Treatability testing to characterize contaminant biodegradability and nutrient content may be needed for any biodegradation technology. A subsurface geologic characterization would be particularly important to characterize the migration of NAPLs. Ground water models are also often needed to predict flow characteristics, changes in contaminant mixes and concentrations, capture zones, and times to reach cleanup levels.
Air stripping involves the mass transfer of volatile contaminants from water to air.
For ground water remediation, this process is typically conducted in a packed tower or an aeration tank. The generic packed tower air stripper includes a spray nozzle at the top of the tower to distribute contaminated water over the packing in the column, a fan to force air countercurrent to the water flow, and a sump at the bottom of the tower to collect decontaminated water. Auxiliary equipment that can be added to the basic air stripper includes automated control systems with sump level switches and safety features such as differential pressure monitors, high sump level switches and explosion proof components, and discharge air treatment systems such as activated carbon units, catalytic oxidizers, or thermal oxidizers. Packed tower air strippers are installed either as permanent installations on concrete pads, on a skid, or on a trailer. Liquid phase carbon adsorption is a full-scale technology in which ground water is pumped through a series of vessels containing activated carbon to which dissolved contaminants are adsorbed.