An Evaluation of Treatment Options for Dairy Farm Wastewaters: Filtration, Aeration, Constructed Wetlands
Agricultural wastewaters are highly concentrated with contaminants. Economical, efficient solutions for managing and disposing of agricultural wastewaters are soon to be required by Ontario legislation. A constructed wetland was assessed on its treatment of dairy milk house washwater. Effluent water quality evaluations revealed BOD5 concentration reductions of 90% during the summer and 82% during the winter. The seasonal TSS removals were 83% during the summer and 79% during the winter. Bench scale column tests determined that intermittent sand filters with gravel caps are appropriate pre-treatment options. The sand columns removed 72% of TSS, and 54% of COD content. The gravel filter columns removed 56% of TSS and 43% of COD content. Complete mix aeration reactors were examined for their efficiency in the removal of COD and nutrients from different types of dairy farm wastewaters. All reactors produced high quality effluent, and first order kinetic rate constants were determined.