Column washing of Bangalore-area industrial sludge removed substantially more metals with hydrochloric acid plus EDTA than with distilled water. This is a remediation experiment relevant to sludge contamination pathways, with no measurements in food or a demonstrated safe land-application endpoint.
Key numbers
| Metal | Initial mg/kg | Water removal % | HCl+EDTA removal % | Dispersion cm²/s | Retardation factor |
|---|---|---|---|---|---|
| Cu | 92.3 | 12.3 | 93.7 | 1.5e-05 | 39 |
| Zn | 152.7 | 5.8 | 98.4 | 7.5e-05 | 35 |
| Fe | 414.5 | 0 | 79.3 | 1.1e-05 | 42 |
| Cr | 74.2 | 0 | 71.2 | 6e-06 | 47 |
| Cd | 4.7 | 0 | 94.2 | 0.00011 | 22.5 |
| Ni | 52.3 | 2.3 | 88.7 | 9e-06 | 45 |
| Pb | 11.2 | 0 | 82.8 | 0.0001 | 39 |
Figure 4 labels provide greater precision: Cu 93.74%, Zn 98.44%, Fe 79.32%, Ni 88.74%, Cd 94.17%, Pb 82.84%, Cr 71.17%. These coexist with the rounded prose values above.
The initial sludge mg/kg reporting basis is not stated in the source.
Methods (brief)
Sludge collected November 2013 and analyzed using USEPA 3050 B. Air-dried, 2 mm-sieved material compacted to 0.98 g/cm³ and 33.5% water content; pore volume 56.55 cm³. Columns compared distilled water against 0.1 N HCl+0.1 N EDTA. Transport parameters fitted to experimental elution curves. Sampling and analytical-replicate counts and numeric detection limits are not provided.
Implications
Supports laboratory washing and contaminant-transport comparisons. Metal-rich leachate still requires management; the study does not establish agricultural reuse or field-scale safety.
Evidence Fitness: EF-2 for source-reported removal and transport estimates; environmental remediation context, with replication and reporting-basis gaps.
Wiki pages this source may touch
- Remediation evidence — drivers and interventions
- Irrigation water and soil amendments as anthropogenic inputs to cropland
- Copper
- Zinc
- Iron
- Chromium
- Cadmium
- Nickel
- Lead
Verification notes
Novel industrial-sludge matrix prevents environmental concentrations entering food rows. The prose order puts Pb 82.8 before Ni 88.7; retain numeric values without the incorrect ranking. The prose 70–95% range conflicts with its exact Zn 98.4%; exact element values govern. Curves have no complete tabulated time series; record a data gap rather than inventing chart precision. Cr is unspeciated, not Cr(VI).
The preserved Library PDF is identified by RPHMI_9; SHA-256 80f4906eb712dfe51c24ac0f3629773ebe37f2f6d852643fe651e666774df5e0. The byline, year and publication were verified in the PDF. DOI provenance and any publication-date differences are described above. Original access location: https://api-journal.accscience.com/journal/AJWEP/16/3/ajw190036/ajw190036.pdf. Source-specific numeric observations, context dispositions, row-fit decisions and remaining gaps are preserved in the structured evidence record. No source value was converted across product, soil, water or experimental matrices during ingest.
Update history
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