Industrial Waste

Industrial wastes are the wastes produced by industrial activities which include materials that are rendered useless during manufacturing processes such as that of factories, industries, mills, and mining operations. This has existed since the start of the Industrial Revolution. Some examples of industrial wastes and sources are chemicals and allied products, solvents, pigments, sludge, metals, ash, paints, furniture and fixtures, paper and allied products, plastics, rubber, leather, textile mill products, petroleum refining and related industries, electronic equipment and components, industrial by‐products, metals, radioactive wastes, miscellaneous manufacturing industries, and the list goes on. Hazardous or toxic wastes, chemical waste, industrial solid waste, and municipal solid waste are also designations of industrial wastes.

More than 12 billion T of industrial wastes are generated annually in the United States alone. This is roughly equivalent to more than 40 T of waste for every man, woman, and a child in the United States. The sheer magnitude of these numbers is cause for big environmental concern and drives us to identify the characteristics of the wastes, the various industrial operations that are generating the waste, the manner in which the waste are being managed, and the industrial pollution prevention policy and strategies. The first portion of this chapter is devoted to pollution prevention hierarchy. Next there is an overview of how life cycle assessment (LCA) tools can be applied to choose best available technologies (BACT) to minimize the waste at various stages of manufacturing processes of products. Finally, a few case studies on industrial competitive processes and products applying LCA tools are reviewed; hence, selections of BACT to demonstrate hierarch pollution prevention (P²) and environmental performance strategies.

Waste as Pollution

A waste is defined as an unwanted by‐product or damaged, defective, or superfluous material of a manufacturing process. Most often, in its current state, it has or is perceived to have no value. It may or may not be harmful or toxic if released to the environment. Pollution is any release of waste to environment (i.e. any routine or accidental emission, effluent, spill, discharge, or disposal to the air, land or water) that contaminates or degrades the environment. Waste is a form of inefficiency, and an “economic system cannot be considered efficient, or ultimately competitive, if it generates waste” (Pauli 1996).

Pollution Prevention in Industries

Pollution prevention (P²) reduces the amount of pollution generated by industries, agriculture, or consumers. In contrast to pollution control strategies, which seek to manage a pollutant after it is produced and to reduce its impact on the environment, the pollution prevention approach seeks to increase efficiency of a process, reducing the amount of pollution generated. Although there is wide agreement that source reduction is the preferred strategy, some professionals also use the term pollution prevention.

With increasing human population, pollution has become a great concern. The US Environmental Protection Agency (EPA) works to introduce pollution prevention programs to reduce and manage waste (USEPA 1992a). Reducing and managing pollution may decrease the number of deaths and illnesses from pollution‐related diseases. As an environmental management strategy, pollution prevention shares many attributes with cleaner production, a term used more commonly outside the United States. Pollution prevention encompasses more specialized subdisciplines, including green chemistry and green design (also known as environmentally conscious design).

We define industrial pollution prevention fairly broadly as any action that prevents the release of harmful materials to the environment. This definition manifests itself in the form of a pollution prevention hierarchy, with safe disposal forms at the base of the pyramid and minimizing the generation of waste at the source at the peak (Figure 6.1).

In contrast, the USEPA definition of pollution prevention recognizes only source reduction, which encompasses only the upper two tiers in the hierarchy – minimize generation and minimize introduction (USEPA 1992a). The EPA describes the seven‐level hierarchy of Figure 6.1 as “environment management options.” The European Community, on the other hand, includes the entire hierarchy in its definition of pollution prevention. The tiers in the pollution prevention hierarchy are broadly described as follows:

