Chapter 3: Literature Review
Introduction
This chapter will review the existing literature on waste management practices in industrial settings. The purpose of this chapter is to develop understanding of current knowledge and research in this area in order to identify knowledge gaps and formulate clear research objectives and questions. The review will cover academic literature from a variety of relevant subject areas including environmental management, industrial engineering, green chemistry, and materials science. Government and industry reports will also be included to incorporate practical knowledge and case studies.
Waste Management Strategies in Industry
There are a variety of strategies that industries employ to manage waste generated from manufacturing processes. The most common approaches can be categorized as follows:
Reduce – Techniques focused on reducing the amount of waste generated at the source. This may involve process modifications, input material changes, improved material utilization, or recycling internally generated scrap/byproducts whenever possible (Klemeš et al., 2018).
Reuse – Reusing materials/components in their original form or with minor reprocessing rather than discarding them as waste. For example, reuse of wooden pallets and refillable containers (Greene et al., 2015).
Recycle – Collecting and processing waste materials so they can be incorporated as feedstock in new products. For example, recycling paper, plastics, metals and glass (Sarabia et al., 2019).
Co-Processing – Using waste as supplemental fuel or raw material substitute in an unrelated industrial process like cement production or mining. For example, using waste oil as fuel in cement kilns (Bourtsalas et al., 2019).
Disposal – Landfilling, incineration or controlled dumping of waste that cannot be prevented, minimized, reused or recycled. These are considered last resort options due to negative environmental impacts (Ren et al., 2018).
Regulations play a key role by discouraging landfilling/incineration and mandating waste prevention, recycling and reuse. Industries consequently focus on the higher strategies of reducing waste at source and maximizing internal recycling to save on disposal/compliance costs (Koroneos et al., 2005). There remain technological and economic challenges in eliminating all waste from production altogether.
Waste Management in Specific Industrial Sectors
This section will summarize waste management approaches adopted across various industrial sectors based on their typical processes and output materials.
Manufacturing – Integrated waste exchange programs within industrial parks facilitate reuse of byproducts between manufacturers. Metalworking waste is commonly recycled. Difficult-to-handle wastes like oils, solvents and sludges are often sent for coprocessing or regulated disposal. New technologies explore integrating green chemistry and design for environment principles (Giannoulis et al., 2017).
Chemicals – Hazardous liquid and solid wastes necessitate treatment/containment. Wastewater is rigorously treated onsite or sent to municipal plants. Solvent recovery systems minimize emissions. Byproducts are evaluated for potential reuse as fertilizers, fuels or feedstocks. Intensifying recycling reduces use of raw materials and virgin fossil fuels (Shen et al., 2009).
Food/Beverage – High volumes of liquid and solid organic waste are generated. Most suitable for anaerobic digestion to produce biogas and fertilizer. Dried food waste also used as animal feed or process fuel. Packaging waste undergoes mechanical or chemical recycling (Mogensen et al., 2018).
Pulp/Paper – Wood waste and process residues burnt as fuel in onsite boilers. Black liquor from pulping recycled in recovery boilers. Sludge dewatered and used for manufacturing roads/construction applications. Non-wood inputs and recovered paper replace virgin fiber needs (Themelis and Ulloa, 2007).
Mining/Quarrying – Minimizing overburden and tailings waste is crucial. Tailings are often stored in engineered ponds for potential reprocessing in future. Acid mine drainage from sulfide-rich tailings requires special treatment (Azapagic, 2004).
Knowledge Gaps and Research Opportunities
Despite progress, there remain opportunities for further improvements in industrial waste management. The following knowledge gaps and research opportunities have been identified based on the literature review:
Need for more holistic systems-based approaches to waste prevention by rethinking production systems, supply chains and industrial symbiosis opportunities.
Development of novel materials, processes and technologies to design wastes out of production through green engineering and sustainable chemistry principles.
Assessment of technical and economic viability of emerging waste treatment methods like plasma gasification, microwave pyrolysis etc. for different waste streams.
Study of behavioral aspects influencing adoption of source reduction and waste minimization practices within industrial organizations.
Evaluation of co-processing higher proportions of alternative waste fuels and feedstocks in place of virgin materials in cement, lime and metal production while controlling emissions.
Investigating waste-derived construction and building materials from industrial byproducts like fly ash, sludge and gypsum for larger scale application.
Closing nutrient and material loops where possible through innovative recycling technologies and conversion of waste into renewable/biodegradable resources.
Improving waste policy frameworks through economic instruments and incentives mainstreaming circular economy principles and life cycle thinking.
Filling geography-specific data gaps on waste generation and management performance across industries and regions.
The above gaps highlight opportunities to progress waste minimization beyond end-of-pipe approaches through cross-disciplinary research and development. The following chapter will outline the research methodology adopted to investigate one such opportunity area of converting waste foundry sands into value-added construction materials.
Andrew Stroud