Browsing by Author "Jensen, Pernille E."
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- Electrodialytic remediation of heavy metal polluted soil: treatment of water saturated or suspended soilPublication . Ottosen, Lisbeth M.; Jensen, Pernille E.; Kirkelund, Gunvor M.; Ferreira, Célia; Hansen, Henrik K.Electrodialytic soil remediation is a method for removal of heavy metals. Good results have previously been obtained with both treatment of a stationary, water saturated soil matrix and with remediation of a stirred suspension of soil in water. The two different setups have different uses. The first as in-situ or on-site treatment when there is no requirement for fast remediation, as the removal rate of the heavy metals are dependent on the distance between the electrodes (everything else equal) and in such application the electrode spacing must have a certain distance (often meters). In the stirred setup it is possible to shorten the transport route to few mm and to have a faster and continuous process. The present paper for the first time reports a direct comparison of the two options. The remediation of the stirred suspension showed faster than remediation of the water saturated soil even without a short distance between the membranes. The acidification of the suspended soil was fastest and following the mobilization of heavy metals. This may indicate that water splitting at the anion exchange membrane is used more efficiently in the stirred setup.
- Electrodialytic upgrading of MSWI APC residue from hazardous waste to secondary resourcePublication . Jensen, Pernille E.; Kirkelund, Gunvor M.; Viader, Raimon Parés; Magro, Catia; Pedersen, Kristine B.; Ferreira, Célia; Ottosen, Lisbeth M.
- Electrodialytic upgrading of three different municipal solid waste incineration residue types with focus on Cr, Pb, Zn, Mn, Mo, Sb, Se, V, Cl and SO4Publication . Jensen, Pernille E.; Kirkelund, Gunvor M.; Pedersen, Kristine B.; Ottosen, Lisbeth M.; Ferreira, CéliaHandling of air pollution control (APC) residues from municipal solid waste incineration (MSWI) is a challenge due to its toxicity and high leaching of toxic elements and salts. Electrodialysis (ED) of the material has shown potential for reduction of leaching of toxic elements and salts to produce a material feasible for substitution of cement in mortar. In this work results of 23 pilot-scale experiments (5–8 kg APC residue each) in electrodialysis stack designed to investigate the leaching properties as a function of time and current density for APC residue from semi-dry and wet flue-gas cleaning systems, as well as MSWI fly ash without flue-gas cleaning products are reported. Significant leaching reduction of the critical elements Pb, Zn and Cl was obtained. The final leaching, however, depended mostly on the initial leaching, thus as leaching from fly ash and residue of wet flue-gas cleaning was lower before treatment compared to residues from semidry flue-gas cleaning, both Pb and Zn leaching could be reduced to lower levels in those materials, and they therefore appear more suitable for use in construction materials. The leaching reduction of Zn and to some degree Pb decreased with longer retention times and higher current densities. Cr and SO4 leaching increased during ED treatment, with lower increase at higher current. Washing or carbonation in combination with ED significantly reduced leaching of Pb and Zn from semidry residue. An indication of a similar effect to carbonation by simultaneous aeration with ED was observed and should be investigated further. While Mn and Mo leaching did not, Se, V and Sb leaching exceeded threshold values in semidry residue. The leaching of V seemed to increase while Se and Sb remained more or less constant during ED treatment.
- Electroremediation of air pollution control residues in a continuous reactorPublication . Jensen, Pernille E.; Ferreira, Célia; Hansen, Henrik K.; Jens-Ulrik, Rype; Ottosen, Lisbeth M.; Villumsen, ArneAir pollution control (APC) residue from municipal solid waste incineration is considered hazardous waste due to its alkalinity and high content of salts and mobile heavy metals. Various solutions for the handling of APC-residue exist, however most commercial solutions involve landfilling. A demand for environmental sustainable alternatives exists and electrodialysis could be such an alternative. The potential of electrodialysis for treating APC-residue is explored in this work by designing and testing a continuous-flow bench-scale reactor that can work with a high solids content feed solution. Experiments were made with raw residue, water-washed residue, acid washed residue and acid-treated residue with emphasis on reduction of heavy metal mobility. Main results indicate that the reactor successfully removes toxic elements lead, copper, cadmium and zinc from the feed stream, suggesting that the electrodialytic technique is an alternative to land deposition of APC-residues.
