Papers by Eric van Hullebusch
Selenium is an essential trace element needed for all living organisms. Despite its essentiality,... more Selenium is an essential trace element needed for all living organisms. Despite its essentiality, selenium is a potential toxic element to natural ecosystems due to its bioaccumulation potential. Though selenium is found naturally in the earth's crust, especially in carbonate rocks and volcanic and sedimentary soils, about 40% of the selenium emissions to atmospheric and aquatic environments are caused by various industrial activities such as mining-related operations. In recent years, advances in water quality and pollution monitoring have shown that selenium is a contaminant of potential environmental concern. This has practical implications on industry to achieve the stringent selenium regulatory discharge limit of 5 μg Se L −1 for selenium containing wastewaters set by the United States Environmental Protection Agency. Over the last few decades, various technologies have been developed for the treatment of selenium-containing wastewaters. Biological selenium reduction has emerged as the leading technology for removing selenium from wastewaters since it offers a cheaper alternative compared to physico-chemical treatments and is suitable for treating dilute and variable selenium-laden waste-waters. Moreover, biological treatment has the advantage of forming elemental selenium nanospheres which exhibit unique optical and spectral properties for various industrial applications, i.e. medical, electrical, and manufacturing processes. However, despite the advances in biotechnology employing selenium reduction, there are still several challenges, particularly in achieving stringent discharge limits, the long-term stability of biogenic selenium and predicting the fate of bioreduced selenium in the environment. This review highlights the significance of selenium in the environment, health, and industry and biotechnological advances made in the treatment of selenium contaminated wastewaters. The challenges and future perspectives are overviewed considering recent biotechnological advances in the management of these selenium-laden wastewaters.
This preliminary study aims to examine, at laboratory scale, the mechanisms and performances prov... more This preliminary study aims to examine, at laboratory scale, the mechanisms and performances provided by coupling the enhanced solubility abilities of cyclodextrin solutions for removal of 2,4,6-Trinitrotoluene (TNT) from contaminated soil with advanced oxidation processes (AOPs) that are regarded as the most effective approaches in treatment of wastewater contaminated with persistent and toxic organic pollutants. In recent years, different Fenton technologies have turned out to be quite appealing to eliminate recalcitrant organic pollutants. Among the different Fenton-like technologies currently available, indirect electrochemical treatment, namely electro-Fenton process, has appeared to be quite efficient in eliminating refractory organic compounds from aqueous media. HPLC/DAD was employed to monitor the TNT degradation and to identify the aromatic intermediates formed during the electro-Fenton oxidation of TNT. Absolute rate constant of TNT hydroxylation by hydroxyl radicals was determined as 2.06 × 10 10 M -1 s -1 using competition kinetics method. Complete mineralization of synthetic solutions was achieved after quite long oxidation time (8 hours). After successive TNT hydroxylations, oxidative opening of the highly oxidized TNT aromatic ring quickly occurred within 20 minutes, leading to the accumulation of two main short chain carboxylic acids such as oxalic and glyoxylic acids. Our results also indicated that cyclodextrin had little effect on the degradation rates of TNT. This relative improvement in TNT degradation could be explained by the formation of the ternary complex (TNT-cyclodextriniron). Degradation of TNT included in cyclodextrin complex was unaffected by hydroxyl radical scavengers which would, in any case, justify the use of a Fenton-like process for the final treatment of soil extract solutions.
Journal of Engineering Science and Technology
The bioleaching of zinc, manganese, chromium, iron and copper from coal ash (fly and bottom) from... more The bioleaching of zinc, manganese, chromium, iron and copper from coal ash (fly and bottom) from coal ash pond using mixed culture of Acidithiobacillus albertensis and Acidithiobacillus thiooxidans was studied. Using the Box-Behnken experimental design, there are three variable parameters used namely: initial bacterial inoculum, % pulp density and weight of sulfur added. After fifteen days of bioleaching, the maximum percentage metals leached were 56.69% Zn, 70.68% Mn, 79.86% Cr, 70.74% Fe and 69.32% Cu at different variable parameters. Also, the solution has an initial pH value of 2 was decrease from a range of 1.39 to 0.61 due to the oxidation of sulfur via microbial activity. Based on the statistical analysis, the experimental data fit the quadratic model for all metal leached. Moreover, using numerical optimization the significant parameters are pulp density and initial mass of sulfur. Using the optimal parameters, the maximum percent metal leached were 56.38% Zn, 70.88% Mn, 85.01% Cr, 74.44% Fe and 74.46% Cu.
