Caustic Recovery In Textile Industry

Caustic Recovery in the Textile Industry Introduction The textile industry uses substantial quantities of caustic (sodium hydroxide) to clean and prepare fabrics for dyeing. Caustic is expensive and its disposal may create a hazardous waste treatment problem. The contaminated dilute caustic from these processes is commonly concentrated and recovered by evaporation. However, evaporators cannot recover highly contaminated caustic. In the past, it had to be neutralized prior to disposal. Now, Du Pont membrane technology can recover highly contaminated caustic. By combining its experience in polymer research, membrane technology, and process engineering, Du Pont brings you customized solutions to your most pressing waste minimization, raw material recovery or liquid processing problems, including caustic recovery. A Du Pont Customized System Provides: n Cost savings Reduced waste caustic discharge Reduced purchased caustic requirements Reduced energy requirements n Process improvements Cleaned caustic for reuse Improved evaporator efficiency Reduced evaporator blowdown Waste treatment savings n Low capital investment q Low operating and maintenance costs n Custom designed turnkey system n Leasing/rental options n Worldwide marketing and technical support team n Performance guarantees* from Du Pont The System The Du Pont Separation Systems’ caustic recovery system is based on CARRE® patented filtration technology, which combines porous stainless steel tubing and state-of-the-art, formed-inplace membranes. For more than ten years, this technology has provided innovative raw material recovery systems for the textile industry that are durable and easy to maintain. A large-scale commercial installation has been operating for several years in caustic recovery at a major South Carolina textile finishing plant.

‘All prices are subject to change without notice and orders are accepted subject only to the prices and terms in effect at the time of order acceptance.

Membrane Contaminated Caustic Coating

Clean Caustic

How the System Works The contaminated caustic feed stream is pumped into one end of a membrane-lined porous stainless steel tube. Water and clean caustic will pass through the wall of the membrane-lined porous tube, where it is recovered for reuse. The concentrated contaminants flow out the other end of the tubing for further treatment or disposal.

Custom Designed to Your Needs Contaminated caustic from the scour saturator and/or the mercerizer range is fed to the membrane system. The membrane system filters and cleans up to 95% of the caustic feed stream while concentrating the contaminants. The clean caustic is recycled directly to the scouring and bleaching processes as well as to the dye house. Clean caustic also can be sent to evaporators for concentration and then reused in mercerization. The concentrated contaminants from the feed system are discharged to waste treatment.

ANNUAL SAVINGS AT VARIOUS CAUSTIC MARKET PRICES 600 500 Savings 400 x1000 300 200 20¢/lb

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SYSTEM SIZE (GPM)

This graph shows the potential savings achievable from reduced fresh caustic consumption and lower neutralization costs, less the caustic recovery system operating costs. The savings are shown for a range of caustic market prices and are for a system operating 6000 hours per year on a 6% caustic feed stream at a 95% recovery rate.

Evaluation of Your Feed Stream The Du Pont design team is available to work with you to analyze your needs. Together we will customdesign the optimal caustic recovery system for your plant. For a preliminary analysis of your process, please contact Separation Systems.

PVA RECOVERY COSTCOMPARISON* 4.0

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Supplier B

Recovery Rate = 2.4MM lbs/yr All costs unitized PVA Recovery Cost Comparison Du Pont systems are competitive/y priced and cost less to operate than other systems. This results from lower energy requirements and lower membrane replacement costs.

PAYBACK ON INVESTMENT

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SYSTEM SIZE (GPM) PVA concentrated from 4-10% Unit operated 6OOO hrs/yr Payback on Investment A DuPont PVA recovery system in many cases can pay for itself in less than one year. Larger systems are the most cost-effective. Payback calculations assume recycled PVA, on average, costs less than $.15/lb versus fresh PVA which can range from $.80-1.00/lb.

Evaluation of Your Feed Stream The Du Pont design team is available to work with you to analyze your needs. Together we will customdesign the optimal solution for your PVA recovery needs. For a preliminary analysis of your process, please contact Separation Systems.

