Overview of Technology Case Study

However, the membrane was found not to be very efficient at removing phenolics. Rejections were in the range of 18% for phenolics. Overall, based on a comparison of total concentratitHis of a pre-designated list of creosote-derived PAH and phenolic semivolatile contaminants in the permeate versus the feed water, the system did not meet the claimed rejectirai efficiency of 90%. 

On the basis of the PAH rejections of over 90%, the permeate would be expected to be acceptable for discharge to POTWs (Publically Owned Treatment Works) with little or no polishing. Other pollutants found in ccaitaminated waters at wood treatment facilities (e.g., polychlorinated dioxins and furans) also are concentrated in the reject stream. Other constituents commonly encountered at such sites including colloidal oils and suspended solids are also extensively removed by the membrane process. Removal efficiencies for oil and grease were 93%. Suspended solids were removed to nrai-detectable levels. These materials did not appear to have an adverse effect on the filtration process. 

The system was found to effectively concentrate organic contaminants into a concentrate of much smaller volume. The volume of wood preserving waste contaminated wastewater was reduced by over 80%. This means that only 20% of the volume of the feed water would require further treatmoit to immobilize or destroy the organic contaminants. 

The filtration unit operated consistently and reliably over a brief testing period. The unit was easy to operate and maintain. The filtration unit operated in a batch mode for six hours each day, for six days, and processed approximately KXX) gallcxis of feed per day. Over the six day test period, permeate flux was relatively constant. Based on a total membrane area of 3(X) ft for the system, the permeate flow rate for the four module filtraticxi unit averaged 2.6 gpm. Excessive fouling of the membrane, necessitating frequent cleaning or regeneration, was not encountered. However, the 

The operating cost for the membrane process as used at American Creosote Works is in the range of 220 - 1,740/1,000 gallons, depending on system size. Major cost contributors are labor and residuals disposal. Labor costs decrease significantly as the scale of the process increases. Auxiliary equipment that could be needed to support this process is comparable to that which would be needed for other above-ground treatment systems such as oil/water separators and clarifiers for pretreatment, and filters, carbon adsorbers, etc, for effluent polishing as required. 

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