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Microalgae-Based Wastewater Treatment Processes and Biorefineries

A special issue of Sustainability (ISSN 2071-1050). This special issue belongs to the section "Sustainable Water Management".

Deadline for manuscript submissions: closed (15 November 2023) | Viewed by 7645

Special Issue Editors

Department of Civil and Environmental Engineering (DICA), Politecnico di Milano, 20133 Milano, Italy
Interests: microalgae-based wastewater treatment systems and biorefineries; photo-oxygenation and CO2 biofixation; respirometric evaluation of biomass growth and inhibition; mathematical modelling; techno-economic assessment
INRIA - National Institute for Research in Computer Science and Control (BIOCORE - Biological Control of Artificial Ecosystems Research Team), 2004 Route des Lucioles, 06902 Sophia-Antipolis, France
Interests: fully predictive mathematical modelling of microalgae-based wastewater treatment systems; numerical optimization of biomass production and nutrient removal/recovery; evaluation and reduction of environmental impacts and greenhouse gases emissions
Italian Institute for Environmental Protection and Research (ISPRA), 00144 Rome, Italy
Interests: microalgal cultivation on wastewaters; biological nitrogen removal; molecular characterization of microalgae-bacteria consortia; application of flow cytometry on complex microbial communities; ecotoxicology assays

Special Issue Information

Dear Colleagues,

We are pleased to launch a Special Issue related to the integration of microalgae cultivation in wastewaters for sustainable nutrient removal/recovery, bioenergy production, and CO2 biofixation.

Conventional wastewater treatment plants (WTTP) typically rely on biological processes to remove nutrients and other contaminants from wastewaters due to their high efficiency and low cost compared to other treatments. These systems can achieve high removal efficiencies for biodegradable organic matter, inorganic nitrogen, and phosphorus compounds. However, the high energy requirement for the oxygenation of mixed liquors in activated sludge processes, and the emissions of large quantities of greenhouse (CO2, N2O) and toxic (NH3) gases, has led to an increasing interest in the use of microalgae-based wastewater treatment processes and biorefineries. The main advantage of integrating microalgae in WWTPs is the possibility of exploiting synergic consortia among microalgae and aerobic bacteria, thus leading to simultaneous nutrient removal, CO2 biofixation, and biomass production. The algal biomass can be valorised in different ways, including the production of biofuels (biogas, bio-biodiesel, bio-hydrogen, among others) and bio-based materials: i) bioplastics; ii) soil biofertilizers and biostimulants; iii) feed for animal consumption; iv) biochar and other bio-absorbent materials. However, several bottlenecks must still be addressed in order to apply this technology at an industrial scale.

This issue aims to collect recent advances and relevant research experiences in microalgae cultivation using municipal and industrial wastewaters based on a biorefinery concept. The Special Issue will cover the following topics:

  • Process validation at the pilot and demonstrative scale (assessment of biomass productivity, nutrient removal/recovery efficiency, CO2 fixation, and biogas upgrading in open systems or closed photobioreactors);
  • Process modelling (definition, calibration, and experimental validation of algae–bacteria growth models);
  • Process optimization (evaluation of optimal management strategies to reduce environmental impacts and/or to increase biomass productivity and nutrient removal/recovery);
  • Advanced monitoring of algal–bacterial populations (respirometry, PAM fluorometry, flow cytometry, next-generation sequencing);
  • Evaluation of optimal working conditions for wastewater-treating photobioreactors (including nutrient availability/inhibition and environmental/operational conditions);
  • Life cycle and environmental impact assessment (LCA studies and assessment of gaseous emissions);
  • Energetic and techno-economic assessment (energy balances, mass flows, and economic evaluations);
  • Biomass harvesting (assessment of low-cost and low-energy processes, use of photo-granules or floccular biomass);
  • Biomass valorisation (such as biofertilizers or biostimulants, bioplastics, biofuels, animal feed, and other valorisation routes).

The submission of all types of articles is highly encouraged, including experimental research, case studies, modelling, and review articles. We look forward to receiving your contributions to draw attention to the sustainability of microalgal cultivation in wastewaters and to enhance the knowledge related to this interesting and promising biorefinery concept.

