3D vegetation net ecological slope purification and regulation system of pond aquaculture

In order to study the building technology of 3D vegetation net slope and its purification and regulatory effects on water quality, this experiment used 3D vegetation net, water conduit and aquatic plants to construct aquaculture pond water purification and regulatory eco-slope system. The results showed that, the 3D vegetation net ecological slope system had the characteristics of sub-flow and surface flow wetland, with void ratio of 4-9%, gradient lower than 1:2.5 and the water flow velocity higher than 0.13 m/s. Under the situation of daily water circulation of 10%, the 3D vegetation net eco-slope system could reduce the ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, total nitrogen and total phosphorus of the aquaculture pond water by 46%, 65%, 49.2%, 64.4% and 39%, respectively; the reduction for chlorophyll-a of the aquaculture pond water was 8.8%. The purification efficiency of the eco-slope for total nitrogen, total phosphate and COD were 0.27, 0.015 and 0.94 g/h·m2, respectively. Compared to the control pond water, the green algae in the 3D vegetation nets eco-slope pond water increased by 10.7% and the blue-green algae decreased by 2.5%, and the Shannon Wiener index (H′) of algae increased by 38%. Simultaneously, the algae density in the experimental pond water reduced by 23% in comparison to the control pond water, in which the density of blue-green algae reduced by 48.4%, and the Cryptophyta and Euglenophyta increased by 24% and 34%, respectively. The dominant algae was more benefit for aquaculture needs in vegetation net eco-slope pond water. The study indicated that the 3D vegetation net eco-slope system has the function of protecting ponds ridge and water purification and regulation, which is a kind of “economical, ecological and emission reduction” technologies.