ANÁLISE COMPARATIVA DAS ALTERNATIVAS PARA TRATAMENTO DE ESGOTOS DE RESIDÊNCIAS UNIFAMILIARES

O objetivo desta pesquisa foi analisar a aplicabilidade dos processos para tratamento de esgotos de residencias unifamiliares no Brasil e as condicoes em que estes seriam recomendados. Foi desenvolvida uma metodologia baseada nos metodos multiobjetivo ELECTRE-III e TOPSIS. Avaliaram-se os seguintes processos: (1) Tanque septico; (2) Tanque septico e filtro anaerobio; (3) Tanque septico e Wetland ; (4) UASB e biofiltro aerado submerso (BAS); (5) Reator UASB e lodo ativado convencional; e (6) Tanque septico e Reator Biologico de Membrana (MBR). Esses processos foram avaliados em tres cenarios: (1) lencol freatico baixo, solo com alta permeabilidade e risco epidemiologico e ambiental pequeno; (2) lencol freatico alto e/ou solo com infiltracao baixa e risco epidemiologico e ambiental grande; e (3) reuso direto nao-potavel da agua. Concluiu-se que, para o Cenario 1, a melhor alternativa e Tanque Septico seguido ou nao por filtro anaerobio. Para o Cenario 2, e mais adequado empregar Tanque Septico seguido por filtro anaerobio ou por Wetland . No Cenario 3, Tanque Septico seguido por MBR e desinfeccao e o ideal, mas a alternativa otima deveria ser Tanque Septico seguido por BAS e desinfeccao, caso relaxassem-se alguns padroes de reuso de agua. COMPARATIVE ANALYSIS OF ALTERNATIVES FOR TREATMENT OF SEWAGE FROM SINGLE-FAMILY RESIDENCES ABSTRACT The objective of this research was to analyse 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.