Urban wastewater (UWW) and landfill leachate (LL) co-treatment using membrane bioreactors (MBRs) is a valuable method for managing LL in cities. Coagulants can enhance the filterability of mixed liquor (ML), but the assessment of fouling is still needed. This research aimed to investigate the effects of co-treating synthetic wastewater (SWW) and real LL on an MBR, as well as the impact of adding poly-aluminum chloride (PACl) and Tanfloc SG. Cell-ultrafiltration experiments were conducted with four different feeds: synthetic wastewater, co-treatment with LL (20% v/v), and co-treatment with the addition of 30 mg L⁻¹ coagulants (either PACl or Tanfloc). Co-treatment aggravated flux loss and reduced the recovery rate; however, Tanfloc and PACl improved recovery after cleaning (by 11% and 9%, respectively). Co-treatment also increased cake and irrecoverable/irremovable inorganic resistances, though coagulants reduced the latter, despite a lower fit of the Hermia models during the first hour of filtration. Co-treatment reduced the removal efficiencies of almost all pollutants analyzed, with the most significant impacts observed on the organic fraction. Coagulants, particularly Tanfloc, enhanced overall performance by improving flux recovery and reducing irreversibility, thus benefiting membrane lifespan. In conclusion, Tanfloc addition yielded the best results in terms of filterability and pollutant removal.

RESUMO Biorreatores com membranas submersas (MBR) produzem efluente de elevada qualidade, porém, para algumas situações de reúso de água ou lançamento em corpos hídricos, ainda pode ser necessária a remoção adicional de coloides e fósforo. Neste estudo, foram avaliadas as eficiências de remoção de cor verdadeira, matéria orgânica e fósforo do efluente de sistema MBR, que tratava esgoto doméstico da moradia estudantil e do restaurante da Universidade São Paulo, por meio de método físico-químico (coagulação/floculação). Em todos os testes, observou-se eficiência de 17 a 35% para remoção de cor verdadeira, com menor remoção na presença do floculante. Por outro lado, não houve remoção de matéria orgânica medida como carbono orgânico dissolvido (COD), o que sugere que a baixa concentração de material particulado no permeado do MBR e as dosagens utilizadas não tenham permitido a formação de flocos que fossem capazes de remover tais compostos. A remoção de fósforo foi superior a 90% em todos os ensaios, resultando em um efluente com concentração residual entre 0,2 e 0,4 mgP.L-1, mesmo com a menor razão molar de metal do coagulante por concentração de fósforo. Os resultados mostram que a aplicação de coagulante em efluente de sistema MBR requer dosagens significativamente menores, em até três vezes, do que a aplicação direta no licor misto (biomassa suspensa no tanque aeróbio), sendo, portanto, uma estratégia atrativa para a redução dos custos relacionados com o uso de coagulantes para a remoção de fósforo e cor.

This study objective was to evaluate hollow fiber membranes for concentration of enveloped enteric viruses in sewage and surface water samples. Microfiltration (MF, 0.2 µm nominal pore size) and ultrafiltration (UF, 100 kDa molecular weight cut‐off) hollow fiber membranes were compared for the concentration of the bovine respiratory syncytial virus, and the influence of initial sample volumes (1, 1.5, and 2 L), permeate recovery rates (60%, 70% and 80% of the initial volume collected as permeate, equivalent to volumetric concentration factors of 2.5, 3.3 and 5), and backwashing was assessed. Polyethylene glycol precipitation followed by centrifugation (PEG‐C) was evaluated both as a stand‐alone method and as a secondary step applied to the membrane concentrate. MF and UF membranes had a similar capacity to retain pollutants and to concentrate organic matter in most parameters and conditions ( p > 0.05). In sewage, increasing the initial volume from 1 to 2 L raised recovery from 20.7 ± 0.1% to 30.0 ± 0.1% with MF and from 20.8 ± 0.1% to 25.3 ± 0.1% with UF ( p < 0.05), whereas changes in the permeate recovery rate produced no significant differences ( p > 0.05). In surface water recovery did not exceed 5.5%, and every increment in the permeate recovery rate produced a significant increase ( p < 0.05). Backwashing had a stronger effect on RNA recovery than pore size or the remaining operational parameters, reaching 29.3 ± 9.3% with MF and 33.8 ± 13.7% with UF in sewage and nearly doubling recovery in surface water. In sewage, PEG‐C alone (14.1%) was statistically similar to membrane filtration alone (12.1% to 12.3%, p > 0.05), while combining both techniques raised recovery to 23.0% to 25.5%. In surface water, membranes alone recovered 0.8% against 2.4% for PEG‐C ( p < 0.05), and the combination of UF with PEG‐C reached 5.7%, making it a valid alternative, albeit more time consuming and requiring additional equipment. Recoveries are expressed as the ratio between the genome copy concentration in the concentrate and in the spiked sample; on a total genome copy basis they correspond to 4% to 9% in sewage and to about 1% in surface water.

Direct membrane filtration (DMF) is an emerging wastewater treatment technology for providing high-quality effluents as well as efficient organic waste recovery from the concentrate. The latter may then be used for methane production, a renewable energy source. However, widespread application of DMF in large systems still faces challenges due to fouling effects. In this work, polyethersulfone-graphene oxide (PES-GO) ultrafiltration membranes were successfully synthesized by phase-inversion and applied for the first time in a DMF system for a real municipal wastewater. The incorporation of GO resulted in membranes showing increased flux recovery, higher rejection capacity and enhanced irreversible fouling resistance which could be mainly attributed to their more hydrophilic and restrictive selective layer. More specifically, PES-GO(0.6%) membrane reached 91% of flux recovery, indicating a substantial improvement in the membrane reusability when compared to PES membrane. The findings of cake layer characterization confirm that changes in the membrane surface caused by the addition of GO allowed for a reduction in protein deposition, and that its contribution to fouling formation during DMF is greater than carbohydrates. Thereby, these results show promising features for GO modified membranes in DMF systems aiming organic matter recovery for self-energy sustainable wastewater treatment plants.