The Effect Of Differenct Substrate And Misgurnus Anguillicaudatus On The Purification Ability And Mechanism Of Constructed Wetland

Biochar has a plentiful pore structure and a large specific surface area,which has especially characteristics such as excellent adsorbability,inoxidizability and anti-biolysis. Biochar can be widely used in industry,agriculture, energy, environment field. However, the application of biochar in the constructed wetland is rarely reported. The purifying capacity and mechanism of the effect of substrate and Misgurnus anguillicaudatus on constructed wetland was researched, based on addition of substrate and Misgurnus anguillicaudatus into constructed wetland.(1) Four kinds of biochar were made by camphor, loquat, evergreen and bamboo, which has abundant pore structure and large specific surface area.Among those biochar, loquat biochar has the largest specific surface area. The adsorption process of nitrogen and phosphorus by biochar is not only the monolayer adsorption but also multilayer adsorption. For adsorption ammonia nitrogen, the adsorption capacity is better in loquat and bamboo biaochar than in camphor and evergreen biaochar. Compared to adsorption phosphorus by evergreen biaochar, camphor and loquat biaochar have higher adsorption capacity.(2) The organic carbon content in constructed wetland has improved after addition of biochar into sand (substrate). In the constructed wetland without Misgurnus anguillicaudatus, after substrate addition 20% biochar with diameter <1mm, the content of EOOC, DOC and TOC of the substrate were increased by 115.16%, 3.14% and 323.43% respectively. Similarily, after addition of Misgurnus anguillicaudatus into the constructed wetland with only sand, the content of EOOC, DOC and TOC were increased by 113.66%, 2.81%and79.16%, respectively.(3) In the constructed wetland without Misgurnus anguillicaudatus and adding 20% biochar with diameter of 1-2mm, the content of ammonia nitrogen of the constructed wetland was decreased by 47.71%, and its nitrate nitrogen was increased by 51.46%. Similarly, the intensity of nitrification and denitrification of the substrate in constructed wetland has increased by 330.65%and 31.59% respectively. In constructed wetland with Misgurnus anguillicaudatus and addition of 10% biochar with diameter of <lmm,ammonia nitrogen was decreased by 11.59%, and its nitrate nitrogen content was increased by 731.51%, and its intensity of nitrification and denitrification of the substrate was increased by 116.93% and 71.81%, respectively.(4) In the constructed wetland without Misgurnus anguillicaudatus and addition 10% biochar with diameter of 1-2mm, the content of Fe/Al-P, Ca-P, IP and TP of the substrate was increased by 8.88%, 1.05%, 2.01% and 15.62%,respectively, but the content of OP of the substrate was decreased by 25.76%.Similarly, in constructed wetland with Misgurnus anguillicaudatus and addition of 10% biochar with diameter of 1-2mm ,the, the content of Fe/Al-P,Ca-P, IP, OP and TP of the substrate was increased by 6.21%, 8.93%, 7.32%,38.21% and 12.97%, respectively.(5) The growth of plant roots can be promoted when addition biochar into the constructed wetladn with only sand as substrate. . In the constructed wetland with Misgurnus anguillicaudatus and addition 20% biochar with diameter <lmm, the total root length and total root volume was increased by 142.40% and 115.57% respectively. Similarly, in constructed wetland with Misgurnus anguillicaudatus and adding 20% biochar with diameter <1mm, the,the total root length and total root volume was increased by 127.98% and 79.04%, respectively.(6) The clogging of the constructed wetland can be eased after adding biochar into constructed wetland with only sand as substrate. In the constructed wetland without Misgurnus anguillicaudatus and adding 10%biochar with diameter of 1-2mm, the permeability coefficient of the constructed wetland was increased by 191.89%. Similarily, in constructed wetland with Misgurnus anguillicaudatus and adding 20% biochar with diameter of <lmm, the permeability coefficient of the constructed wetland was increased by 48.54%.(7) The effluent quality can be obviously improved after adding biochar into constructed wetland. Constructed wetland with adding 10% biochar with diameter of <lmm, the removal rate of CODcr, ammonia nitrogen, total nitrogen was the biggest. In the constructed wetland with Misgurnus anguillicaudatus and adding 10% biochar with diameter of <lmm, the removal rate of CODcr, ammonia nitrogen, total nitrogen has increased by 3.13%, 2.98%and 3.45%, respectively.