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Cited by 16Urban Stormwater Management SolutionsEnvironmental remediation with nanomaterialsAdsorption and biosorption for pollutant removal

Application of Biochar in Stormwater Treatment: Experimental and Modeling Investigation

Open access
Hasan, Md Sazadul, Vasquez, Raul, Geza, Mengistu·2021·Processes
DOI 10.3390/pr9050860
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Abstract

This research investigated the removal of heavy metal ions (Cd, Cu, Pb, and Zn) and metalloid (As) common to stormwater runoff onto biochar-based media arranged in multiple configurations. Laboratory scale column experiments were conducted to quantify heavy metal removal efficiencies using sand, biochar, and nZVI-modified biochar (BC-nZVI) in four media configurations: a homogeneous mixture of sand and biochar (BCM); biochar layered in sand (BCL); BC-nZVI layered in sand (BCZ); and sand as a control. An inverse modeling approach was implemented to measured moisture and experimental data to determine media hydraulic parameters (θr, θs, α, n and Ks) and adsorption coefficients. The experiment was conducted using laboratory synthesized stormwater over 200 days at a rate of 5 cm/day. BCZ exhibited an excellent removal (99%) of As due to the high attachment to nZVI, via surface complexations. Biochar with abundant surface oxygen functional groups exhibited a great (99%) removal of Cd and Zn in both BCL and BCM columns. Water contents were observed 66.0, 44.3, 41.4, and 7.2% for BCL, BCM, BCZ, and sand, respectively. The attachment coefficients varied from 21.5 to 44.9, 16.1 to 19.3, 18.8 to 26.0, and 9.6 to 19.9 L/kg for BCL, BCM, BCZ, and sand, respectively. This study’s output provides useful information for stormwater management practices.

AI snapshot

Written from the paper’s full text.

TL;DR

This study tested sand, biochar–sand mixtures, layered biochar, and nZVI-modified biochar in laboratory columns for stormwater heavy-metal removal, coupled with HYDRUS 2D inverse modeling. Layered biochar (BCL) performed best for most metals, while nZVI-modified biochar (BCZ) was best for arsenic.

Key findings

  • BCZ was best for As removal: the abstract reports 99% removal, and the results report a 97.7% average at 200 days, compared with BCL 96.3%, BCM 95.4%, and sand 79.0%.
  • Biochar media removed Cd and Zn well: the abstract reports 99% removal of Cd and Zn in both BCL and BCM; results report BCL at 99% for both, BCM at 93% for Cd and 95% for Zn, and sand at 1.2% for Cd and 9% for Zn.
  • Cu and Pb were efficiently removed by all configurations, including sand, with 98–100% removal reported.
  • Water contents were reported as 66.0, 44.3, 41.4, and 7.2% for BCL, BCM, BCZ, and sand, respectively; attachment coefficients ranged from 21.5–44.9 L/kg for BCL, 16.1–19.3 L/kg for BCM, 18.8–26.0 L/kg for BCZ, and 9.6–19.9 L/kg for sand.

Methods

  • Laboratory column experiment with four media configurations in triplicate: sand control, homogeneous sand–biochar mixture (BCM), biochar layered in sand (BCL), and nZVI-modified biochar layered in sand (BCZ); biochar was 5% by weight.
  • Synthetic stormwater was applied at 5 cm/day for 200 days; effluent was collected weekly and analyzed by ICP-MS for As, Cd, Cu, Pb, and Zn.
  • HYDRUS 2D was used to inversely model moisture sensor data for hydraulic parameters (θr, θs, α, n, Ks), then solute transport modeling with a linear isotherm estimated attachment coefficients (Kd); SEM-EDS, BET, and FTIR characterized media.

