Research Of The Purification And Anti-pollution Ability Of Ligularia To Livestock Wastewater

Livestock waste water, contains high concentration organic matter and N,P, cause Water Eutrophication easily if it discharges directly to river or ocean. Constructed wetland is an important technical means to control agricultural nonpoint source water pollution. And wetland plants is an important part in constructed wetland system, choosing the appropriate plant is the key to building artificial wetlands. Ligularia, usually grows in Marshes, wet meadows, edge of river, hill or forest. It has strong vitality and ability of cold resistance. At present, using Ligularia as a constructed wetland plant for wastewater treatment has not been reported. Therefore, this paper is the first time to apply it to wetland. Through simulating constructed wetland, by treating it with two concentration livestock wastewater, it studied the purification capacity and the effects of it on the growth and physiologic characteristic of Ligularia. Then discussed the purification capacity and tolerance ability of Ligularia for livestock wastewater, in order to offer the theoretical basis that Ligularia can be used as a new wetland plant in constructed wetland. The results show that:Ligularia wetland system for livestock waste water has a high removal rate of pollutants, and more suited to deal with the wastewater that has organic contaminant as the main pollutants. The removal rate of Ligularia wetland to the higher concentration of livestock wastewater on TP, TN, COD and NH4+-N reached 92.73%,82.44%,82.78% and 87.75%, to the middle concentration of livestock wastewater it also reached 93.50%,88.79%,82.56% and 96.07%.Rhizosphere urease activity and the phosphatase activity of Ligularia wetland substrate has all improved. Rhizosphere urease activity of substrate had a significant positive correlation with the removal of TN, it can be used as an evaluation index of removal rate of TN. and phosphatase activity had a positive correlation with the removal of TP but which was showed not significant. This shows that the removal of phosphorus in Ligularia wetland is not due to Ligularia absorbing inorganic phosphorus he which from organic phosphorus hydrolysis by phosphatase, but through physical adsorption.Ligularia has a well-developed root system, is an excellent wetland plant. Ligularia organs biomass, nitrogen and phosphorus content, and accumulation of nitrogen and phosphorus were all increased with the concentration of livestock waste water increasing. Ligularia could transfer nitrogen and phosphorus from the underground part to the ground part, and it performed active absorbing even in higher concentration. So we can remove nitrogen and phosphorus though harvest the ground part of Ligularia. In addition, Ligularia has strong absorbing capacity to nitrogen, and the ability of absorbing phosphorus is relatively small.After livestock wastewater treatment, the leaf length and width, and the plant height of Ligularia were increased, and the promoting role showed more apparently in higher concentration. Meanwhile, the ornamental quality of Ligularia also increased.The higher concentration livestock wastewater showed greater influence on the physiological characteristics of Ligularia. The POD activity, SOD activity and root activity both decreased at first, and increased to a higher level. The content of Pro decreased at first, and increased later, then declined to a lower level at last. The variation of MDA content performed a irregular trend, but it was lower than the natural status Ligularia overall. The membrane showed no obvious electrolyte leakage phenomena to the end. POD activity, content of MDA and Pro, membrane permeability and root activity all showed Ligularia was under the stress environment in a short time, but it could adapt to the higher Concentration of livestock wastewater environments through self-regulation. This shows Ligularia has a strong stress resistance.Ligularia belong to shade plants, it has shade-tolerant ability. After livestock wastewater treatment, the chlorophyll, chlorophyll a and chlorophyll b content in Ligularia leaf increased with the concentration increasing. The chlorophyll a/b value Ligularia in higher concentrations was greater than the middle concentration, and Ligularia in the middle concentration was similar to the natural growth state. In addition, under livestock wastewater treatment, the photosynthetic rate, stomatal conductance, intercellular CO2 concentration and transpiration rate of Ligularia leaf was increased, and the Ligularia in higher concentration was bigger than the one in middle concentration.In summary, Ligularia had good purification effects for the two concentration of livestock wastewater, and had strong absorbing ability of nitrogen and phosphorus too. Livestock wastewater promote the growth and ornamental quality of Ligularia, and the photosynthesis has also been strengthened. In addition, the internal physiological of Ligularia could adapt to both two concentration of livestock wastewater by self-regulation. Therefore, Ligularia has good cleaning ability and tolerance capabilities for livestock wastewater, it is an excellent wetland plant.