
Roger B HerbertUppsala University | UU · Department of Earth Sciences
Roger B Herbert
PhD
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61
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Introduction
Publications
Publications (61)
Mine drainage water may contain high levels of nitrate (NO3-) due to undetonated nitrogen-based explosives. The removal of NO3- and nitrite (NO2-) in cold climates through the microbial process of denitrification was evaluated using a pilot-scale fixed-bed bioreactor (27 m3). Surface water was diverted into the above-ground bioreactor filled with s...
The article demonstrates a method for the adaptation of denitrifying woodchip bioreactors for the removal of sulfate as well. Sulfate is removed by sulfate reduction and subsequent iron sulfide precipitation.
Denitrifying woodchip bioreactors are potential low‐cost technologies for the removal of nitrate (NO3⁻) in water through denitrification. However, if environmental conditions do not support microbial communities performing complete denitrification, other N transformation processes will occur, resulting in the export of nitrite (NO2⁻), nitrous oxide...
At the Kiruna iron ore mine in northern Sweden, mine drainage and process water contain elevated concentrations of nitrate (NO3−) from the use of ammonium nitrate fuel oil explosives. In order to investigate the treatment capacity of a denitrifying woodchip bioreactor technique for the removal of NO3− through denitrification, a bioreactor was insta...
Microplastics accumulate in stormwater and can ultimately enter freshwater recipients, and pose a serious risk to aquatic life. This study investigated the effectiveness of lab-scale horizontal flow sand filters of differing lengths (25, 50 and 100 cm) in retaining four types of thermoplastic microplastics commonly occurring in stormwater runoff (p...
Denitrifying woodchip bioreactors (DWBs) have been proven as efficient nature-based solutions to remove nitrate from water. Exploring denitrification and other processes in DWBs facilitates improving their design. We used the Multi Rate Mass Transfer (MRMT) approach to simulate the reactive transport processes of nitrogen species in a DWB located a...
Nitrogen (N) pollution is a major threat to ecosystems and a driver of climate change through emissions of the greenhouse gas nitrous oxide (N2O). Mining activities are increasingly recognized for contributing to N pollution due to undetonated, N-based explosives. A woodchip denitrifying bioreactor, installed to treat nitrate-rich leachate from was...
A field-scale woodchip bioreactor was installed at the Kiruna iron ore mine (northern Sweden) for the removal of NO3- in mine and process water originating from the use of ammonium nitrate based explosives. Over a period of two years, the woodchip bioreactor removed an average incoming NO3- concentration of 22.0±0.3 mg N L-1 to below detection limi...
Nitrate removal rates in a mixture of pine woodchips and sewage sludge were determined in a controlled laboratory environment (column studies) at 5°C, 12°C and 22°C, and at two different hydraulic residence times (HRT; 58.2-64.0 hours, and 18.7-20.6 hours), with the objective of providing guidelines for the construction of a field-scale denitrifyin...
A geochemical assessment of seasonal dynamics in the groundwater chemistry of the National Capital Territory (NCT), Delhi, was attempted through geochemical modelling, mineral precipitation sequences with rainfall and water evaporation cycle. Saturation indices calculated using PHREEQC indicated that the degree of water–rock equilibrium changes sig...
Weathering of rocks that regulate the water chemistry of the river has been used to evaluate the CO2 consumption rate which exerts a strong influence on the global climate. The foremost objective of the present research is to estimate the chemical weathering rate (CWR) of the continental water in the entire stretch of Brahmaputra River from upstrea...
Study region: Arsenic enriched groundwater regime within low-industrialized Brahmaputra floodplains in Assam, NE India.
Study focus: We examined the origin, distribution and processes of As release by investigating the salient groundwater chemistry and subsurface sedimentological characteristics. Besides collection of groundwater samples from domes...
The bond distances in hydrated arsenic oxyacid species in aqueous solution have been studied by EXAFS spectroscopy and large angle X-ray scattering, LAXS. These results have been compared to structures in the solid state, as found in an extensive survey of available crystal structures. Protonated oxygen atoms can be distinguished with a longer As-O...