Limitations

  • The paper does not include a dedicated limitations section. It states that metal concentrations were higher than normally observed in stormwater to shorten breakthrough time and that this was not expected to affect conclusions; it also states the stormwater was laboratory-synthesized.
  • Evident from the text: the study is laboratory-scale, not field-scale, and the elevated synthetic concentrations limit direct extrapolation to real stormwater.
  • The paper notes that free drainage was not accomplished and water stored in column bottoms, affecting moisture readings; it also suggests BCZ may have lost fine particles during ethanol rinsing, reducing surface area from 400 to 23.94 m²/g after modification.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.3390/pr9050860

Cites

57 of 57 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

6 of 40 cited sources checked · 2 supported · 0 flagged · accuracy not yet measured

  • Findingcitation

    The spectra of biochar proved the presence of carbon and oxygen functional groups such as -OH, aliphatic, C=O, aromatic ring, and etheric C-O-C group.

    “The spectra of biochar proved the presence of carbon and oxygen functional groups such as -OH (at 3405 cm -1 ), aliphatic (2920 cm -1 ), C=O (1617 cm -1 ), aromatic ring (1384 cm -1 ), and etheric C-O-C group (1088 cm -1 ) [48].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [48] Lara, 2013, Quantitative differentiation between soil organic carbon and biochar carbon in Aridisol, Int. J. Agric. Nat. Resour. source

      Table 2, reproduced in the ‘Amounts of TOC from soil, humic acid, biochar and humidified soils’ section (page unavailable), identifies all five functional groups in the biochar’s FTIR spectra. The citing sentence’s etheric C-O-C value of 1088 cm⁻¹ is not supported: the table gives 1115–1130 cm⁻¹. It also gives 1385 cm⁻¹, rather than 1384 cm⁻¹, for the aromatic C-C group. (LLM, conf=0.90)

      Experimental — accuracy not yet measured
  • Premisecitation

    BCZ has magnetic characteristics that benefit copper adsorption.

    “BCZ does have magnetic characteristics [52,53] which benefit copper adsorption, but the increased surface area of BCL has more effect on removal efficiency.”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [52] Han, 2015, Magnetite impregnation effects on the sorbent properties of activated carbons and biochars, Water Res. source

      Section 3.2.2 (p. 16) says magnetite contributes to some extent to copper sorption by the paper’s MagOrgBio composites. The paper does not identify or test BCZ, so it cannot establish that BCZ’s magnetic characteristics benefit its copper adsorption. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
    • cites [53] Zhu, 2017, Magnetic nanoscale zerovalent iron assisted biochar: Interfacial chemical behaviors and heavy metals remediation performance, ACS Sustain. Chem. Eng. source
  • Findingreasoning

    BCZ (BC-nZVI layered in sand) achieved 99% removal of As.

    “BCZ exhibited an excellent removal (99%) of As”
    Quote in the paperSubstantial claim
  • Findingown data

    Biochar has abundant surface oxygen functional groups.

    “Biochar with abundant surface oxygen functional groups”
    • Also stated in: § 3.1. Media Characteristics · boosted
      “The FTIR spectrum confirmed the presence of abundant functionals groups on biochar and BC-nZVI surfaces shown in Figure 4.”
    Quote in the paperSubstantial claim
  • Findingown data

    Water contents were 66.0, 44.3, 41.4, and 7.2% for BCL, BCM, BCZ, and sand, respectively.

    “Water contents were observed 66.0, 44.3, 41.4, and 7.2% for BCL, BCM, BCZ, and sand, respectively.”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim. 20
  • May combine two claims. 48

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The common bioretention media has a top layer of mulch (2-3 inches) followed by a homogenous mixture that is more than 80% sand, 8-12% fines, and 3-5% organic matter.

    “The common bioretention media has a top layer of mulch (2-3 inches) followed by a homogenous mixture that is more than 80% sand, 8-12% fines, and 3-5% organic matter [15].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [15] Winston, 2016, Quantifying volume reduction and peak flow mitigation for three bioretention cells in clay soils in Northeast Ohio, Sci. Total Environ. source

      The Introduction describes bioretention media as predominantly sand mixed with fines and organic matter. The Site Descriptions report 7.5 cm (about 3 inches) of mulch over all three cells and more than 80% sand, but they do not establish the quoted percentages as a common specification: the UC cell had 13% fines, while the two HA cells had only 1.0% and 1.4% organic matter. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    Hydrologic changes associated with urban growth are increased runoff peak, runoff volume, and reduced time to peak.

