Abstract
BackgroundUsing liquid digestate from the biogas industry as a medium to culture lipid-producing microalgae is considered mutually beneficial for digestate valorization and for reducing the cost of microalgal cultivation. However, the low transmittance and high ammonium (NH4+-N) levels in liquid digestate negatively influence microalgae growth.ResultsStruvite precipitation was used to pretreat liquid digestate. To obtain struvite-precipitated supernatant with an ideal transmittance, NH4+-N concentration, salinity, and N:P ratio for microalgal growth, there should be a 1:1.2:1.2 NH4+:Mg2+:PO43− molar ratio in the liquid digestate, with KH2PO4 and MgCl2 added through continuous stirring. The addition and stirring was subsequently stopped when the pH reached 8.5. Of the nine tested microalgae species, Dictyosphaerium ehrenbergianum exhibited the best growth in the supernatant. The biomass productivity and lipid content of D. ehrenbergianum cultured in the struvite-precipitated supernatant were 161.06 mg/l/days and 34.33%, respectively, which was higher than when cultured in the standard BG-11 medium. Moreover, the struvite-precipitated supernatant improved the accumulation of monounsaturated fatty acids and saturated fatty acids.ConclusionsThis study described a new way to combine liquid digestate treatment and microalgal biodiesel production. The struvite-pretreated liquid digestate can be used to culture D. ehrenbergianum for biodiesel production.
Highlights
Using liquid digestate from the biogas industry as a medium to culture lipid-producing microalgae is considered mutually beneficial for digestate valorization and for reducing the cost of microalgal cultivation
Optimization of struvite precipitation The concentrations of Chemical oxygen demand (COD), N H4+-N, NO3−-N, and PO43−-P in the digestate used in this study were 629.05, 591.2, 0.07, and 9.87 mg/l, respectively
The sources of M g2+ and PO43− significantly affected the quality of the struvite-precipitated supernatant [12]
Summary
Using liquid digestate from the biogas industry as a medium to culture lipid-producing microalgae is considered mutually beneficial for digestate valorization and for reducing the cost of microalgal cultivation. The low transmittance and high ammonium (NH4+-N) levels in liquid digestate negatively influence microalgae growth. Microalgae are considered one of the most promising biofuel feedstocks [1, 2]. The high cultivation cost is still a limiting factor for its further commercialization [3]. Using wastewater for microalgal cultures is considered mutually beneficial, because the wastewater provides nutrients for microalgal growth, while the microalgae remove pollutants from the wastewater [4, 5]. Land application is the primary method for managing digestate from livestock farms [7].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
