Abstract:Nutrient-rich biogas slurry containing N and P is potential culture media for microalgae. Some researchers also conducted a series of relative studies. However, the effect of different biogas slurry on the subsequent microalgae culture is significantly different because the miscellaneous germs in biogas slurry can inhibit the microalgae growth. Furthermore, the variety and quantity of bacteria in biogas slurry digested at medium temperature (35℃) and high temperature (55℃) are also significantly different. However, fewer systematic comparison of biogas slurry digested at medium temperature (35℃) and high temperature (55℃) is found based on microalgae culture. Therefore, the Chlorella pyrenoidosa (FACHB-5) and the Chlorella vulgaris (FACHB-8) were employed as algae species in this experiment. The effect of broth being the culture medium (BG11) mixed with the autoclaved and non-autoclaved biogas slurry of pig manure after anaerobic digestion at 35℃and 55℃ on following microalgae growth was studied by using artificial climate incubator. The specific culture temperature, light intensity, continuous light period, air flow and additive ratio of biogas slurry were (26±1)℃, 4000lx, 24h, 1.5L/min and 20%, respectively. The results indicated that the effect of biogas slurry digested at 55℃ was better than that of biogas slurry digested at 35℃, and the growth rate of microalgae obvious cultured in the biogas slurry of anaerobic fermentation at 55℃ was more superior. Moreover, there was no difference in early adaptation period of microalgae growth between autoclaved biogas slurry and non-autoclaved biogas slurry. However, the growth rate of microalgae cultured in autoclaved biogas slurry was slightly optimal in middle and late period. What’s more, the algae species used in this experiment could adapt to the culture environment with biogas slurry addition well. The growth of Chlorella pyrenoidosa (FACHB-5) was superior to that of Chlorella vulgaris (FACHB-8). The microalgae also decreased the ammonium nitrogen, total nitrogen, total phosphorus and chemical oxygen demand (COD) in biogas slurry significantly, which was favorable for the purification and comprehensive utilization of biogas slurry. The research provided a theoretical basis for the subsequent research and application of microalgae culture with biogas slurry.