    “Hydrologic changes associated with urban growth are increased runoff peak, runoff volume, and reduced time to peak [1].”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [1] Goonetilleke, 2005, Understanding the role of land use in urban stormwater quality management, J. Environ. Manag. source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    BMP technologies have been developed to manage urban runoff and improve water quality, and LID bioretention cells are one BMP found to be an effective means of reducing heavy metals found in runoff.

    “Best management practice (BMP) technologies have been developed to manage urban runoff and improve water quality [12], and lowimpact development (LID) bioretention cells are one BMP found to be an effective means of reducing heavy metals found in runoff [13].”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [12] Shojaeizadeh, A., Geza, M., McCray, J., and Hogue, T.S. (2019). Site-scale integrated decision support tool (i-DSTss) for stormwater management. Water, 11. source
    • cites [13] Shojaeizadeh, A., Geza, M., Bell, C., McCray, J., and Hogue, T. (2021). A site-scale tool for performance-based design of stormwater best management practices. Water, 13. source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Both biochar media were 5% by weight in all cases, which is a common amendment ratio found in the literature.

    “Both biochar media were 5% by weight in all cases, which is a common amendment ratio found in the literature [43,44].”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [43] Li, 2016, Biochar amendment immobilizes lead in rice paddy soils and reduces its phytoavailability, Sci. Rep. source

      The Methods (Growth conditions and seed treatment) show that this paper used a 5% by-weight biochar amendment, alongside 0% and 2.5% treatments. That supports 5% as an example of a ratio used in the literature, but the paper does not establish that it is a common ratio. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
    • cites [44] Jain, 2018, Biochar amendment for batch composting of nitrogen rich organic waste: Effect on degradation kinetics, composting physics and nutritional properties, Bioresour. Technol. source

  • May combine two claims.

    Findingown data

    Attachment coefficients varied from 21.5 to 44.9, 16.1 to 19.3, 18.8 to 26.0, and 9.6 to 19.9 L/kg for BCL, BCM, BCZ, and sand, respectively.

    “The attachment coefficients varied from 21.5 to 44.9, 16.1 to 19.3, 18.8 to 26.0, and 9.6 to 19.9 L/kg for BCL, BCM, BCZ, and sand, respectively.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Arsenic effluent concentration after 160 days of dosing in BCZ was 0.016 mg/L, whereas BCL and BCM exhibited 10-fold higher (0.164 mg/L) As concentrations at effluents.

    “For example, arsenic effluent concentration after 160 days of dosing in BCZ (BC-nZVI layered column) was 0.016 mg/L, whereas BCL and BCM exhibited 10-fold higher (0.164 mg/L) As concentrations at effluents.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    After 169 days of dosing, negligible (0.07 mg/L) effluent concentrations of Cd were observed in BCL and BCM columns, whereas BCZ and sand columns released 1.96 and 27.68 mg/L.

    “After 169 days of dosing, negligible (0.07 mg•L -1 ) effluent concentrations of Cd were observed in BCL and BCM columns, whereas BCZ and sand columns released 1.96 and 27.68 mg•L -1 ,”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Under the same conditions, BCL averaged 96.3%, BCM 95.4%, and sand 79.0% arsenic removal efficiency.

    “Under the same conditions, BCL averaged a removal efficiency of 96.3%, followed by BCM at 95.4%, and sand at 79.0%.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    BCZ was best at retaining arsenic, with average efficiency 97.7% after 200 days at 5 cm/day.

    “BCZ appeared to be the best at retaining the arsenic, with an average efficiency of 97.7% after 200 days of constant application at 5 cm/day.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Effluent Cd concentrations in BCL and BCM columns were 0.07 mg/L, whereas BCZ and sand columns released 1.96 and 27.68 mg/L, respectively.

    “(0.07 mg•L -1 ) effluent concentrations of Cd were observed in BCL and BCM columns, whereas BCZ and sand columns released 1.96 and 27.68 mg•L -1 , respectively.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    All media configurations were efficient in removing Cu; all effluent concentrations were <0.027 mg/L compared to the influent concentration of 2.5 mg/L after 200 days of dosing.

