EXPERIMENTAL STUDY ON DISSOLVED OXYGEN IMPROVEMENT METHOD OF BRACKISH LAKE

Abstract

 Experimental study was carried out in the Abashiri Lake where is brackish lake with double-layered formation of freshwater and saltwater. In order to improve the dissolved oxygen of the salt water layer, we examined the water quality change at the time of oxygen supply using by the gas dissolving apparatus (WEP). we collected anearobic water on site and supplying oxygen by WEP in a circulating water tank. It was able to oversaturate dissolve oxygen upto 40 mg/L when pure oxygen gas used.
 Hydrogen sulfide as a toxic substance accumulates in anearobic water of Abashiri lake with a high concentration of 130 mg/L. When supplying oxygen, It is clear that hydrogen sulfide oxidized to solid sulfur which is not harmful. Moreover, It became clear that orthophosphoric acid in water was reduced by contacting with the bottom sludge if anaerobic water completely oxidized with hydrogen sulfide. On the other hand, it was found that oxygen supply for several days does not affect ammonium nitrogen.