Abstract: A chlorine injector for treatment of effluent includes apparatus which provides two separate vacuum forces that supplement each other to create sufficient vacuum force to draw chlorine from a chlorine tank and inject it into a sewage effluent tank for treatment of the effluent therein. The apparatus includes a water chamber positioned above the surface of the effluent, an airlift tube extending from the water chamber having its intake end submerged in the effluent and its discharge end inside of the water chamber at the upper portion thereof, an overflow return pipe extending from the water chamber to return excess effluent to the tank, and the chlorine injection assembly having the double vacuum means comprising a first eductor nozzle leading from the bottom of the water chamber to discharge into a second induction nozzle having a flared intake end, creating a first vacuum at this point by the venturi effect.