Phycoremediation and simultaneous production of protein‐rich algal biomass from aquaculture and agriculture wastewaters

Abstract

BACKGROUND: Microalgae cultivation in wastewaters is a potential remediation technology for converting residual nutrients into valuable biomass for biofuels, fertilizers, animal and aquaculture feeds, and bio-based chemicals. The objective of this study was to determine the potential for microalgae phycoremediation of aquaculture and agriculture wastewaters for sustainable production of nutrient-rich algal biomass.RESULTS: Thirty-seven aquaculture and agriculture wastewaters were evaluated as growth media for two freshwater, chlorophytic microalgae strains (Chlorella sorokiniana SMC14M and Scenedesmus sp. AMDD). Although nutrient levels and physicochemical parameters of the wastewaters varied widely, phycoremediation efficiency of nitrogen and phosphorous was high (> 70%) for a large majority of them, with both microalgae strains. Photobioreactor cultivation (300 L) of C. sorokiniana grown on finfish aquaculture wastewater (CA2) and standard growth medium (SGM) exhibited similar biomass production levels and nutritional compositions of moisture (4.9-5.0%), ash (5.9-6.1%), nitrogen (8.6-8.8%), protein (41.0-42.1%), lipid (8.6-8.8%), carbohydrate (38.3-39.3%) and gross energy (22.2-22.3 MJÁkg −1 ) with highly similar fatty acid and amino acid profiles.CONCLUSIONS: This study demonstrates that the use of freshwater microalgae to remediate various aquaculture and agriculture wastewaters, while producing valuable nutrient-rich biomass, is feasible. We have found that a particular finfish aquaculture wastewater (CA2) contains all of the nutrients required for rapid microalgae growth, avoiding the need for expensive commercial fertilizers. The biochemical composition of C. sorokiniana grown on CA2 aquaculture wastewater has good potential for use as a nutrient-rich ingredient for animal and aquaculture feeds, fertilizers products, biofuels and other applications, resulting in remediated water that could be reused.

Application of microalgae in wastewater: opportunity for sustainable development

“…The availability and balance of these macroelements in the growth medium can significantly impact the growth rate, biomass production, and overall health of microalgae cultures. This suggests that the adequate rate of available assimilable nitrogen, phosphorus, and carbon based on the C/N and N/P ratio would be 30 and 16 respectively, although variations have been reported (Bhatti et al, 2023).…”

Influence of desalination concentrate medium on microalgal metabolism, biomass production and biochemical composition

“…5 To address this issue, researchers have explored alternative cultivation strategies for microalgae using various types of wastewaters, including anaerobic digestate abattoir effluent, 2,6 sanitary landfill leachate, 7 textile dye effluent, 8 olive mill waste 9 and aquaculture and aquaculture wastewaters. 10,11 These studies have been focused on evaluating the ability of microalgae to remove N and P efficiently, and in some cases, heavy metals from wastewater. 12,13 Another area of research has involved cultivating both freshwater and marine microalgal species in desalination concentrate (DC) for simultaneous desalination wastewater treatment and biomass production.…”