Anaerobic treatment of methanol condensate from pulp mill compared with anaerobic treatment of methanol using mesophilic UASB reactors

The feasibility of anaerobic treatment of methanol condensate from pulp and paper mill in UASB reactor was investigated and compared with the anaerobic treatment of methanol. The UASB reactor treating methanol condensate was operated for 480 days with minimum problems of overload. COD removal from methanol condensate and methanol under normal operating conditions ranged from 84–86% to 86–98%, respectively. Under optimal conditions (OLR = 5.0 g COD L−1 day−1, CODinfluent = 11.40 g L−1) a methane yield of 0.29 NL CH4 per g CODremoved (at standard temperature and pressure) was achieved during the treatment of methanol condensate. The recovery time of the microorganisms after several overloads was decreasing each time probably due to the adaptation to methanol condensate. These findings indicate that methanol condensate can be efficiently treated in a UASB reactor with the benefit of biogas production. As a bonus effect of the treatment, much of the smell of the feed was eliminated.

► Methanol condensate was evaluated for the anaerobic treatment for the first time.
► COD removal of the condensate was 84–86% and that of methanol was 86–98%.
► 92% and 89% of degraded COD converted to CH4 in methanol condensate and methanol.
► Adaptation of microbes to the toxicity of methanol condensate over period of time.
► The anaerobic treatment markedly reduces the bad smell of the condensate.