Abstract
We assessed the performance of a commercial jokaso system with a membrane in treating domestic wastewater, including wastewater from garbage disposal systems. We then sprinkled the treated wastewater over sedum propagated on the rooftop of a building to evaluate the ability of the plant to remove phosphorus and nitrogen from the wastewater. In a 6-month demonstration test the membrane-treated wastewater showed stable qualities, with low BOD and SS, for example. There were only low counts of Escherichia coli, and no Legionella bacteria were observed. Furthermore, the phosphorus and nitrogen in the water applied to the rooftop greening were absorbed by the sedum. Rates of removal were phosphorus (66%) and nitrogen (55%). Unlike discharging the wastewater directly to a river, spraying treated wastewater onto the sedum reduced the phosphorus and nitrogen contents. In addition, the final effluent from the rooftop greening had a low concentration of organics, with an average pH of 8.3 and no observable Legionella, so percolation of the effluent through the soil and utilizing it as recycled water presented no problems. Finally, we estimated the water balance of the rooftop greening system using a jokaso system with membrane and offered two model cases.
