Methanotroph-microalgae co-culture for greenhouse gas mitigation: Effect of initial biomass ratio and methane concentration

Ruiz-Ruiz, Patricia; Gómez-Borraz, Tania L.; Revah, Sergio; Morales, Marcia

doi:10.1016/j.chemosphere.2020.127418

Cited by 32 publications

(9 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Dissolved methane can be biologically oxidized by methanotrophs (Ruiz-Ruiz et al, 2020). Methanotrophs are part of a larger group of bacteria called methylotrophs that typically utilize single-carbon compounds like methane, methanol, formic acid or even formaldehyde as carbon and energy source (Chistoserdova et al, 2009).…”

Section: Dissolved Methane Removal From Anaerobic Effluentmentioning

confidence: 99%

Low-temperature anaerobic wastewater treatment by granulated biomass

Safitri¹

2022

View full text Add to dashboard Cite

In this study, long-term operation of up-flow anaerobic sludge blanket (UASB) system treating real municipal wastewater at decreasing temperatures (25, 16, 12, 8.5, 5.5, and 2.5 °C) and variable organic loading rates from 1.0 gCOD·l⁻¹·d⁻¹ up to 15.2 gCOD·l⁻¹·d⁻¹ was investigated over 1025 days. Experiments were performed in two parallel in-house designed laboratory-scale UASB reactors, which were operated continuously with hydraulic retention time of 16.7 h down to 1.1 h. Stable COD removal efficiencies of 50 - 70 % were achieved at 25 °C down to 8.5 °C with loading up to approximately 15.2 gCOD·l-1·d-1. COD removal efficiencies were reduced at temperatures below 8.5 °C, but significant methane formation was observed even at 2.5 °C at reduced loading (up to 5 gCOD·l-1·d-1). More than 90% of COD removed was converted to methane, and the methane yield did not change significantly with respect to temperatures. The overall COD balance closed at above 90% of the inlet COD at all operating temperatures and organic loading rates. Temperature affected the reactor performances, microbial community structure, and the degradation pathway of organic matter with acetoclastic methanogen played significant roles. Acetate was the primary precursor of methanogenesis pathway at low-temperatures. Microbial communities proved the adaptation ability to very low-temperatures down to 2.5 °C regardless of the operating organic loading rates; psychrotolerant. Additionally, an anaerobic granulated biofilm system at 25 °C and different organic loading rates (1, 3, 8, 10, 15, and 20 gCOD·l-1·d-1) was modelled in AQUASIM 2.1 to predict and simulate biofilm model implementation and assumptions specific to the granules as a fixed biofilm in UASB reactor system in this study. Simulated organic loading rates scenario results showed COD removal efficiencies (62 - 69%) and methane fraction (83 - 88%) in biogas at steady-state conditions decreased with the increasing organic loading rates. All simulations predicted an increased pH profile, from pH 7 in the outer layer to approximately pH 8.3 in the core of granules, under increasing organic loading rates, but the biomass composition and active biofilm regions were not significantly affected by organic loading rate variable. UASB effluent post-treatment investigations, specifically on dissolved methane and nutrient removal, were performed as supplementary studies. A methanotrophic-cyanobacterial syntrophy was established in the existing oxygenic photogranules to remove dissolved methane. This syntrophy was maintained and propagated in a continuously operated reactor (hydraulic retention time of 12 h), proven by observed biomass yield and dissolved methane removal by approximately 2.4 gVSS·gCH₄⁻¹ and 85%, respectively, with COD balance closed at around 91%. Community analysis suggested methanotrophs and phototrophs syntrophy, and the cross-feeding between photogranules of different community compositions, containing methanotrophic bacteria, phototrophs, and non-methanotrophic methylotrophs. Nutrient removal from filtered UASB secondary effluent was investigated using several microalgal strains based on a literature review: Chlorella vulgaris, Chlorella sorokiniana, Tetradesmus obliquus, Haematococcus pluvialis, and Microchloropsis salina. Microalgae strain C. sorokiniana presented the ability to grow in wastewater in all the tested culture conditions, suggesting high adaptability and viability of the strain in this specific type of filtered UASB secondary effluent. The results also implied nutrient removal achieved 62% of total nitrogen removal and 97% of total phosphorous removal, when applying C. sorokiniana in the batch systems with hydraulic retention time of 9 days. The growth potential and the nutrient removal capacity of C. sorokiniana in a continuous laboratory-scale photobioreactor were also investigated. The system removed total nitrogen and total phosphorous by approximately 17% and 27%, respectively, with hydraulic retention time of 5.5 days. High ammonium removal yet high nitrate release indicated microalgae-nitrifiers imbalance in the photobioreactor system. Unfavorable growth factor for microalgae in the photobioreactor could be carbon-limited media in wastewater (2C:22N:1P). Adding an external source of CO2 to control alkalinity, pH, and provide carbon source for microalgal growth is most probably needed for further investigation. Even though nutrient removal efficiencies in continuous photobioreactor were significantly lower than the batch test, biomass yield in the photobioreactor was higher (0.16±0.02 gTNremoved∙gSS-1 and 0.03±0.005 gTPremoved∙gSS-1), compared to the batch test (0.04±0.01 gTNremoved∙gSS-1 and 0.02±0.002 gTPremoved∙gSS-1). High biomass production suggested that microalgal-based treatment for UASB effluent could offer a resource recovery potential. Overall, this study demonstrated the feasibility of UASB system treating municipal wastewater at low-temperatures and variable loadings in a long-term application. In combination with suitable post-treatments, UASB system showed a viable secondary pre-treatment option unit process for achieving lower carbon footprint wastewater treatment and resource recovery at low-temperatures. The robustness exhibited to low-temperature and variable loading conditions provides a solid basis for further research and potential applications. Further advances in an integrated UASB system and post-treatment unit processes investigation will be needed for pilot- and/or full-scale applications in the future.

