Cyanobacterial Biomass Produced in the Wastewater of the Dairy Industry and Its Evaluation in Anaerobic Co-Digestion with Cattle Manure for Enhanced Methane Production

Abstract

The unique perspective that microalgae biomass presents for bioenergy production is currently being strongly considered. This type of biomass production involves large amounts of nutrients, due to nitrogen and phosphorous fertilizers, which impose production limitations. A viable alternative to fertilizers is wastewater, rich in essential nutrients (carbon, nitrogen, phosphorus, potassium). Therefore, Arthrospira platensis was cultivated in 150 mL photobioreactors with 70% (v/v) with the wastewater from a dairy industry, under a regime of light:dark cycles (12 h:12 h), with an irradiance of 140 μmol m−2 s−1 photon. The discontinuous cultures were inoculated with an average concentration of chlorophyll-a of 13.19 ± 0.19 mg L−1. High biomass productivity was achieved in the cultures with wastewater from the dairy industry (1.1 ± 0.02 g L−1 d−1). This biomass was subjected to thermal and physical treatments, to be used in co-digestion with cattle manure. Co-digestion was carried out in a mesophilic regime (35 °C) with a C: N ratio of 19:1, reaching a high methane yield of 482.54 ± 8.27 mL of CH4 g−1 volatile solids (VS), compared with control (cattle manure). The results demonstrate the effectiveness of the use of cyanobacterial biomass grown in wastewater to obtain bioenergy.

Agro-Industrial Wastewaters for Algal Biomass Production, Bio-Based Products, and Biofuels in a Circular Bioeconomy

“…MM2 tolerates up to 80% of CH 4 , while a native strain of Nannochloropsis gaditana can tolerate 100% CH 4 without significant changes in biomass production and growth [147], meaning that biogas can be bubbled through culture media for CO 2 absorption (biogas upgrading is discussed in Section 5). The capacity of nutrient assimilation of these photosynthetic microorganisms reduces the risk of contamination of water bodies by effluent releases [148].…”

Effect of temperature and the Carbon-Nitrogen (C/N) ratio on methane production through anaerobic co-digestion of cattle manure and Jatropha seed cake

“…The co-digestion of different matrixes: agroindustrial and urban wastewater, sludge from domestic water treatment plants, animal excrements (cattle, pigs, chickens, horses), plant biomass, algae, and microalgae, has been evaluated with mixed results. Thus Álvarez et al [16] performed the co-digestion of pre-treated cyanobacterial biomass (Arthrospira platensis) and raw cattle manure in a mesophilic regime (30ºC) and with a C: N ratio of 19: 1, they reached a methane yield of 482.54 ± 8.27 mL of CH4 g -1 volatile solid (VS). Kethobile et al [15] used the torrefaction method to transform solid products into thermal energy.…”

Coupling dairy wastewaters for nutritional balancing and water recycling: sustainable heterologous 2-phenylethanol production by engineered cyanobacteria

“…On the other hand, cyanobacteria, which constitute a group of ancient ubiquitous phototrophic bacteria (Abed et al, 2009;Garcia-Pichel, 2009), are resistant to extreme conditions of temperature, pH, heavy metals, and high salinity and, thus, are suitable for bioremediation (Gaurav et al, 2018;Ahmad, 2022;Lakmali et al, 2022). Although cyanobacteria have the ability to successfully remove nitrogen and phosphate from wastewaters (Lincoln et al, 1996;Kumar et al, 2011;El-Sheekh et al, 2011;Jitha and Madhu, 2016;Kabariya and Ramani, 2016;Ouhsassi et al, 2020;Álvarez et al, 2020;Ahmad, 2022), they have been mainly investigated for the production of high-value compounds, both naturally produced and metabolically engineered, thanks to their ease of genetic manipulation. These compounds can be extruded or derivatives of biomass, such as pigments (Kabariya and Ramani, 2018;Menin et al, 2019;Arashiro et al, 2020;Thevarajah et al, 2023).…”

“…These compounds can be extruded or derivatives of biomass, such as pigments (Kabariya and Ramani, 2018;Menin et al, 2019;Arashiro et al, 2020;Thevarajah et al, 2023). Alternatively, cyanobacteria have been exploited for disinfection treatment of waste effluents (Samiotis et al, 2023), and their biomass has been used as a substrate for fermentation processes (Möllers et al, 2014;Comer et al, 2020;Álvarez et al, 2020;De Oliveira et al, 2022). Thus, exploiting nutrient-rich wastewaters as growth substrates not only facilitates the cultivation of microalgae and cyanobacteria but also serves the dual purpose of contaminant removal and reduction in freshwater usage.…”