Organic substrates in reactive barrier systems are often heterogeneous material mixtures with relatively large contrasts in hydraulic conductivity and porosity over short distances. These short-range variations in material properties imply that preferential flow paths and diffusion between regions of higher and lower hydraulic conductivity may be i...
Laboratory column experiments have been conducted to determine nitrate removal rates from mine effluents by denitrification, with the purpose of providing initial data for the construction of a pilot scale reactive barrier system at the Malmberget iron mine, Sweden. Experiments were conducted at several different flow rates at 5C, 10C and room temp...
The contribution of the milling, smelting, and refining of sulfide ores to Hg emissions and to Hg byproduction is not adequately quantified in a global context. In this study, we estimate Hg emissions from the pyrometallurgical treatment of Cu, Pb, and Zn sulfide ores. We base our calculations on quantities processed and Hg content in Cu, Pb, and Z...
Iron isotope ratios were determined for the pore water, the 1 M HCl/1 M hydroxylamine hydrochloride (HAH)-extractable solid phase, and the total extractable solid phase from sulfidic mine tailings in Impoundment 1, Kristineberg mine, northern Sweden. Within the tailings, pyrite oxidation occurs in a distinct Fe-depleted oxidation zone, and the grea...
Column experiments investigated the stabilization of waste rock from Ljusnarsberg mine in Kopparberg, Sweden. In order to inhibit the generation of acidic leachate from the waste rock, biosludge and a Ca carbonate – rich residue from the paper industry were mixed with the sulfidic mine waste. The results of the column experiments indicate that the...
Groundwater down-gradient from a mine rock dump in Dalarna, Sweden was sampled from the onset of snowmelt runoff (April) until October in order to investigate seasonal variations in groundwater composition. The results demonstrate that considerable variation in solute concentration (Al, Cu, Fe, SO42−, Zn) and acidity occurs in groundwater; the grea...
Unexpectedly high aluminium concentrations beside fluoride and essential elements are released from metal salts adsorbed to volcanic ash. Through simulation of the mixing of pristine volcanic ash leachate with fresh water and seawater using PHREEQC, we found an increased potential toxicity in fresh waters through the combination of high aluminium a...
Sulfide mineral oxidation in mine tailings deposits poses a long term threat to surrounding ground water and surface waters. Soil or water cover remediation aims at reducing the rate of sulfide mineral oxidation by decreasing the O2 ingress rate. In this study, the authors addressed the rate of sulfide oxidation and pH buffering in ∼33 months long,...
Pyrite oxidation rates were examined at various concentrations of dissolved oxygen (DO) in the presence of the sulfur and iron oxidizer Acidithiobacillus ferrooxidans. Five different batch experiments were performed at room temperature for 75 days under various DO levels (273, 129, 64.8, 13.2, and ≤0.006 μM), containing pyrite grains (particle size...
The microbial population of a sludge amended leaf compost material utilized for treatment of artificial acid mine drainage was studied by culture-independent molecular methods. Iron-rich and sulfurous wastewater (artificial acid mine drainage) was circulated through a column bioreactor for 16 months. After 12 months the column was inoculated with a...
Effective treatment techniques for eliminating iron-oxidizing (IOB) and sulfur-oxidizing bacteria (SOB) are required for the comparison of abiotic and microbial sulfide oxidation rates and mechanisms in mine tailings. This study evaluates the effect of autoclaving, repeated heating, ethanol treatment, antibiotic treatment, gamma-radiation, and wash...
The MiMi programme has studied the processes in deposits of sulphide containing mine tailings. The aim has been to understand the chemical and transport processes sufficiently well to design methods that will hinder unacceptable releases of acidity, toxic metals and other substances to the environment. The time scales considered have been hundreds...
In bioreactor systems for the treatment of metal-contaminated water, pretreatment with zerovalent Fe can be exploited for oxygen consumption and H2 production. In this study, a column experiment is used to investigate the changes in surface chemistry and solid phase products that result from the reaction of a Zn-sulphate-lactate solution with zerov...
This work focuses on sulfide mineral oxidation rates under oxic conditions in freshly processed pyrite-rich tailings from the ore concentrator in Boliden, northern Sweden. Freshly processed tailings are chemically treated in the plant to kill bacteria and to obtain increased metal yields, resulting in a high pH level of 10–12 in the process water....
