Operação de filtros biológicos percoladores pós-reatores UASB sem a etapa de decantação secundária

Abstract

ResumoA pesquisa teve por objetivo avaliar filtros biológicos percoladores (FBP) pós-reatores UASB operando sem a etapa de decantação secundária, em termos da remoção da demanda bioquímica e química de oxigênio (DBO e DQO) e sólidos suspensos totais (SST). O aparato experimental consistia em um reator UASB que alimentava quatro FBP em paralelo, preenchidos com diferentes materiais suporte. O reator UASB operou em regime hidráulico permanente, e três condições operacionais foram impostas aos FBP durante o período experimental. Em geral, os sistemas UASB/FBP foram capazes de promover o atendimento aos padrões de lançamento. Em condições de baixas cargas orgânicas volumétricas (COV), o uso de materiais de enchimento de maior área superficial específica não proporcionou ganhos expressivos em termos de desempenho. Contudo, o uso de meio suporte baseado em espumas de poliuretano propiciou melhoria significativa na qualidade do efluente final. O uso de sistemas UASB/FBP sem decantadores secundários parece ser uma promissora alternativa para a simplificação operacional da tecnologia, e uma importante estratégia para o tratamento de efluentes domésticos em países em desenvolvimento. No entanto, o sucesso do emprego desta tecnologia fica condicionado ao correto gerenciamento do lodo anaeróbio do reator UASB, a fim de que sejam evitadas sobrecargas nos FBP.Palavras-chave: esgoto doméstico; filtro biológico percolador; operação sem decantadores secundários; pós-tratamento; reator UASB. AbstractThe research aimed at evaluating the operation of trickling filters (TF) post-UASB reactors without the secondary sedimentation stage, in terms of biochemical and chemical oxygen demand (BOD and COD) and total suspended solids (TSS) removal. The experimental apparatus consisted of one UASB reactor followed by four TF in parallel, each one filled with a different packing media. The UASB reactor was operated at a permanent hydraulic regime, while three operational conditions were imposed to the TF during the experimental period. In general, the UASB/TF systems were able to comply with the discharge standards. At low organic loading rates (OLR), no improvements in terms of organic matter removal, with the use of higher surface area packing media were observed.However, the use of a sponge-based packing media provided significant improvements on final effluent quality. The use of UASB/TF systems without secondary sedimentation can constitute an attractive alternative in terms of operational simplification of this technology, and an important strategy for domestic wastewater treatment in developing countries. However, the success of this technology is strictly connected to the correct anaerobic sludge management of the UASB reactor, in order to avoid overloads on the TF.

Use of expanded polystyrene (EPS) as a support media for trickling filters applied to wastewater treatment

“…The overall efficiency was compromised by the low performance presented by the UASB reactor in this study. However, when we evaluate the final effluent in terms of BOD, efficiency is compatible with that of the literature (Almeida et al 2011;Bressani-Ribeiro et al 2018), reaching 91%. At this point, it is important to highlight that such efficiency was obtained without the presence of a secondary clarifier.…”

“…Therefore, we can see that EPS proved to be another alternative material that could be used in sewage treatment. The quality of the final effluent has always been within the limits of several global laws and compatible with materials used in sewage treatment plants at a full scale that use patented materials (Tonetti et al 2019), and also compatible with studies that used alternative materials (Almeida et al 2011).…”

“…Within this perspective, the combination of UASB (upflow anaerobic sludge blanket) and trickling filter (TF) has been widely applied and studied in Brazil, India, and Latin America (Chernicharo and Nascimento 2001;Almeida et al 2011;Bressani-Ribeiro et al 2018).…”

“…The trickling filter (TF) is a low-cost aerobic system that does not need an electric power source that promotes aeration, as in the case of activated sludge (Ali et al 2017). Some authors suggest a greater simplification of the construction and operation of the system when evaluating changes in the secondary clarifier, or even its removal from the process flowchart (Chernicharo and Nascimento 2001;Almeida et al 2011).…”