APPARATUS FOR DOWN-WELL OXYGEN-TRANSFER INTO CONTAMINATED AQUIFERS

In-situ methanotrophic bioremediation of ground water contaminated with petroleum hydrocarbons and chlorinated aliphatic hydrocarbons (CAHs) often require the addition of O-2 for compound oxidation. The purpose of this research was to test the feasibility of a down-well gas-transfer apparatus for adding O-2 directly into recirculating ground water. At times it may be desirable to add other gases as well, such as methane for CAH cometabolism. A high downward velocity of water through the inlet tube of an inverted cone prevented upward movement of injected O-2 bubbles. The addition of gas-liquid mixing cones within the transfer section of the inverted cone increased the turbulence below the inlet. Complete dissolution of gases is possible. The relationships between O-2 transfer rate and system variables such as pressure loss, water flow rate, and N-2 content in the influent water were evaluated. A significant factor affecting O-2 mass transfer was the total dissolved gas content in the water entering the transfer device. From the results of this study, a design for practical conditions of operation was developed.