This paper discusses the solid phase Fe–S geochemistry of a reactive barrier at the Nickel Rim mine site (Ontario, Canada). The barrier, designed to treat groundwater contaminated by acid mine drainage, is composed of leaf and municipal compost and wood chips. This study shows that S is accumulating in the organic material as primarily acid volatil...
Compositional zoning in iron oxyhydroxides precipitated from mine drainage-contaminated groundwater was studied by electron microprobe (EMP) analysis. The observed zoning is characterized by variations in Al, Fe, S, and Si concentrations, with mean precipitate concentrations of ca. 56.0 wt.% Fe, 1.1 wt.% Al, 2.0 wt.% Si, and 0.5 wt.% S. The analyse...
A permeable reactive barrier, designed to remove metals and generate alkalinity by promoting sulfate reduction and metal sulfide precipitation, was installed in August 1995 into an aquifer containing effluent from mine tailings. Passage of groundwater through the barrier results in striking improvement in water quality. Dramatic changes in concentr...
This study characterizes the surface chemistry and morphology of poorly crystalline iron sulfides precipitated in a chemically defined growth media for sulfate-reducing bacteria. The precipitates were analyzed by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Based on XRD results, the prec...
The discharge of acidic mine drainage waters onto a hillslope in Dalarna, central Sweden, has lead to the contamination of
the podzol soils with Cu, Fe, Ni, Pb, Zn and sulfate. Samples from contaminated and reference soils have been collected for
chemical and mineralogical analyses. Jarosite is identified by x-ray diffraction analysis as a precipit...
This study investigates the retention of heavy metals in secondary precipitates from a sulfidic mine rock dump and underlying
podzolic soils by means of mineralogical and chemical extraction methods. The rock dump, which is at least 50 years old, consists
of a 5–10-cm-thick leached zone and an underlying 110–115-cm-thick accumulation zone. Optical...
This study characterizes various chemical and mineralogical properties of goethite and jarosite from a mine drainage environment using chemical extraction techniques, X-ray diffractometry (XRD), 57Fe M6ssbauer spectroscopy and scanning electron microscopy (SEM). Goethite and jarosite precipitates were collected from leachate-contaminated soils and...
This study provides a characterization of goethite and lepidocrocite precipitates that form from ground water contaminated by acid mine leachate in Dalarna, Sweden. Chemical extraction techniques and electron microprobe analyses indicate that Al, Cu, Ni, S, Si, Ti, and Zn may be retained in the goethite structure. The metals are retained by either...
The ferric minerals goethite, lepidocrocite, and jarosite precipitate from groundwater contaminated by mine waste leachate in Dalama, Sweden. Goethite and lepidocrocite occur as massive precipitates at the water table, cementing together mineral grains and smaller rock fragments. Analysis of the precipitates by SEM indicates that they are primarily...
Recently investigations have shown that the annual flux of lead from shotgun pellets to shooting range soils is significant in some countries. This paper presents the data of chemical and mineralogical analyses of soils and Pb-pellet crusts from five shooting ranges in Sweden and, based on these results, evaluates the retention of lead in these sho...
In order to determine which processes may be controlling the evolution of the leachate plume, the geochemical mass-transfer model PHREEQE is used to evaluate a possible reaction pathway controlling the reaction of the leachate plume with uncontaminated groundwater and the till aquifer. The results suggest that silicate weathering and goethite preci...
The cover is designed with a 0.5 m layer of clay covered by a 1.5 m layer of glacial till. Evaluation of cover effectiveness is based on: 1) the reduction of leachate production, and 2) the ability of the clay layer to remain water saturated and avoid cracking. The numerical model SUTRA simulates unsaturated flow in the cover, with results interpre...
The production of acidic mine waters containing high concentrations of sulphate and metals are of great environmental concern. One method for removing metals from leachate waters is by stimulating sulphate reduction in a treatment system, thereby producing alkalinity and hydrogen sulphide. Dissolved metals and hydrogen sulphide may then precipitate...
Thesis (Ph. D.)--Uppsala University, 1995. Includes bibliographical references.