COMPARATIVE ANALYSIS OF ALTERNATIVES FOR TREATMENT OF SEWAGE FROM SINGLE-FAMILY RESIDENCES

What is it about?

The objective of this research was to analyze the applicability of processes for treating sewage from single-family dwellings in Brazil and the conditions under which they would be recommended. A methodology was developed based on the multi-objective ELECTRE-III and TOPSIS methods. The following processes were evaluated: (1) Septic tank; (2) Septic tank and anaerobic filter; (3) Septic tank and Wetland; (4) UASB and submerged aerated biofilter (BAS); (5) UASB reactor and conventional activated sludge; and (6) Septic tank and Biological Membrane Reactor (MBR). These processes were evaluated in three scenarios: (1) low water table, soil with high permeability, and small epidemiological and environmental risk; (2) high water table and / or soil with low infiltration, and great epidemiological and environmental risk; and (3) direct non-potable water reuse. The conclusion was that for Scenario 1 the best alternative is Septic Tank followed or not by an anaerobic filter. For Scenario 2, it is more appropriate to use a septic tank followed by an anaerobic filter or by Wetland. In Scenario 3, Septic Tank followed by MBR and disinfection is ideal, but the optimal alternative should be Septic Tank followed by BAS and disinfection, if some water reuse standards were relaxed.

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Why is it important?

In this research, a simplified methodology for the technological assessment of decentralized sewage treatment processes, specific to a single-family residence, was developed, using a multi-objective and multi-criteria decision analysis approach with a discrete variable and constructing the problem to obtain a hierarchical solution.

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