Dr. Simone Rossi
Dr. Francesca Casagli
Dr. Micol Bellucci
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sustainability is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • integration of microalgae cultivation in wastewaters
  • sustainable nutrient removal/recovery
  • bioenergy production
  • CO2 biofixation

Published Papers (4 papers)

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Research

21 pages, 1410 KiB  
Article
Ultrafiltration Harvesting of Microalgae Culture Cultivated in a WRRF: Long-Term Performance and Techno-Economic and Carbon Footprint Assessment
by Juan Francisco Mora-Sánchez, Josué González-Camejo, Guillermo Noriega-Hevia, Aurora Seco and María Victoria Ruano
Sustainability 2024, 16(1), 369; https://doi.org/10.3390/su16010369 - 31 Dec 2023
Cited by 1 | Viewed by 989
Abstract
A cross-flow ultrafiltration harvesting system for a pre-concentrated microalgae culture was tested in an innovative anaerobic-based WRRF. The microalgae culture was cultivated in a membrane photobioreactor fed with effluent from an anaerobic membrane bioreactor treating sewage. These harvested microalgae biomasses were then anaerobically [...] Read more.
A cross-flow ultrafiltration harvesting system for a pre-concentrated microalgae culture was tested in an innovative anaerobic-based WRRF. The microalgae culture was cultivated in a membrane photobioreactor fed with effluent from an anaerobic membrane bioreactor treating sewage. These harvested microalgae biomasses were then anaerobically co-digested with primary and secondary sludge from the water line. Depending on the needs of this anaerobic co-digestion, the filtration harvesting process was evaluated intermittently over a period of 212 days for different operating conditions, mainly the total amount of microalgae biomass harvested and the desired final total solids concentration (up to 15.9 g·L−1 with an average of 9.7 g·L−1). Concentration ratios of 15–27 were obtained with average transmembrane fluxes ranging from 5 to 28 L·m−2·h−1. Regarding membrane cleaning, both backflushing and chemical cleaning resulted in transmembrane flux recoveries that were, on average, 21% higher than those achieved with backflushing alone. The carbon footprint assessment shows promising results, as the GHG emissions associated with the cross-flow ultrafiltration harvesting process could be less than the emissions savings associated with the energy recovered from biogas production from the anaerobic valorisation of the harvested microalgae. Full article
(This article belongs to the Special Issue Microalgae-Based Wastewater Treatment Processes and Biorefineries)
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13 pages, 3345 KiB  
Article
Treatment and Valorization of Agro-Industrial Anaerobic Digestate Using Activated Carbon Followed by Spirulina platensis Cultivation
by Ángela Sánchez-Quintero, Marie-Ange Leca, Simona Bennici, Lionel Limousy, Florian Monlau and Jean-Baptiste Beigbeder
Sustainability 2023, 15(5), 4571; https://doi.org/10.3390/su15054571 - 03 Mar 2023
Cited by 7 | Viewed by 1637
Abstract
The increased production of biogas through the anaerobic digestion (AD) process has raised several concerns regarding the management of liquid digestate, which can present some environmental risks if not properly handled. Among the different techniques to treat AD digestate, microalgae and cyanobacteria cultivation [...] Read more.
The increased production of biogas through the anaerobic digestion (AD) process has raised several concerns regarding the management of liquid digestate, which can present some environmental risks if not properly handled. Among the different techniques to treat AD digestate, microalgae and cyanobacteria cultivation has emerged as a sustainable approach to valorizing digestate while producing valuable biomass for production of biofuels and high value bioproducts. However, the intrinsic parameters of the liquid digestate can strongly limit the microalgae or cyanobacteria growth as well as limit the uptake of residual nutrients. In this study, the detoxification potential of activated carbon (AC) was evaluated on agro-industrial liquid digestate prior to Spirulina platensis cultivation. Different doses of AC, ranging from 5 to 100 g/L, were tested during adsorption experiments in order to determine the adsorption capacity as well as the removal efficiency of several compounds. Experimental results showed the high reactivity of AC, especially towards phosphate (PO4-P), total phenol (TP) and chemical oxygen demand (COD). At a dosage of 50 g/L, the AC pretreatment successfully achieved 54.7%, 84.7% and 50.0% COD, TP and PO4-P removal, corresponding to adsorption capacity of 94.7 mgDCO/g, 17.9 mgTP/g and 8.7 mgPO4-P/g, respectively. Even if the AC pretreatment did not show significant effects on Spirulina platensis growth during toxicity assays, the AC adsorption step strongly participated in the digestate detoxification by removing hardly biodegradable molecules such as phenolic compounds. Full article
(This article belongs to the Special Issue Microalgae-Based Wastewater Treatment Processes and Biorefineries)
