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Used extensively by the food, chemical, and pharmaceutical industries, the mechanical-vapor-recompression (MVR) process is viewed as a reliable method for recovering demineralized water from concentrated brines. Devon Energy has supported the operation of an advanced MVR system at a north-central Texas (Barnett shale region) treatment facility. At this facility, pretreatment included caustic addition and clarification for total-suspended-solids and iron control. Pretreated shale-gas flowback water was then sent to three MVR units, each rated at 2,000-2,500 B/D (318-398 m 3 /d). Data were collected during a 60-day period in the summer of 2010. Distilled-water recovery volume averaged 72.5% of the influent water to the MVR units. The influent total dissolved solids (TDS) fed to the MVR units averaged just under 50 000 mg/L. More than 99% of the TDS were captured in the concentrate stream. The fate of multivalent cations; total petroleum hydrocarbons (TPH); and benzene, toluene, ethylbenzene, and xylenes (BTEX) throughout the treatment system was determined. Most of the iron and TPH removal (90 and 84%, respectively) occurred during pretreatment. The total removal of iron, magnesium, calcium, barium, and boron from the distillate exceeded 99%. BTEX removal from the distillate exceeded 95%. Electric power at the facility was provided by two natural-gas generators, and compressors associated with the MVR units were driven by natural-gas-fueled internal-combustion engines. Energy requirements at the entire treatment facility were tracked daily by total natural-gas use. Best-fit correlations between treated water and distillate production vs. total plant use of natural gas indicated that there was a base power load throughout the facility of approximately 120 to 140 Mscf/D (3400 to 3960 m 3 /d) of gas. Approximately 48 scf natural gas/bbl influent water treated (270 m 3 /m 3 influent) or 60.5 scf/bbl distillate produced (340 m 3 /m 3 distillate) was required; this represents an energy cost of less than USD 0.25/bbl treated (USD 0.04/m 3 treated) and approximately USD 0.30/bbl of distillate product generated (USD 0.048/m 3 distillate), assuming a natural-gas cost of USD 5/million Btu (USD 4.72/GJ). Performance in terms of water recovery and product-water quality was stable throughout the 60-day test.

Belt‐thickening processes are used for preliminary dewatering of flocculent sludges such as polymer‐conditioned wastewater sludges, industrial sludges, and water treatment silts. These processes are also directly or indirectly used as the lead‐in step in belt‐pressing dewatering of these types of sludges. In the belt press application, improperly drained sludge can yield failure of the subsequent pressing steps. This paper is Part I of a series on the laboratory simulation of belt‐pressing dynamics and addresses the mathematics of the gravity drainage of conditioned sludges through short depths on fabric filter cloth. The rate of water drainage through the fabric filter for sludge from a given source and treated with constant polymer doses per dry weight of sludge solids is a function of the total volume of the sample, the solids fraction within the sample, the specific resistance of the forming cake, and the specific resistance of the filter cloth. A drainage rate model that fits the general shape of drainage rate from numerous sludges is derived. Methods for using the proper test volume in batch tests in relation to full‐scale dynamic presses are presented. Finally, a simple test method for determining the resistance through the filter cloth on full‐scale presses is suggested. Data from 12 test conditions including five types of sludges are analyzed. The model appears to adequately account for volumetric changes, sludge concentration changes, and changes in belt resistance in laboratory drainage tests.