By using the innovative NPHarvest-process wastewater treatment plants can get an efficient pretreatment while producing ecological fertilizer simultaneously.
Wastewaters contain large amounts of phosphorus and nitrogen, which are valuable nutrients. Aalto University’s NPHarvest process enables recovery of these nutrients as clean ammonium sulfate and sludge containing phosphorus and calsium, which can be used as ecological fertilizers. The process produces ecological fertilizer as an end-product and, at the same time, saves energy and natural resources by recycling nutrients of wastewater.
Solids and phosphorus in the wastewater are separated in ballasted sedimentation using a side-product of lime production. The nitrogen recovery process is based on transforming ammonium nitrogen to ammonia gas. Ammonia is separated by stripping through a gas permeable hydrophobic membrane. This enhances the efficiency of the process significantly.
Nutrient recovery happens as a part of normal wastewater treatment process when using the NPHarvest process. The process is beneficial especially to those wastewaters which have more nutrients than the usual municipal waters. Suitable wastewaters for the process are for example reject water from digestion, urine, landfill leachate and septic waste. NPHarvest technique has been proved to be efficient during pilot testing in real environments.
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