Whey permeate as a phosphorus source for algal cultivation

Microalgal cultivation for biodiesel and feed requires recycled nutrient resources for a sustainable long-term operation. Whey permeate (WP) from dairy processing contains high organic load (lactose, oils, and proteins) and nitrogen (resources tested for microalgal cultivation) and organic phosphorus (P) that has not yet been tested as a P source for microalgal cultivation. We explored the potential of green algae strains (brackish) and polyculture (freshwater) in exploiting P from WP added to a medium based on either seawater (7 psu) or landfill leachate. Both strains showed a capacity of using organic P in WP with equal growth rates (0.94-1.12 d(-1)) compared with chemical phosphate treatments (0.88-1.07 d(-1)). The polyculture had comparable growth rate (0.25-0.57 d(-1)) and biomass yield (152.1-357.5 mg L-1) and similar or higher nutrient removal rate in the leachate-WP medium (1.3-6.4 mg L-1 day(-1) nitrogen, 0.2-1.1 mg L-1 day(-1) P) compared with the leachate-chemical phosphate medium (1.2-4.7 mg L-1 day(-1) nitrogen, 0.3-1.4 mg L-1 day(-1) P). This study showed that WP is a suitable P source for microalgal cultivation over a range of salinities. To date, this is the first study demonstrating that raw WP can replace mineral P fertilizer for algal cultivation. Practitioners PointsWhey permeate is a comparable phosphorus source to standard fertilizers used in algal cultivation.Green algae removed phosphorus effectively from whey permeate.Microalgal cultivation is a good approach for treatment of whey permeate in combination with a nitrogen-rich wastewater.

Automated summary

Microalgal cultivation for biodiesel and feed can use whey permeate as a sustainable source of nutrients. Green algae strains and polyculture showed an ability to use organic phosphorus from whey permeate and had similar or higher growth rates and nutrient removal rates compared to chemical phosphate treatments. This study demonstrated that raw whey permeate can replace mineral phosphorus fertilizer for algal cultivation.