Fernando Hermes Passig

The support media of upflow anaerobic hybrid reactors (UAHB) facilitates the formation and retention of microbial biofilm and the contact between the influent and microorganisms. Previous studies demonstrated the importance of support media height (SMH) to organic matter removal; however, the influence of this parameter in the UAHB reactor performance under varying conditions is still a gap. The Central Composite Design (CCD) method was applied to optimize the removal of organic matter by varying the cross-sectional area and height of the reactor based on 42 studies. The modelling indicated 72-87% COD removal efficiencies with 0.007 m² cross-sectional area and 0.75 m height, with 5.5 L total volume. Thus, three pilot-scale UAHB reactors, filled with Corrugated Polyvinyl Chloride (PVC) rings at different heights (6, 15, and 24 cm), were operated with a hydraulic retention time of 10 h, treating synthetic effluent with a COD of 490 mgO₂ L^-1. Unlike previous studies, this study evaluated identical UAHBs operating in parallel under controlled conditions. The UAHB reactors presented stability, buffering capacity, and neutral pH during the operation. The reactor with higher SMH (24 cm) achieved higher removal efficiencies of turbidity (90%), COD (72.6%), and TS (63%). Variations in SMH affected reactor performance, as corroborated by the negative and 'very strong' correlation for turbidity, COD, and TS and a 'moderate' correlation for fixed and volatile solids. The novelty of this study lies in its comprehensive assessment of how varying SMH affects UAHB reactor performance, guiding future advancements in its design for efficient wastewater treatment.

The objective of this research was to evaluate the influence of the recirculation rate on nutrient removal and on the hydrodynamic behavior of a fixed-bed anaerobic-aerobic reactor, operated on a bench scale, in the treatment of sanitary effluent. Different recirculation ratios (0.5, 1.0 and 1.5) were tested with a constant air flow of 10 L min-1. During the operation period, the physicochemical parameters were analyzed. Hydrodynamic tests were also carried out using pulse stimulus-response tests with the eosin Y tracer, to evaluate the hydrodynamic behavior and investigate anomalies. The 50% recirculation ratio proved to be the condition with the highest removal efficiency for total solids (83%). The 100% recirculation ratio was the most efficient for TKN (97%) and Nammon (99%). For the recirculation ratio of 150%, the highest removal efficiency was for phosphorus (33%). As for hydrodynamic behavior, according to the correlation of the theoretical uniparametric models tested, it is possible to state that the recirculation ratios of 50%, 100% and 150% presented correlation coefficients that indicate complete mixing, with good hydraulic efficiency for recirculation. of 100%. By varying these factors, it was possible to verify the influence of the recirculation ratio on the removal of nitrogen and phosphorus, as well as on the hydrodynamic behavior of the reactor.

O objetivo deste trabalho foi avaliar o desempenho de um sistema combinado utilizado na remoção de nitrogênio e fósforo, com variação do tempo de detenção hidráulica (TRH) e da taxa de recirculação (R). O sistema foi composto por três reatores sequenciais operados em série, composto por um reator anaeróbio (20 L), um reator aeróbio de leito fixo (19 L) e um filtro percolador (16 L). Foram testadas as razões de recirculação de 150, 100 e 50% e TDH de 9, 7 e 5 h, com vazão de aeração constante de 10 L min-1. Para avaliação do sistema foram analisados temperatura do líquido, pH, alcalinidade total, alcalinidade do bicarbonato, ácidos voláteis, oxigênio dissolvido, demanda química de oxigênio, nitrogênio total Kjeldahl, nitrogênio amoniacal, nitrito, nitrato e fósforo total. O sistema combinado atingiu eficiências de remoção de matéria orgânica de 99%, 98% e 98% para as taxas de recirculação de 50, 100 e 150%, respectivamente. Sob as mesmas taxas de R, as eficiências de remoção de NTK resultaram em 96, 89 e 87%, e as eficiências de remoção de PT em 78, 82 e 77%, respectivamente. Quando operado com TDH de 9, 7 e 5 h, o sistema combinado atingiu eficiências de remoção de 86, 96 e 98% para DQO, 90, 93 e 94% para NTK e 74, 89 e 95% para PT, respectivamente. A melhor condição operacional foi estabelecida experimentalmente com a taxa de recirculação de 150% e TDH de 5 h. Entretanto, após a validação experimental por DCCR (por desejabilidade), a condição operacional ótima resultou na taxa de recirculação de 123% e TDH de 5 h para eficiências de remoção de NTK e TP.