Water, Air, & Soil Pollution, 2015
Characterization of the coal ash from a typical coal-fired circulating fluidized bed (CFB) power ... more Characterization of the coal ash from a typical coal-fired circulating fluidized bed (CFB) power plant in the Philippines was done by studying physical and chemical properties as well as toxic elements content from Semirara and Indonesian fly and bottom ashes. Laboratory-scale experiment was carried out using serial batch leaching procedure (SBLP) to determine the leaching behavior of toxic elements from coal ashes and to mimic the environmental condition using sulfuric acid. From the X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses, the main compound present is CaO which makes the coal ash alkaline in nature. Moreover, SiO 2 , Fe 3 O 4 , and other trace minerals are also present. Also, toxicity characterization leaching procedure (TCLP) shows that more than 99 % of chromium and arsenic remain in the coal ashes matrix. The results of the chemical analysis of eluates deduced by the application of standard leaching tests according to TCLP method indicated that hazardous elements such as heavy metals and metalloids contained in fly and bottom ashes could potentially be transferred to the liquid phase. According to the Microtox analysis, the bottom ashes are less toxic than fly ashes due to the vaporization of toxic elements during the combustion and their subsequent adsorption on the surface of fly ashes. Furthermore, leaching of chromium from the coal ash samples was significantly affected by initial pH of the leachant adjusted with sulfuric acid. The highest leaching rate was reached using the combined condition of pH of 8, contact time of 8 h, and L/S of 5. With these conditions, the leaching rate of chromium from SBA is 0.059, from SFA is 0.070, from IBA is 0.054, and from IFA is 0.06 g Cr/g of ash per hour. Based on literature, the results are relatively comparable.
Waste Management, 2015
An effective strategy for environmentally sound biological recovery of copper and gold from disca... more An effective strategy for environmentally sound biological recovery of copper and gold from discarded printed circuit boards (PCB) in a two-step bioleaching process was experimented. In the first step, chemolithotrophic acidophilic Acidithiobacillus ferrivorans and Acidithiobacillus thiooxidans were used. In the second step, cyanide-producing heterotrophic Pseudomonas fluorescens and Pseudomonas putida were used. Results showed that at a 1% pulp density (10g/L PCB concentration), 98.4% of the copper was bioleached by a mixture of A. ferrivorans and A. thiooxidans at pH 1.0-1.6 and ambient temperature (23±2°C) in 7days. A pure culture of P. putida (strain WCS361) produced 21.5 (±1.5)mg/L cyanide with 10g/L glycine as the substrate. This gold complexing agent was used in the subsequent bioleaching step using the Cu-leached (by A. ferrivorans and A. thiooxidans) PCB material, 44.0% of the gold was mobilized in alkaline conditions at pH 7.3-8.6, and 30°C in 2days. This study provided a proof-of-concept of a two-step approach in metal bioleaching from PCB, by bacterially produced lixiviants.
Journal of Engineering Science and Technology
The bioleaching of zinc, manganese, chromium, iron and copper from coal ash (fly and bottom) from... more The bioleaching of zinc, manganese, chromium, iron and copper from coal ash (fly and bottom) from coal ash pond using mixed culture of Acidithiobacillus albertensis and Acidithiobacillus thiooxidans was studied. Using the Box-Behnken experimental design, there are three variable parameters used namely: initial bacterial inoculum, % pulp density and weight of sulfur added. After fifteen days of bioleaching, the maximum percentage metals leached were 56.69% Zn, 70.68% Mn, 79.86% Cr, 70.74% Fe and 69.32% Cu at different variable parameters. Also, the solution has an initial pH value of 2 was decrease from a range of 1.39 to 0.61 due to the oxidation of sulfur via microbial activity. Based on the statistical analysis, the experimental data fit the quadratic model for all metal leached. Moreover, using numerical optimization the significant parameters are pulp density and initial mass of sulfur. Using the optimal parameters, the maximum percent metal leached were 56.38% Zn, 70.88% Mn, 85.01% Cr, 74.44% Fe and 74.46% Cu.
