Domestic sewage management for elevated phenol and surfactant levels using Algal Bacterial Consortia (ABC) in a hybrid moving bed membrane bioreactor (MBMBR) system

Abstract

In recent years, significant shifts have been witnessed in water, sanitation, and hygiene practices, leading to notable increases in phenol and surfactant concentrations, particularly in the aftermath of the COVID-19 pandemic. This research proposes a novel solution – an Algal Bacterial Consortia (ABC) integrated within a hybrid Moving Bed Membrane Bioreactor (MBMBR) system for treating sewage with elevated phenol and surfactant levels. The system demonstrated an average removal efficiency exceeding 90 % for common pollutants in the influent, including ammonia (~70 mg/L), nitrate (~40 mg/L), and chemical oxygen demand (~750 mg/L), all achieved within a short hydraulic retention time of <6 h. It achieved average removal rates of approximately 90 % for surfactants and 87 % for phenols. The integration of algae in the ABC system significantly reduced dependence on external aeration, as indicated by dissolved oxygen levels. This enhancement highlights the potential of algae to substantially lower operational costs. The system's resilience was evaluated under various conditions, from intrinsic to harsh environments, and compared to non-ABC systems to ascertain the role of algae in making the system resilient to high pollutant loads. Toxicological studies using the MTT assay further confirmed the non-toxic nature of the treated wastewater. The research further proposes the degradation pathways of phenols and surfactants via mass spectrometry to analyze the persistence of their byproducts. SEM revealed distinct morphological differences between ABC and conventional heterotrophic sludge. EDS further highlighted the contrasting elemental composition between the heterotopic and ABC sludge. FTIR analysis provided insights into the chemical properties of the ABC sludge and heterotrophic sludge. This study demonstrates the scientific value of integrating algal-bacterial consortia for wastewater treatment, offering a sustainable and cost-effective solution for emerging contaminants, enhancing system resilience to high pollutant loads, and providing insights into sludge management and pollutant degradation pathways for broader environmental applications.