\it United States Environmental Protection Agency Industrial Environmental Research Laboratory Research Triangle Park NC 27711 Research and Development EPA-600/S2-83-027 June 1983 Project Summary Closed-Cycle Textile Dyeing: Full- Scale Hyperfiltration Demonstration Craig A, Brandon Hyperfiltration (reverse osmosis) is a membrane separation technique that has been used effectively to desalinate seawater. Successful desalination mem- branes were not applicable in many cases to the harsher industrial effluents. Because expensive energy, process chemicals, and water are used in in- dustrial processes and then are dis- charged to treatment facilities, the use of various membranes to recover water, energy, and process chemicals was studied in a series of government-spon- sored research projects. The results of the research led to the current project of joining a full-scale dynamic-mem- brane hyperfiltration (HF) system with an operating dye range, a multi-pur- pose machine with a variety of effluents, presenting a good test situation for demonstrating HF recovery equipment on industrial process effluents. The results of this demonstration and other related information show that an HF recovery system will yield a payout time of 1 to 5 years where there are simultaneous benefits for water, energy, and chemical recovery and/or where significant waste treatment costs can be abated. The report describes the design and construction of the HF equipment; pre- sents and evaluates monitoring data from 1 year of operation; gives costs for equipment installation, and opera- tion and credits for savings due to recycle; and describes the primary ob- jectives of an 18-month project exten- sion. This Project Summary was developed by EPA's Industrial Environmental Re- search Laboratory, Research Triangle Park. NC, to announce key findings of the research project that is fully docu- mented in a separate report of the same title (see Project Report ordering information at back). Introduction LaFrance Industries, LaFrance, SC, in cooperation with the U.S. Environmental Protection Agency, the U.S. Department of Energy, and the U.S. Department of Interior, is involved in a project coupling a full-scale hyperfiltration (HF) system with a pro- duction dye range: the objective is demon- strating the practicality of HF in recycling both hot renovated water and reconstituted dye formulations from dye wash water. The technical studies leading to this de- monstration project have been reviewed, and the progress of the project through the design phase has been reported. The equipment has been in operation for over 12 months, and recycled water is now used routinely. Laboratory tests of the dye and auxiliary chemicals reused have been completed, and an initial full-scale reuse of chemicals has been tested. The reuse of dyes and chemicals will be further studied during the extension of this project (April 1982 through September 1983). The project period covered by this report is April 1979 through April 1982. Range Process and Effluent Characteristics The subject range is used for dyeing, bleaching, and scouring a variety of velour fabrics. It consists of a dye applicator, spiral atmospheric steamer, and a washing section (Figure 1). The washing section contains, in sequence, a jet washer, a dip ------- Plant Water Supply Permeate Dye Solution ! To Drain + 1 t \-' To Surge Tank Figure 1. Continuous dye range schematic. box. and two Rotojet* washers. The range operates 3 shifts per day, 5 to 7 days per week, controlled at speeds of 9 to 36 m/min, depending on the product Cotton, acrylic, nylon, rayon, and polyester fabrics, and their blends are processed. Although several classes of dyes are used (direct, basic, disperse, acid, and reactive), and the wash water effluent components vary in dye type and concen- tration, the types of auxiliary chemicals are common to all wash water effluents from the dyeing operations. The dye formula- tions contain dyes, a thickener, surfactants, and in some cases dye solvents. While about 85 percent of the dyes are exhausted on the fabric, the remaining dyes and most of the auxiliary chemicals are removed by the washing process. Analyses of com- posite effluents from the dye pad applicator and the plant tap water are presented in Table 1. Table 1 also shows representative con- centrations and flow from the washing section. An important part of the project was the successful reduction of the flow rate of wash water through the range by converting to counterftow and using higher temperatures. The resulting wash water flow was reduced from about 400 m3/d (75 gpm) to 190 m3/d (35 gpm) without loss of washing effectiveness. Recovery Process The recovery system and its interaction with the dye range is shown in Figure 2. The wash water is collected continuously from the range. Despite the lapse of time between production lots for cleaning the equipment and filling the dye pad, the water flow is continued to reduce the color in the water in the washers (by about 30 percent). A production lot can be treated in the HF system as a "batch" which contains chemicals from a single dye for- mulation, when knowledge of the