| 研究実績の概要 |
LPS endotoxins are bacterial by-products that present a possible threat to humans if ingested. Investigation explored different removal methods to remove the LPS endotoxin from the reclaimed wastewater:1)Long term Soil aquifer treatment; 2)Coagulation and flocculation; 3)filtration through positively charged micro structure membranes.
1)Long term operation of soil aquifer treatment of endotoxin proved that the efficiency decreases over time. After one year of operation, bacterial growth in the soilleads to LPS endotoxin production in the soil lowering its removal efficiency. In addition, longer operation leads to a degradation of the soil adsorption capacity.
2)Coagulation and flocculation process provided satisfactory results in reducing LPS endotoxins in water as a first barrier. The highest endotoxin removal was achieved at an aluminum sulfate dose of 80 mg/L at a pH of 4.69. However the optimum pH for DOC and turbidity removal is 6.35.The residual LPS endotoxin concentration was significantly higher than the reported value in tap and groundwater. This suggests a need for further treatments for safe potable reuse.
3)With respect to positively charged micro structure membranes, the study confirmed the assumption that positively charged membranes are an effective alternative for LPS endotoxin removal from reclaimed wastewater. Indeed, comparable or even better removal efficiency of LPS endotoxin Removal using positively charged membranes than the microfiltration was observed, even though it has a larger pore size.
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