Financial comparison of sewage treatment and disposal systems in rural areas

Resumo

Studies show that conventional sanitation technologies, due to their high costs, end up excluding rural populations. Among the options for the treatment and final disposal of sewage in rural areas we can mention septic tanks with sump and biodigester tanks with filtering gardens.  In view of the above, the objective of this article is to make a financial comparison of two individual sewage treatment systems: septic tank with floor drain, and biodigester septic tank with filtering garden. To perform the financial analysis in the case of the septic tank with drain, the amounts were calculated based on the dimensions indicated by ASPROESTE (2018). For the biodigester septic tank with filtering garden, the quantities of materials indicated by ASPROESTE (2018) were adopted for the case of a residence with 5 people. Finally, after the quantities raised, taking as a basis the prices contained in the National Research System of Costs and Indexes of Civil Construction (SINAPI) the costs of implementation of these devices were estimated. The results show that the septic tank system with drain presented a cost of R$ 2580.22 and the biodigester tank system a total cost of R$ 8,682.93. It is concluded that the biodigester septic tank system is more expensive, but allows the reuse of the effluent as biofertilizer, and the values found are relatively high for low-income populations, being indicated the creation of government programs, which deliver these devices for the poorest population.