    “Comparison of influent and effluent concentrations showed that all media configurations were efficient in removing Cu; all effluent concentrations were <0.027 mg•L -1 compared to the influent concentration of 2.5 mg•L -1 after 200 days of dosing.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Sand performance was poor for Cd removal, as it was for As.

    “Sand performance was poor for Cd removal, as it was for As.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    BCM was comparable at top and bottom sensor, at 26.6% and 20.5% at steady state, respectively.

    “BCM was comparable at the top sensor and the bottom sensor, at 26.6% and 20.5% at a steady state, respectively.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    At steady state, sand column sensor one, two, three were 4.3, 4.1, and 25.3%, respectively.

    “At steady state, sensor one, sensor two and sensor three were, 4.3, 4.1, and 25.3%, respectively.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning

    BCL removal efficiency was similar to BCM, with BCL slightly more efficient (99 vs 95% for Zn and 99 vs 93% for Cd).

    “The removal efficiency was similar between the two, with BCL being slightly more efficient than BCM (99 vs. 95% for Zn and 99 vs. 93% for Cd).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    In sand column, storage in bottom and sensor at bottom had water content 28.0% at steady state, well over free drainage value expected.

    “Similar to the sand column, there was storage in the bottom of the column and the sensor located at the bottom of the column had a water content reading of 28.0% at a steady state; a value that was well over the free drainage value expected.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Cadmium was effectively retained by all biochar mixtures, but sand showed poor removal efficiency.

    “Cadmium was effectively retained by all biochar mixtures, but sand showed a poor removal efficiency.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    BCL had best retention of cadmium with removal efficiency 99% and effluent concentration 0.216 mg/L.

    “BCL had the best retention of cadmium with a removal efficiency of 99%, and an effluent concentration of 0.216 mg/L.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Sand layer above biochar layer had water content 12.0% at steady state, more than double control column of sand at same sensor reading.

    “The sand layer above the biochar layer had a water content that was 12.0% at a steady state, more than double the control column of sand at the same sensor reading.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Average Cd removal efficiency for sand was 1.2% compared to 90, 93, and 99% in BCZ, BCM, and BCL, respectively.

    “The average removal efficiency for sand was only 1.2% compared to 90, 93, and 99% in BCZ, BCM, and BCL, respectively.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Sand is traditionally used as bioretention media; it showed efficient removal of Cu and Pb in this study.

    “Sand is a material that is traditionally used as bioretention media; it showed efficient removal of Cu and Pb in this study.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    BCZ performed better in As removal, indicated by high affinity of As to nZVI, and BC-nZVI is therefore an efficient medium for As removal from stormwater.

    “BCZ performed better in As removal, indicated by the high affinity of As to nZVI, and BC-nZVI is therefore an efficient medium for As removal from stormwater.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Pure biochar layer was best at retaining water, with middle sensor reading 66.0% at steady state.

    “The pure biochar layer was the best at retaining water, with the middle sensor reading 66.0% at a steady state.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Arsenic had noticeable affinity for nZVI, validated by efficient removal in BCZ, whereas BCM and BCL performed efficiently regarding Cd and Zn removal.

    “Arsenic had a noticeable affinity for nZVI, which was validated by efficient removal in BCZ, whereas BCM and BCL performed efficiently regarding Cd and Zn removal.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    BCL had best Zn removal efficiency at 99%, followed by BCM (95%) and BCZ (94%).

    “BCL had the best removal efficiency at 99%, followed by BCM (95%) and BCZ (94%).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    BCZ top sensor was 8.0% at steady state, indicating middle nZVI biochar layer affected water content on sand layer above.

    “The sensor located at the top of the column was 8.0% at steady state, indicating that the middle nZVI biochar layer affected the water content on the sand layer above.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Sand column sensors one and two had a difference of <0.5%, verifying storage in bottom of column.

    “The sand column sensors one and two had a difference of <0.5%, verifying the assumption of storage in the bottom of the column.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Even sand had satisfactory removal efficiencies for some metals; however, sand had the only breakthroughs seen in the experiment (Cd, Zn).

