Uddin et al. 2023 — Wastewater treatment technologies for municipal landfill leachate (Springer book-chapter review)

Thirty-two-page narrative review of treatment technologies for municipal landfill leachate (LL), organised into physicochemical processes (coagulation-flocculation, ammonium stripping, chemical precipitation, membrane filtration, activated carbon adsorption), biological processes (aerated lagoons, activated sludge, sequencing batch reactor, rotating biological contactor, trickling filter, moving-bed biofilm reactor, fluidised-bed biofilm reactor, membrane bioreactor, constructed wetlands, myco-remediation, phytoremediation, anaerobic filter, UASB, ANAMMOX), and combined treatment trains. The chapter catalogues COD, BOD, NH3-N, and (in passing) heavy-metal removal efficiencies restated from ~110 primary references; it is descriptive in form, with no primary sampling, no inclusion criteria, no quality assessment, and no quantitative meta-synthesis. Heavy metals are mentioned only in narrow vignettes — granular activated carbon (GAC) removal of Cd/Cr/Mn/Pb/Zn at pH 6–7.7 (Wasay et al. 1999), Cr3+/Cu2+ removal by NTR-7250 nanofiltration membrane (Urase et al. 1997), Ni(II)/Cd(II) removal by kaolinite ion exchange (Majone et al. 1998), and lime precipitation of Cu/Ni/Mn/Pb/Fe (Cecen and Gursoy 2000). The chapter’s primary focus is COD and ammoniacal-nitrogen removal, not heavy-metal occurrence in food or supply chains. Relevance to the Heavy Metal Index is leads-only: the chapter provides upstream context for landfill-leachate contamination pathways (relevant to e-waste, soil-contamination, and groundwater pathways feeding into food supply chains in regions with active municipal solid waste disposal) but no primary occurrence data on any food matrix, ingredient, product, or regulation. Evidence tier C.

Key numbers

The chapter restates figures from its primary references rather than reporting any author-derived measurements. Each value below is the chapter’s restatement, not a verified primary number; cross-check against the underlying paper before any quantitative use.

Heavy-metal removal vignettes

• Granular activated carbon (GAC) vs granular activated alumina (GAA) vs ferric chloride (Wasay et al. 1999, restated p. 121): GAC was the most effective of three adsorbents tested for heavy-metal removal of cadmium, chromium, manganese, lead, and zinc from LL; about 80–96 % of heavy metal was removed at pH 6–7.7 with 2 g/L of GAC. Adsorption followed a Freundlich isotherm.
• NTR-7250 nanofiltration membrane (Urase et al. 1997, restated p. 119): 99 % heavy-metal removal whose original metal concentrations were 0.69 mg/L Cr3+ and 0.23 mg/L Cu2+. Cr species is reported as the trivalent cation in the chapter; the chapter does not specify how Cr-VI would behave on the same membrane.
• Coagulation-flocculation with FeCl3 (Tatsi et al. 2003 / Urase et al. 1997, restated p. 116): heavy-metal removal by precipitation more effective at pH 9.0 than at pH 4.0, the actual LL pH. Ferric chloride removed 55 % of organic compounds vs 43 % for alum at the same dose (Amokrane et al. 1997).
• Chemical precipitation with lime (Cecen and Gursoy 2000, restated p. 117): lime was effective for uptake of “copper, nickel, manganese, lead, and iron” from LL; no numeric efficiencies provided.
• Kaolinite ion exchange (Majone et al. 1998, restated p. 135): 99 % Ni(II) and 90 % Cd(II) removed from initial concentrations of 0.94 mg/L Ni and 0.002 mg/L Cd, respectively.

COD, BOD, NH3-N removal headlines (non-metal, recorded as upstream-pathway context)

