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MAR-30-193 TUE 08:3,.J:SHELL STOCKTON #894 P03 E[VVn= LTD. 2.0 PROCESS DFSCRIP"17ION This section provides an overview of the GAC Fluid Bed process, from contaminated groundwater or process water feed to clean water product. A simplified description of each piece of equipment in the system is provided, as well as a discussion of the basic process theory and chemistry. 2.1 Process Overview Figure Ll presents a process flow schematic of the GAC Fluid Bed process. Influent feed enters the process through a duplex strainer to remove any large or fibrous material which may be harmful to or settle out in the plant components or piping system. Nutrients are then added to the feed. As indicated, the influent feed is mixed with part of the treated effluent recycled from the fluid bed bioreactor. The mixed stream enters the suction side of the fluidization pumps. The system hydraulics and valving are such that as the influent flow increases, the recycle flow decreases. This allows the flow through the fluidization pumps to remain essentially constant over a wide range of turndown of the influent flow. Meanwhile, oxygen is generated in a batch-type pressure-swing adsorption (PSA) system, which is supplied with dry, pressurized air from a compressor in series with a dryer. The PSA system uses a pair of pressure tanks filled with beads of zeolite which serve to hold back nitrogen molecules while allowing oxygen molecules to pass. Oxygen purity is typically 90 to 95%. The tanks are operated in an alternating mode, with one tank generating oxygen while the other is being purged of oxygen-depleted air (about 12% oxygen). An oxygen holding tank serves to smooth the delivery flow and pressure. The pressurized water leaving the fluidization pump it injected with oxygen from the PSA unit. The piping circuit includes a bubble trap, and a system for collecting, recycling, and reinjecting undissolved oxygen upstream of the bubble trap. Oxygenated water exits the bubble trap and is monitored for dissolved oxygen (and pH - optional) prior to entering the fluid bed reactor. The water stream is injected at the bottom of the fluid bed reactor vessel through an arrangement of multiple nozzles, operating in parallel via a manifold system. The nozzles assure that the water flow is distributed evenly under the fluidized bed. The fluid bed vessel contains a bed of GAC, completely immersed in water. The GAC serves two functions: 1) it provides a surface to anchor the microbes, enabling them to remain in place in a flowing water stream which would r` otherwise carry them out of the system, and 2) it adsorbs and concentrates organic molecules for the microbes to break down. Page 2-1