The Study Of Purification Capacity Of Different Aquatic Plants Configuration Mode To The Landfill Leachate Tail Water

With the rapid economic development and the accelerated process of urbanization, China's urban waste keeps increasing. Because of its complex composition, high concentrations, changes in water quality and other characteristics, landfill leachate tail water often difficult to achieve "Solid Waste Landfill Pollution Control Standard" (GB16889-2008) after treatment. It became an urgent problem to study and solve. The aquatic plant remediation technology is advanced in diversity, pertinence and high effectiveness with low operating costs, easy to maintain to keep nice landscape, which will provide new ideas and approaches for the land leachate tail water treatment.Based on the quality of landfill leachate tail water of Laogang Garbage Landfill, the study took Acorus calamus, Iris pseudacorus, Typha orientalis, Thalia dealbata and Arundo donax as research objects. The purification capacity of aquatic plants and their different combinations to the landfill leachate tail water was studied with application of determining water quality indices, biomass growth rate, plant height increment, root length increment and plant nitrogen & phosphorus enrichment. It would play a guidance and reference role in aquatic plants remediation selection and configuration to the landfill leachate tail water treatment.The result showed that:1. Acorus calamus, Iris pseudacorus, Typha orientalis and Thalia dealbata had significant improvement for TN, TP, NH4+-N and COD removal. The major portion of the treated water meets "Solid Waste Landfill Pollution Control Standard"(GB 16889-2008).2. With concentration of landfill leachate tail water lowered, stress of landfill leachate tail water weakened, plant FW&DW growth rate, plant height increment, root length increment and plant nitrogen & phosphorus enrichment showed increasing trend. Iris pseudacorus grew best of all.3. When mixed planting with other plants, the FW&DW growth rate of Acorus calamus, Iris pseudacorus and Thalia dealbata rose significantly. When all three plants mixed planting, the FW&DW growth rate of them was the largest. However, because of the growphase, intraspecific and interspecific competition, plant height and root length increment varied according to different species.4. Different plant have different tolerance and purification capacity:The death rate of Arundo donax was high in various concentrations of landfill leachate tail water. This showed that the tolerance capacity of Arundo donax was weak and it was not suitable for landfill leachate tail water purification. The growth of Typha orientalis was inhibited in high concentrations of leachate tail water. So it is only suitable for low concentration of the leachate tail water purification. Acorus calamus had the best phosphorus removal capacity. Iris pseudacorus had the best nitrogen removal capacity, while Thalia dealbata had the best COD removal capacity and the largest plant nitrogen and phosphorus enrichment per plant.5. When mixed planting with other plants, the removal rate of TN and TP in the landfill leachate tail water by Acorus calamus, Iris pseudacorus amd Thalia dealbata treatments rose significantly. When all three plants mixed planting, the removal rate of TN and TP was the largest. But the removal rate of NH4+-N and COD had no significant difference between single-species planting and mixed planting.6. The statistical analysis of plant nitrogen and phosphorus enrichment by different treatments showed that:when Acorus calamus, Iris pseudacorus amd Thalia dealbata mixed planting, total plant nitrogen and phosphorus enrichment rose significantly. When two species of them mixed planting, total plant nitrogen and phosphorus enrichment rose on the whole, as well. When the three species mixed planting, the plant nitrogen and phosphorus enrichment of Acorus calamus and Iris pseudacorus rose significantly, while that of Thalia dealbata decreased significantly.7. Compared to single species planting, mixed planting could reduce the stress of landfill leachate tail water, improve biodiversity, structure and function of system, increase the conversion means of matter and energy of the food chain (net). It could be a more stable water purification system and improve the purification capacity of aquatic plants on the landfill leachate tail water.