show abstract

Section: Dissolved Methane Removal From Anaerobic Effluentmentioning

confidence: 99%

Low-temperature anaerobic wastewater treatment by granulated biomass

Safitri¹

2022

View full text Add to dashboard Cite

show abstract

“…A large number of articles have reported the achievements of microalgae co-cultivation in bioethanol production, wastewater treatment, and greenhouse effect mitigation. [46][47][48] In the culture environment where microalgae and microbes coexist, microalgae and microorganisms have formed a close connection through the oxygen required for photosynthesis and the carbon dioxide produced. Liu et al 49 mixed the two Chlorella species with different proportions of oleaginous yeast.…”

Section: Wileyonlinelibrarycom/jsfamentioning

confidence: 99%

Research advancement and commercialization of microalgae edible oil: a review

Xue

et al. 2021

J Sci Food Agric

View full text Add to dashboard Cite

The global food crisis has led to a great deal of attention being given to microalgal oil as a sustainable natural food source. This article provides an overview of the progress and future directions in promoting the commercialization of microalgal edible oils, including microalgal triglyceride accumulation, suitable edible oil culture strategies for high nutritional value, metabolic engineering, production, and downstream technologies. The integration of the production process, biosafety, and the economic sustainability of microalgal oil production are analyzed for their critical roles in the commercialization of microalgal edible oil to provide a theoretical and scientific basis for the comprehensive development and utilization of microalgal edible oil.

show abstract

“…In the methanotrophs–photoautotrophs cooperative system, the microalgae (or photosynthetic bacteria) provide the O 2 for the methanotrophs, which in turn provide the microalgae with carbon. These studies explore the potentiality of using the methanotrophs–microalgae cooperative system to produce bioproducts, , to treat wastewater, and to reduce greenhouse gas emissions. ,,, Compared with the two-stage process, the co-culture of methanotrophs and microalgae (Co-MM) has more potential for application because of the low demand for facilities. However, the interaction between microalgae and methanotrophs in Co-MM has not been comprehended yet.…”

Section: Introductionmentioning

confidence: 99%

Mixotrophic Cultivation of Microalgae Using Biogas as the Substrate

et al. 2022

Environ. Sci. Technol.

View full text Add to dashboard Cite

Biogas utilization through biotechnology represents a potential and novel technology. We propose the microalgal mixotrophic cultivation to convert biogas to microalgae-based biodiesel, in which methanotroph was co-cultured to convert CH4 to organic intermediate (and CO2) for microalgal mixotrophic growth. This study constructed a co-culture of Methylocystis bryophila (methanotroph) and Scenedesmus obliquus (microalgae) with biogas feeding. Compared with the single culture of S. obliquus, higher microalgal biomass but a lower chlorophyll concentration was observed. The organic metabolism-related genes were upregulated, verifying microalgal mixotrophic growth. The stoichiometric calculation of M. bryophila culture shows that M. bryophila tends to release organic matter rather than grow under a low O2 content. M. bryophila rarely grew under five different light intensities, indicating that M. bryophila acts as a biocatalyst in the co-culture. The organic intermediate released by methanotroph increased the maximum biomass of microalgal culture, accelerated nitrogen absorption, accumulated more monounsaturated fatty acids, and improved the adaptation to light. The co-culture of microalgae and methanotroph may provide new opportunities for microalgae-based biodiesel production using biogas as a substrate.

show abstract

Methanotroph-microalgae co-culture for greenhouse gas mitigation: Effect of initial biomass ratio and methane concentration

Cited by 32 publications

References 40 publications

Low-temperature anaerobic wastewater treatment by granulated biomass

Low-temperature anaerobic wastewater treatment by granulated biomass

Research advancement and commercialization of microalgae edible oil: a review

Mixotrophic Cultivation of Microalgae Using Biogas as the Substrate

Contact Info

Product

Resources

About