Recovery of phosphorus from sewage sludge


170606 anpf phos4you smallIn the Phos4You project (PHOSphorus recovery from waste water FOR YOUr Life), which links a consortium of EU partners from water companies, wastewater-treatment plants and universities, coordinated by the Lippeverband (Germany), we will extend a process used until now for phosphorus removal from sewage-sludge incineration ash (Doetsch et al., 2010) to partially dried sewage sludge directly. After the sludge has been dried to a defined water content, in a leaching step phosphorous is transferred into the leach liquor. Unfortunately, contaminants like iron, aluminum and heavy metals are leached as well and have to be removed by appropriate steps. This is achieved by applying a reactive-extraction step and fractionated precipitation. Finally the phosphorous is precipitated in a form, which can directly be used as fertilizer ingredient.

We optimize the process e.g. with respect to water content to be reached after drying, leach pH, etc. for optimal process performance, where these conditions need to be adjusted to the local conditions of each individual wastewater-treatment plant based on appropriate modelling. This will be achieved by establishing a mobile process setup, which will then be used in bypass at different locations to develop and validate the models applied in a corresponding simulation tool. The process optimization will also be guided by life-cycle analysis. In the entire project consortium this process will be compared to other alternative ways to recycle the phosphorous from the wastewater.

 

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