The effect of temperature on the anaerobic co-digestion of poultry droppings and sugar mill press mud

Abstract

Press mud (PM), generated from sugar mills, and poultry droppings (PD) are treated as waste materials and may be a solution for a country’s energy deficit in that their anaerobic co-digestion can produce high-value bio-energy in the form of biogas. Both a batch experiment and continuous experiments in continuous stirred tank reactor (CSTR) were conducted to determine the optimal temperature from the mesophilic temperature regimes in terms of methane yield. Also studied was the variability of other major parameters at varying temperatures with co-digestion of PM and PD in microbial consortia. The average highest ultimate methane yield and specific methane yields were 325 and 260 normalized litre per kg volatile solids (NL kg⁻¹ VS) for the batch and continuous experiments, respectively. The maximum average specific methane yields were obtained at 35–45 °C, as expected, but yields did not differ significantly. The rate of methane production was relatively lower at temperatures of less than 35 °C and significant yield differences were found among temperatures of 35, 30, 25 and 20 °C. The results show that the temperature influenced the anaerobic digestion performance significantly. The optimum temperature was predicted using MINITAB-18 software according to the best-fit regression models, and modeling showed the optimal temperature was 44 °C.

Keywords:

• Optimization of temperature
• poultry droppings
• press mud
• co-digestion
• methane

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by IFC and DANIDA Bangladesh [grant number 600237].