    “Even sand had satisfactory removal efficiencies for some metals; however, sand did have the only breakthroughs seen in the experiment (Cd, Zn).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Sand was a poor adsorbent of zinc with removal efficiency 9% and effluent concentration 22.6 mg/L.

    “The sand was found to be a poor adsorbent of zinc with a removal efficiency of 9%, and effluent concentration of 22.6 mg/L.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    BCM sensor three at bottom had water content 44.3% at steady state, higher than top and middle sensors.

    “Sensor three, located at the bottom of the column, had a water content value of 44.3% at a steady state, which was higher than the other sensors located in the top and middle of the column.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Biochar layer had moisture content 64%, nZVI 39%, biochar homogenous mixture 27%, and sand 4.3% at steady states.

    “The biochar layer had a moisture content of 64%, nZVI was 39%, biochar homogenous mixture was 27%, and sand was 4.3% at steady states.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Established treatment methods of urban runoff include liquid extraction, precipitation, reverse osmosis, and ion exchange, which achieve acceptable discharge concentrations but are not always economical or technically feasible.

    “Established treatment methods of urban runoff include liquid extraction, precipitation, reverse osmosis, and ion exchange, methods which achieve acceptable discharge concentrations; however, they are not always economical or technically feasible [5].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [5] Jang, 2005, The removal of heavy metals in urban runoff by sorption on mulch, Environ. Pollut. source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Cadmium, copper, lead, mercury, nickel, and zinc are common metals found in stormwater and are listed on the EPA's priority pollutants.

    “Cadmium, copper, lead, mercury, nickel, and zinc are common metals found in stormwater and are listed on the EPA's priority pollutants [3].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [3] Mulligan, 2001, Remediation technologies for metal-contaminated soils and groundwater: An evaluation, Eng. Geol. source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Bioretention cells in two Maryland locations removed median 76% copper, 57% lead, and 83% zinc.

    “Bioretention cells were fabricated successfully using variations of sand, silt, clay, and organic matter in two Maryland locations to monitor heavy metal removal performance, and median values for effluent percent removals based on combined data sets (both cells) were 76% copper, 57% lead, and 83% zinc [14].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [14] Li, 2009, Water quality improvement through reductions of pollutant loads using bioretention, J. Environ. Eng. source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Health problems associated with heavy metal exposure include respiratory system damage, nervous system damage, and cancer.

    “Health problems associated with heavy metal exposure include respiratory system damage, nervous system damage, and cancer [4].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [4] Su, 2014, A review on heavy metal contamination in the soil worldwide: Situation, impact and remediation techniques, Environ. Skept. Crit.

  • May combine two claims.

    Premisecitation

    Biochar is abundant and inexpensive to produce and exhibits a huge potential for applications in stormwater treatment.

    “Biochar is another emerging material, which is both abundant and inexpensive to produce [19], and exhibits a huge potential for applications in stormwater treatment [20][21][22].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [19] Akhil, D., Lakshmi, D., Kartik, A., Vo, D.-V.N., Arun, J., and Gopinath, K.P. (2021). Production, characterization, activation and environmental applications of engineered biochar: A review. Environ. Chem. Lett., 1–37. source
    • cites [20] Ashoori, 2019, Evaluation of pilot-scale biochar-amended woodchip bioreactors to remove nitrate, metals, and trace organic contaminants from urban stormwater runoff, Water Res. source
    • cites [21] Mohanty, 2018, Plenty of room for carbon on the ground: Potential applications of biochar for stormwater treatment, Sci. Total Environ. source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Early filter materials for heavy metal adsorption included peanut hulls, chitosan, zeolite, and mulch, and recent materials include calcite, sand, iron fillings, nanoscale metal oxides, zero-valent iron, biochar, or combinations of these materials.

