Study On The Effect Of Micro-Nano Bubbles On Promoting Growth Of Iris Pseudacorus L. And Vallisneria

Eutrophication has become the main form of inland water pollution in China,algal blooms occurred frequently in many lakes and reservoirs,affecting the quality and availability of surface water,also bringing huge environmental pressure and serious economic loss.A new generation of Micro-Nano Bubbles Generating Device(MNBGD)were designed and developed to govern eutrophication or black smelly water by its intermittent effect.Associated with the vegetation restoration techniques on eutrophication,MNBGD can improve water environment and separate the algae from water.We also found that the size effect of Micro-Nano Bubbles(MNB)can significantly enhance the growing speed and quality of plants around the water,it also provide a new way to promote the effect of vegetation restoration technology for water pollution control.In recent years,micro-nano bubbles was used widely in the field of environmental protection,the diameter of micro-nano bubbles had a unique size effect,showing unusual physicochemical properties.In this work,the size effect of micro-nano bubbles on promoting the growing speed and quality of plants in water ecological system was investigated,forecasted the prospect of micro-nano bubbles used in water ecosystem repair engineering.Meanwhile the micro-nano bubbles was used in processing Iris pseudacorus L.and Vallisneria to study how the aeration and density of micro-nano bubbles to effect the growth rate of submerged plants and of emergent plants.(1)In the effect experimentation of Micro-Nano Bubbles Generating Device to generate the bubble,the diameter of micro bubbles and the dissolved oxygen in the water were measured,compared with the ordinary bubble,the results showed that the diameter of bubbles generated by micro-nano bubbles generating device is in the level of micron or even nanometer,at the same time,the dissolved oxygen increased from 0 mg/L to 11.4 mg/L in a relatively short period of time,the oxygen transfer efficiency is far greater than the ordinary aeration.After the treated by micro-nano bubbles aeration,the dissolved oxygen in the water beyond the normal condition of oxygen content the upper limit of 14%,decreased from 11.4 mg/L to 10.9 mg/L in 180 min,micro-nano bubbles density have a long half-life time.These results proved that the quality of micro-nano bubbles generating device meeted the requirements of following experiment;(2)The growth rate of Iris pseudacorus L.was promoted obviously in the water treated by micro-nano bubbles aeration,and its physicochemical indices are much higher than Iris pseudacorus L.grown in water processed by ordinary bubble aeration: the average value of root length,chlorophyll a,chlorophyll b,carotenoid were higher than 91.68%,61.36%,91.27%,58.03%;the average value of superoxide anion and the relative electrical conductivity were lower than 45.89% and 49.84%,the average value of water content is higher than 1.13 percentage points.In the actual water ecosystem repair engineering,the physicochemical indices of the Iris pseudacorus L.grown in water processed by micro-nano bubbles aeration are much higher than Iris pseudacorus L.grown in water processed by non-bubble aeration,such as the average value of root length,plant height,chlorophyll a,chlorophyll b,carotenoid were higher than 23.91%,10.1%,153.02%,144.33%,101.6%;the average value of superoxide anion and the relative electrical conductivity were lower than 30.88% and 21.12%,the average value of water content is higher than 1.79 percentage points;(3)The size effect of micro-nano bubbles is one of the factors to improve the growing speed and quality of plant,by controlling dissolved oxygen in water at the same amount,compared micro-nano bubbles aeration and ordinary bubble aeration,the results showed that even in the same amount of dissolved oxygen in water,the physicochemical indices of the Vallisneria grown in water processed by micro-nano bubbles is much higher than the Vallisneria grown in water processed by ordinary bubble,because of the growth of plant is accelerated by the size effect of micro-nano bubbles.In the actual water ecosystem repair engineering,with the decrease of micro-nano bubbles density,the effect on promoting the growth of plant decreased.Even the root of Vallisneria planting in sediment was not contact directly with water processed by micro-nano bubble aeration,its growth rate and quality are still affected by micro bubbles;(4)In different culture method,the effect on promoting the growth of Vallisneria caused by micro-nano bubbles were not at the same level,the botanical indices of Vallisneria planting in soil were better than Vallisneria planting in water,but the morphological indices of Vallisneria planting in water were better than Vallisneria planting in soil,which indicates micro-nano bubbles can influence the organization such as root and leaf contacting directly with water,but the Vallisneria planting in soil can absorb the nutrient in sediments more easily,its botanical indices shows better;(5)In the prevention engineering of water pollution,micro-nano bubbles can improve the growth rate and quality of plants growing around water,combined with vegetation restoration measures,the synergistic effect of governing water pollution will be more effective.