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DEMONSTRATION OF A MAXIMUM RECYCLE, SIDESTREAM SOFTENING SYSTEM AT A PETROCHEMICAL PLANT AND A PETROLEUM REFINERY
Citation:
Matson, J., W. Mouche, E. Rosenblum, AND L. McGaughey. DEMONSTRATION OF A MAXIMUM RECYCLE, SIDESTREAM SOFTENING SYSTEM AT A PETROCHEMICAL PLANT AND A PETROLEUM REFINERY. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/2-84/176.
Description:
New full-scale maximum recycle sidestream softening systems at USS Chemicals, Houston, Texas and TOSCO refinery, Bakersfield, California were evaluated as a technology to achieve zero wastewater discharge. Softener process efficiency was optimum at a pH control range of 10.3 to 10.5 at 40C and using a high mixing intensity. A problem of heat exchanger biofouling from the high dissolved organics in recycle water was effectively controlled by using Bromocide with chlorine. A total organic carbon balance over the cooling water system showed raw makeup water and process water contribute 1/3 and 2/3 of the organics, respectively. Major organic sinks were drift (60%), biodegradation (30%), and volatilization (10%). Softener sludge as analyzed for chromium by leachate tests was classified as nontoxic. Heat exchanger equipment averaged two mils/year internal corrosion. External corrosion from drift aerosols was corrected by installation of a ferrous sulfate reactor in the blow down system and improved drift eliminators in cooling towers. The TOSCO water problem of high silica and low magnesium was corrected by adding caustic and magnesium sulfate to the softener. Both plants operated satisfactorily at near zero liquid discharge. Operating costs and benefits are discussed.