Abstract: A sludge evaporation tunnel and associated method for producing a solid fertilizer product from a sludge. The sludge evaporation tunnel includes a floor surface for supporting a relatively thin layer of sludge from which water is to be evaporated, a cover over the floor for retaining heat and preventing dilution of the sludge layer by rainwater, one or more inlets for introducing sludge into the evaporation tunnel, means for moving and turning over the layer of sludge as water is progressively evaporated from the sludge, and an outlet through which the solid fertilizer product exits. The sludge evaporation tunnel may form part of a larger waste treatment system that includes a digester or anaerobic lagoon, which separates a waste animal slurry into sludge and a dilute waste slurry, and a dilute waste evaporation tunnel.