Effects of different addition ratios of unsterilized chicken manure biogas slurry on Chlorella cultivation

Abstract

ABSTRACT Microalgae cultivation in wastewater is an economic way to solve environment problems. This study determined the effects of unsterilized chicken manure biogas slurry (UCMBS) on microalgal cultivation. UCMBS (at ratios of 10, 20, and 30%) was mixed with a BG11 culture medium to cultivate Chlorella pyrenoidosa (CP) and C. vulgaris (CV) as experimental microalgal species. Both these species adapted well to the biogas slurry culture environment after a short inhibition period, when the UCMBS addition ratios were lower at 10% and 20%. However, when the UCMBS addition ratio was higher (30%), the growth status of CP was better than that of CV. Compared with CV, CP was more adaptable to a high-concentration biogas slurry culture environment. Under the experimental conditions, the addition of 20% UCMBS resulted in better CV growth and comprehensive removal efficiency of total nitrogen, total phosphorus, chemical oxygen demand, and ammonia nitrogen than the addition of 10 and 30% UCMBS did. The maximum total nitrogen, ammonia nitrogen, total phosphorus, and chemical oxygen demand removal rates of the system were 90.6, 95.8, 93.5, and 89.8%, respectively. This study therefore provides fundamental information for further optimization and use of unsterilized biogas slurry to cultivate microalgae.