Figure 1.6 The interrelationship of sources, systems, and sinks for a cyclic (Zero Emissions) materials use pattern.

1.9 The New Role of Process Engineers and Engineering Firms

      Chemical process and product design engineers, environmental engineers, and consulting engineering firms can play a pivotal role as industries move toward the Zero Emissions or Zero Discharge paradigm, especially firms whose traditional niche has been to treat waste so that it is benign and acceptable for discharge. The role for these engineers in the twenty‐first century is to transform the effluent of one process to serve as the raw material for another process. The new role is not simply facilitating waste exchange; rather, the new jobs include the following:

      What this means for engineering firms is the need for a broader set of engineering skills and services. As can be seen, consulting engineering firms will find that achieving Zero Emissions entails expertise in areas that have not been part of engineering curriculum, or the professional engineer's exam.

      Zero Emissions engineers need to be not only well trained in design for the environment, concurrent engineering, and industrial engineering but also be able to think and design outside the traditional boundaries of the factory to work in terms of industrial clusters.

Many of the skills and services enumerated above would be applicable to the development of an agro‐industrial cluster such as the one in Namibia, described in Mini‐Case Study 1.1.

Mini‐Case Study 1.1 Beer to Mushrooms: Focusing on the Productivity of Raw Materials

      In the town of Tsumeb in the African desert, Namibian nationals will be implementing Zero Emissions technology at a brewery inaugurated in January of 1997. The three main inputs into beer – grain, water, and energy – are scarce commodities in a developing nation. Brewing uses only 8–10% of the nutrients in grain, consumes 10 L of water for every liter of beer produced, and generally requires imported coal, an expensive and polluting energy source.

      The lignin‐cellulose component of spent grain, which makes up 70–80% of its bulk, is indigestible to cattle, but it is easily broken down by the enzymes of mushrooms. It takes 4 T of spent grain to produce 1 T of mushrooms, which are a potentially lucrative cash crop for export, because most southern African nations currently import mushrooms. The protein content of the spent grain – up to 26% – is used by earthworms, which in turn are fed to chickens and pigs. Processing the waste from the animals in a digester could supply all of the vapor energy required for brewing. Brewery wastewater is high in nutrients but is too alkaline for crops. However, it can be used to grow spirulina, which generate up to 70% protein.

      The brewery's thermal waste could heat greenhouses or the brewery. These interrelated industries will form an optimal industrial cluster for increasing the productivity of the brewery's raw materials in ways that also produce food for humans that is high in nutritional value.

1.10 Zero Discharge (Emissions) Methodology

      Over the last few years, the members of zero discharge communities and industries have developed a five‐step methodology for implementing Zero Emissions. Pauli's Breakthroughs (1996) provides a far more comprehensive approach that extends well beyond the manufacturing site. The summary provided here emphasizes the use and impact of a ZD approach at the manufacturing level.

      1.10.1 Analyze Throughput

      The first step toward achieving Zero Discharge and/or Zero Emissions is an in‐depth review of the industry to see if total throughput is possible. This means determining whether all material inputs can be found in the final product – if there are no wastes, all inputs must have ended up in the product. One of the few industries where this can occur is cement manufacturing. In the Mini‐Case Study 1.1, however, only a small fraction of the nutrients in the grain ends up in beer.

      If throughput is not total, the next step is to determine whether the products manufactured can be easily reintegrated into the ecosystem without additional costs for processing, energy, or transportation. However, since this is rarely possible, most industries will not achieve Zero Discharge unilaterally.

      Process and product design engineers will probably find their first opportunities by meeting with their traditional clients, analyzing each client's throughput, and looking for opportunities for pollution prevention and waste minimization that the client's in‐house experts may not have seen. The analysis would include evaluating products and services presently being produced, processes and materials used, and management of environmental issues including energy efficiency, as well as clarifying the full scope of emissions.

      1.10.2 Inventory Inputs and Outputs

      Once the initial analysis has determined that total throughput is not possible, and that wastes will be generated, the next step is to assess the industry's inputs and outputs, and to inventory all the outputs (“wastes”). A diagram of the inputs and outputs of a system like that of Figures