    “early research of filter materials used for the adsorption of heavy metals included peanut hulls, chitosan, zeolite, and mulch [6][7][8], and recent materials used for heavy metal adsorption are calcite, sand, iron fillings, nanoscale metal oxides, zero-valent iron, biochar, or combinations of these materials [9][10][11].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [6] Orlando, 2001, Synthesis and applications of chitosan mercaptanes as heavy metal retention agent, Int. J. Biol. Macromol. source
    • cites [7] Erdem, 2004, The removal of heavy metal cations by natural zeolites, J. Colloid Interface Sci. source
    • cites [8] Brown, 2000, Evaluation of the adsorptive capacity of peanut hull pellets for heavy metals in solution, Adv. Environ. Res. source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    A bioretention shoulder in Seattle removed 79% copper and 86% zinc.

    “A similar study by monitoring a bioretention shoulder in Seattle, Washington, consisting of washed gravel and a soil mixture, 70% sand and 30% organic compost, removed 79% of copper and 86% zinc [16].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [16] Chapman, 2010, Performance assessment of a street-drainage bioretention system, Water Environ. Res. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductreasoning

    All columns were fed by a single influent tank to maintain the constituent's uniformity in the stormwater solution.

    “All columns were fed by a single influent tank to maintain the constituent's uniformity in the stormwater solution.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The column experiment used four different combinations of media in triplicate for a total of 12 columns.

    “The column experiment used four different combinations of media in triplicate for a total of 12 columns (Figure 1).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    BCM and sand removal efficiency can be explained by surface area; BCM has a larger surface area than sand, providing more sites for copper adsorption.

    “BCM and sand removal efficiency can be explained by the same reasoning; BCM has a larger surface area than the sand; therefore, more sites for adsorption of copper.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The model implemented the soil hydraulic functions proposed by Van Genuchten and Mualem to describe the soil water retention curve.

    “The model implemented the soil hydraulic functions proposed by Van Genuchten and Mualem [46,47] to describe the soil water retention curve using the following formulae, Equations ( 4)-(8):”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [46] Mualem, 1976, A new model for predicting the hydraulic conductivity of unsaturated porous media, Water Resour. Res. source
    • cites [47] 1980, A closed-form equation for predicting the hydraulic conductivity of unsaturated soils, Soil Sci. Soc. Am. J. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    nZVI is a nanoparticle gaining recognition in environmental remediation due to its cost-effectiveness, significant surface area, and reducing properties.

    “nZVI is a nanoparticle gaining recognition in environmental remediation due to its cost-effectiveness, significant surface area, and reducing properties [32].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [32] Hasan, 2021, Graphene oxide transport and retention in biochar media, Chemosphere source

  • May combine two claims.

    Interpretationown data

    EDS site mapping confirmed the presence of nZVI, and the porous areas of biochar seemed to have an agglomeration of nZVI, possibly due to nanoparticles attaching and accumulating to the rough edges.

    “An EDS site mapping (Figure 3) confirmed the presence of nZVI, and the porous areas of biochar seemed to have an agglomeration of nZVI, possibly due to the nanoparticles attaching and accumulating to the rough edges.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The HYDRUS 2D model uses the two-dimensional form of the Richards equation for flow simulation.

    “The HYDRUS 2D model uses the two-dimensional form of the Richards equation (Equation ( 3)) for flow simulation [45].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [45] Šimůnek, J., van Genuchten, M., and Sejna, M. (2012). HYDRUS Technical Manual: The HYDRUS Software Package for Simulating the Two-and Three Dimensional Movement of Water, Heat and Multiple Solutes in Variably-Saturated Porous Media, PC-Progress. Technical Manual Version 2.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Metal removal efficiency increases with increasing nZVI:biochar mass ratios, where efficiencies reached 100% when the addition of nZVI/biochar was >2:1.

    “Additionally, metal removal efficiency increases with increasing nZVI:biochar mass ratios, where efficiencies reached 100% when the addition of nZVI/biochar was >2:1 [34].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [34] Zhou, 2014, Biochar-supported zerovalent iron for removal of various contaminants from aqueous solutions, Bioresour. Technol. source

  • May combine two claims.

    Study design and conductreasoning

    Metal concentrations used in the experiment were higher than normally observed in stormwater to reduce time for breakthrough, and this was not expected to affect the conclusions because the main objective was to evaluate relative performance of media configurations.

