Synthesis of Microalgal Photogranules for Hydroponics Effluent Treatment

• Microalgal photogranules (MPGs) were developed using Scenedesmus obliquus.

• MPGs achieved ≥90% pollutant removal from hydroponic effluents (HE).

• MPGs showed biomass productivity of 0.18 g L–1 day –1 and CO2 fixation of 25.53 g L–1 day –1.

• Matured MPGs had excellent settling (SVI 30 min = 20 mL/g) and robust structure.

• 16S rRNA analysis showed cyanobacterial dominance, boosting pollutant removal.

Insights on the Use of Activated Sewage Sludge for Microalgae Harvesting and Improved Biogas Production

• Sewage sludge-mediated microalgal biomass harvesting was investigated.

• 100 % microalgal biomass settling achieved with 1 : 4 S/A ratio within 8.5 h. 

• Metabolically active microorganisms and pH variation involved in biomass settling.

• Anaerobic digestion of microalgae with sewage sludge significantly increases biomethane yield. 

Use of microalgal-fungal pellets for hydroponics effluent recycling and high-value biomass production 

• Fungus-mediated microalgal biomass pelletization was investigated.

• 100 % Pelletization of S. obliquus achieved using A. fumigatus at an F:A 1:3 within 6 h.

• Metabolically active fungi with opposite charges facilitate pelletization.

• MAFP could effectively uptake inorganic nutrients from HE within a short time.

• HE grown MAFP rich in metabolites, ideal for biomethane.

Photosynthetic bioconversion of hydroponic effluent into biochemical-rich biomass for microalgal biorefineries

• The study found that S. obliquus sp. 1 had the highest uptake of nutrients and biomass production in hydroponic effluent, making it a potential candidate for hydroponic effluent recycling and resource recovery.

• Microalgae showed effective growth and nutrient removal capabilities in hydroponic effluent, indicating their potential as a solution for wastewater treatment.

• The study identified correlations between nutrient removal, biochemical composition, and microalgae, highlighting the importance of specific biomolecules and nutrients for the growth and productivity of microalgae.

Allelopathic effect of benzoic acid (hydroponics root exudate) on microalgae growth

• Hydroponic effluent (HE) can be a low-cost growth media for microalgae for resource recovery and water recycling due to the presence of residual nutrients.

• The presence of root exudates, particularly benzoic acid, may cause toxicity in microalgae, making it necessary to test allelopathic effects of benzoic acid on microalgal growth.

• Chlorella pyrenoidosa showed a higher biomass concentration than Chlorella sorokiniana during 96-hour batch growth at the tested benzoic acid doses.

• Both Chlorella pyrenoidosa and Chlorella sorokiniana showed growth stimulation and growth inhibition at different benzoic acid doses, indicating allelopathic behavior.

Anaerobic digestion as a tool to manage eutrophication and associated greenhouse gas emission

• Eutrophicated lakes are a considerable source of greenhouse gas (GHGs) emissions.

• Algae-based treatment and regulation are suggested to combat eutrophication.

• Algae mediated treatment and harvesting as central dogma for circular bio-economy.

• Anaerobic digestion facilitates energy and nutrient recovery from wastewater.