Temperature analysis of a novel MAIB reactor during the treatment of wastewater from recycled paper mill

Anaerobic digestion (AD) is an essential technology for wastewater management, resource recovery and biogas production, and it is considered as an efficient and reliable treatment method for many wastewaters. Operating parameters have been shown to directly affect the stability and treatment performance of AD, especially temperature. For 180 days, the AD of recycled paper mill wastewater (RPMW) was carried out in a modified anaerobic inclining-baffled (MAIB) reactor under various temperature conditions, i.e. 29 °C (low mesophilic), 37 °C (mesophilic) and 55 °C (thermophilic). It was found that total COD removal of 94, 96 and 76%, and methane yields of 0.125, 0.196 and 0.256 L CH4/g CODremoved were attained at temperatures of 29, 37 and 55 °C, respectively. Throughout the three transition periods, the pH level in the MAIB reactor fluctuated slightly within the range of 5.8–6.5 without affecting the system stability. The results concluded that thermophilic condition strongly influenced the MAIB reactor performance, leading to lower COD removal, higher methane yield and gradually recovered pH level. Highlights Novel modified anaerobic inclining-baffled (MAIB) reactor, which combines the development of attached and settled microorganisms, was operated for the treatment of recycled paper mill wastewater (RPMW).; The operational temperature intensive analysis of MAIB was investigated at thermophilic and mesophilic conditions.; The system compartmental characteristics were also analyzed and discussed.