AGRONOMICS AND INORGANICS PARAMETERS OF SLUDGE, SANITIZED BY ALKALINE STABILIZATION, GENERATED IN SYSTEMS CONTAINING ANAEROBIC TREATMENT PROCESSES OF SEWAGE: A CASE STUDY OF THE STATE OF PARANÁ, BRAZIL

Abstract

The agricultural use is an environmentally sustainable destination for sewage sludge because it promotes the recycling of nutrients and is beneficial to the cultivation of plants and to the physicochemical and biological characteristics of the soil. The Parana is one of the Brazilian states where the sewage sludge has agriculture as a priority disposal. The composition of sewage sludge to be disposed for agricultural use is related to the sewer from which it was originated and the process of treatment of the sewage and of the sludge. The way of treatment and of hygienization affects the final characteristics of the sewage sludge. This case study aimed to evaluate the differences in composition of sewage sludge batches generated, in the Parana, in systems containing anaerobic treatment and sanitized by prolonged alkaline stabilization, in relation to the agronomic and inorganic parameters (metals), from 2011 to 2013. Differences in the process of dewatering, hygienization and generation of batches, possibly, explain the differences of the agronomics parameters results verified between the batches produced in Sludge Management Units of the interior of the State, compared to the batches of the Curitiba Metropolitan Region. There was a large variability in the concentration of inorganic parameters of batches, probably associated to differences in sewage basins. Batches showed levels of inorganic parameters on average 89% below the limits of the State of Parana, the Resolution of the State Environment Cabinet (Sema 021/09).