Converting Waste-to-Energy, and in particular MSW, are hot topics throughout the global landscape. The conversion process, which consists of a number of physical and complex chemical steps, serves a much needed civic function that at the end of the day produces potentially carbon-neutral energy in the form of electrons or fuels such as diesel, ethanol, etc. Additionally, it furthers benefits the environment by reducing the amount of landfill disposed wastes and subsequent methane emissions.
The contribution of methane emissions from landfills compared to all other anthropogenic sources of methane emissions is shown below (EPA):
Waste management is primarily landfills and one of the major sources of methane emissions. This commentary does not discuss the overall Global Warming Potential (GWP) of methane emissions relative to other Greenhouse Gases (GHG). Also, it does not discuss the complexities of the converting solid wastes to energy. This will be covered in later discussions.
The conversion process and the ability to convert it efficiently into energy starts with the waste itself. So what then is solid waste? On the surface, it’s a seeming simple answer – “anything discarded that is not a liquid or gas.” But then again we have the U.S. Government to show us otherwise.
In very general terms, MSW includes non-hazardous solid waste from residential, multifamily, commercial, and institutional (eg., schools, government offices) sources, see following chart (EPA). This definition excludes many materials that are frequently disposed with MSW in landfills, such as combustion ash, water and wastewater treatment residuals, and construction and demolition debris.
The remainder of this conversation is devoted to Uncle Sam’s definition of “solid waste,” in its entirety Agree, it may make boring reading but there is a logical conclusion that can be derived from this specification. So if you like stop here and skip over to the concluding remarks at the end of the commentary.
For better or worse, this is the unabridged definition from the U.S. National Archives and Records Admiration, Electronic Code of Federal Registration
This unabridged definition is taken from Subpart A, Section 261.2 Definition of Solid Waste. PART 261 “Identification and Listing of Hazardous Waste; The U.S. National Archives and Records Administration, Electronic Code of Federal Registration. Part 261 includes Subparts B and C. Other sections in Subpart A, include: 261.1 Purpose and scope. 261.2 Definition of solid waste. 261.3 Definition of hazardous waste. 261.4 Exclusions. 261.5 Special requirements for hazardous waste generated by conditionally exempt small quantity generators. 261.6 Requirements for recyclable materials. 261.7 Residues of hazardous waste in empty containers. 261.8 PCB wastes regulated under Toxic Substance Control Act. 261.9 Requirements for Universal Waste.
For better or worse, here it goes.
261.2 Definition of solid waste.
(a)(1) A solid waste is any discarded material that is not excluded under 261.4(a) or that is not excluded by a variance granted under 260.30 and 260.31 or that is not excluded by a non-waste determination under 260.30 and 260.34.
(2)(i) A discarded material is any material which is:
(A) Abandoned, as explained in paragraph (b) of this section; or
(B) Recycled, as explained in paragraph (c) of this section; or
(C) Considered inherently waste-like, as explained in paragraph (d) of this section; or
(D) A military munition identified as a solid waste in 266.202.
(ii) A hazardous secondary material is not discarded if it is generated and reclaimed under the control of the generator as defined in 260.10, it is not speculatively accumulated as defined in 261.1(c)(8), it is handled only in non-land-based units and is contained in such units, it is generated and reclaimed within the United States and its territories, it is not otherwise subject to material-specific management conditions under 261.4(a) when reclaimed, it is not a spent lead acid battery (see 266.80 and 273.2), it does not meet the listing description for K171 or K172 in 261.32, and the reclamation of the material is legitimate, as specified under 260.43. (See also the notification requirements of 260.42). (For hazardous secondary materials managed in land-based units, see 261.4(a)(23)).
(b) Materials are solid waste if they are abandoned by being:
(1) Disposed of; or
(2) Burned or incinerated; or
(3) Accumulated, stored, or treated (but not recycled) before or in lieu of being abandoned by being disposed of, burned, or incinerated.
(c) Materials are solid wastes if they are recycled —or accumulated, stored, or treated before recycling—as specified in paragraphs (c)(1) through (4) of this section.
(1) Used in a manner constituting disposal. (i) Materials noted with a “*” in Column 1 of Table 1 are solid wastes when they are:
(A) Applied to or placed on the land in a manner that constitutes disposal; or
(B) Used to produce products that are applied to or placed on the land or are otherwise contained in products that are applied to or placed on the land (in which cases the product itself remains a solid waste).
