Desaguamento e higienização de lodo de esgoto utilizando estufa agrícola sobre leitos de secagem

Abstract

The sewage sludge is the main waste, in volume, in Sewage Treatment Plants and, after undergoing hygienization processes, it can be used as biosolid in the agriculture. In this scenario, the objective of this research is to study greenhouses performance on dewatering and sanitation of discarded sludge, based on long exposition to sunlight on dewatering beds, in a Sewage Treatment Plant applying Upflow Anaerobic Sludge Blanket Reactor associated with submerged aired biofilter. This research was carried on large scale at the Sewage Treatment Plant of Castelo using three consecutive repetitions lasting 28 days each. For all the runs it was used four dewatering beds, two covered by greenhouse modules and two exposed to weather conditions. The total solids rate applied on the dewatering beds ranged from 6,4 kgSST.m-2 to 17,8 kgSST.m-2, being used as comparing parameter for the outcomes. For the sludge water content removal, the covered bed 1, which had lesser total solid rates, showed the best results, reaching total solid rates of up to 6,4%. For microbiologic parameters, it was observed by the end of the 28 days: only the covered bed 2, during the second repetition, showed results of fecal coliform below 10³ NMP/gST; only for repetition 3 was not observed Salmonella in all four beds; and viable helminths eggs reduction was not enough for characterizing biosolid as Class A, according established by 375/2006 Resolution of Conama.