Characterization of the coal ash from a typical coal-fired circulating fluidized bed (CFB) power ... more Characterization of the coal ash from a typical coal-fired circulating fluidized bed (CFB) power plant in the Philippines was done by studying physical and chemical properties as well as toxic elements content from Semirara and Indonesian fly and bottom ashes. Laboratory-scale experiment was carried out using serial batch leaching procedure (SBLP) to determine the leaching behavior of toxic elements from coal ashes and to mimic the environmental condition using sulfuric acid. From the X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses, the main compound present is CaO which makes the coal ash alkaline in nature. Moreover, SiO 2 , Fe 3 O 4 , and other trace minerals are also present. Also, toxicity characterization leaching procedure (TCLP) shows that more than 99 % of chromium and arsenic remain in the coal ashes matrix. The results of the chemical analysis of eluates deduced by the application of standard leaching tests according to TCLP method indicated that hazardous elements such as heavy metals and metalloids contained in fly and bottom ashes could potentially be transferred to the liquid phase. According to the Microtox analysis, the bottom ashes are less toxic than fly ashes due to the vaporization of toxic elements during the combustion and their subsequent adsorption on the surface of fly ashes. Furthermore, leaching of chromium from the coal ash samples was significantly affected by initial pH of the leachant adjusted with sulfuric acid. The highest leaching rate was reached using the combined condition of pH of 8, contact time of 8 h, and L/S of 5. With these conditions, the leaching rate of chromium from SBA is 0.059, from SFA is 0.070, from IBA is 0.054, and from IFA is 0.06 g Cr/g of ash per hour. Based on literature, the results are relatively comparable.
ABSTRACT Cementitious materials biodeterioration in sewer networks is an important problem for se... more ABSTRACT Cementitious materials biodeterioration in sewer networks is an important problem for sewer networks managers. This deterioration process is due to the implication of two biofilm involved in the sulfur cycle. Microorganisms of the first biofilm will reduce sulfate and organic sulfur compounds into H2S in the effluent and then, the second biofilm oxidizes it into sulfuric acid in the structure headspace. This biogenic acid usually leads to the cementitious matrix dissolution. However, cementitious materials do not equivalently face biogenic acid attack. In very aggressive conditions, those made of ordinary Portland cement are highly deteriorated while those based on calcium aluminate cement show good on-site performances. So far, only chemical testing standard procedures are available to predict service life of materials intended for sewer networks but they are not representative of the phenomenon because they do not consider microbial development. Nowadays, it is necessary to develop a new test that could be standardiable involving microorganisms. Such a test has been developed at Ifsttar and provides interesting results.
ABSTRACT Sewer networks should withstand several aggressions, including biodeterioration processe... more ABSTRACT Sewer networks should withstand several aggressions, including biodeterioration processes. This study is focusing on cementitious materials since, depending on their composition, these materials do not display the same behaviour when biogenic sulfuric acid attack occurs. In severe conditions, ordinary Portland cement materials can be deteriorated, while calcium aluminate cement (CAC) materials show good resistance to biogenic corrosion. Results show that this durability difference is due to the difference of cement mineralogy. Firstly, the H2S abiotic oxidation into elemental sulfur is less favourable on CAC. Hence it provides much less nutrients for sulfur-oxidizing microorganisms. Then, the presence of high aluminium content in CAC provides a combination of interesting properties to face biogenic acid attack. The hydrated alumina reacts with acid to create an alumina gel layer, stable up to pH 3-4. The acid attack leads to the release of aluminium ions displaying a bacteriostatic effect on neutrophilic sulfur-oxidizing microorganisms. Finally, an alumina gel precipitates on the surface. This gel has an impact on cement surface porosity which therefore reduces the acid impact and probably limiting biofilm adhesion.
International Biodeterioration & Biodegradation, 2013
Sewer networks contain many aggressive and corrosive agents for pipe materials. One type of damag... more Sewer networks contain many aggressive and corrosive agents for pipe materials. One type of damage can be ascribed to concrete corrosion by biogenic sulfuric acid. According to field data, cementitious materials have different behaviors depending in particular on cement type: Those made with calcium aluminate cement (CAC) offer better performance than those made of ordinary Portland cement (OPC). The development of an accelerated and accurate laboratory test is essential to better understand the mechanisms involved for all cementitious materials. However, to define such a test, some additional knowledge is required. The present study deals with in situ experiments in order to determine the biochemical parameters influencing the behaviors of OPC and CAC materials. Based on these determinations, supplemented by laboratory studies, it can be concluded that abiotic oxidation of hydrogen sulfide, bioreceptivity of the mineral surface, and growth of bacterial strains depend greatly on cementitious material types. All these results, complemented by literature data, lead to consideration of what the best parameters are to study biodeterioration of cementitious materials, and have been helpful in designing the biodeterioration chamber tested.
Journal of Environmental Monitoring, 2003
... 4 (pH 3) leaching 17.0% of total Co content at the stage 3 of the scheme B were effective ext... more ... 4 (pH 3) leaching 17.0% of total Co content at the stage 3 of the scheme B were effective extractants for the relevant target phases in extracting ... forms stable metal complexes with C 2 O 4 2− ions like [Cr(C 2 O 4 ) 3 ] 3− being extracted into the solution from the solid residue. ...
