Effects on the Contents of Dissolved Oxygen in Water and Water Quality by the Photosynthesis of Four Submerged Plants in Urban Polluted Water

Abstract

Hypoxia of Urban polluted river will cause water blacking and stinking. Experiments on reaeration of four kinds of submerged plants were designed under nature light and dark condition in static water, and nature light condition in flowing water. The four kinds of submerged plants ware cultured in clean water and sewage individually for one week, then the concentration of dissolved oxygen (DO) in clean water and DO, chemical oxygen demand (COD), ammonia nitrogen (NH4 +-N) in sewage ware determined to study the Variation Characteristics of DO and the other indexes in water. Results show that: Four kinds of submerged plants shows the ability of reaeration, and the reaeration effect is more and more obvious with the increasing of light intensity in a certain range. Submerged plants showed good removal effect of NH4 +-N, the removal rates of NH4 +-N by Hydrillaverticillata, Vallisneriaspiralis, Hornwort and Myriophyllumverticillatum (95.05%, 92.74%, 89.45% and 88.29% respectively after they lived under natural light condition for 16days. In contrast, the removal effect of COD is not significant. Results show that the change of COD of water is irregular, the index even showed an increasing trend in the latter stage. The experiment shows that, the four submerged plants have a good effect on river reaeration and purification. They can be recommended as an auxiliary measure in the pollution treatment of urban river.