Fresh pig urine is unsuitable for microalgae cultivation due to its high concentrations of NH4 +-N, high pH and insufficient magnesium. In this study, fresh pig urine was pretreated by dilution, pH adjustment, and magnesium addition in order to polish wastewater and produce microalgae biomass. Chlorella vulgaris was cultured in an in-house-designed light-receiving-plate (LRP)-enhanced raceway pond to treat the pretreated pig urine in both batch and continuous mode under outdoor conditions. NH4 +-N and TP in wastewater were detected, and the growth of C. vulgaris was evaluated by chlorophyll fluorescence activity as well as biomass production. Results indicated that an 8-fold dilution, pH adjusted to 6.0 and MgSO4·7H2O dosage of 0.1 mg·L−1 would be optimal for the pig urine pretreatment. C. vulgaris could stably accumulate biomass in the LRP-enhanced raceway pond when cultured by both BG11 medium and the pretreated pig urine. About 1.72 g·m−2·day−1 of microalgal biomass could be produced and 98.20% of NH4 +-N and 68.48% of TP could be removed during batch treatment. Hydraulic retention time of 7-9d would be optimal for both efficient nutrient removal and microalgal biomass production during continuous treatment.
Bibliographical noteFunding Information:
Funding: This research was funded by the National Natural Science Foundation of China (No. 21466022, 21706087, 21766019, 21878139); The “Post-doctoral Innovative Talents Support Program” (BX20190147); The Funding for postdoctoral research projects in Jiangxi Province (2019KY04); The Key Project of Jiangxi Provincial Department of Science and Technology (20161BBF60057, 20181BBF60026).
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- Chlorella vulgaris
- Chlorophyll fluorescence
- Hydraulic retention time
- Nutrient removal
- Photosynthetic reactor
- Pig urine