Environmental Science and Pollution Research, 2016
Various mineral processing operations to produce pure metals from mineral ores generate sludges, ... more Various mineral processing operations to produce pure metals from mineral ores generate sludges, residues, and other unwanted by-products/wastes. As a general practice, these wastes are either stored in a reservoir or disposed in the surrounding of mining/smelting areas, which might cause adverse environmental impacts. Therefore, it is important to understand the various characteristics like heavy metal leaching features and potential toxicity of these metallurgical wastes. In this study, zinc plant leach residues (ZLRs) were collected from a currently operating Zn metallurgical industry located in Minas Gerais (Brazil) and investigated for their potential toxicity, fractionation, and leachability. Three different ZLR samples (ZLR1, ZLR2, and ZLR3) were collected, based on their age of production and deposition. They mainly consisted of Fe (6-11.5 %), Zn (2.5 to 5.0 %), and Pb (1.5 to 2.5 %) and minor concentrations of Al, Cd, Cu, and Mn, depending on the sample age. Toxicity Characteristic Leaching Procedure (TCLP) results revealed that these wastes are hazardous for the environment. Accelerated Community Bureau of Reference (BCR) sequential extraction clearly showed that potentially toxic heavy metals such as Cd, Cu, Pb, and Zn can be released into the environment in high quantities under mild acidic conditions. The results of the liquid-solid partitioning as a function of pH showed that pH plays an important role in the leachability of metals from these residues. At low pH (pH 2.5), high concentrations of metals can be leached: 67, 25, and 7 % of Zn can be leached from leach residues ZLR1, ZLR2, and ZLR3, respectively. The release of metals decreased with increasing pH. Geochemical modeling of the pH-dependent leaching was also performed to determine which geochemical process controls the leachability/solubility of the heavy metals. This study showed that the studied ZLRs contain significant concentrations of non-residual extractable fractions of Zn and can be seen as a potential secondary resource for Zn.
Environmental pollution (Barking, Essex : 1987), Jan 18, 2016
The remediation of a genuinely PAH-contaminated soil was performed, for the first time, through a... more The remediation of a genuinely PAH-contaminated soil was performed, for the first time, through a new and complete investigation, including PAH extraction followed by advanced oxidation treatment of the washing solution and its recirculation, and an analysis of the impact of the PAH extraction on soil respirometry. The study has been performed on the remediation of genuine PAH-contaminated soil, in the following three steps: (i) PAH extraction with soil washing (SW) techniques, (ii) PAH degradation with an electro-Fenton (EF) process, and (iii) recirculation of the partially oxidized effluent for another SW cycle. The following criteria were monitored during the successive washing cycles: PAH extraction efficiency, PAH oxidation rates and yields, extracting agent recovery, soil microbial activity, and pH of soil. Two representative extracting agents were compared: hydroxypropyl-beta-cyclodextrin (HPCD) and a non-ionic surfactant, Tween(®) 80. Six PAH with different numbers of rings ...
Journal of hazardous materials, Jan 9, 2015
The release of hydrophobic organoxenobiotics such as polycyclic aromatic hydrocarbons, petroleum ... more The release of hydrophobic organoxenobiotics such as polycyclic aromatic hydrocarbons, petroleum hydrocarbons or polychlorobiphenyls results in long-term contamination of soils and groundwaters. This constitutes a common concern as these compounds have high potential toxicological impact. Therefore, the development of cost-effective processes with high pollutant removal efficiency is a major challenge for researchers and soil remediation companies. Soil washing (SW) and soil flushing (SF) processes enhanced by the use of extracting agents (surfactants, biosurfactants, cyclodextrins etc.) are conceivable and efficient approaches. However, this generates high strength effluents containing large amount of extracting agent. For the treatment of these SW/SF solutions, the goal is to remove target pollutants and to recover extracting agents for further SW/SF steps. Heterogeneous photocatalysis, technologies based on Fenton reaction chemistry (including homogeneous photocatalysis such as p...
Http Dx Doi Org 10 1080 10643389 2012 741307, Mar 6, 2014
Soils contaminated by hydrophobic organic pollutants are a common concern since they are extremel... more Soils contaminated by hydrophobic organic pollutants are a common concern since they are extremely difficult to remove and their potential toxicological impacts are significant. As an alternative to traditional pump-and-treat technologies, soil washing and soil flushing are conceivable and efficient approaches. Extracting agents like cyclodextrins are compared to traditional surfactants, co-solvents and less conventional agents. Ability of cyclodextrin derivatives to form a ternary pollutant-cyclodextrin-iron complex allows discussing about promising integrated treatments requiring modified Fenton treatments like electro-Fenton process with or without combination to a biological step and a recirculation loop.
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Papers by Eric van Hullebusch