Using rabbit manure as raw material, three distinct types of rabbit manure biochar (RBC400, RBC500, and RBC600) were prepared via pyrolysis at 400 °C, 500 °C, and 600 °C, respectively. The effects of pyrolysis temperature on the physicochemical properties of biochar were examined by scanning electron microscopy, Brunauer–Emmett–Teller analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction techniques. Rabbit manure biochar was used to activate permonosulfate (PMS) to degrade rhodamine B (RhB). The findings revealed that RBC600 prepared at 600 °C showed the strongest catalytic activity due to its abundant pores and pore structure, high graphitization, and high carbonization degree. Under optimal reaction conditions (0.4 g/L PMS and 0.6 g/L RBC600), the degradation rate of 50 mg/L RhB reached 93.38% within 60 min. RBC600 can be effectively recovered, and effective catalytic activity can be sustained after five cycles. The quenching and EPR experiments showed that both free-radical (SO4−and ·OH) and non-free-radical (1O2) pathways contributed to the degradation of RhB, in which1O2performed a dominant role. In conclusion, the new PMS activator prepared in this study not only realizes the “waste to waste” use of manure waste but also provides technical support for the efficient resource-based treatment of organic wastewater.Keywords:rabbit manure;biochar;permonosulfate;advanced oxidation;rhodamine B
Mixed bacterial syngas fermentation is a promising carbon-neutral method for producing acetic acid and ethanol. However, the bacterial community and metabolic pathways were different in the growth and ethanol production stages, whereas the activity of the bacterial community greatly depended on the pH of the culture. In this study, the effect of pH on syngas fermentation performance and microbial community composition under continuous gas supply was investigated. The mixed bacteria grew fastest at a pH of 7, while a constant pH of 6 led to the highest ethanol concentration of 5.15 g L −1 , which was 160 % higher than that at pH 7. Based on this, a two-step pH regulation method was proposed in this study to improve the ethanol production. Initially, the culture pH was maintained at 7 to create optimal growth conditions. Once bacterial density stabilized, it was then changed to a pH 6 to promote ethanol production. By doing this, compared with the control group, the maximum ethanol concentration (5.85 g L −1 ) increased by 148.9 %, the ethanol production rate (2.41 g L −1 d −1 ) increased by more than 8 times. This two-step pH regulation method ensured a high bacterial density and effectively stimulated ethanol production during syngas fermentation.
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