Photosynthetic microbial fuel cell with polybenzimidazole membrane: synergy between bacteria and algae for wastewater removal and biorefinery

Abstract

Here, we demonstrate a very efficient simultaneous approach of bioenergy generation from wastewater and added-value compounds production by using a photosynthetic microalgae microbial fuel cells (PMFC), based on polybenzimidazole (PBI) composite membrane as separator. The use of PBI was proved to be very promising, even more convenient than Nafion™ in terms of energy performances as well as cost and sustainability. This polymer is also easily autoclavable, so allowing a re-use of the separator with a consequent beneficial cost effect. Two PMFCs were investigated: 1) Pt electrocatalysed and 2) Pt-free. They were operated as microbial carbon capture (MCC) device under continuous illumination, by using a domestic wastewater as anolyte and Scenedesmus acutus strain in the catholyte. The Pt-based cell allowed to generate higher volumetric power density (∼400 mW m−3) after more than 100 operating days. This resulted in an improved wastewater treatment efficiency, determined in terms of normalised energy recovery (NER > 0.19 kWh kgCOD−1 in case of Pt). The CO2 fixation of the PMFC-grown microalgae leaded to a high accumulation of added-value products, namely pigments and fatty acids. A significant quantity of lutein was observed as well as a relevant amount of other valuable carotenoids, as violaxanthin, astaxanthin and cantaxanthin. The lipids were even excellently accumulated (49%dw). Their profile was mainly composed by fatty acids in the range C16-18, which are particularly indicated for the biofuel production. These results demonstrate the feasibility and the implemented sustainability of such PMFCs as a great potential technology for the wastewater treatment and the simultaneous production of valuable products.

Sustainable Materials and their Contribution to the Sustainable Development Goals (SDGs): A Critical Review Based on an Italian Example

“…For example, microalgal was used as filler in the production of bioplastic [ 59 ] (SDGs 14–15). To close the circle after their uses in bio-remediation, these microalgae can be used as a biofuel source [ 60 ] (SDG 11).…”

“…Then, several resources of the current worldwide research are addressed to find alternatives for energy production and to identify suitable fuels able to avoid fossil sources drawbacks (SDGs 7–11). Some potential solutions are based on the production of new electrochemical devices from biowaste [ 60 , 70 ].…”

Current State of the Worldwide Renewable Energy Generation: a Review

“…In Italy, it was implemented a very efficient simultaneous approach of bioenergy generation from wastewater and value-adding compounds production employing photosynthetic microbial fuel cells such as microalgae, based on membranes made of polybenzimidazole. These electrochemical devices are a promising option, given its low cost and sustainability [44]. Wastewater provides nutrients for microalgae growth, offering a new opportunity for biodiesel production.…”

Biohydrogen from Microalgae: Production and Applications

“…MFCs have significant environmental benefits. Thanks to the biological processes underlying their functioning, they can combine energy production with other functions, such as bioremediation activities [91][92][93]. It also bypasses the hydrogen storage limitation, since hydrogen is produced and utilized almost at the same time in the anodic chamber.…”