Novel methods and apparatuses are disclosed for the treatment of wastewater to reduce, often associated, offensive odors. Irrigation of oxygenated liquid on top of a permeable cover effectively creates an aerobic treatment zone at the top of the lagoon whereby odorous gases being produced anaerobically below the cover are metabolized within this zone before being released to the atmosphere. This same system also serves to increase evaporation from the overall waste handling system therefore substantially reducing or eliminating the need for land application of treated wastewater.