(ii) However, commercial chemical products listed in 261.33 are not solid wastes if they are applied to the land and that is their ordinary manner of use.
(2) Burning for energy recovery. (i) Materials noted with a “*” in column 2 of Table 1 are solid wastes when they are:
(A) Burned to recover energy;
(B) Used to produce a fuel or are otherwise contained in fuels (in which cases the fuel itself remains a solid waste).
(ii) However, commercial chemical products listed in 261.33 are not solid wastes if they are themselves fuels.
(3) Reclaimed. Materials noted with a “—” in column 3 of Table 1 are not solid wastes when reclaimed. Materials noted with an “*” in column 3 of Table 1 are solid wastes when reclaimed unless they meet the requirements of 261.2(a)(2)(ii), or 261.4(a)(17), or 261.4(a)(23), or 261.4(a)(24) or 261.4(a)(25).
(4) Accumulated speculatively. Materials noted with a “*” in column 4 of Table 1 are solid wastes when accumulated speculatively.
Note: The terms “spent materials,” “sludges,” “by-products,” and “scrap metal” and “processed scrap metal” are defined in 261.1.
(d) Inherently waste-like materials. The following materials are solid wastes when they are recycled in any manner:
(1) Hazardous Waste Nos. F020, F021 (unless used as an ingredient to make a product at the site of generation), F022, F023, F026, and F028.
(2) Secondary materials fed to a halogen acid furnace that exhibit a characteristic of a hazardous waste or are listed as a hazardous waste as defined in subparts C or D of this part, except for brominated material that meets the following criteria:
(i) The material must contain a bromine concentration of at least 45%; and
(ii) The material must contain less than a total of 1% of toxic organic compounds listed in appendix VIII; and
(iii) The material is processed continually on-site in the halogen acid furnace via direct conveyance (hard piping).
(3) The Administrator will use the following criteria to add wastes to that list:
(i)(A) The materials are ordinarily disposed of, burned, or incinerated; or
(C) The materials contain toxic constituents listed in appendix VIII of part 261 and these constituents are not ordinarily found in raw materials or products for which the materials substitute (or are found in raw materials or products in smaller concentrations) and are not used or reused during the recycling process; and
(ii) The material may pose a substantial hazard to human health and the environment when recycled.
(e) Materials that are not solid waste when recycled. (1) Materials are not solid wastes when they can be shown to be recycled by being:
(i) Used or reused as ingredients in an industrial process to make a product, provided the materials are not being reclaimed; or
(ii) Used or reused as effective substitutes for commercial products; or
(iii) Returned to the original process from which they are generated, without first being reclaimed or land disposed. The material must be returned as a substitute for feedstock materials. In cases where the original process to which the material is returned is a secondary process, the materials must be managed such that there is no placement on the land. In cases where the materials are generated and reclaimed within the primary mineral processing industry, the conditions of the exclusion found at 261.4(a)(17) apply rather than this paragraph.
(2) The following materials are solid wastes, even if the recycling involves use, reuse, or return to the original process (described in paragraphs (e)(1) (i) through (iii) of this section):
(i) Materials used in a manner constituting disposal, or used to produce products that are applied to the land; or
(ii) Materials burned for energy recovery, used to produce a fuel, or contained in fuels; or
(iii) Materials accumulated speculatively; or
(iv) Materials listed in paragraphs (d)(1) and (d)(2) of this section.
(f) Documentation of claims that materials are not solid wastes or are conditionally exempt from regulation. Respondents in actions to enforce regulations implementing subtitle C of RCRA who raise a claim that a certain material is not a solid waste, or is conditionally exempt from regulation, must demonstrate that there is a known market or disposition for the material, and that they meet the terms of the exclusion or exemption. In doing so, they must provide appropriate documentation (such as contracts showing that a second person uses the material as an ingredient in a production process) to demonstrate that the material is not a waste, or is exempt from regulation. In addition, owners or operators of facilities claiming that they actually are recycling materials must show that they have the necessary equipment to do so. This is only Section 261.2
In closing, should you have made it this far, it is clear that all solid waste are not created equal. This hints at the subsequent difficulty in developing a robust process that feeds garbage in front end and spits out electrons or a desired fuel at the back end. Furthermore, the composition of solid waste is exasperated by differences in municipality, region and country.
As Monty Python would say: “Sort, Sort and More Sort.”
By. Dr. Barry Stevens