Industrial Environmental Management. Tapas K. Das
Toluca facility is two separate systems: a sanitary water system that biologically treats wastewater from the complex's restrooms, showers, cafeterias, and other domestic areas, and a manufacturing‐process water system that chemically treats wastewater mixed with heavy metals and paint from the assembly plant. The latter also treats wastewater containing emulsified and soluble oils from the facility's stamping, transmission, and engine plants.
In the sanitary water system, domestic water is collected and sent through a screening mechanism before moving on to the biological treatment system's equalization tank, ensuring a constant, even flow of water through the system. This water is then passed through jet aeration sequential batch reactors that treat the water with microorganisms and air to reduce the biological oxygen demand (BOD) and chemical oxygen demands (COD), as well as suspended solids. The complex uses the 150 000–200 000 gpd of disinfected water to irrigate its landscape. The microorganisms and solids recovered from the batch reactors are then sent through a sludge digester and eventually a filter press that eliminates the water. While the dewatered sludge is used as fertilizer, the filtered water re‐enters the system.
Wastewater from the Toluca facility's three machining plants is directed through the manufacturing‐process system where it is first chemically treated, passing through a filtering screen. In a separate tank, chemicals are used to de‐emulsify the free‐floating oils that comprise most of the waste. Afterward, the oils are removed and stored in another tank before disposal. The process water from the machining plants is then mixed with water from the assembly plant that contains residue from the spray painting, phosphating, E‐coating, and body‐wash operations. Upon being mixed with a combination of ferric chloride, lime and magnesium oxide, metal pollutants and silica are rendered insoluble and turned into sludge that is removed and sent to a landfill. Then, to further lower the proportion of unwanted organic compounds, the water is pumped to a biological system that reduces the BOD to 20–30 ppm.
1.11.5.2 Results
Since installing the wastewater recovery system, the Toluca facility has noted several benefits, including decreased production and operation costs, reduced aquifer use, better environmental friendliness, and greater employee safety (Zacerkowny 2002). Moreover, the integrated system helps preserve the environment, is safe for employees to work with, and provides almost 7000 jobs to local residents. The Toluca industrial complex uses approximately 250 000 gpd of water, recovering more than 95% of its processing water. The ZLD system allows the facility to treat more than 550 000 gpd, significantly reducing the amount of water that must be drawn from the local aquifer. Using treated water might also extend the life of the facility's equipment, as the salt content of the processed industrial water is much lower than that of the aquifer.
1.11.6 In the Full ZD (Emission) Paradigm
Designing ZD systems requires an expansion of the focus and outputs of the traditional design engineer. Concurrent engineers need to incorporate design for the environment. Industrial engineers need to think in terms of industrial clusters. Environmental engineers need to understand upstream processes better so that they can develop designer wastes. Environmental engineers also need to revamp their processes to begin mimicking resource refining.
ZD engineering firms are expected to be working with design for environment engineers, concurrent engineers, and industrial engineers. They should all be seeking to design wastes, conversion processes, and industrial clusters. Setting the stage for overall product design, the industrial ecology approach assists companies in looking beyond the product to its functionality over its life cycle. Services and products should be designed and delivered differently as the following six strategic elements of industrial ecology are applied:
Selection of materials with desired properties at the outset
Use of “just in time” materials
Substitution of processes to eliminate toxic feedstock
Modification of processes to contain, remove, and treat toxics in waste streams
Engineering of a robust and reliable process
Consideration of durability and end of life recyclability
ZD solutions that use conversion technologies should be developed, designed, built, and marketed by the appropriate professionals who understand not only the industrial clusters and the processes involved but also the upstream and downstream requirements.
1.11.6.1 Opening New Opportunities
As the ZD mission gains currency, new opportunities are revealed – to provide cost‐saving new design applications, to design new product lines, and to win new customers. These opportunities include the following:
Finding cost savings and new revenues in existing operations. Initial cost savings at existing operations should come from pollution prevention and waste minimization, which may already have been optimized. However, new revenues will come from identifying a viable market for the waste stream after it has been converted.
Entering new markets for existing goods and services. New markets will be entered when cluster partners are identified; for example, brewery specialists will expand into agricultural sectors. The market for handling “designer wastes” is expected to grow significantly, especially for firms specializing in reprocessing. Producers of a wide range of materials processing equipment such as grinding, sifting, sorting, purifying, separating, and packaging will find new markets. However, in some cases the conversion process will be handled by an intermediary company that will alter the wastes mechanically, chemically, or biologically to meet customer specifications.
Developing new technologies, processes, and materials. Many of the pollution control firms will begin partnering with the upstream commodity producers (e.g. petroleum, chemical, and mining companies) and learning their refining techniques.
Supporting the organizational changes, and technical and information needs of a Zero Emissions‐based economy. This will be a business opportunity primarily for those offering skills in informational and organizational systems.
Integrating technologies and methods into innovative new systems. As Zero Emissions expands, professionals from different sectors will connect to benefit from each other's skills and experience.
Developing the infrastructure for eco‐industrial parks. Requires equipment to channel the flow of materials, water, or heat between plants and communities. Civil engineering firms that specialize in urban design and infrastructure systems should find great opportunities in providing the integrated system designs.
1.11.6.2 Providing Return on Investment
A simple economic metric, return on investment (ROI) is a quick measure of when an item will pay for itself. The time between the initiation of an investment and the achievement of ROI is called the payback period. Pollution control technology, which is not traditionally viewed as an investment that is able to generate a return on investment, is usually measured in terms of lowest available cost to meet regulatory guidelines (see also Chapter 7). If wastes are viewed as materials, however, as in ZD, the whole picture changes. Some have joked about giving all materials produced in a facility a product name and an advertising budget and/discontinuing any “product” that does not sell.
Engineers have historically been compensated based on overall project cost. Incentives need to be shifted to designs that reduce material and energy flows. Compensation based on energy efficiency is being implemented in some projects and it is successful because energy efficiency can be measured in a single unit (joules of energy saved). While material flows are not as easy to quantify in a single unit, waste recovery systems can provide an excellent return on investment, as illustrated in Mini‐Case Study 1.3.