Exploring indigenous freshwater chlorophytes in integrated biophotovoltaic system for simultaneous wastewater treatment, heavy metal biosorption, CO2 biofixation and biodiesel generation

Elvis Kodzo Ahiahonu; William Wilson Anku; Ashira Roopnarain; Ezekiel Green; Mahloro Hope Serepa-Dlamini; Penny Poomani Govender

doi:10.1016/j.bioelechem.2022.108208

Exploring indigenous freshwater chlorophytes in integrated biophotovoltaic system for simultaneous wastewater treatment, heavy metal biosorption, CO₂ biofixation and biodiesel generation

Bioelectrochemistry. 2022 Oct:147:108208. doi: 10.1016/j.bioelechem.2022.108208. Epub 2022 Jul 16.

Authors

Elvis Kodzo Ahiahonu¹, William Wilson Anku², Ashira Roopnarain³, Ezekiel Green⁴, Mahloro Hope Serepa-Dlamini⁴, Penny Poomani Govender⁵

Affiliations

¹ Department of Chemical Sciences, University of Johannesburg, Doornfontein Campus, P.O. Box 17011, Johannesburg 2028, South Africa; Environmental Protection Agency, P.O Box MB 326, Accra, Ghana.
² Department of Chemical Sciences, University of Johannesburg, Doornfontein Campus, P.O. Box 17011, Johannesburg 2028, South Africa; CSIR-Water Research Institute, P. O. Box M. 32, Accra, Ghana.
³ Microbiology and Environmental Biotechnology Research Group, Institute for Soil, Climate and Water- Agricultural Research Council, Private Bag X79, Pretoria 0001, South Africa.
⁴ Department of Biotechnology and Food Technology, Faculty of Science, University of Johannesburg, Doornfontein Campus, PO Box 17011, Doornfontein, Johannesburg 2028, South Africa.
⁵ Department of Chemical Sciences, University of Johannesburg, Doornfontein Campus, P.O. Box 17011, Johannesburg 2028, South Africa. Electronic address: pennyg@uj.ac.za.

PMID: 35872372
DOI: 10.1016/j.bioelechem.2022.108208

Abstract

The study explored the combined photosynthetic activities of two green microalgal species, Tetradesmus obliquus and Tetradesmus reginae, on an integrated biophotovoltaic (BPV) platform for simultaneous wastewater treatment, toxic metal biosorption, carbon biofixation, bioelectricity generation and biodiesel production. The experimental setup comprised of a dual-chambered BPV with copper anode surrounded by T. obliquus in BG11 media, and copper cathode with T. reginae in municipal wastewater separated by Nafion 117 membrane. The study reported a maximum power density of 0.344 Wm^-2 at a cell potential of 0.415 V with external resistance of 1000 Ω and 0.3268 V maximum open-circuit voltage. The wastewater electrical conductivity and pH increased from 583 ± 22 to 2035 ± 29.31 mS/cm and 7.403 ± 0.174 to 8.263 ± 0.055 respectively, signifying increased photosynthetic and electrochemical activities. Residual nitrogen, phosphorus, chemical oxygen demand, arsenic, cadmium, chromium and lead removal efficiencies by T. reginae were 100%, 80.68%, 71.91%, 47.6%, 88.82%, 71.24% and 92.96%, respectively. T. reginae accumulated maximum biomass of 0.605 ± 0.033 g/L with a CO₂ biosequestration rate of 0.166 ± 0.010 gCO₂/L/day and 42.40 ± 1.166% lipid content. Methyl palmitate, methyl undecanoate and 13-octadecenoic acid with relative abundances of 37.24%, 24.80% and 12.02%, respectively were confirmed.

Keywords: Algae; Biodiesel generation; Biophotovoltaic; CO(2) biofixation; Heavy metal biosorption; Wastewater treatment.

MeSH terms

Biofuels
Biomass
Carbon Dioxide / chemistry
Chlorophyceae*
Copper
Fresh Water
Metals, Heavy*
Microalgae*
Wastewater / chemistry
Water Purification*

Substances

Biofuels
Metals, Heavy
Waste Water
Carbon Dioxide
Copper