WASTEWATER TREATMENT APPARATUS

PROBLEM TO BE SOLVED: To provide a wastewater treatment apparatus which increases a treatment speed in spite of retaining an organic-material decomposition-treatment capacity with high performance in an anaerobic environment.SOLUTION: The wastewater treatment apparatus has an anaerobic treatment tank, a sulfate storage tank, a sulfate addition apparatus and a sulfate addition-amount control apparatus. The anaerobic treatment tank retains a methanogen and a sulfate-reducing bacteria internally and purifies the entered wastewater. The sulfate storage tank stores a sulfate. The sulfate addition apparatus adds the sulfate stored in the sulfate storage tank to the wastewater entering the anaerobic treatment tank. When necessity of increasing or decreasing of the sulfate addition-amount for the wastewater is estimated in order to maintain the state that the methanogen and the sulfate-reducing bacteria are made to coexist in the anaerobic treatment tank, the sulfate addition-amount control apparatus controls an addition amount of the sulfate by the sulfate addition apparatus on the basis of this estimation result.