ANAEROBIC TREATMENT METHOD

PROBLEM TO BE SOLVED: To provide an anaerobic treatment method capable of executing a stable operation regardless of variations of atmospheric temperatures.SOLUTION: The provided anaerobic treatment method includes a cooling step S40 of cooling, in a case where the temperature of an organic effluent is judged to be or estimated to become higher than a set temperature on the basis of detection results from temperature detection units 53 and 54 acquired at a temperature detection step S20, the organic effluent. The set temperature is therefore set so as to induce, on an occasion for lowering the temperature of the organic effluent to a goal level, a temperature variation optimal for methanogens within an anaerobic treatment tank 12, and the organic effluent can be cooled based on the set temperature. It accordingly becomes possible not only to abate, even during a season having a great atmospheric temperature variation, shocks exerted onto the methanogens within the anaerobic treatment tank 12 due to a rapid temperature loss of the organic effluent but, by promoting a proactive low-temperature acclimatization, also to execute a stable operation.