Waste Minimization Techniques in Production Processes
Minimization Methods
Minimization techniques and procedures can vary significantly across production processes. They don’t necessarily require advanced technologies or large capital investments. Many techniques involve simple changes in material handling and good housekeeping practices.
Four Main Groups of Minimization Techniques
- Inventory Management
- Modification of Production Processes
- Volume Reduction
- Recycling and Recovery
Inventory Management
This involves establishing proper control of raw materials, intermediate products, finished goods, and associated waste streams at all stages of storage and handling.
Two Aspects of Inventory Management
a) Stock Control
This well-known industrial technique, recognized for its economic importance (e.g., “zero stock”), also offers significant benefits for waste minimization.
Good Practices Include:
- Purchasing only the necessary raw materials for a specific period.
- Using appropriate, preferably recyclable, packaging in the required size and volume.
- Establishing mechanisms to market expiring or obsolete commodities and products.
- Implementing quality control procedures for purchased products before acceptance.
- Thoroughly analyzing any new process, considering the compounds involved, with special emphasis on toxicity and lifespan.
b) Handling of Products and Raw Materials
The stages of production, transportation, and storage, where handling of products, raw materials, and finished or semi-finished goods occurs, can generate a high percentage of waste.
2. Changing Production Processes
The cheapest waste is the waste that is not generated. The same product can often be manufactured using different processes. The choice of process depends on several factors, such as initial investment, overall cost, and technology availability.
By considering the waste produced by different industrial processes, we can see that waste can be minimized without compromising product quality, either by choosing environmentally sound techniques or by modifying stages or procedures within the production process.
a) Changes in Products, Raw Materials, and Other Processes
To explore the application of these methods, it’s helpful to start from the beginning of the production process and question the necessity or desirability of the elements involved in a given product and its manufacturing. This critical view can reveal opportunities to minimize waste volume and toxicity through changes.
Example: Replacing solvent-based inks with organic water-based inks.
b) Improvements and Equipment Replacement
Installing new machinery and improving existing equipment almost always increases productivity, reduces energy consumption, and improves raw material utilization, resulting in less waste.
However, environmental aspects and costs must also be considered in these decisions. An economically attractive option might be technologically inferior, offering apparent savings but with a significant environmental impact and ultimately higher costs due to waste management.
Example: Sealing all units containing cleaning solvents.
c) Improved Operation and Maintenance Procedures
This is one of the most important and economical methods for waste reduction. It aims to prevent waste generation caused by human intervention or equipment defects and failures through precise maintenance, machinery development, and appropriate plant operations.
Volume Reduction
This section covers techniques for separating different waste types generated in a plant, particularly distinguishing recyclable or recoverable waste from that containing toxic and hazardous components.
Two Groups of Techniques for Reducing Special Waste Volume
a) Segregation at Source
This is one of the simplest and most economical minimization practices. It can be used with most waste types and usually requires minimal process changes.
b) Concentration
These techniques reduce waste volume through a process of concentration, usually by removing a non-hazardous component, such as water. Concentration methods include gravity and vacuum filtration, ultrafiltration, reverse osmosis, freeze-evaporation, filter presses, heat drying, and compaction.
Recycling and Recovery
After exhausting all waste reduction options, the best management alternative is to utilize the generated waste through recycling, either in the same process or another, within the same plant or another, or by recovering valuable residual materials.
a) Direct Use in Production Processes
In most cases, the best place for waste recycling is within the generating process itself. Slightly contaminated materials are good candidates for recycling.
Example: Synthetic Fibers: Recovery of cleaning solvents by distillation unit.
There’s a growing trend for suppliers to be responsible for recycling and managing waste from their products, such as packaging, expiring raw materials, and cleaning solvents. This can present additional business opportunities for suppliers.