ANOXIC AIR STRIPPING OF GROUNDWATER FOR IRON CONTROL

AIR STRIPPING IS ONE OF THE MOST ECONOMICAL PROCESSES FOR THE REMOVAL OF VOLATILE ORGANIC EHMICALS (VOCS) FROM GROUNDWATER. HOWEVER, UNDER SOME CONDITIONS, THE FORMATION OF SCALE AND SLIME DUE TO THE OXIDATION OF DISSOLVED IRON FOULS THE PACKING AND REDUCES AIR FLOW AND TREATMENT EFFICIENCY. THE OBJECTIVE OF THIS PHASE I PROGRAM IS TO DETERMINE THE FEASIBILITY OF STRIPPING THE GROUNDWATER WITH A RECIRUCLATING AIR STREAM THAT IS DEPLETED WITH OXYGEN (ANOXIC). RECENT CLEAN-AIR REGULATIONS REQUIRE THAT STRIPPING OFF-GASES BE PURIFIED BEFORE RELEASE TO THE ATMOSPHERE. ONCE THE CONTAMINANT VOCS HAVE BEEN REMOVED, HOWEVER, THE STRIPPING AIR CAN BE RECYCLED. IF THIS RECIRCULATING STREAM IS HEATED BY INJECTION OF FLUE GAS FROM A GAS BURNER, IT WILL BECOME DEPLETED IN OXYGEN AND RICH IN CO2. THE TREATMENT COSTS ARE ESSENTIALLY ZERO SINCE THE HEATING IS, IN ANY CASE, REQUIRED FOR THE GAS PURIFICATION STEP. WATERS WITH HIGH PH/HIGH ALKALINITY MAY ADDITIONALLY REQUIRE PH REDUCTION BY ACID ADDITION FOR EFFECTIVE FOULING CONTROL. TESTS ARE PROPOSED IN PHASE I TO DETERMINE THE EXTENT TO WHICH ACID NEUTRALIZATION IS IN FACT REQUIRED WHEN STRIPPING WITH AN ANOXIC GAS.