Sustainable Nutrient Removal System With Johkasou and Bio‐Geofilter Hybrids

Johkasou and biogeofilter hybrids have been developed to remove nutrients from domestic wastewater. Granulated coal ash, a by-product of coal-fired power plants, was used as the base material for the biogeofilter installed at the rear stage of the Johkasou system. The biogeofilter showed stable nutrient removal performance, which was attributed to both uptake by plants and adsorption by granulated coal ash. Flowering plants were best at removing phosphorus, while green manure crops were better at removing nitrogen. The phosphorus adsorbed onto the granulated coal ash could easily be used for plant growth. Hence, the regeneration of phosphate adsorption sites on granulated coal ash by plants is advantageous for extending the operational lifespan of the phosphate adsorption process and lowering maintenance costs. The proposed system is able to respond to fluctuations in concentrations of wastewater and seasonal changes, making it a viable decentralized wastewater treatment system for regions without established sewerage networks.