Fossa agroecológica: aspectos de dimensionamento e diretrizes construtivas para sistemas sustentáveis de saneamento rural

Abstract

Access to adequate sanitation conditions is one of the axes of global action guided by the United Nations 2030 Agenda, guided by sustainable development goal number 6 (clean water and sanitation). One of the problems of basic sanitation, among its four axes of action - water supply, effluent treatment, solid waste and rainwater - is the population's access to sewage collection and treatment services, mainly because conventional treatment systems can be quite expensive depending on the location of implementation, which sometimes makes it impossible for the population to have access to this essential service. When the sewage network is not an alternative for the disposal of the effluents produced, individual solutions are used to treat these effluents and prevent them from being released into the open air or directly into water bodies, causing a series of problems. This paper presents the agroecological septic tank, an individual alternative for treating sewage generated in the building itself, which, in addition to being a sustainable alternative from an environmental and economic point of view, is also accessible from a construction point of view and requires minimal maintenance, in addition to producing fruits that can be consumed or serve as a landscape composition when ornamental plants are used. Considering that until 2024 there was no guide document as a standard for sizing this system and that all research uses the same principle for calculations regardless of the application, which can result in malfunction of the system, this paper aims to identify sizing and construction methods for agroecological septic tanks. Through the literature review carried out, it was noticed that for sizing the agroecological septic tank, the evapotranspiration basin (EB) component presents a well-established sizing methodology, with Pamplona and Venturi (2004) and Galbiati (2009) as reference sources. Regarding the banana circle (BC) component, the dimensioning does not follow a standard, being subjective and defined according to the needs and understanding of each author. Regarding the construction methods, the methodology is well defined: the BET is mostly built using the ferrocement technique, and the digestion chamber uses unusable tires in its construction; the BC, in turn, consists of a circular trench dug in the ground and filled with organic materials.