Caracterização do lodo bruto da ETE-Maratoan de Crateús-CE e tratamento a partir da compostagem para fertilização de solos

Abstract

Sewage sludge corresponds to a potential source of risks to public health and the environment, but they have great compostable potential, because it consists of several microbial communities. The final disposal of this waste, for the most part, is carried out in landfills, incineration and agriculture and its generation grows while the amount of degraded areas also, Brazil is the largest consumer of chemical fertilizers and the country with the most agricultural areas in the world. Composting is one of the solutions to avoid the disposal of biodegradable waste in landfills. The nutrients contained in the slable make the use of it as organic fertilizer a promising alternative, transforming it into something economically valuable. The objective of this research was to verify the feasibility of composting as a sustainable alternative for the final disposal of sludge generated at sewage treatment plants in the city of Crateús, Ceará, Brazil, generating a compound with the potential to increase soil fertility. For composting, two composters were built, with S1 consisting of 30:70 (sodo:structuring) and S2 40:60, with a duration of 75 days of operation. A collection was performed before the beginning of composting, for physicochemical and microbiological characterization of fresh slable and one at the end of the treatment process for characterization of the compounds formed. After the collections, the parameters were analysed: temperature, pH, total alkalinity, electrical conductivity, volatile fatty acids (GVA), moisture content, solids and nitrogen series, total phosphorus, Chemical Oxygen Demand (WFD), Total Organic Carbon (TOC), sulfides and sulfates, as well as total coliform and Escherichia coli (E. coli) and inorganic substances (heavy metals and some nutrients). During composting, daily analyses of pH, temperature, humidity and luminosity were performed using the PHD-3000 digital soil pH meter 4 in 1. The results obtained indicate that the final compounds of the compost trees contain nutrients, such as nitrogen and phosphorus, are capable of providing the liquid mineralization of these necessary for plant growth, and cycling of nutrients in the soil. There were significant reductions in the initial concentration of E. Coli after treatment, the stability of the two compounds was below 0.70 (SV/ST) being favorable for agricultural application purposes and possible to qualify them in biosolids. The concentrations of metals also presented values below the limits established by Brazilian legislation, allowing their valorization. However, there is only a restriction on the amount of E. Coli found because the concentrations exceed the maximum concentration limit allowed by CONAMA Resolution No. 375/2006.