compo- sition is important to the reuse or disposal of the chemicals. The washing section effluents (HF sup- ply) are usually highly colored, and removal of 97 percent of the dyes is considered necessary to avoid possible staining of the fabric subjected to recycle water. The auxiliary components must also be re- moved sufficiently to provide wash water with concentration differences suitable for effectively washing the fabric. The concentrate produced by the HF unit contains dye concentrations much lower than those in the dye pad solution, but comparable concentrations of auxiliary chemicals. Based on pilot studies, reuse of the HF concentrates in dye formulation is feasible with about 75 percent savings in auxiliary chemicals and about 10-20 percent savings in dyes, depending on the dye class. Effective reuse of the residual dyes and auxiliary chemicals in the HF concentrate depends on the ability to add dyes to achieve the required shade, hue, and crocking characteristics needed in production. Reuse of the HF concentrate can be enhanced by judicious scheduling of dyeing lots, as to shade and dye class as well as by employing the experimentally determined guideline of using only 25 percent of the auxiliary components in each reuse dye formulation. To this end, Table 1. Chemical Characteristics of the Dye Flange Effluent Average Concentration or Flow Assay Flow, l/min. BOD, mg/l COD. mg/l Conductivity, \unS/cm Alkalinity , mg/l Color, ADMI Hardness, mg/l pH Phenols, mg/l TOG mg/l Total Solids, mg/l Suspended Solids, mg/l Dissolved Solids, mg/l Chromium, mg/l Copper, mg/l Iron, mg/l Manganese, mg/l Nickle, mg/l Zinc, mg/l Magnesium, mg/l Calcium, mg/l Dye Pad 12-35" 5,400 23,900 1580-28,000° 4,150 98,800 —C 3.6-10.9° 0.84 6,250 20,900 1,730 19,200 5.3 19.2 2.8 0.2 0.1 2.7 10.4 7.4 Composite3 Effluent 138 200 1,200 200-2,000 180 1,750 30 5.0-10.5 _d 325 1,140 45 1,100 0.2 0.2 0.63 0.1 0.007 0.25 8.5 3.5 Tap Water - - 9 90 - — 9 7.05 - — 60 3 57 0.002 - 0.022 - - — 1.00 2.36 (*) Tradename, Binks Manufacturing Co., Franklin Park, IL "Representative values based on measurements at various flow rates of wash water. bDye pad flow depends on cloth pickup. Pad drops are added directly to the HF concentrate without going through the HF unit °Values were estimated without averaging. ''Sample color interferes with analytical procedure. ------- Permeate Plant Water I \Dye Pad o Steamer "------- additive to match the desired shade for each lot No auxiliary chemicals were added, and more dye was used than the original formulation called for. The final shade for both lots was slightly dark, indicating perhaps too much dye was added The techniques and production procedures for reuse of recovery system concentrate will be developed during the extension phase of the project Figure 4 shows HF unit performance characteristics from data obtained shortly after the membranes were washed. With the HF unit in this unfouled condition, all the dye-range hot water requirements were supplied by the recovery system. As shown in Figure 4, the HF unit pressure profile is closely predicted by a mathe- matical model using the feed fluid char- acteristics and inlet and outlet flows to predict the HF unit performance. As the unit becomes fouled, the inlet fluid pres- sure increases until an upper limit is reached and the inlet fluid bypass opens. Extensive membrane fouling has been experienced. In attempts to remove the various foulants, washing has involved the use of detergents and emulsifiers to re- move silicones (antifoams), enzymes to remove carbohydrates (undissolved guar gum, the dye thickener), acetic acid and citric acid at pH = 4 to remove hard water scaling, and dye solvents to remove de- posited dye particles and precipitates of the reaction of basic and direct dyes. Membrane cleaning frequencies and meth- ods are continuing to be studied. The proper design capacity of the unit would permit completely closed cycle op- eration; in fact production of the HF unit has equaled 1 50 percent of the range water requirements immediately after each cleaning of the membranes. Membrane fouling, however, has limited the average production of the HF unit to about 60 percent of the capacity required for a complete closed cycle operation. The problem of membrane fouling, which will continue to be investigated during the extension of the project may be solved by one or more of three approaches: (1) modification of frequency and duration of cleaning, (2) modifications of present methods of removing membrane foulants, using various cleaning agents not now used, and (3) substitution for chemicals and components currently used in dyeing to avoid or reduce membrane fouling. Economics The evaluation of the HF process included an analysis of its economics. HF is a technology that effects pollution control by recycle and recovery. Capital (including 1000 900 800 700 600 S 500 i£ 400 300 200 100 41 gpm. Supply Flow 5 gpm Concentrate Flow Measured Model Temperature = 88°C Total System Length \ I 1 250 500 750 Flow Path Length, meters 1000 Figure 4. Single pass membrane unit pressure profile as a function of membrane length. installation) and operating