tertiäärikäsittelymenetelmiä

Tertiary treatment methods, also known as advanced wastewater treatment, are processes designed to further purify wastewater beyond secondary treatment. These methods aim to remove specific pollutants that remain after conventional biological treatment, such as nutrients, suspended solids, and dissolved organic matter. The primary goals of tertiary treatment are to protect receiving water bodies from eutrophication, improve water quality for reuse, and meet stringent environmental discharge standards.

Common tertiary treatment techniques include nutrient removal, which specifically targets nitrogen and phosphorus. Phosphorus removal can be achieved through chemical precipitation, often using metal salts like alum or ferric chloride, which form insoluble phosphate compounds that can be settled out. Nitrogen removal typically involves biological processes like nitrification and denitrification. Nitrification converts ammonia to nitrates, and denitrification, under anoxic conditions, converts nitrates to nitrogen gas, which is released into the atmosphere.

Other advanced methods focus on removing residual suspended solids and organic matter. Filtration, using sand, gravel, or membrane filters, can remove finely suspended particles. Activated carbon adsorption is effective in removing dissolved organic compounds, color, and odor. Advanced oxidation processes, such as ozonation or UV irradiation, can break down recalcitrant organic pollutants and disinfect the water. Membrane technologies, like reverse osmosis and ultrafiltration, offer high levels of purification, removing a wide range of contaminants and producing high-quality effluent suitable for reuse in irrigation, industrial processes, or even drinking water after further treatment. The choice of tertiary treatment method depends on the specific wastewater characteristics and the desired effluent quality.