Anaerobic Digestion of Algae Biomass to Produce Energy during Wastewater Treatment

Abstract

Water resource recovery facilities (WRRFs) are asked to improve both energy efficiency and nutrient removal efficacy. Integration of algaculture offers several potential synergies that could address these goals, including an opportunity to leverage anaerobic digestion at WRRFs. In this study, bench-scale experiments are used to measure methane yield during co-digestion of Scenedesmus dimorphus or mixed WRRF-grown algae with WRRF biosolids. The results indicate that normalized methane yield decreases with increasing algae content in a manner than can be reasonably well fit using linear regression (R(2) = 67%). It is thus possible to predict methane yield for any mixture of algae and biosolids based on the methane yield of the biosolids alone. Using revised methane yields, the energy return on investment of a typical WRRF increases from 0.53 (without algae) to 0.66 (with algae). Thus, algae-based wastewater treatment may hold promise for improving WRRF energy efficiency without compromising effluent quality.

Strategies to Optimize Microalgae Conversion to Biogas: Co-Digestion, Pretreatment and Hydraulic Retention Time

“…The methane yield of the co-digestion reactor was higher than that obtained co-digesting sewage sludge with Spirulina maxima (50% VS each) at 20 days of HRT (0.36 L CH 4 /g VS) [ 22 ], and similar to that obtained co-digesting Scenedesmus sp. or native microalgal biomass (25% VS) with sewage sludge (75% VS) at 15 days of HRT (0.39 and 0.51 L CH 4 /g VS, respectively) [ 23 ].…”

Anaerobic Process

“…Therefore, conclusion can be made that buffer should be added to all the mixing ratio of food waste and CEPT sludge for improvement of methane yield under both mesophilic and thermophilic conditions. Peng et al (2016) integrated algae biomass with biosolids of water resource recovery facility for energy recovery. Bench-scale tests were conducted to investigate whether algae biomass could have synergetic effects with biosolids in water resource recovery facility.…”

Anaerobic digestion of microalgal biomass for bioenergy production, removal of nutrients and microcystin: current status

“…Anaerobic digestion of microalgal has been extensively studied (Passos et al 2015a; Koc ßer and € Ozc ßimen 2018; Wirth et al 2018;Zabed et al 2019b;Choudhary et al 2020). AD of microalgal biomass is successful, for instance, wastewater treatment (Peng and Colosi 2016;Olsson et al 2018), decrease eutrophication (Pugliese et al 2015) and yield biomethane (Milledge et al 2019). It may be noted that microalgae biomass has been considered as an alternative renewable resource as there has been no competition with food crops for arable land for its cultivation.…”

“…2020). AD of microalgal biomass is successful, for instance, wastewater treatment (Peng and Colosi 2016; Olsson et al . 2018), decrease eutrophication (Pugliese et al .…”