    “Metal concentrations (shown in Table 2) used for the experiment were at higher ranges than normally observed in stormwater to reduce the amount of time required for a breakthrough to occur.This was not expected to affect the conclusions, because the main objective of the experiment was to evaluate the relative performance of the media configuration used in the study.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    HYDRUS 2D is a finite element model for simulating the movement of water, heat, and multiple solutes in variably saturated media.

    “The HYDRUS 2D program is a finite element model for simulating the movement of water, heat, and multiple solutes in variably saturated media [45].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [45] Šimůnek, J., van Genuchten, M., and Sejna, M. (2012). HYDRUS Technical Manual: The HYDRUS Software Package for Simulating the Two-and Three Dimensional Movement of Water, Heat and Multiple Solutes in Variably-Saturated Porous Media, PC-Progress. Technical Manual Version 2.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationown data

    The reduction in BET surface area after modification is attributable to filtering out fine particles during the modification process and the occupancies of biochar pores by nZVI particles.

    “This is attributable to filtering out fine particles during the modification process and the occupancies of biochar pores by nZVI particles after modification, as seen from SEM-EDS analysis.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Biochar-based adsorbents, including the nZVI modified form, exhibited excellent performance in removing As from water, primarily due to large surface area, abundant functional groups, and favorable chemical properties for attachment.

    “Biochar-based adsorbents, including the nZVI modified form, exhibited excellent performance in removing As from water, primarily due to it having a large surface area, abundant functional groups, and favorable chemical properties for the attachment [37].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [37] Amen, 2020, A critical review on arsenic removal from water using biochar-based sorbents: The significance of modification and redox reactions, Chem. Eng. J. source

  • May combine two claims.

    Interpretationown data

    This indicated free drainage was not accomplished and there was water storage in bottom of column.

    “This was another indication that free drainage was not accomplished and there was water storage in the bottom of the column.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    There was noticeable loss in water retention potential in nZVI biochar, and loss of pore space in BCM and BCZ decreased retention and contact time with biochar functional groups, limiting pollutant removal.

    “Thus, there was a noticeable loss in water retention potential in nZVI biochar, and the loss of pore space in BCM and BCZ decreased retention and contact time with biochar functional groups, limiting pollutant removal.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Previous literature found that plant-based biochar adsorption was dominantly controlled by cation exchange.

    “Previous literature [54] found that plant-based biochar adsorption was dominantly controlled by cation exchange.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [54] Harvey, 2011, Metal interactions at the biochar-water interface: Energetics and structure-sorption relationships elucidated by flow adsorption microcalorimetry, Environ. Sci. Technol. source

  • May combine two claims.

    Interpretationown data

    This study showed that application of biochar as a bioretention media would enhance stormwater treatment and reduce heavy metal discharge to groundwater and streams.

    “This study showed that the application of biochar as a bioretention media would enhance stormwater treatment and reduce heavy metal discharge to groundwater and streams.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Interpretationnone given

    Possible adsorption mechanisms of Cd by biochar are cation exchange, surface complexation, precipitation, and electrostatic interactions.

    “The possible adsorption mechanisms of Cd by biochar are cation exchange, surface complexation, precipitation, and electrostatic interactions.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    The homogenous mixture of sand and biochar in BCM allowed the metal solution to pass with higher velocity through the media, and there was reduced contact time for physical adsorption compared to BCL.

    “The homogenous mixture of sand and biochar in BCM allowed the metal solution to pass with higher velocity through the media, and there was reduced contact time for physical adsorption in comparison to the BCL.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    Biochar's metal retention abilities can be attributed to greater surface area, which increases physical adsorption sites.

    “Biochar's metal retention abilities can be attributed to the greater surface area, which increases physical adsorption sites.”
    Quote in the paperNot a substantial claim
57 of 57

  • The paper relies on this without support.

    Laboratory column results are indicative of field-scale bioretention performance for stormwater treatment.

    “The experiment was conducted in larger columns to better represent field conditions, compared to adsorption experiments that rely on batch reactors to test adsorbent performance.”
    “This study's output provides useful information for stormwater management practices.”

  • The authors state this as an assumption.

    BCZ would outperform both BCL and BCM.

    “The assumption was that BCZ would outperform both BCL and BCM [9].”