• Nanofiltration alone removed 50 % NH3-N and 66 % COD from initial 220 mg/L NH3-N and 920 mg/L COD; ammonium stripping at pH 11 removed 89 % NH3-N and 21 % COD at the same initial concentrations (Bonmatí and Flotats 2003, restated p. 116).
• Ammonium stripping removed about 85 % of NH3-N from anaerobically pretreated leachate from the Oyaderi landfill, Turkey, initial 1025 mg/L (Calli et al. 2005, restated p. 116).
• Reverse osmosis: 96–97 % COD and NH3-N removal from a South Korean landfill with initial concentrations 1500 mg/L COD and 1400 mg/L NH3-N (Ahn et al. 2002, restated p. 120); 98 % NH3-N removal from dioxin-laden leachate with initial NH3-N 33.7 mg/L (Ushikoshi et al. 2002, restated p. 119).
• Struvite chemical precipitation removed about 98 % NH3-N at pH 7.5 with 20 % COD removal (Calli et al. 2005, restated p. 117).
• Activated sludge process: COD reduced to 150–500 mg/L (from initial 270–1000 mg/L), BOD < 7 mg/L, NH4+-N < 13 mg/L at 5–10 °C with plastic-carrier addition (Hoilijoki et al. 2000, restated p. 122).
• UASB reactor: 77–91 % COD removal in continuous-flow mode; 71–92 % in sequential-batch UASB at 0.6–19.7 g/L/day COD loading (Kennedy and Lentz 2000, restated p. 131); 82.4 % COD at mesophilic conditions, 12.5 kg m⁻³ d⁻¹ loading rate, influent 70,390–75,480 mg/L COD (Ye et al. 2011, restated p. 131).
• ANAMMOX: 94 % total-nitrogen removal at influent 1330 mg/L NH3-N and 2250 mg/L COD using continuous nitration + anammox for mature LL (Wang et al. 2016, restated p. 132); 95 % total-nitrogen removal at 3000 ± 100 mg/L influent NH3-N over 107 days using two-stage anammox with sequencing biofilm batch reactor (Miao et al. 2016, restated p. 132).
• Constructed wetlands: >90 % removal of pharmaceuticals/PCPs, endocrine disruptors, antibiotic-resistance genes, and antibiotic-resistant genes from mature landfill leachate using full-scale hybrid CW (Yi et al. 2017, restated p. 129); 61 % total PFAS and 50–96 % of individual PFASs removed by full-scale tropical CW (Yin et al. 2017, restated p. 129).

Process taxonomy (chapter framework, §7.2)

The chapter’s organising taxonomy is three groups: (1) physicochemical processes; (2) biological processes (aerobic and anaerobic); (3) combinations of physicochemical and biological processes. Within physicochemical: coagulation-flocculation, ammonium stripping, chemical precipitation, membrane filtration (MF/UF/NF/RO), activated carbon adsorption (GAC/PAC), ion exchange, electrochemical treatment. Within biological-aerobic: aerated lagoon, activated sludge, sequencing batch reactor (SBR), rotating biological contactor (RBC), trickling filter (TF), moving-bed biofilm reactor (MBBR), fluidised-bed biofilm reactor (FBBR), membrane bioreactor (MBR), constructed wetlands, myco-remediation, phytoremediation. Within biological-anaerobic: anaerobic filter (AF), up-flow anaerobic sludge blanket (UASB), anaerobic ammonium oxidation (ANAMMOX).

Methods (brief)

Narrative book-chapter review of secondary literature. No PRISMA, no inclusion criteria, no quality assessment, no formal extraction, no quantitative synthesis. ~110 references cited in the version of the chapter under review. Authors are affiliated with the Industrial and Environmental Sustainability Laboratory, Department of Biotechnology, SRM Institute of Science and Technology, Kattankulathur, Chennai. The corresponding author (Ramani Kandasamy, ramani@srmist.edu.in) is the senior PI; the first author (Maseed Uddin) is a DST-INSPIRE Fellow (Fellowship/2019/IF190897). Funding declared: DST/SYP/YO/2019/1360(G), Science for Equity and Empowerment Division (SEED). The chapter cites primary literature spanning 1994–2020 (most-recent references are 2019–2020). No conflicts of interest declared in the visible chapter pages.

Limitations

C-tier review with no primary data. The chapter’s quality and citeability are limited by several features:

• Heavy metals are a peripheral, not central, focus. The chapter is fundamentally a COD/BOD/NH3-N removal review; heavy-metal removal is mentioned in five short vignettes (above) without systematic treatment, without speciation discipline (Cr is not consistently disambiguated between Cr-III and Cr-VI; iAs and tAs are not discussed), and without consideration of how leachate heavy-metal load varies with landfill age (Kjeldsen et al. 2002 is cited for “the composition of leachate is highly dependent on the age of the landfill” but no metal-by-age table is presented).
• No primary measurements. Every numerical statement in the chapter restates a single primary reference; the chapter does not pool, average, or systematically compare across references. Several restated figures should be verified against their primary sources before downstream use — in particular the GAC 80–96 % heavy-metal removal claim (Wasay et al. 1999) is given without specifying which metal in the Cd/Cr/Mn/Pb/Zn list achieves which efficiency at which initial concentration.
• Some restatements appear internally garbled. For example, p. 121 says GAC was “most effective in the heavy metal removal such as cadmium, chromium, manganese, lead, and zinc. About 80–96% of heavy metal at a pH range of 6–7.7 was removed with 2 g/L of GAC” — the singular “heavy metal” against five named metals leaves it ambiguous whether the 80–96 % range is per-metal or pooled across all five.
• Chromium speciation is inconsistent. The chapter discusses Cr3+ (trivalent chromium) in the nanofiltration vignette but does not raise Cr-VI in the heavy-metal-removal context, despite Cr-VI being the speciation-of-concern for human-health toxicology. The chapter does mention “removal of metals using FeCl3” without disambiguating which Cr species precipitates at pH 9.0.
• No regulatory framing. The chapter does not engage with discharge standards as numbers (only “stringent discharge standards”) and does not relate landfill-leachate heavy-metal removal to drinking-water, surface-water, or groundwater regulatory limits.
• No food-supply-chain bridge. The chapter does not discuss how municipal-landfill-leachate contamination reaches agricultural soils, groundwater used for irrigation, or food crops. The food-pathway implications must be drawn from elsewhere; this chapter only documents the within-treatment-plant engineering.
• English-language editing is uneven. Several sentences require re-reading to parse; section 7.2.1.4 is titled “Membrane Filtration Tecnologies” (sic). Section numbering jumps from 7.2.1 to 7.2.2 without intervening 7.2.1.6 closure; figure captions are inconsistent in style.