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18 pages, 2707 KiB  
Article
Impact of Bioaugmentation on the Bioremediation of Saline-Produced Waters Supplemented with Anaerobic Digestate
by Aurélien Parsy, Cecilia Sambusiti, Claire Gassie, Patrick Baldoni-Andrey, Frédéric Périé and Rémy Guyoneaud
Sustainability 2023, 15(3), 2166; https://doi.org/10.3390/su15032166 - 24 Jan 2023
Cited by 5 | Viewed by 1675
Abstract
Bioremediation of produced waters has been widely investigated in the last decades. More recently, microalgae-based treatments have been developed to produce biomass. The objective of this study was to determine, at lab scale, the remediation efficiency of three origin of microorganisms: a consortium [...] Read more.
Bioremediation of produced waters has been widely investigated in the last decades. More recently, microalgae-based treatments have been developed to produce biomass. The objective of this study was to determine, at lab scale, the remediation efficiency of three origin of microorganisms: a consortium of three halotolerant and halophilic microalgae and their associated bacteria, bacteria from liquid digestate, and aromatic-degrading bacteria selected to perform bioaugmentation. The medium was composed of artificial oil-produced water and seawater, and contained nutrients from liquid digestate. In order to identify what plays a role in nitrogen, chemical oxygen demand, and aromatics compounds elimination, and to determine the effectiveness of bioaugmentation to treat this mix of waters, 16S rRNA analyses were performed. Combination of microorganisms from different origins with the selected aromatic-degrading bacteria were also realized, to determine the effectiveness of bioaugmentation to treat these waters. Each population of microorganisms achieved similar percentage of removal during the biological treatment, with 43–76%, 59–77%, and 86–93% of elimination for ammonium, chemical oxygen demand, and aromatic compounds (with 50% of volatilization), respectively, after 7 days, and up to with 100%, 77%, and 99% after 23 days, demonstrating that in the case of this produced water, bioaugmentation with the specialized aromatic-degrading bacteria had no significant impact on the treatment. Regarding in detail the populations present and active during the tests, those from genus Marinobacter always appeared among the most active microorganisms, with some strains of this genus being known to degrade aromatic compounds. Full article
(This article belongs to the Special Issue Microalgae-Based Wastewater Treatment Processes and Biorefineries)
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21 pages, 2974 KiB  
Article
Phototrophic Bioremediation of Municipal Tertiary Wastewater Coupling with Lipid Biosynthesis Using Scenedesmus dimorphus: Effect of Nitrogen to Phosphorous Ratio with/without CO2 Supplementation
by Mohammed Omar Faruque, Mohammad Mozahar Hossain, Wasif Farooq and Shaikh Abdur Razzak
Sustainability 2023, 15(2), 1409; https://doi.org/10.3390/su15021409 - 11 Jan 2023
Cited by 2 | Viewed by 1270
Abstract
Scenedesmus dimorphus was utilized for the tertiary treatment of municipal wastewater in an effort to remove nutrients from secondary treated wastewater. In addition to the concurrent generation of biomass containing lipids for biofuel production. The effect of nitrogen to phosphorous (N:P) ratios (1:1 [...] Read more.
Scenedesmus dimorphus was utilized for the tertiary treatment of municipal wastewater in an effort to remove nutrients from secondary treated wastewater. In addition to the concurrent generation of biomass containing lipids for biofuel production. The effect of nitrogen to phosphorous (N:P) ratios (1:1 to 8:1) in culture media without carbon dioxide (CO2) supplementation (air supply alone, Case 1) and with CO2 supplementation (2% CO2 in air, Case 2) was investigated through a series of systematic parametric batch experiments. Case 2 produces greater biomass at all N:P ratios than Case 1. In Case 1, the highest biomass output for a N:P ratio of 8:1 is 567 mg/L at pH 8.4. In Case 2, however, the maximum biomass yield is 733 mg/L when the N:P ratio is 2:1 and the pH is 7.23. Scenedesmus dimorphus is capable of absorbing nitrogen and phosphorous from wastewater in a CO2 environment and at the optimal N:P ratio. In Case 1, total nitrogen removal ranges from 28% to 100% and in Case 2, total nitrogen removal ranges from 60% to 100%, depending on the N:P ratio. For an initial concentration of 13 mg/L, the total phosphorous removal ranges from 37% to 57%, depending on the N:P ratio in both cases. Case 2 yields a maximum lipid content of 29% of the biomass dry weight when the N:P ratio is 1:1. These results suggest the viability of removing nutrients from secondary treated wastewater utilizing microalgae Scenedesmus dimorphus and lipid biosynthesis in the generated biomass. Full article
(This article belongs to the Special Issue Microalgae-Based Wastewater Treatment Processes and Biorefineries)
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