Anodizing solutions are not generally filtered on non-automated plants, although periodic batch filtration is desirable. Seal solutions benefit from continuous or bypass filtration, and may also require periodic carbon treatment to remove discolouration from the dyes used. A filtration system comprising a main filter element and an activated carbon chamber can provide continuous protection throughout […]
Alkaline soak-cleaning solutions and electro-cleaners generally accumulate considerable amounts of solids and organic contaminants, as well as floating scum. This last is normally removed by skimming. Solids can be removed by settlement when the plant is idle, followed by decanting (drawing off of) the fluid, and removal of the settled solids. Fluid itself is replaced […]
It is normal, in non-automated acid cleaning and pickling baths, for there to be no filtration of the solutions, the solid contaminants being allowed to settle out of suspension. Batch filtration can, however, substantially improve acids life and simplify waste treatment. A typical array of equipment used for pickling solution recycling is shown in Figure […]
A number of surface treating processes require a rinsing fluid, which dissolves salts produced in the process. It is possible to recover more than 80% of the salts in a rinsing fluid using electrodialysis equipment. This electrochemical process is particularly suitable for recovering salts of silver, copper, nickel and zinc. The method involves a large […]
Aqueous degreasing processes use alkaline or acid solutions containing chemicals and various additives. These baths become contaminated with oil and when the bath loses its efficiency, its contents have to be renewed, at a high cost, or the oil must be removed. A well tested method for oil removal is based on using CFCC (carbon […]
Manufactured metal parts and finished products may go through a whole series of surface treatment processes. These include chemical and electrochemical operations such as washing, pickling, degreasing, phosphating, galvanizing, plating, etc. as well as numerous rinsing stages. Considerable economies can result from effective filtration and clarification of the various fluids involved, and, in the case […]
Several applications for ultrafiltration and reverse osmosis are being employed in the textile industry. These include the treatment of size and latex contaminated effluents, wool wash waters and effluents from dying operations. The membrane processes are alternatives to the classical mechanical, biological, and physical-chemical processes, such as precipitation, flocculation, flotation and adsorption. An increasing use […]
Massive quantities of water are consumed in the pulp and paper industry. Water is used as the suspending liquid for the pulping process and the bleaching stages as well as for washing. As a result, large volumes of effluent water are produced that need to be filtered. Ultrafiltration processes have proved successful for the treatment […]
Process filtration in the manufacture of paints and inks includes the treatment of adhesives, resins, and process and wastewater, as well as paints, varnishes, inks and other coatings. Bag filters ( Figure 4.31) and bonded media filters are often used for highviscosity applications such as the removal of oversize particles from paints and inks. Cathodic […]
Filtration is normally called for prior to filling toiletry and cosmetic containers. Sheet filters are normally employed for this purpose. In this sector are commonly found applications for medium or fine clarification, involving eau-de-Cologne lotions, aftershave preparations, toilet waters, etc. (some of which are spirit based and some water based). Ultrafiltration is used, in the […]
