In the wastewater treatment process, there are three main steps that each help remove contaminants and further prepare water for safe release back into the environment. The steps are completed in order, beginning with primary treatment and ending with either secondary or tertiary treatment. The extent of processing is dependent on both the level of contamination and the composition of the wastewater.
PRIMARY Treatment Systems: The main goal of primary processing is to allow enough time for sedimentation and separation to occur so that solid waste can be removed. Heavier solids sink while lighter solids like oils and grease float to the surface. The resulting sludge is removed from the water and sent for further processing.
SECONDARY Treatment Systems: Secondary treatment involves the use of microorganisms to degrade and digest contaminants such as organic matter through oxidation. Biofiltration, aeration, and oxidation ponds are all treatment methods used in this step.
TERTIARY Treatment Systems: Tertiary systems prepare water for release into the environment. It is important that treated wastewater effluent meets local and national regulations for water quality before it is released. To accomplish this, materials like activated carbon, sand and membranes are typically used.