This article throws light upon the four main techniques of waste reduction used in industries. The techniques are: 1. Inventory Management 2. Production-Process Modification 3. Volume Reduction 4. Recovery and Reuse.
Technique # 1. Inventory Management:
Proper control over the materials used in the manufacturing process is an important factor to reduce waste generation in industries. By reducing both the quantity of hazardous materials used in the process and the amount of excess raw materials in stock, the quantity of waste generated can be reduced.
This can be done in two ways i.e. establishing material-purchase review and control procedures and inventory tracking system.
Developing review procedures for all material purchased is the first step in establishing an inventory management program in industries. Procedures should require that all materials be approved prior to purchase. In the approval process all production materials are evaluated to examine whether they contain hazardous constituents and whether alternate non-hazardous materials are available.
Another inventory management procedure for waste reduction is to ensure that only the needed quantity of a material is ordered for. This will require the establishment of a strict inventory tracking system. Purchase procedure must be implemented which ensures that materials are ordered for only on an as-needed basis and that only the amount needed for a specific period of time is ordered for.
Technique # 2. Production-Process Modification:
In industries, changes can be made in the production process, which will reduce waste generation. This reduction can be accomplished by changing the materials used to finish the product or by more efficient use of input materials in the production process or both.
Potential waste minimization techniques can be divided into three categories:
(i) Improved operating and maintenance procedures,
(ii) Material change and
(iii) Process-equipment modification.
Improvement in the operation and maintenance of process equipment can result in significant waste reduction in industries. This can be accomplished by reviewing current operational procedures or lack of procedures and examination of the production process for ways to improve its efficiency.
Instituting standard operation procedures can optimise the use of raw materials in the production process and thus reduce the potential for materials to be lost through leakage and spill. A strict maintenance program, which stresses corrective maintenance, can reduce waste generation caused by equipment failure.
An employee-training program is a key element of any waste reduction program. Training should include correct operating and handling procedures, proper equipment use, recommended maintenance and inspection schedules, correct process control specifications and proper management of waste material.
Hazardous materials used in either a product formulation or a production process may be replaced with a less hazardous or non-hazardous material. This is a very widely used technique and is applicable to most manufacturing processes.
Implementation of this waste reduction technique may require only some minor process adjustments or it may require extensive new process equipment. For example, a circuit board manufacturer can replace solvent-based product with water-based flux and simultaneously replace solvent vapour degreaser with detergent part washer.
Installing more efficient process equipment or modifying existing equipment to take advantage of better production techniques can significantly reduce waste generation. New or updated equipment can use process materials more efficiently creating less waste.
Additionally such efficiency reduces the number of rejected or off-specification products, thereby reducing the amount of material which has to be reworked or disposed off. Modifying existing process equipment can be a very cost-effective method of reducing waste generation in industries.
In many cases the modification can just be relatively simple change in the way the materials are handled within the process to ensure that they are not wasted. For example, in many electronic manufacturing operations, which involve coating of a product, such as electroplating or painting, chemicals are used to strip off coating from rejected products so that they can be recoated.
These chemicals, which may include acids, caustics, cyanides etc. are often a hazardous waste and must be properly managed.
Technique # 3. Volume Reduction:
Volume reduction includes those techniques that remove the hazardous portion of a waste from a non-hazardous portion. These techniques are usually to reduce the volume, and thus the cost of disposing off a waste material. The techniques that can be used to reduce waste-stream volume can be divided into 2 general categories: source segregation and waste concentration.
Segregation of wastes is in many cases a simple and economical technique for waste reduction. Wastes containing different types of metals can be treated separately so that the metal value in the sludge can be recovered.
Concentration of a waste stream may increase the likelihood that the material can be recycled or reused. Methods include gravity and vacuum filtration, ultra filtration, reverse osmosis, freeze vaporization etc. For example, an electronic component manufacturer can use compaction equipment’s to reduce volume of waste cathode ray-tube.
Technique # 4. Recovery and Reuse:
This technique could eliminate waste disposal costs, reduce raw material costs and provide income from a salable waste. Waste can be recovered on-site, or at an off-site recovery facility, or through inter industry exchange.
A number of physical and chemical techniques are available to reclaim a waste material such as reverse osmosis, electrolysis, condensation, electrolytic recovery, filtration, centrifugation etc. For example, a printed-circuit board manufacturer can use electrolytic recovery to reclaim metals from copper and tin-lead plating bath.
However, recycling of hazardous products has little environmental benefit if it simply moves the hazards into secondary products that eventually have to be disposed off. Unless the goal is to redesign the product to use nonhazardous materials, such recycling is a false solution.
Sustainable Product Design:
Minimization of hazardous wastes should be at product design stage itself keeping in mind the following factors.
i. Rethink the product design:
Efforts should be made to design a product with fewer amounts of hazardous materials. For example, the efforts to reduce material use are reflected in some new computer designs that are flatter, lighter and more integrated. Other companies propose centralized network similar to the telephone system.
ii. Use of renewable materials and energy:
Bio-based plastics are plastics made with plant-based chemicals or plant-produced polymers rather than from petrochemicals. Bio-based toners, glues and inks are used more frequently. Solar computers also exist but they are currently very expensive.
iii. Use of non-renewable materials that are safer:
Because many of the materials used are non-renewable, designers could ensure that the product is built for re-use, repair and/or upgradeability. Some computer manufacturers such as Dell and Gateway lease out their products thereby ensuring they get them back to further upgrade and lease out again.
One of the major challenges is recycling the printed circuit boards from the electronic wastes. The circuit boards contain such precious metals as gold, silver, platinum, etc. and such base metals as copper, iron, aluminum, etc. One way the e-waste is processed is by melting circuit boards, burning cable sheathing to recover copper wire and open- pit acid leaching for separating metals of value.