Sewage to energy: harnessing algae-fungi consortium for bioremediation

Abstract

With increasing population and urbanization, the demand for water has been rising worldwide. In parallel, the generation of wastewater contaminated with a surfeit of emerging chemicals is likely to increase. The conventional sewage treatment plants are insufficient to account for the presence of micropollutants, highlighting the need for eco-friendly, nature-based solutions with higher efficiency in wastewater treatment, degradation of complex emerging compounds, and resource recovery. The present study evaluates the efficiency of monoculture microalgae (Scenedesmus dimorphus; A), bacteria (Bacillus subtilis; B1 and Pseudomonas aeruginosa; B2), and filamentous fungi (Aspergillus niger; F1 and Penicillium crustosum; F2) and their consortium for the treatment of wastewater in ambient environmental conditions operated at a hydraulic retention time of 72 h. The wastewater was characterized by higher chemical and biological oxygen demands (COD: 1386.67 ± 73.2 mg/l; BOD₅: 225.8 ± 5.02 mg/l), nutrients (NO₃^--N: 4.86 ± 0.038 mg/l; PO₄^3--P: 1.71 ± 0.057 mg/l), and trace amounts of heavy metals. The potential of byproduct biomass for the application of clean energy was also explored. The treatment efficiency of consortium systems was higher than that of monoculture treatment. The algae-fungi consortium (F1A and F2A) showed a higher PO₄^3--P removal efficiency up to 97–98%. In contrast, the fungi consortium (F1F2) treatment showed significantly higher reduction in Cr, Mn, Ni, Cu, Pb, and NO₃^--N concentration from the wastewater. In the present study, the algae-fungi consortium biomass exhibited a higher heating value of 19.16 ± 0.46 MJ/kg and carbon content (48.3%), compared to the algae and algae-bacteria consortia. Elemental composition and GC-MS analysis of harvested biomass as a byproduct suggest that the algae-fungi consortium has potential for treatment of sewage and industrial wastewater along with large-scale biofuel production.

Keywords

Bioremediation / Consortium / Microalgae / Mycoremediation / Wastewater treatment / Circular economy

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Funding

Department of Biotechnology, Ministry of Science and Technology, India(BT/PR20543/BCE/8/1398/2016)

RIGHTS & PERMISSIONS

The Author(s), under exclusive licence to the International Society of Energy and Environmental Science