costs (including membrane maintenance) are shown in Table 2. Savings from recycle of energy, chemicals, and water and the reduction of waste treatment or disposal costs depend on the specific conditions at any site. In Table 2, the potential savings at LaFrance, when chemical recovery is implemented and membrane washing procedures are better developed to maintain 100 percent unit capacity, result in a payout time of 3.3 years. Even shorter payout periods can be expected in industrial situations where expensive chemicals can be recovered and high water and waste treatment costs can be avoided Conclusions For 12 months a production size HF unit has been integrated with a manufacturing dye range resulting in the full scale recycle of hot wash water from a dynamic mem- brane HF system. The results have demon- strated satisfactory use of permeate re- covered from all types of effluents from this multi-purpose range. Although per- meate is always used when available, because of membrane fouling its availa- bility has been limited to about 60 percent of the production. Full-scale use of the HF concentrate to formulate solutions for dyeing has been demonstrated in selected cases. The eventual extent of such reuse of HF concentrate will depend on experience and the economic incentive. Throughout the 12 months of demonstration, the membranes remained stable with respect to rejection. It has been demonstrated that stainless steel tube bundles may be used in reforming membranes after several months of exposure to wash water. Mem- brane cleaning and foulant removal pro- cedures will be developed during the ex- tended evaluation period. No buildup of solute components was observed in the permeate during a continuous recycle run of 4 hours; thus the expected normal continuous recycle period of 8 to 24 hours should not be limited by component build- up. The capital and operating costs of HF were documented. The payout time for the capital cost of this demonstration will be 3.3 years (after taxes) (Table 2) when the full potential for reuse is achieved. Where there are simultaneous benefits for 4 ------- water, energy, and chemical recovery and/ or where significant waste treatment costs can be abated by reuse/or by volume reduction of pollutants, HF will yield an even shorter payout time. Recommendations The results of the demonstration project can be enhanced by further study to in- crease chemical reuse and to improve performance of the hyperfiltration unit. Extending this project will permit this full-scale installation to be used to: con- tinue full-scale reuse testing of HF con- centrates; continue documentation of the operation, including savings, for an addi- tional 12 months: and study membrane fouling and develop better cleaning pro- cedures. A goal of the fu rther study of the reuse of HF concentrate could be demonstration through full-scale implementation with selected production lots, including: pro- duction scheduling, color matching tech- niques, and reuse of HF concentrate con- sisting of mixtures from several produc- tion dye lots. Reuse of 100 percent of HF concentrate will probably never be practical. This full- scale production unit could be used to further study the disposal of H F concentrate, a new form of industrial effluent The disposal of HF concentrate, because of the small volume and high concentration, may be amenable to disposal by chemical pro- cessing, not normally considered for waste treatment The applicability of the results of this demonstration of high temperature dy- namically formed HF membranes on reus- able porous stainless steel tubes can be extended to many industrial situations. Sintered metal tubing can be widely applied to hot, corrosive, and dirt-laden industrial effluents. The dynamic technique of mem- brane formation is inherently versatile, permitting in-situ membrane replacement and the use of a wide variety of membrane materials selected for specific separation requirements. Research in membrane tailoring for selected important industrial categories would also be valuable. Table 2. Summary of Economics for Lafranee Present Potential Capital Costs, $HF unit Installation Total Operating Costs,$/yr Membrane Maintenance Operator, Maintenance, Overhead Total $300,000 184,000$484,000 $20,000 39,000$ 59,000 $300,000 184,000$484,000 $20,000 39,000$ 59,000 Savings, $/yr Overhead Energy Water and Treatment Chemicals Total Return on Original Investment % Internal Rate of Return, % Payout Time, yr$ 13,000 45,400 6,900 25,000 $90,300 -0- -0- 12$ 13,000 125.000 20,000 130,000 $288,000 20 24 3.3 Craig A. Brandon is with Carre, Inc., Seneca, SC 29678. Robert V. Hendricks is the EPA Project Officer (see below). The complete report, entitled "Closed-Cycle Textile Dyeing: Full-Scale Hyper- filtration Demonstration," (Order No. PB 83-193219; Cost:$13.00, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Industrial Environmental Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 ------- United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 Postage and Fees Paid Environmental Protection Agency EPA 335 Official Business Penalty for Private Use \$300 Css AGENCY CHICAGO IL 60&04 -------