RESUMEN

The contamination of water sources by pharmaceutically active compounds (PhACs) and their effect on aquatic communities and human health have become an environmental concern worldwide. Membrane bioreactors (MBRs) are an alternative to improve biological removal of recalcitrant organic compounds from municipal sewage. Their efficiency can be increased by using high retention membranes such as forward osmosis (FO) and membrane distillation (MD). Thus, this research aimed to evaluate the performance of an anaerobic osmotic MBR coupled with MD (OMBR-MD) in the treatment of municipal sewage containing PhACs and estrogenic activity. A submerged hybrid FO-MD module was integrated into the bioreactor. PhACs removal was higher than 96% due to biological degradation, biosorption and membrane retention. Biological removal of the PhACs was affected by the salinity build-up in the bioreactor, with reduction in biodegradation after 32 d. However, salinity increment had little or no effect on biosorption removal. The anaerobic OMBR-MD removed >99.9% of estrogenic activity, resulting in a distillate with 0.14 ng L-1 E2-eq, after 22 d, and 0.04 ng L-1 E2-eq, after 32 d. OMBR-MD treatment promoted reduction in environmental and human health risks from high to low, except for ketoprofen, which led to medium acute environmental and human health risks. Carcinogenic risks were reduced from unacceptable to negligible, regarding estrogenic activity. Thus, the hybrid anaerobic OMBR-MD demonstrated strong performance in reducing risks, even when human health is considered.

Asunto(s)

Aguas del Alcantarillado , Purificación del Agua , Anaerobiosis , Reactores Biológicos , Humanos , Membranas Artificiales , Ósmosis , Preparaciones Farmacéuticas , Aguas Residuales

RESUMEN

Anaerobic digestion is certainly one of the options that can help solve the dilemma of energy demand, waste management and climate crisis mitigation mainly. Under ideal conditions, it is expected that all biomethane will be transferred from the liquid to the gaseous phase, ensuring maximum recovery. However, for concentrated wastewater or complex organic waste blends composed of functional groups with different sizes, the molecular interactions become important since the system is not only biphasic. Since the formation and transfer of a gas is related to the equilibrium condition, a thermodynamic approach could help to estimate the degree of variation of biomethane between the liquid and gaseous phases. Therefore, this investigation aimed to obtain the distribution between liquid and gaseous phases of the biomethane produced in the sewage sludge anaerobic digestion considering the substrate as a non-ideal solution. The nonlinear differential equations of the ADM1 were integrated with Aspen Plus® to verify the equilibrium conditions and the model was calibrated with data obtained through experiments conducted in a lab scale sequence batch reactor (SBR) fed with synthetic substrate (1500 mgCOD.L-1) and inoculated with flocculent sludge (500 mgSSV.L-1) from a full-scale UASB reactor. Considering the thermodynamic approach, the percentage of dissolved biomethane remains below the 2.97% percentage estimated by using the ADM1. It is possible to state that the principle of ideality is maintained in the system. On the other hand, CO2 phase distribution was considerably affected by the species defined in the equilibrium reactions. Therefore, it can be stated that Henry's Law simplification in ADM1 model is valid to represent the phenomenon investigated.

Asunto(s)

Metano , Aguas del Alcantarillado , Anaerobiosis , Reactores Biológicos , Digestión , Gases , Metano/química , Aguas del Alcantarillado/química , Termodinámica , Eliminación de Residuos Líquidos

RESUMEN

Reliable Life Cycle Assessment (LCA) indicators for wastewater treatment plants (WWTP) construction and operation phases are still a demand mainly in developing countries. Thus, the purpose of this paper was to present and discuss the environmental performance of a full-scale WWTP installed in a Brazilian city using LCA approach. The treatment process consists of a UASB reactor followed by constructed wetlands, which makes it particularly attractive to developing countries due to its operational simplicity. The Life Cycle Inventory (LCI) was developed from a WWTP design and operation data including those of untreated wastewater and effluent quality. The results show that the environmental impacts from construction phase should not be neglected in LCA studies of low complexity treatment technologies (e.g. UASB reactor, constructed wetlands and pond systems). There is a trade-off between the use of materials and energy for construction and the low energy and materials consumption during the operation phase in these systems. The majority share of hydroelectric generation in the energy matrix and the combination of anaerobic and natural processes for wastewater treatment have contributed to a smaller impact potential for the operation phase. The LCA approach should be associated with plans and actions to face the challenges of providing wastewater treatment in developing countries. Only in this way, compliance with the eco-efficiency targets and protect public health will be guaranteed.