Näringsborttagning

Näringsborttagning, or nutrient removal, is a crucial process in wastewater treatment aimed at reducing the levels of essential nutrients, primarily nitrogen and phosphorus, from effluent before it is discharged into receiving waters. These nutrients, while vital for aquatic life in moderation, can cause significant environmental problems when present in excess.

High concentrations of nitrogen and phosphorus can lead to eutrophication, a process where excessive algal blooms occur. These blooms deplete dissolved oxygen in the water as they decompose, creating hypoxic or anoxic conditions that are harmful or even lethal to fish and other aquatic organisms. This can disrupt the entire aquatic ecosystem.

Nitrogen removal typically involves biological nitrification and denitrification processes. Nitrification converts ammonia to nitrates under aerobic conditions, and denitrification then converts nitrates to nitrogen gas, which is released into the atmosphere, under anoxic conditions. Phosphorus removal can be achieved through chemical precipitation, where chemicals like aluminum sulfate or ferric chloride are added to form insoluble phosphate compounds that can be settled out, or through biological nutrient removal processes that encourage microorganisms to absorb and store phosphorus within their cells.

Effective näringsborttagning is essential for protecting water quality, preserving biodiversity in aquatic environments, and preventing the degradation of natural water bodies. It is a key component of modern wastewater treatment strategies worldwide.