Implications

This source has minimal direct value for the Heavy Metal Index. The wiki’s scope is heavy-metals occurrence in food and personal-care supply chains; this paper is a wastewater-treatment engineering chapter focused on landfill-leachate effluent management. It is retained as a leads document for two narrow purposes:

Upstream-contamination-pathway leads. The chapter documents that municipal landfill leachate contains Pb, Cd, Cr, Cu, Ni, Mn, Zn, and Fe at levels requiring active engineered removal, with composition varying by landfill age (Kjeldsen et al. 2002, Kulikowska and Klimiuk 2008). For HMI pages on metal-source contamination of agricultural soils (the rare cases where the wiki documents upstream sources rather than food-level occurrence), this provides background on the leachate composition and on the standard treatment technologies that remove these metals before discharge to receiving water bodies. The chapter does not, however, document leachate-to-soil or leachate-to-groundwater transfer rates, nor the food-chain consequences of incomplete treatment.

Treatment-technology vocabulary leads. The chapter is a useful entry point for mechanism vocabulary if any future HMI page touches industrial- or municipal-effluent treatment as a contamination-mitigation pathway (e.g., the food-processing-water treatment side of HMTc supply-chain audits). Standard methods named: coagulation-flocculation, ammonium stripping, chemical precipitation (struvite, lime), microfiltration / ultrafiltration / nanofiltration / reverse osmosis, granular and powdered activated carbon, ion exchange, electrochemical treatment, aerated lagoon, activated sludge, sequencing batch reactor, rotating biological contactor, trickling filter, moving-bed biofilm reactor, fluidised-bed biofilm reactor, membrane bioreactor, constructed wetlands, myco-remediation, phytoremediation, anaerobic filter, UASB, ANAMMOX. Cite the primary references the chapter cites, not the chapter, when referencing specific efficiency figures.

The chapter does not provide primary contamination data on any food matrix, ingredient, product, or regulation. No contamination_profile synthesis is triggered.

Wiki pages this source may touch

• lead
• cadmium
• chromium
• nickel
• copper
• manganese
• zinc

Verification notes

• Frontmatter metals: uses [Pb, Cd, Cr, Ni, Cu, Mn, Zn]. Cr-VI is not listed separately because the chapter discusses Cr3+ (the nanofiltration vignette) and unspeciated “chromium” (the GAC vignette) but does not measure Cr-VI specifically. The chapter does not raise Cr-VI in any of its heavy-metal vignettes. Cu, Mn, and Zn are off the canonical HMTc 10-analyte list but are explicitly named in the chapter’s heavy-metal vignettes and are precedented in earlier source pages (e.g., aishwarya2024-extremophiles-bioremediation-review which carries Cu and Zn). Fe is mentioned in the lime-precipitation vignette but is not listed in metals: because Fe is not within the HMI metals taxonomy; it appears in the body text only.
• Frontmatter matrices: uses [landfill-leachate, municipal-solid-waste]. These are descriptive environmental-matrix slugs new to this source page; they are plausible analogues to existing slugs (leachate, industrial-waste, e-waste precedented elsewhere) but should be confirmed against the matrices controlled vocabulary on the next Karen review.
• ingredients: [], products: [], jurisdictions: [] are intentionally empty: the chapter is a treatment-engineering review with no food-supply-chain, food-product, or jurisdiction-specific occurrence findings.
• sample_n: null, sample_population is the review’s authorship/affiliation framing rather than a sample-size claim (no primary measurement in the chapter).

Page history

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