Fig. 4From: Comprehensive evaluation of a cost-effective method of culturing Chlorella pyrenoidosa with unsterilized piggery wastewater for biofuel productionThe boxplots of alpha indices (Chao1 and ACE). CA means sparging air, CC sparging simulated flue gas, PA means culturing C. pyrenoidosa with sparging air, and PC means culturing C. pyrenoidosa with sparging simulated flue gas. *Indicates that there was a significant difference with P < 0.05. The statistical test used to compare the indices was the Wilcoxon signed-rank testBack to article page