Combined anaerobic reactor and settler

An installation for the anaerobic purification of a liquid effluent which comprises a reactor tank, an after-settler compartment located in the top part for settling and separating the sludge and liquid, means for introducing the liquid effluent in the reactor tank and means for separating the gases from said sludge and liquid, said after-settler compartment comprising an inlet opening for the mixture of sludge and liquid from the reactor tank and an outlet opening to recycle said sludge and liquid to said reactor tank, said outlet opening being positioned at a level lower than said inlet opening, first deflecting means serving as shield for said inlet opening and second deflecting means for said outlet opening to and from said after-settling compartment respectively positioned in the reactor tank so that the upward flow of developed gases is kept away from said openings, separate interception compartment and outlet means for said gases, the bottom of the after-settling compartment being inclined downwardly towards said outlet opening to allow sludge settled therein to move to said outlet opening by its own weight, said first deflecting means being positioned at a level higher than said outlet opening to allow the gas generated by the anaerobic fermentation in the reactor tank to entrain liquid and sludge while rising in the reactor tank outside the after-settling compartment up to said first deflecting means.