Abstract: A waste water treatment system includes a preliminary first stage separator for separating an aqueous phase from other materials. A pressure vessel sedimentation follows for removing most of the remaining solids from the waste material. The liquid and a minor fraction of the solids then pass on to an evaporation vessel where the water vapor is removed, compressed and passed through a condenser inside the evaporator vessel to recycle heat in the evaporator. The condenser is a stacked plate heat exchanger of unique design with the plates separated by steam gaskets and water gaskets to provide a very high heat transfer surface area to volume ratio. The condensate from the condenser passes through a second heat exchanger that heats the liquid flowing into the evaporator. The effluent water is purified by the evaporation. The residual solids may be heat treated to evaporate residual moisture and to sterilize the solids using a steam-jacketed auger. The resultant solids may be used as fertilizer.