| | When land application guidelines derived from wastewater irrigation criteria (Alberta Environmental Protection, 1997) are met, Snowfluent is a safe, environmentally sustainable winter treatment method for high nutrient, high organic matter wastewaters. Application of Snowfluent-treated wastewater is recommended for pasture, alfalfa, hay and fall seeded crops because of prolonged snowcover. Moisture and plant nutrients remain in place until snowmelt. Depending on the size of the snow piles, melting continues through to June, making water and nutrients available throughout the growing season.
Odour from anaerobic decomposition of nutrient-rich, high BOD wastewater in lagoons is a problem irrespective of what treatment and land application system is used. However, the 1997 tests with fresh wastewater did not produce significant odour. Odour impacts off-site could be minimized by processing wastewater fresh from the food processing plant in the winter. When weather or operating conditions do not allow the Snowfluent; system to operate, storage in lagoons and odour treatment at the lagoons may be required. However, Snowfluent; treatment of fresh wastewater offers the opportunity to minimize the storage time in lagoons and divert significant volumes of wastewater directly to field application. From these tests, pathogens and BOD in fresh wastewater were treated at snowmaking and in the snow piles to produce a meltwater that met land application criteria in 100% of the samples for pathogens and, in 90% of the samples, for BOD.
Snowfluent processed wastewater had substantial benefit to an alfalfa hay crop, increasing growth and reducing weeds. Survival of the second year stand was not affected by delayed exposure from under snow cover.
In these tests where the wastewater’s salt concentrations did not meet irrigation guidelines, impacts on groundwater were limited to increases in sodium, potassium and dissolved organic carbon in the immediate area of the snow piles. Concentrations of these parameters decreased quickly with distance from the snow piles. Impacts observed in soils were temporary increases in sodium throughout the soil profile and increases in potassium in surface soils. No Snowfluent-related increases of nitrate or fecal coliforms in groundwater were observed.
Useful chemical separations occurred as the Snowfluent processed wastewater snow piles aged. Soluble salts were transported to the bottom of the snow pile with early meltwater, 80% of the soluble salts appearing in the first 20% of meltwater. Insoluble and less-soluble constituents of the wastewater remained in place, resulting in a residue rich in nitrogen, phosphorus and potassium. |
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