The potential role of energy-from-waste air pollution control residues in the industrial ecology of cement

Abstract

Industrial ecology draws an analogy between industrial activity and natural ecosystems with the inherent implication that, in its ideal form, an industrial ecosystem cycles resources efficiently, with minimisation of waste. Industrial symbiosis between the cement and other industries can make a substantial contribution to sustainability. About 3.6 Gt of cement were produced globally in 2011, consuming more than 5 Gt of raw materials and about 11% of total industrial energy, and leading to about 7% of global CO2 emissions. In the same year, global generation of municipal solid waste (MSW) was estimated at 1.3 Gt, of which about 16% was thermally processed, usually by combustion to generate energy-from-waste (EfW). This equates to about 2.1% of total industrial energy consumption, but would generate about 6 Mtpa of air pollution control (APC) residues. Use of these EfW APC residues in blended cements has been suggested, but they contain soluble toxic elements and are classified as hazardous wastes in most jurisdictions. This paper discusses the effects of incorporating EfW APC residues on the technical performance of blended cements, and on several characteristics of importance for the environmental acceptability of this practice, including 1) total inorganic pollutant concentrations in blended cements, 2) pH-dependent leachability of toxic metal pollutants, e.g., according to BS EN 12457-2, and DD CEN/TS 15364, and 3) diffusion controlled leaching of monolithic blended cement pastes, e.g., according to EA NEN 7375. Potential pollutants, especially Pb and Zn, but also Cd, Hg, Sb, Sn and Se, were found to be enriched in EfW APC residues relative to cements. Apart from their potential to pollute the environment, metals in APC residues can affect cement hydration and hardening, and this has been observed. EfW APC residues also contain high levels of several elements that are problematic for quality control of blended cements, notably chloride, which causes steel reinforcement corrosion, and alkalis (Na, K), implicated in the destructive alkali-silica reaction. Although leaching data for both granular and monolithic samples suggest that the mobility of low concentrations of metal pollutants is reduced in cement-based matrices, leachability of chloride remains high, and leaching of soluble constituents in APC residues can also be expected to increase paste porosity over time. Furthermore, the literature indicates that pozzolanic or cementing properties of EfW APC residues are not sufficiently strong or reliable to justify their use as a cement replacement, and there is also the potential for components of APC residues to cause other deleterious expansion reactions in cement-based materials. Therefore, industrial ecology cannot solve the problem of management of EfW APC residues through incorporating them in blended cements without radically rethinking the principle that "dilution is not the solution to pollution", which underlies much waste management legislation. Relaxation of these principles would also have undesirab...

The Potential of Industrial Symbiosis: Case Analysis and Main Drivers and Barriers to Its Implementation

“…In addition to the barriers to the creation and development of industrial symbiosis, which are often referred to in the literature, such as a lack of trust among potential collaborators [33,116], the risks and uncertainties associated with the costs and benefits of such synergies [18,131], and a lack of knowledge [34,41], there are other more specific obstacles that impede these new uses. Current legislation restricting the integration of new waste materials into productive processes [132,133] and the toxicity of some of these waste materials [134] are examples of barriers that can hinder the flow of waste materials and thus condition the development of future synergies. Thus, several studies have investigated future relationships of industrial symbiosis with a focus on the use of new waste materials and their reutilisation in the manufacture of existing or new products.…”

Developmental exposure to environmentally relevant concentrations of bifenthrin alters transcription of mTOR and ryanodine receptor-dependent signaling molecules and impairs predator avoidance behavior across early life stages in inland silversides (Menidia beryllina)

“…Furthermore, results from this and earlier studies evaluating picomolar effects of bifenthrin fall in line with conclusions made for multiple contaminants that lower concentrations do not necessarily mean less toxicity (Norman et al, 2015). Researchers and pesticide regulators thus need to re-think the principle that ‘dilution is the solution to pollution’, which underlies chemical management and mitigation (Stegemann, 2014). …”

Co-processing of raw and washed air pollution control residues from energy-from-waste facilities in the cement kiln

“…While this practice can improve material resource efficiency, most wastes contain contaminants. Cleaner production through co-processing therefore requires a good understanding of the impacts of these contaminants on the cement manufacturing process, cement quality, and the environment (Stegemann 2014). The air pollution control residue (APCR) that arises from combustion of municipal solid waste to generate energy-from-waste (EfW) is an example of a candidate waste for co-processing.…”

“…Attempted APCR treatments reported in the literature include separation processes (e.g., Quina et al 2018), blending with cement (stabilization/solidification) before landfill or utilization in construction (Stegemann 2014), and thermal methods. Thermal techniques, including vitrification, melting and sintering (Astrup et al 2008), e.g., to produce glass (Wexell 2005), ceramics (Amutha Rani et al 2008) and lightweight aggregates (Quina et al 2014), have been investigated for treatment and disposal or utilization of APCR.…”