  • The authors state this as an assumption.

    A significant surface area reduction occurred in BC-nZVI compared to biochar during the synthesizing process.

    “A significant surface area reduction was expected in BC-nZVI compared to biochar (used in BCL and BCM) during the synthesizing process (discussed in Section 2.1.1).”

  • The authors state this as an assumption.

    BCZ may have suffered from the cleaning process, losing fine particles when rinsed with ethanol to prevent excessive oxidation.

    “The assumption is that BCZ may have suffered from the cleaning process, losing fine particles when rinsed with ethanol to prevent excessive oxidation.”

  • The authors state this as an assumption.

    A linear isotherm approach can quantify Kd values based on the measured metal concentrations.

    “A linear isotherm approach was assumed to quantify K d values based on the measured metal concentrations and displayed in Table 4.”

  • The authors state this as an assumption.

    BCM would have very similar water content values throughout the column given free drainage.

    “The expectations were that BCM would have very similar water content values throughout the column given free drainage.”
6 of 6

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Four listed column configurations are called three

    Minor

    The setup describes C1 through C4 while calling them three combinations; it also explicitly states elsewhere that there were four combinations.

  • Abstract understates the BCZ attachment-coefficient maximum

    Minor

    The abstract gives a maximum BCZ attachment coefficient of 26.0 L/kg, but Table 4 lists a BCZ value of 26.5 L/kg for Cd.

  • Arsenic removal is reported as both 99% and 97.7% for BCZ

    Minor

    The abstract reports 99% arsenic removal by BCZ, whereas the results report an average of 97.7% after 200 days. Rounded to a whole percent, 97.7% is 98%, not 99%.

  • BCM has two different bottom-sensor readings at steady state

    Minor

    One passage assigns the BCM bottom sensor a steady-state reading of 20.5%; the next assigns the bottom-located sensor three a steady-state reading of 44.3%.

  • Iron oxidation state in the reaction conflicts with the named reagent

    Minor

    The synthesis specifies ferrous sulfate, whose iron is Fe(II), but the stated reaction starts with Fe(III).

  • Abstract and Table 4 disagree on the sand coefficient minimum

    Minor

    The abstract gives the minimum sand attachment coefficient as 9.6 L/kg, while Table 4 lists 9.5 L/kg.

  • Sensor three is placed at both the top and bottom

    Minor

    The methods place sensor three near the top of the column, but the results identify it as being at the bottom.

7 of 7

Cites

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Cited by

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Related

Authors
Hasan, M. S., Vasquez, R., & Geza, M.
Affiliations
  • South Dakota School of Mines and Technology (US)
  • South Dakota Department of Environment &amp; Natural Resources, Rapid City, SD 57701, USA
Corresponding author
Geza, Mengistu
ORCID
Venue
Processes
Publisher
MDPI AG
Published
2021-05-13
Volume
9
Issue
5
Pages
860
ISSN
2227-9717 (ISSN-L)
DOI
10.3390/pr9050860
OpenAlex
W3160454767
Semantic Scholar
7afb15b1db04ee09ddc1ce2b5297128470cd3b2a
Cited by
16
References
56
Citations by year
2026: 2 · 2025: 3 · 2024: 3 · 2023: 2 · 2022: 5 · 2021: 1
FWCI
0.88
Type
journal article
Language
en
Open access
Licence
Locations
  • Processes (publishedVersion, cc-by)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
  • Nelson Foundation Grant (03618)
  • Water Resources Foundation (437000)
Topics
  • Physical Sciences › Environmental Science › Environmental Engineering › Urban Stormwater Management Solutions
  • Physical Sciences › Engineering › Biomedical Engineering › Environmental remediation with nanomaterials
  • Physical Sciences › Environmental Science › Water Science and Technology › Adsorption and biosorption for pollutant removal
Keywords
biochar, stormwater treatment, heavy metal removal, arsenic, cadmium, copper, lead, zinc, nanoscale zero-valent iron, column experiments, inverse modeling, hydraulic parameters, adsorption coefficient, surface complexation, stormwater runoff, media configuration

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-18.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-18.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

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