Estudo de viabilidade econômica da implantação de leito de secagem para tratamento de efluentes sanitários gerados em uma mineradora no estado do Pará

Abstract

Waste management is one of the main challenges of modern society, especially when it comes to finding more sustainable and economical alternatives for the treatment and disposal of these materials. In this context, biosolids, a byproduct generated from wastewater treatment, have been identified as a possible source of nutrients and organic matter for agriculture and other sectors, thus contributing to a more circular economy. Biosolids contain a large amount of nutrients that can be used to improve soil quality and increase agricultural productivity (OLIVEIRA et al., 2018). In addition, the use of biosolids as fertilizer can reduce the need for chemical inputs, contributing to the reduction of the environmental impact associated with final disposal (RIBEIRO et al., 2015). This study was conducted in a mining company in the state of Pará, Brazil, which has eight decentralized anaerobic wastewater treatment plants. The study aimed to define the treatment route for biosolids, as well as to evaluate the economic viability of implementing a drying bed for the production of biosolids to be applied in the restoration of degraded areas. It was found that 11,776 kg of total suspended solids (TSS) per year of sludge are generated, resulting in the design of a drying bed with three cells, each with 22 m², an operation cycle of 25 days, and a Surface Application Rate of 13.30 Kg TSS/m²xdia. For sanitization, CaO was chosen. The implementation cost of the drying bed was R$ 100,358.70, operational costs were R$ 2,059.62/month, and the solution via incineration was R$ 18,415.80/month. Based on the simple and discounted payback, the investment returns in approximately 7.14 and 7.19 months, respectively, and is part of the synergistic costs with the current sanitation management. The other indicators point to the investment as viable and capable of financial surplus. Therefore, the company will have financial and environmental gains with the implementation of the project.