Sistema térmico de higienização e secagem de lodo de esgoto movido a energia solar e a biogás

Abstract

Sewage sludge is a solid waste arising from the treatment of domestic sewage. Its destination must be environmentally sound and sanitary safe, to comply with the laws in force in Brazil. To meet this expectation, the sludge must be subjected to a process that promotes its cleaning and drying. Among the techniques which can be used for this purpose, there is a thermal process. However, a power source capable of transferring heat to the sludge is necessary. A pilot system consisting of two prototype was built to transfer heat to sludge through underfloor heating, powered by solar energy and biogas. The results showed that solar energy promotes the preheating of system and when operated with biogas acting with complementary energy source, provides the increase in sewage sludge at thermal levels compatible to their cleaning and drying. The average temperatures obtained in the prototypes 1 and 2 they reached 66,97 and 77,35°C, respectivaly. The total solids concentration they reached 86,69 e 88,07%, respectively. It was also found that biogas production in Sewage Tratament Plants is sufficient to feed a Thermal system of hygienization and drying of the sewage sludge low cost. The prototype 1 presented a autonomy of 165%, while the prototype 2 presented a autonomy of 295%.