ANAEROBIC TREATMENT APPARATUS

PURPOSE:To hold the developing interface of the sludge bed of an anaerobic treatment tank to a proper range by providing an upward sludge blanket type anaerobic treatment tank, a means circulating a part of treated water as circulating water and a control part controlling the flow velocity of circulating water corresponding to the detected value of the gas amt. of the anaerobic treatment tank. CONSTITUTION:When raw water is treated in an anaerobic treatment apparatus, a raw water pump 7 and a circulating pump 4 are operated to introduce the raw water in a raw water tank 6 into an ascending flow type sludge blanket anaerobic treatment tank 1. The digestion gas generated by anaerobic treatment is discharged through a GSS separator 2 but, at this time, the generated amt. of the gas is detected by a gas flowmeter 8 and the detected value is inputted to a controller 9. The controller 9 has an inverter mechanism altering the frequency of the motor of a circulating pump 4 and controls the number of rotations of the circulating pump 4 on the basis of the inputted detected value of the generation amt. of the gas in order to set circulating water to proper flow velocity. The height of the sludge bed of the anaerobic treatment tank 1 can be held to a proper range.