Remoção de lodo de lagoas de estabilização e seu acondicionamento em bag

Abstract

This work aimed to study the sludge removal from stabilization ponds, to evaluate the reduction of pathogen load, transport costs for disposal and trying to achieve the required quality for sludge application on agriculture, thereby promoting the nutrients recycling to the biogeochemical cycles. Amongst the options for removal that were studied, the combined system of dredging and polymer application, followed by conditioning and sludge dewatering in high-strength polypropylene “BAG”, was selected. The experiment was conducted at the Business Unit of High Paranapanema - Sabesp, because this treatment plant faced with operational difficulties and the distance to transport the wastes to licensed landfills was very long. Thus, the waste transport was costly, since landfills in the region were not authorized to receive the sludge. Another disposal option, co-processing cement industry, was not feasible economically, mainly due to the high amount of water contained in the waste. If the sludge could not be used directly on agriculture, the amount of water must be reduced before transporting or other uses. The proposed methodology (sludge removal ), was made be evaluated by analyzing weekly the sludge quality from the BAGs. Six months after the operation of sludge dewatering packed in bag, it was detected an absence of viable helminth eggs, salmonella, protozoa and coliforms. These results indicated that the process removed the pathogenicity of the sludge tailoring it to the wastewater disposal, as to the parameters evaluated. The sludge in the bag reached total solids of 34.10% after 374 days and was classified as Class II A - Not dangerous, not inert. The cost of the removal of 2000 m3 sludge with an average of 12% solids, by means of the dredging and placing in bag was US$ 4.67 inha-1 year-1.