Polyvinyl Alcohol Recovery in the Textile Industry Introduction PVA is applied as a size to the warp yarns prior to weaving to improve loom efficiencies. While sizing is necessary for textile processing, the PVA coating must be removed (the fabric must be desized) prior to subsequent bleaching or dyeing. Not only is PVA expensive, but disposal of the used solution also may require expensive waste treatment. However, Du Pont membrane technology can be used for economical reclamation and reuse of PVA. By combining its experience in polymer research, membrane technology and process engineering, Du Pont brings you customized solutions to your most pressing waste minimization, raw material recovery or liquid processing problems, including PVA recovery. A Du Pont Customized System Provides: n Cost savings Reduced waste PVA discharge Reduced purchased PVA requirements q Process improvements Waste treatment savings n Low capital investment n Low operating and maintenance costs n Custom designed turnkey system n Leasing/rental options n Worldwide marketing and technical support team n Performance guarantees*. from Du Pont The System Separation Systems’ PVA recovery system is based on CARRE® patented filtration technology, which combines porous stainless steel tubing and stateof-the-art, formed-in-place membranes. For more than ten years, CARRE® technology has provided innovative raw material recovery systems for the textile industry. This technology for PVA and other raw material recovery has proven to be durable and easy to maintain. Turnkey design provides easy installation.

‘All prices are subject to change without notice and orders are accepted subject only to the prices and terms in effect at the time of order acceptance.

Membrane Coating

Concentrate Permeate

The membrane device separates a liquid stream into two components; a stream concentrated in suspended or high-molecular-weight dissolved solids and a clean permeate stream.

How the System Works The dilute PVA stream from the desizing process is pumped into membrane-lined stainless steel porous tubes. Water and any existing low-molecular-weight contaminants (such as dissolved salts and oils) are drawn off through the membrane. The purified and concentrated PVA flows out the other end of the tubes. The water (permeate) will contain a very low level of PVA and can be reused or further processed for discharge. The concentrated PVA stream can be recycled to the slasher for size reuse.

Du Pont membrane system recovers waste from plating baths, reduces raw materials expenses Du Pont membrane systems, based on reverse osmosis (RO) technology, are being used to recover plating salts from five separate plating bath rinse streams at a leading sporting ammunition manufacturer. This process substantially reduces capital, raw material and waste treatment operating expenses. Supplied by Du Pont Separation Systems, a division of the Du Pont Company, systems such as these replaced a lime treatment process at the plant. In the lime process, lime was added to the used plating rinse water and combined with waste metals to form a sludge, which was deposited in two large impoundment lagoons. However, changes in EPA regulations made this type of treatment impractical. Use of the lagoons could continue only if extensive modifications were made. These include double lining each of the lagoons and installing expensive monitoring equipment to insure that none of the leachate escapes to the surrounding groundwater. In addition, the company would have to install double-walled piping from the plant to the lagoon, along with a separate, additional leachate monitoring system. The cost for all this amounted to several million dollars in capital equipment, as well as additional expenses for labor and operations. The company contacted Du Pont Separation Systems to see what options there were to minimize these expenses. Du Pont Separation Systems suggested the use of a hybrid membrane system based on RO. They performed an in-house treatability test on a synthetic waste solution to demonstrate

the design, Subsequent to this, the results were confirmed via on-site testing with a pilot system. Separation Systems installed full-scale closed-loop RO systems on the ammunition manufacturer’s plating line rinse streams. RO works by passing a liquid through a membrane to separate its various components. In desalination, where the process has been used for more than 15 years, RO separates pure water from saline solutions. In the plating rinse recovery application, RO separates process rinse water into two streams: pure water that can be refed to the rinse tanks and a highly concentrated plating salt solution that can be reused in the plating bath (see Figure 1). The new system is helping the company cut costs Continued on reverse side