Economic viability of the agricultural recycling of sewage sludge in Brazil

The sewage sludge can be used for agricultural recycling as biosolids, since all the legal requirements are fulfilled, in plantations whose edible part does not have contact with the ground, thus its use is not allowed with the oleraceous, tubers, roots and flooded cultures. Considering that, from data collected by the Sanitation Company of Parana (SANEPAR), the agronomic analysis reports of 10 lots of biosolids processed at Ouro Verde Sludge Management Unit, in the city of Foz do Iguacu, Brazilian state of Parana, were checked, relating the concentration of nutrients N, P, K, Ca and Mg. Assuming the biosolids are given to farmers, responsible for transportation costs, the material becomes attractive only when equivalent to mineral fertilizers cost. By determining the price of fertilizers by the lot of biosolids, the distance that justifies its utilization was established. The main results found allow the conclusion that biosolids have from R$30.83 to R$167.32 of fertilizers per ton, considering the worst and best case scenario, respectively. The compensatory distance has exceeded 1500 km, increasing the possible use by producers from other cities or states. The reduction of the humidity content in the material is directly proportional to economy granted to the producer.   Key words: Biosolids, fertilizer, cost.