Electroplating-bath effluents secondary resource
Metal-bearing liquids originating from industrial electroplating baths, represented by five Cu, Ni, Pd and Au bath effluents supplied by Galvanica Aricci Srl, Ghisalba, Italy, in Ciani et al. (2026). These compositionally different process liquids are distinct from electroplating wastewater-treatment sludge, metallic electroforming scrap and laboratory metal-salt solutions. The study's Ni(1)+Cu mixture is an experimental combination of two supplied liquids, not a sixth independently sampled waste stream. No criticality designation is inherited from constituent metals.
Microbial & Biochemical Mechanisms (1)
Conditional metal biosorption by pretreated cyanobacterial cultures
biosorption
Microbial
Associated Organisms:
Dactylococcopsis salina 16Som2 (NCBITaxon:3045848), Cyanothece sp. CE4 (NCBITaxon:3045849)
Pretreated EPS-producing cyanobacterial cultures confined in dialysis tubing were associated with control-corrected aqueous metal depletion from actual plating-bath effluents in laboratory batch assays. Nickel uptake depended on culture and effluent; palladium and gold uptake was smaller on a molar dry-biomass basis. Biosorption is the source interpretation, without establishing a specific EPS ligand, active metabolism, isolated metal product or industrial deployment.
Experimental Context & Analytical Limits:
Ciani2026 sections 2.1-2.3 and 3.1 used Dactylococcopsis salina 16Som2, Cyanothece sp. CE4 and the unresolved Cyanothece-like co-culture Vi22M. One-week seawater-medium cultures were grown at 26±0.5 degrees C, pH 8.5±0.5, continuous 200 micromol photons/m2/s white light and CO2-enriched air. Whole cultures were confined in 12-14 kDa dialysis tubing and pretreated with 0.1 M HCl or NaOH; identically pretreated cultivation medium without biomass served as the abiotic comparator. Section 3.1 assigns HCl treatment to Ni(1)+Cu/Ni(2) and NaOH to Pd/Au, but section 3.2 later calls the Ni/Cu pretreatment alkaline; the conflict remains unresolved. Biosorbent dry-weight concentrations were 0.6, 1.0 and 0.8 g/L for 16Som2, Vi22M and CE4, respectively. Small dialysis bags (surface/volume 3.7/cm) contacted effluent at a biosorbent:effluent volume ratio of 1:10 in 100 mL glass cylinders, 25 degrees C, 200 rpm and 24 h. The cylinder size is not a stated working volume. ICP-OES measured residual effluent metals; uptake was normalized against the medium-only comparator per gram biomass dry weight. Drying at 105 degrees C was for analytical dry-weight determination, not documented preparation of a dried biosorbent. Viability after pretreatment, axenicity and individual Vi22M membership were not established. Nominal triplicates have missing and zero entries in the SI.
Ciani2026 sections 2.1-2.3 and 3.1 used Dactylococcopsis salina 16Som2, Cyanothece sp. CE4 and the unresolved Cyanothece-like co-culture Vi22M. One-week seawater-medium cultures were grown at 26±0.5 degrees C, pH 8.5±0.5, continuous 200 micromol photons/m2/s white light and CO2-enriched air. Whole cultures were confined in 12-14 kDa dialysis tubing and pretreated with 0.1 M HCl or NaOH; identically pretreated cultivation medium without biomass served as the abiotic comparator. Section 3.1 assigns HCl treatment to Ni(1)+Cu/Ni(2) and NaOH to Pd/Au, but section 3.2 later calls the Ni/Cu pretreatment alkaline; the conflict remains unresolved. Biosorbent dry-weight concentrations were 0.6, 1.0 and 0.8 g/L for 16Som2, Vi22M and CE4, respectively. Small dialysis bags (surface/volume 3.7/cm) contacted effluent at a biosorbent:effluent volume ratio of 1:10 in 100 mL glass cylinders, 25 degrees C, 200 rpm and 24 h. The cylinder size is not a stated working volume. ICP-OES measured residual effluent metals; uptake was normalized against the medium-only comparator per gram biomass dry weight. Drying at 105 degrees C was for analytical dry-weight determination, not documented preparation of a dried biosorbent. Viability after pretreatment, axenicity and individual Vi22M membership were not established. Nominal triplicates have missing and zero entries in the SI.
Curated Evidence Points:
Support
Source:
ciani2026
Sections 2.1-2.2, Table 1 and Figure 1 establish the real liquid-feed origin, assay and comparator. The original Cu liquid had pH 1.66 and 29.52 mg/L Cu; preliminary biosorption and chemical neutralization attempts were unsuccessful. Ni(1) and Cu liquids were subsequently mixed 4:1 by volume, giving source-reported pH 2.41, 598 mg/L Ni and 6 mg/L Cu. Ni(2) was a separate liquid with 386.94 mg/L Ni and initial pH 4.11. These arms are not pooled or interpreted as dilution-only replicates. Table 1 nd means not detected with an unspecified limit, not zero.
