Kinetic Model of Anaerobic Digestion from Chicken Manure and Thai Rice Noodle Wastewater in Continuous Reactors

A kinetic model was used to describe the anaerobic co-digestion of chicken manure (CM) and Thai rice noodle wastewater (TRNW) in continuous reactors. This research investigated the effects of mixing interval and hydraulic retention time (HRT) on methane production and other related kinetic parameters. Experiments were carried out in three identical reactors with different mixing conditions: 1) without mixing, 2) mixing every 6 hours, and 3) mixing every 12 hours. Each reactor was operated at HRT of 10, 20, and 30 days, respectively. The anaerobic co-digestion was conducted at room temperature (28-30 ºC). The results showed that the co-digestion provided suitable initial conditions for anaerobic microorganisms in terms of pH level (7.1 ± 0.04), alkalinity (3,420 ± 20.00 mg/LasCaCO3), and volatile fatty acid (VFA) concentration (480 ± 10.00 mg/LasCH3COOH). The co-digestion of the mixing interval of every 12 hours and HRT of 10 days provided the highest methane production potential with an average of 261 mLCH4/gCOD. The model was validated statistically and can provide beneficial information for designing co-anaerobic wastewater treatment plants in the mixing interval and HRT suitable for biogas production.