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Biological treatment systems work by modifying the local environment to select for a particulaz <br />biologically-mediated reaction (e.g., sulfate reduction) while supplying a source of easily <br />digested organic carbon. In all cases, biological treatment systems require time for development <br />of the microbial community. As a consequence, the results presented in the following subsection <br />represent the data that were available, but do not necessarily represent operation of the biological <br />systems at optimum conditions. <br />4.3.1 Bioreactor Treatment <br />The first water treatment option discusses the application of anabove-ground bioreactor. In this <br />scenario, groundwater would be pumped from groundwater wells to anabove-ground bioreactor. <br />Treatment would be accomplished anaerobically in a high-rate Upflow Anaerobic Sludge <br />Blanket (UASB) or Expanded Granulaz Sludge Bed (EGSB) system (as manufactured by <br />Biothane Corporation of Camden, New Jersey, or acceptable equivalent) (Figure 4-2), followed <br />by an aerobic treatment system to remove manganese. <br />4.3.1.1 System Description <br />As the groundwater is pumped to anabove-ground bioreactor, a source of easily digested organic <br />carbon (e.g., molasses or methanol) would be added. The organic cazbon would then be <br />anaerobically consumed by fermentative bacteria. The sulfate- and sulfiu-containing organic <br />compounds would be converted by sulfate reducing bacteria into sulfides, which may appeaz as a <br />biogas in the anaerobic effluent. <br />The closed-loop, anaerobic effluent, is stripped in a packed bed stripping column before being <br />dischazged and recycled to the anaerobic reactor (Figure 4-2). The stripper gas is subsequently <br />purged in an absorber where hydrogen sulfide and colloidal sulfur aze formed. The purged gas is <br />recirculated for use as stripper gas. Surplus biogas (i.e., the amount generated in the anaerobic <br />reactor) is taken out after the absorber. As a result, the gas is of good quality (low in hydrogen <br />sulfide) and can be used as an energy source or dischazged into the atmosphere. <br /> <br />Battle Movrtlarn Resources, /nc. <br />p:~/002671reporlslmarchrpAtr26wtrmngtmarch.dac 43 March 11. 1999 <br />