Mohammadmehrab Mahdavipayam - Department of Agricultural Machinery Engineering, Faculty of Agricultural Engineering and Technology, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran
Shahin Rafiee - Department of Agricultural Machinery Engineering, Faculty of Agricultural Engineering and Technology, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran
Elham Abdollahzadeh Sharghi - Environmental Group, Department of Energy, Materials and Energy Research Center, Karaj, Iran
Soleiman Hosseinpour - Department of Agricultural Machinery Engineering, Faculty of Agricultural Engineering and Technology, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran

Less energy required due to the omission of aeration and biogas production made anaerobic wastewater treatment more usable rather than aerobic wastewater treatment in the industry. Up-flow anaerobic sludge blanket (UASB) reactors have appeared as one of the most commonly used methods for the wastewater treatment of pharmaceutical industry. The aim of this work was to assess the biogas production rate in a lab-scale UASB reactor, fed with spearmint essential oil wastewater (SEOW). SEOW contains a high level of COD (6757.5±214.2 mg/L), and phenolic compounds (382.7±87.5 mg/L). During the 102 days UASB operation at high sludge retention time and hydraulic retention time of 60 h, organic loading rate (OLR) was increased from 0.12 to 2.70 g COD/L.d through increasing influent SEOW concentration. The optimum OLR was found to be 2.70 g COD/L.d, where 71.8±1.9% COD reduction with 32.201±7.167 L/d biogas production containing 62.0±5.6% and 23.4±4.8% methane and carbon dioxide, respectively was obtained. At the higest OLR employed, biogas yield and specific biogas production rate were 498.548±98.050 L/kg CODremoved and 0.658±0.146 L/g MLSS.d, respectively with the net heating value of 23.8 (MJ/m3).

Spearmint essential oil wastewater (SEOW), Up-flow anaerobic sludge blanket (UASB), Phenol, Chemical oxygen demand (COD), Biogas