Pollution scouring

Over time, finish components tend to separate and migrate within the fiber and throughout the yam package. With nylon, the ionic emulsifiers and antistats tend toward the core of the fiber whereas the hydrocarbon lubricants remain on the surface. It is, therefore, essential to scour yams and fabrics at neutral to basic pH to reemulsify the lubricant and remove the finish emulsifier prior to dyeiag. In formulating any new finish, environmental issues such as biodegradabihty, water and air pollution must be considered (137). 

An electrochemical system combining scouring, mercerising and bleaching has been proposed. It is a non-polluting method based on an electrochemical cell, the cathode of which produces the base to mercerise and bleach, whilst the anode produces an acid to neutralise the base remaining after mercerisation [321]. 

Scouring of wool is mainly done by detergent and solvent. The main components of wool scouring waste water are wool grease, suint and dirt and excrement. Table 13.13 shows the pollutant load of the wool scouring effluent. The detergent... 

Reinforced concrete road bridges are gradually deteriorating due to various adverse factors that may significantly influence their performance and safety. The main factors include chemical attacks (chlorides, atmospheric CO2, pollutants SO2 and NOj,), physical effects (frost, scouring), overloaded trucks, natural disasters (floods, extreme winds) and vandalism. It is recognised e.g. in COST 345 (2004) or by Rafiq et al. (2004) that deterioration of reinforced concrete... 

As the first step in the wet processing sequence, substrates are typically cleansed of contaminants that inhibit sorption or interfere with reaction of the processing solutions used for dyeing, printing, and finishing. A wide variety of contaminants are present in raw fibers [48], As the fiber is heated or scoured, these contaminants are liberated into water and air as pollutants. Due to the massive amounts of fibers used, impurities present even in trace quantities can be important pollutants. The total polyester/cotton fiber wastes (from all sources in the United States) is estimated to be 4.5 x 10 lb annually [31]. 

Mercerization is a process of treating cotton and cotton/polyester woven goods with 20% caustic solution under tension to enhance dyeability, appearance, and luster. The pollutant is wastewater of very high alkalinity or neutralization salts. This waste stream can be recycled through evaporative caustic reclamation systems, but that is rare in commerce. Another potential reuse strategy for this waste stream is scouring. 

Once the dyeing cycle is complete, the CO is gasified to recover the excess dye. Unburdened, the clean CO cycles back into the dyeing vessel for reuse, a manoeuvre that saves energy, water, and the heavy metals that comprise much of the toxic runoff into our planet s polluted waterways, according to DyeCoo. The process isn t without its limitations, however. DyeCoo is currently only able to dye scoured (or prewashed) polyester fabric, although the company notes that it s working on a version that will dye unscoured fabric, as well as reactive dyes for cellulosie textiles made from plants. 

Does not use boilers, screen printing machines, drying ovens, or cleaning and scouring chemicals, thereby eliminating major sources of pollution. Eliminates water in the color application step and simplifies the process, creating revolutionary possibilities of new industry and employment in unfarmable, arid regions of the world. 

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