communities in Italy. The plant in Jesi serves 60,000 residents. Siemens is the world’s largest automation vendor.


The dryer will reduce sludge production from 16,500 to 4,125 tons per year. The plant, which also has a natural gas boiler, recovers thermal energy from the cogeneration plant, thus reducing CO2 emissions.


With the sludge belt driver, evaporation takes place when biosolids come in contact with the heated air. Biosolids are evenly distributed on the entire belt width to cause uniform evaporation across the two-belt system configuration. Belt speed and process air temperature are adjusted for different residence times based on required product moisture to meet final use or disposal requirements.


Siemens says its technology was selected because of its high reliability and safety, low maintenance, and high automation level. Other advantages include high energy efficiency, minimal environmental impact, and agriculture-grade pathogen reduction.


Italy produces approximately 4 million tons of biosolids annually – almost half of which is currently sent to landfill with another quarter used for agricultural purposes. Limited landfill space and rising transportation costs are heightening the need to use technologies that reduce sludge volume.