A continuous protein-rich Chlorella sp. HL-1 production system in piggery anaerobic digestion effluent

• Published in: Biomass conversion and biorefinery 2024-04, Vol.14 (8), p.9441-9453
• Main Authors: Lu, Xiongxiong, Liao, Min, Hu, Kangyou, Luo, Yixin, Xie, Xiaomei, Gan, Xinjun
• Format: Article
• Language: English
• Subjects: Anaerobic digestion; Biomass; Biotechnology; Chlorella; Continuous production; Cultivation; Dilution; Energy; Heavy metals; Nutrients; Optimization; Original Article; Proteins; Renewable and Green Energy; Resource utilization
• ISSN: 2190-6815; 2190-6823
• DOI: 10.1007/s13399-022-03131-7

To achieve a mostly nutrients recovery from wastewater to biomass production, a protein-rich Chlorella sp. HL-1 was isolated from piggery anaerobic digestion effluent (PADE), and then a series of experiments were conducted in PADE to optimize culture conditions. The optimal cultivation conditions were initial inoculation of 0.61 g·L −1 , pH 8.5, the salinity of 1.5‰, and the dilution rate of 1:2 (PADE: freshwater was 1:2, v/v, 587.67 mg·L −1 TIN). Based on the above conditions, construct a continuous protein-rich Chlorella sp. HL-1 production system in a six-day production interval in undiluted PADE. In the system, at the end of every cycle, discharge 1/3 volume of the culture broth to separate Chlorella . Meanwhile, add the same volume of PADE to start new cyclic cultivation. After five consecutive production cycles, the system could obtain 10.50 ± 0.34 g·L −1 biomass production, and heavy metals such as Cd and Pb in Chlorella sp . HL-1 were within the standards (EC No 1881/2006). Furthermore, the protein content of Chlorella sp. HL-1 was stable at 51.14 ± 0.86% DW, making it possible to be additional nutrients for animals. Meanwhile, the system could achieve 67.00 ± 2.21% %TIN and 71.07 ± 1.09% total phosphorus (TP) removal. Such results demonstrated the feasibility of the continuous production system in converting nutrients from PADE to biomass production of Chlorella sp. HL-1 at a safe mode, and the system might be a better pathway for resource utilization and nutrient removal pretreatment of PADE.