Performance of co‐culture strategy on nutrient removal and biogas upgrading by strigolactone induction

Abstract

AbstractIn this study, we investigated the performance and elucidated the synergistic effects of microalgae–fungi symbionts co‐cultured with 10−7 and 10−9 mol L−1 of GR24 and supplemented with endophytic bacteria, multi‐walled carbon nanotubes (MWCNTs) or vitamin B12 (VB12), on nutrient removal and biogas upgrading. The results showed that the microalgae–fungi–bacteria symbiotic system co‐cultured with 10−9 mol L−1 GR24 presented the optimal growth performance of 0.368 ± 0.04 d−1, chlorophyll a of 249.36 ± 22.31 μg L−1, and extracellular carbonic anhydrase activity of 42.55 ± 3.755 enzyme units. In this co‐culture system, the organic matter, nutrients, and CO2 purification obtained the highest removal efficiency, with 81.35 ± 7.96% for chemical oxygen demand, 83.56 ± 7.91% total nitrogen, 84.17 ± 7.95% total phosphorus, and 63.72 ± 6.06% CO2. The symbiont system also greatly increased the methane content in the biogas by 30.67%. The remarkable performance of the microalgae–fungi–bacteria symbiotic system shows its ability to be broadly applied in simultaneous biogas upgrading and wastewater treatment.Practitioner Points The optimal GR24 concentration for microalgae–fungi consortia was 10−9 M. Endophytic bacteria were superior to MWCNTs and VB12. Fungi–algae–bacteria consortia presented excellent growth and removal performance. Removal efficiencies of COD, TN, and TP were about 81% under optimum treatment.