This paper describes the methods and procedures of pollution prevention which have been applied in process industries with a case study of waste minimization in the textile industry. The waste minimization procedure developed by the United States Environmental Protection Agency (US EPA) was first used and later extended by additional steps which were found appropriate for use in process industries in order to obtain optimal waste minimization options. Mass and energy balances were produced, and the whole process was examined in a machine and piece dyeing mill. The analysis of steam distribution, steam utilization, and the condensate system was carried out. Several options for waste minimization were proposed and their implementation was able to decrease waste water production by 21%, consumption of dyes by 24%, textile auxiliaries and chemicals by 14%, and steam usage by 25%. The flue gas and greenhouse effect gases could also be reduced a great deal. The payback period of the proposed options is less than 1 year. Some practical improvements were introduced directly, while the implementation of other options depended on the financial ability of the factory. Some of them (good housekeeping and regular maintenance) will be introduced through the introduction of the Total Quality Management system.

An integral approach to waste minimization in process industries

A process for recycling and reconstituting flexographic inks from wash water resulting from cleaning the rollers and other components of a flexographic printing press. The process includes the steps of circulating the wash water through a cross-flow ultrafilter to separate an optically-clear filtrate from a first concentrate containing suspended ink solids, bacteria, and macromolecules. Thereafter, the filtrate is directed through a reverse-osmosis filter to separate from the filtrate a second concentrate containing dissolved ink components and the remaining bacteria. The first and second concentrates are then combined together with a compatible biocidal agent to form a stable, biologically-inactive additive that is mixed with fresh ink concentrate to form pressready flexographic printing ink.

Process for recycling and reconstituting flexographic inks

A process and apparatus are disclosed for separating an aqueous cleaner solution from contaminants that accumulate as the cleaner is used in washing manufactured objects, such as machine parts or printed circuit boards. In the separation process, filtration of contaminated aqueous cleaner solutions using a membrane of an appropriately chosen pore size removes oils, greases, fluxes, rosins and other emulsified or dispersed contaminants from the cleaners while permitting the molecules of the cleaner itself to stay in solution. The filtered cleaner solution is then recycled to the wash tank. Also disclosed are a process and apparatus for treating the rinse water used to rinse objects that are cleaned with the recycled cleaner.

Recycling and recovery of aqueous cleaner solutions

Recycling and recovery of aqueous cleaner solutions and treatment of associated rinse water

In the recycling of Nylon 6 and Nylon 6,6 polyamides from post-consumer or post-industrial waste, a process is disclosed to separate Nylon 6 and Nylon 6,6 polyamides from commingled polyolefin waste components, particularly polypropylene, by admixing the waste with an ester solvent composition and heating the admixture to a temperature above the melting temperature of the contained polyolefins to form an ester solvent composition further containing dissolved polyamide polymer and a separate immiscible liquid polyolefin phase. The ester solvent composition preferably contains ethylene carbonate, propylene carbonate, butylene carbonate, or mixtures thereof.

Separation of polyolefins from nylons

Process of treating waste water from a textile vat dyeing operation containing water, vat dyes, and dissolved and undissolved impurities including salts, lint, foreign matter, etc. to produce a concentrate suitable for direct reuse in the vat dyeing operation to conserve the use of dyes and water, as follows. Undissolved impurities of a predetermined particle size are filtered out. Thereafter, the waste water is concentrated and filtered down to a concentrate of a ratio of from about 30/1 to 200/1 while removing excess water and a substantial portion of the remaining impurities and retaining substantially all of the vat dyes and a desired amount of water. The latter step is preferably performed by circulating the waste water through a reverse osmosis filtration device, while separating the waste water into a permeate containing excess water an a substantial portion of the remaining impurities including salts and a concentrate containing substantially all of the vat dyes and a desired amount of water, and by removing the permeate and retaining the concentrate for use in the dyeing operation.

Process of treating waste water from a textile vat dyeing operation to produce a concentrate for reuse

OF THE DISCLOSUREProcess of treating waste water from a textile vat dyeing operation containing water, vat dyes, and dissolved and undissolved impurities including salts, lint, foreign matter, etc. to produce a concentrate suitable for direct reuse in the vat dyeing operation to conserve the use of dyes and water. Un-dissolved impurities of a predetermined particle size are filtered out. There-after, the waste water is concentrated to a ratio of from about 30/1 to 200/1 by circulating the waste water through a reverse osmosis filtration device, while separating the waste water into a permeate containing excess water and a substantial portion of the remaining impurities including salts and a concent-rate containing substantially all of the vat dyes and a desired amount of water, and by removing the permeate and retaining the concentrate for reuse in the dyeing operation.

Ernest A. Freeman

Papers

Process of treating waste water from a textile vat dyeing operation to produce a concentrate for reuse

Recovering dye by reverse osmosis through feed-built medium on a support