Ravinnonpoisto

Ravinnonpoisto refers to the process of removing nutrients, primarily phosphorus and nitrogen, from wastewater. This is a crucial step in wastewater treatment to prevent eutrophication of receiving water bodies like lakes and rivers. Eutrophication is an over-enrichment of water with nutrients, leading to excessive algae growth, oxygen depletion, and harm to aquatic ecosystems.

There are two main methods for nutrient removal: biological and chemical. Biological nutrient removal utilizes microorganisms that naturally consume and transform nitrogen and phosphorus compounds. This often involves specific stages within a wastewater treatment plant, such as anoxic and aerobic zones, to facilitate the different microbial processes required. Nitrogen removal typically involves nitrification, where ammonia is converted to nitrate, followed by denitrification, where nitrate is converted to nitrogen gas, which is released into the atmosphere. Phosphorus can be removed biologically through the action of phosphorus-accumulating organisms (PAOs) that store excess phosphorus within their cells.

Chemical nutrient removal involves the addition of chemicals, such as metal salts (e.g., aluminum sulfate or ferric chloride) or polymers, to precipitate phosphorus out of the wastewater. This forms solid flocs that can then be removed through sedimentation or filtration. While chemical methods can be effective, they often produce more sludge and can be more costly. Often, a combination of biological and chemical methods is employed to achieve the highest levels of nutrient removal. The specific techniques and their effectiveness depend on factors such as the influent wastewater characteristics, the treatment plant design, and operational parameters.