Decentralized Domestic Effluent Treatment System to Attend a Single-Family Residence

Abstract

In Brazil, in semi-urban and rural regions, the absence of basic sanitation becomes more evident, above all, the lack of sanitary sewage, caused by the high cost of implementation and maintenance of centralized systems with collection networks and sewage treatment plants. Given this reality, decentralized systems have been widely used in semi-urban and rural housing centers, providing treatment with efficiency and low cost, besides having an important role in expanding the care of sewage services, especially in areas devoid of sewage collection networks. This research proposes the integration of theoretical models based on the contributions of researchers to the subject, with the equations established by the technical standards ABNT (NBR 7229/1993) and a (NBR 13969/1997) related to effluent treatment, using the theory present in the literature to size an individual system of treatment of domestic effluents, which meets a single-family residence, seeking to generate knowledge for practical application in localities devoid of sewage collection network. For this, it was designed to form an integrated form, a treatment system containing three reservoirs, with the septic touch initiating the purification process, directed to the liquid part for biological treatment in the anaerobic filter, with anaerobic microorganisms stabilizing the organic matter before final disposal of the effluent in the sink. In general, decentralized systems are considered by several researchers as an efficient solution in the treatment of domestic sewage. NBR 13969/1997 defines the likely ranges of removal of pollutants, according to the type of treatment, where the combined septic tank system and anaerobic filter achieved good results in the removal of (BOD), (DQO), (SNF) and sedimentable solids, increasing treatment efficiency and meeting the parameters for effluent disposal in the environment as permitted by CONAMA Resolution No. 430/2011. Regarding the cost of implementation, the budget was obtained by budget spreadsheets, using the unit prices of the National System of Research of Costs and Indexes of Civil Construction, reference, Recife, July 2021. With the treatment system designed in an integrated way, standing out for the lower cost and smaller built area, reducing the costs of implantation by 28% compared to the system with the separate projected reservoirs.