• Sources reduction. Reduce to a minimum the formation of nonsalable by‐products in chemical reaction steps and waste constituents (such as tars, fines, etc.) in all chemical and physical separation steps and cut and down as much as possible on the amounts of process materials that pass through the system unreacted or are transformed to make waste. This implies minimizing the introduction of materials that are not essential ingredients in making the final product. For examples, plant designers can decide not to use water as a solvent when one of the reactants, intermediates, or products could serve the same function, or they can add air as an oxygen source, heat sink, diluent, or conveying gas instead of large volumes of nitrogen.
• Reuse. Avoid combining waste streams together with no consideration to the impact on toxicity or the cost of treatment. It may make sense to segregate a low‐volume, high‐toxicity wastewater stream from high‐volume, low‐toxicity wastewater streams. Examine each waste stream at the source and identify any that might be reused in the process or transformed or reclassified as valuable coproducts.Figure 6.1 Environmental protection hierarchy.
• Recycling. It is the process of converting waste materials into new materials and objects. It is an alternative to “conventional” waste disposal that can save material and help lower greenhouse gas (GHG) emissions. Recycling can prevent the waste of potentially useful materials and reduce the consumption of fresh raw materials, thereby reducing energy usage, air pollution (from incineration), and water pollution (from landfilling).Recycling is a key component of modern waste reduction and is the third component of the “Reduce, Reuse, and Recycle” waste hierarchy (Lienig and Bruemmer 2017). Thus, recycling aims at environmental sustainability by substituting raw material inputs into and redirecting waste outputs out of the economic system (Geissdoerfer et al. 2017).There are some ISO standards related to recycling such as ISO 15270:2008 for plastics waste and ISO 14001:2004 for environmental management control of recycling practice. Materials to be recycled are either brought to a collection center or picked up from the curbside, then sorted, cleaned, and reprocessed into new materials destined for manufacturing.In the strictest sense, recycling of a material would produce a fresh supply of the same material – for example, used office paper would be converted into new office paper or used polystyrene foam into new polystyrene. However, this is often difficult or too expensive (compared with producing the same product from raw materials or other sources), so “recycling” of many products or materials involves their reuse in producing different materials (e.g. paperboard) instead. Another form of recycling is the salvage of certain materials from complex products, either due to their intrinsic value (such as lead from car batteries, or gold from circuit boards) or due to their hazardous nature (e.g. removal and reuse of mercury from thermometers and thermostats).
• Recover energy value in waste. As a last resort, spent organic liquids, gaseous streams containing volatile organic compounds, and hydrogen gas can be burned for their fuel value. Often the value of energy and resources required to make the original compounds is much greater than that which can be recovered by burning the waste streams for their fuel value (also see in Figure G.1).
• Treat for discharge. Before any waste stream is discharged to the environment, measure should be taken to lower its toxicity, turbidity, global warming potential, pathogen content, and so on. Examples include biological wastewater treatment, carbon adsorption, filtration, and chemical oxidation.
• Safe disposal. Render waste streams completely harmless so that they do not adversely impact the environment. In this book, we define this as total conversion of waste constituents to carbon dioxide, water, and nontoxic minerals. An example would be post treatment of a wastewater treatment plant effluent in a private wetland. So‐called secure landfills do not fall within this category unless the waste is totally encapsulated in granite.
• Incineration. It is a disposal method in which solid organic wastes are subjected to combustion so as to convert them into residue and gaseous products. This process reduces the volumes of solid waste by 80–95%. Incineration and other high temperature waste treatment systems are sometimes described as “thermal treatment.” Incinerators convert waste materials into heat, gas, steam, and ash. Incineration is carried out both on a small scale by individuals and on a large scale by industry. It is used to dispose of solid, liquid, and gaseous waste. It is recognized as a practical method of disposing of certain hazardous waste materials (such as biological medical waste). Incineration is a controversial method of waste disposal, due to issues such as emission of gaseous pollutants.Incineration is common in countries such as Japan where land is more scarce, as the facilities generally do not require as much area as landfills. Waste‐to‐energy or energy‐from‐waste (see Appendix G) are broad terms for facilities that burn waste in a furnace or boiler to generate heat, steam, or electricity. Combustion in an incinerator is not always perfect and there have been concerns about pollutants in gaseous emissions from incinerator stacks. Particular concern has focused on some very persistent organic compounds, such as dioxins, furans, and PAHs, which may be created and which may have serious environmental consequences.

Defining Process Pollution Prevention (P³)

The fundamentals and strategies of “process pollution prevention” (P³) is the simultaneous realization of further waste reduction (environmental impact) and improvement of production (economic incentive).

(6.1)

Any time a pound is reduced in waste stream it is likely that it would end up in a product (Eq. 6.1). The goal is a closed loop in the economic subsystem, so that wastes inevitably created by human activities do not escape to contaminate the environment. There is a demand for technologies to manage and convert today’s wastes into usable feedstocks to enhancing profitable pollution prevention. Chemical process design engineer and consulting firms will provide focal services to meet this demand through technology development, process intensification, system integration, and facility operation. Effective process and product stewardship requires designs that optimize performance throughout the entire life cycle. The next section would focus on process LCA, while similar concepts and tools are applied to desired product life cycles, highlighted with a few streamlined case studies.