- Kinetics of electrodialytic extraction of Pb and soil cations from a slurry of contaminated soil finesPublication . Jensen, Pernille E.; Ottosen, Lisbeth M.; Ferreira, Célia; Villumsen, ArneThe objective of this work was to investigate the kinetics of Pb-removal from soil fines during electrodialytic remediation in suspension, and study the simultaneous dissolution of common soil cations (Al, Ca, Fe, Mg, Mn, Na and K). This was done to evaluate the possibilities within control of the remediation process to leave a final product suitable for reuse. The Pb-remediation process could be divided into four phases: (1) a “lag-phase”, (2) a period with a high removal rate (7.4 mg/day in average at 40 mA), (3) a period with a low removal rate, and (4) a period where no further Pb-removal was obtained. During the first phase, dissolution of carbonates was the prevailing process, resulting in a corresponding loss of soil mass. During this phase, the investigated ions accounted for the major current transfer, while, as remediation proceeded, hydrogen ions increasingly dominated the transfer. During phase (3) the high conductivity and low voltage suggested that removal may be accelerated by increasing the current density. Overall, 97% of the Pb could be extracted, reducing the final Pb-concentration to 25 mg/kg. The order of removal rates was: Ca > Pb > Mn > Mg > K > (Al and Fe).
- Mercury levels in fly ash and APC residue from municipal solid waste incineration before and after electrodialytic remediationPublication . Ferreira, Célia; Kirkelund, Gunvor M.; Jensen, Pernille E.Fly ash (FA) and Air Pollution Control (APC) residues collected from three municipal solid waste incinerators (MSWI) in Denmark and Greenland were treated by electrodialytic remediation at pilot scale for 8 to 10 h. The original residues and the treated material were analysed for mercury (Hg) in order to assess the influence of the electrodialytic treatment on the concentrations of this element. Mercury levels varied with the MSWI residue, ranging from 0.41 mg kg−1 in FA sample from electrostatic precipitator (ESP) to 8.38 mg kg−1 in MSWI residues from a semi-dry system with lime and activated carbon. Two distinct behaviours were observed for mercury as a result of the electrodialytic treatment. This element became enriched in the MSWI residues from the semi-dry system with activated carbon, whereas it decreased in ESP’s and cyclone’s FA. This work presents for the first time information about the effect of electrodialytic treatment on mercury levels and discusses the valorisation options for these MSWI residues.
- The influence of electrodialytic remediation on dioxin (PCDD/PCDF) levels in fly ash and air pollution control residuesPublication . Ferreira, Célia; Kirkelund, Gunvor M.; Jensen, Pernille E.Fly ash and Air Pollution Control (APC) residues collected from three municipal solid waste incinerators in Denmark and Greenland were treated by electrodialytic remediation at pilot scale for 8e10 h. This work presents for the first time the effect of electrodialytic treatment on polychlorinated dibenzo-pdioxins (PCDD) and polychlorinated dibenzofurans (PCDF), and how these levels impact on the valorization options for fly ash and APC residue. PCDD/PCDF levels in the original residues ranged between 4.85 and 197 ng g1 , being higher for the electrostatic precipitator fly ash. The toxic equivalent (TEQ) varied ten fold, ranging 0.18e2.0 ng g1 ITEQ, with penta and hexa-homologs being most significant for toxicity. After the electrodialytic treatment PCDD/PCDF levels increased in the residues (between 1.4 and 2.0 times). This does not mean PCDD/PCDF were synthesized, but else that soluble materials dissolve, leaving behind the non-water soluble compounds, such as PCDD/PCDF. According to the Basel Convention, PCDD/ PCDF levels in these materials is low (<15 mg WHO-TEQ kg1 ) and the fly ash and APC residue could eventually be valorized, for instance as construction material, provided end-of-waste criteria are set and that a risk assessment of individual options is carried out, including the end-of-life stage when the materials become waste again.