The Optimal Planting Coverage Rate and Wastewater Concentration for Water Spinach Floating Bed on Geese Wastewater Purification

摘要

The goal of this study was to explore the optimal planting coverage rate and wastewater concentration required by water spinach floating bed system for the purification of geese farm wastewater. The results showed that the floating bed with water spinach in high concentration wastewater had better removal rates on ammonia nitrogen (NH 4+-N), total nitrogen (TN) and total phosphorus ( TP) (P 0.05). There was no significant difference on the removal of nutrients except turbidity (NTU) among the different plant coverage rages (P0.05). The floating bed system with water spinach removed heavy metals ( Hg, As and Zn) in different concentration wastewater, with removal rates of 22.21similar to 68.20, 40.00similar to 52.94 and 100.00. Water spinach in low concentration wastewater had significant higher root length, stem height and weight gain (P0.05) than medium and high concentration wastewater. The TN and TP contents of water spinach stem leaf in high concentration wastewater were significantly higher than other groups(P0.05). The concentration of heavy metals (Pb, Cd, As and Hg) in water spinach in all groups was far below the national food safety standard. In general, the water spinach floating bed is suitable for the purification of medium and low concentration wastewater, and the optimal coverage rate is 40similar to 60.