An inlet assembly for an abatement apparatus includes an inlet nozzle defining a non-circular inlet aperture coupleable with an inlet conduit providing an effluent gas stream for treatment by the abatement apparatus, at least one outlet aperture and a nozzle bore extending along a longitudinal axis between the non-circular inlet aperture and the outlet aperture for conveying the effluent gas stream from the non-circular inlet aperture to the outlet aperture for delivery to a treatment chamber of the abatement apparatus, the nozzle bore defining an inlet portion extending from the non-circular inlet aperture, a flow-dividing structure positioned downstream of the inlet portion and configured to separate the effluent gas stream into at least a pair of effluent gas streams and an outlet portion extending to the outlet aperture and configured to convey the pair of effluent gas streams to the treatment chamber of the abatement apparatus.