Support
Source:
ciani2026
Section 3.2, Figure 2 and Table S2 support Ni uptake by 16Som2 from Ni(2): the three SI entries are 168.81, 162.87 and 178.24 mg Ni/g biomass DW, also reported as 2.88, 2.77 and 3.04 mmol/g. These are specific uptake values relative to the abiotic comparator, not percentages of feed metal recovered. The authors report no significant Cu removal or improvement from the Ni(1)+Cu mixture; this null interpretation is retained alongside small nonzero SI Cu entries.
Partial
Source:
ciani2026
Section 3.3, Figures 3-4 and Tables S3-S4 support lower, culture-dependent Pd/Au uptake. The original PDF axes and captions use micromol/g DW for these figures, whereas the XML/HTML captions say mmol/g DW. Table S3 gives 16Som2 Pd entries 8.14, 8.09 and 0.00 mg/g, which do not reproduce the main-text 76.2±0.3 micromol/g summary when all three rows are included. Table S1 has a missing CE4 row and S3 a missing Vi22M row despite nominal triplicates. Missing values are not zero, and the unexplained zero row is not silently discarded; the Pd summary is not accepted as a reconciled estimate. The section 3.2 statement that Cu/Zn uptake was always below 20 micromol/g also conflicts with higher entries in Tables S1-S2. These inconsistencies limit quantitative comparisons.
Partial
Source:
ciani2026
Sections 3.2-3.3 and conclusions propose EPS binding and metal competition, but the real-feed assays do not directly localize metal, resolve oxidation states, selectively remove EPS or establish a molecular cause. The medium-only control accounts for some abiotic losses but does not identify every removal pathway or provide a reported pH-matched time course. No desorption, isolated metal yield, product purity, reuse-cycle performance or plant treatment is demonstrated.
Context_only
Source:
ciani2024
Printed pages 34-37, Figure 2 and supplementary Figure S1 document culture provenance, partial 16S assignments and the earlier assay protocol. The acid pretreatment was deionized water for 16 h, 0.1 M HCl for 30 min and water overnight; this does not establish an analogous NaOH treatment duration in 2026. Equation 5 defines uptake from blank-versus-treatment solution concentrations and biomass mass. The 2024 Cu/Ni/Zn assays used laboratory salt solutions and controlled pH, so their performance and microscopy are not transferred to the real effluents.
Context_only
Source:
genbank16som2
The original accession linked by both studies resolves to partial 16S sequence OQ945751.1 with strain 16Som2 and taxon 3045848; this supports the named culture linkage without independently demonstrating culture purity or mechanism.
Context_only
Source:
genbankce4
OQ945752.1 resolves to Cyanothece sp. CE4 with source strain CE 4 and taxon 3045849. No accession or taxon identifier is invented for the Vi22M co-culture.
Sources & References
-
ciani2026: Ciani, Capelli, Daly, de Philippis and Adessi (2026). Toward Industrial Application of Cyanobacterial Biosorption: Insights From Real Electroplating Effluents. Water Environment Research 98:e70366. DOI 10.1002/wer.70366. Complete seven-page original, Table 1, Figures 1-4 and original Supporting Information Tables S1-S4 inspected; PDF versus XML figure-caption units differ.
https://doi.org/10.1002/wer.70366 (accessed 2026-10-14) -
ciani2024: Ciani, Decorosi, Ratti, De Philippis and Adessi (2024). Semi-continuous cultivation of EPS-producing marine cyanobacteria: A green biotechnology to remove dissolved metals obtaining metal-organic materials. New Biotechnology 82:33-42. DOI 10.1016/j.nbt.2024.04.004. Complete ten-page original and four-page supplement; protocol and sequence context, not a second real-effluent experiment.
https://doi.org/10.1016/j.nbt.2024.04.004 (accessed 2026-10-14) -
genbank16som2: NCBI GenBank OQ945751.1: Dactylococcopsis salina 16Som2 partial 16S ribosomal RNA gene; source strain 16Som2 and taxon 3045848. Sequence context, not a whole genome or independent proof of metal-binding function.
https://www.ncbi.nlm.nih.gov/nuccore/OQ945751.1 (accessed 2026-10-14) -
genbankce4: NCBI GenBank OQ945752.1: Cyanothece sp. CE4 partial 16S ribosomal RNA gene; source strain CE 4 and taxon 3045849. Sequence context only.
https://www.ncbi.nlm.nih.gov/nuccore/OQ945752.1 (accessed 2026-10-14) -
ncbi3045848: NCBI Taxonomy 3045848: Dactylococcopsis salina 16Som2, strain rank. Current authoritative XML checked with the linked sequence.
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=3045848&mode=Info (accessed 2026-10-14) -
ncbi3045849: NCBI Taxonomy 3045849: Cyanothece sp. CE4, species rank in the database despite the unresolved species epithet. Current authoritative XML checked with OQ945752.1.
https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=3045849&mode=Info (accessed 2026-10-14)
Curation History
| Timestamp | Curator | Action | Summary |
|---|---|---|---|
2026-10-14T21:48:46.981396+00:00 |
codex (GPT-6) | CREATE | Curated actual electroplating-bath liquid provenance and conditional cyanobacterial biosorption from complete Ciani2026 original/SI, with related synthetic-protocol context, current sequence/taxon grounding and explicit source contradictions; no isolated recovery or inherited criticality. |
Record source: data/records/electroplating-bath-effluents.yaml