Industrial Environmental Management. Tapas K. Das

Figure 1.7 Metals‐specific Sherwood plot for waste streams: minimum concentration of metal wastes undergoing recycling versus metal prices.

      Source: From Johnson et al. (2007). American Chemical Society.

Figure 1.8 A Sherwood diagram showing the correlation between the selling price of materials and their degree of dilution in the matrix from which they are separated.

      1.11.3 Investment Recovery

      During the transition to Zero Emissions, another early need will be for companies to fill the “decomposer niche,” a term for a specialized form of recycling developed by Raymond Cote at Dalhousie University in Ottawa (1995). Just as decomposer organisms turn dead animals and vegetable matter into forms that can become food for other animals and plants, decomposer niche companies will “consume” otherwise unusable wastes by processing them into usable feedstock or disassembling equipment and marketing reusable components and materials.

      The work of decomposers also can be visualized as investment recovery. Taking a systematic approach to ending waste, investment recovery is a traditional service, according to Cote, “an integrated business process that identified, for redeployment, recycling, or remarketing, nonproductive assets generated in the normal course of business.” These assets include idle, obsolete, unused, or inoperable equipment, machinery, or facilities; excess raw materials, operating inventories, and supplies; construction debris; equipment and fixtures in facilities scheduled for demolition; off‐grade, out of specification, or discontinued products; and process waste (Cote 1995, 2003).

      The goal of investment recovery is to develop strategies and procedures to recapture the highest value from all surplus assets in a company or community. It seeks to reduce operating and disposal costs, prevent disposal of assets as waste, and find markets for redistributing the by‐products for increased economic value. One of the operating paradigms for an investment recovery firm would be integration of its functions into a comprehensive strategy for an eco‐industrial park. Firms that specialize in this work base their fees on a retainer plus a percent of savings and/or revenues if there is an incentive.

      1.11.4 New Technologies and Materials

      During transitional stages, existing industries can be identified as potential members of a cluster if minimal design engineering can make them compatible and most of the transfers of materials are occurring in a more basic commodity form, rather than as “designer wastes.” Once Zero Emissions has been incorporated at the drawing board level, facilities can be planned to work together in clusters so that the by‐products of each enterprise meet the feedstock specifications of other industries in the cluster. This will require innovations in materials and methods alike.

      1.11.4.1 New, Less Toxic Chemicals and Materials

Examples of new materials include biopolymers, fiber‐reinforced composites, high‐performance ceramics, and extra‐strength concrete. To meet basic environmental requirements, new materials will be biodegradable, nonpolluting, recyclable or convertible; made from renewable resources; have low energy requirements in production and use; and provide a final product with greater strength and durability and lower weight and volume.

      Mini‐Case Study 1.2 DaimlerChrysler's ZD Wastewater Treatment Plant in Mexico

      DaimlerChrysler's production complex in Toluca, Mexico, home of the Chrysler PT Cruiser, has received much attention not only because of its in‐demand product but also because of its state‐of‐the‐art ZD wastewater treatment plant (WWTP). Located 37 miles north of Mexico City, Toluca suffered for years from a worsening water shortage due to urban sprawl, regional drought, and increased industrial activity. The city is one of the leading producers of beverages, textiles, and automobiles in Mexico, as well as a center for food processing.

      DaimlerChrysler, one of Mexico's largest manufacturers, mindful of the mounting strain on the world's natural resources, has consistently sought ways to decrease operational waste, reduce costs, and increase process efficiencies. Upon locating in Mexico, the automaker began to study the region's rapidly dropping aquifer, hoping to minimize the stress on this valuable resource, yet keep its operations in compliance with the federal government's water quality standards.

      In 1999, the company hit upon a solution. It would build its own $17 million WWTP that would treat sanitary and manufacturing‐process water generated by the facility's four separate plants – engine, transmission, stamping, and assembly. And to make this WWTP truly state of the art, a comprehensive zero liquid discharge (ZLD) system would be installed. By using a ZLD system, the Toluca complex would avoid further depleting the local aquifer, the environmentally friendly and cost‐efficient system would discharge no process water, but rather would recycle it to use throughout the facility. It was projected that implementing a ZLD solution and thus reusing water could extend the facility's life without disrupting production and causing costly overhauls.

      1.11.4.2 Improved Processes

      Consultants can help managers cut costs and create new values by instituting real‐time monitoring and eliminating inefficiencies in the use of resources all along a product's life cycle. These inefficiencies include incomplete utilization of material and energy resources, poor process controls, product defects, waste storage costs, discarded packaging, costs passed on to consumers for pollution or low energy efficiency, and the ultimate loss of resources through disposal and dissipative use. Poor resource productivity also can entail costs for waste disposal and regulatory penalties. Methods that are less energy‐intensive and more labor‐intensive are more sustainable environmentally and socially.

      1.11.5 New Mindset

      As a result of changes in materials and processes, engineering professionals will have to expand the purview of their design parameters. A larger, more integrated design for facilities and manufacturing processes is called for. This is where design for environment comes in: DFE examines the life cycle of the product and considers not only its primary use but the environmental consequences of its production, assembly, testing, servicing, and recycling. In designing an eco‐industrial park, for example, manufacturing processes would be linked to material flows and to energy flows. As a result, the design period and overall costs would be higher. Return on investment, however, would be much shorter (see Sections 7.3 and 7.3.1).

      1.11.5.1 System Design

      DaimlerChrysler put in operation ZLD systems of two kinds. The first uses reverse osmosis (RO) to produce a concentrate of total dissolved solids (TDS), which is sent to a large evaporator and eventually on to a lagoon or solar evaporator pond. Used in dry, arid areas of low elevation, this system is frequently found in the WWTPs of Northern Mexico's automotive facilities. The other system, used at the Toluca facility, softens and removes silica from the RO concentrate through microfiltration before sending the water on to another RO unit where it is further concentrated. Water is then returned and blended with the water from the first stage water, where the concentrate is sent on to either an evaporator or a crystallizer to dry TDS to powder and eliminate the need to dispose of liquid.

In essence, industrial plants with ZLD installations can expect to recover nearly 100% of water that would otherwise be discharged to the environment as wastewater. At the Toluca facility, the WWTP recovers 95% or more of the water used for processing, with a recovery rate of up to 237 500 gallons per