primääripuhdistuksen

Primääripuhdistus is a Finnish term referring to the primary stage of wastewater treatment. This process focuses on the physical removal of solid materials from raw sewage. The main objective is to separate settleable solids and floating debris before the wastewater undergoes further treatment.

Typically, primääripuhdistus involves passing the influent through screens or grit chambers. Screens are used to remove larger items such as rags, sticks, and other debris that could clog downstream equipment. Grit chambers are designed to allow heavier inorganic materials like sand, gravel, and eggshells to settle out. Following screening and grit removal, the wastewater flows into primary clarifiers, also known as sedimentation tanks. In these large tanks, the flow velocity is reduced, allowing suspended organic solids to settle to the bottom as sludge, and lighter materials like grease and oil to float to the surface.

The settled sludge is then collected and typically sent for further processing, such as digestion or dewatering. The partially treated wastewater, now called effluent, is then directed to secondary treatment stages, where biological processes are used to remove dissolved and suspended organic matter. Primääripuhdistus significantly reduces the overall organic load and the amount of suspended solids in the wastewater, making subsequent treatment more efficient and effective. It is a fundamental step in most municipal and industrial wastewater treatment systems.