Djurdja Kerkez

Degradation of Anthraquinone Dye Reactive Blue 4 in Pyrite Ash Catalyzed Fenton Reaction

Pyrite ash (PA) is created by burning pyrite in the chemical production of sulphuric acid. The high concentration of iron oxide, mostly hematite, present in pyrite ash, gives the basis for its application as a source of catalytic iron in a modified Fenton process for anthraquinone dye reactive blue 4 (RB4) degradation. The effect of various operating variables such as catalyst and oxidant concentration, initial pH and RB4 concentration on the abatement of total organic carbon, and dye has been assessed in this study. Here we show that degradation of RB4 in the modified Fenton reaction was efficient under the following conditions: pH = 2.5; [PA]0 = 0.2 g L−1; [H2O2]0 = 5 mM and initial RB4 concentration up to 100 mg L−1. The pyrite ash Fenton reaction can overcome limitations observed from the classic Fenton reaction, such as the early termination of the Fenton reaction. Metal (Pb, Zn, and Cu) content of the solution after the process suggests that an additional treatment step is necessary to remove the remaining metals from the water. These results provide basic knowledge to better understand the modified, heterogeneous Fenton process and apply the PA Fenton reaction for the treatment of wastewaters which contains anthraquinone dyes.

Preremedial assessment of the municipal landfill pollution impact on soil and shallow groundwater in Subotica, Serbia

Most regional municipal solid waste landfills in Serbia are operated without control of landfill leachate and gas or with no regard for implementation of national and European legislation. For the first time in Serbia, groundwater and soil at a landfill were subject to systematic annual monitoring according to national, European legislation and adopted methodologies. Characterisation of the groundwater and soil samples from the landfill included ten metals (Fe, Mn, As, Zn, Cd, Pb, Ni, Cr, Cu and Hg), 16 EPA PAHs, nutrients and certain physicochemical parameters, in order to assess the risks such poorly controlled landfills pose to the environment. This impact assessment was performed using specially adapted pollution indices: LWPI, the Single factor pollution index and the Nemerow index for groundwater, and geo-accumulation index, ecological risk factor and selected rations of PAHs for soil. The data analysis included multivariate statistical methods (factor analysis of principal component analysis (PCA/FA)) in order to assess the extent of the contaminants detected in the groundwater and soil samples. The pollution indices (LWPI: 3.56-8.89; Nemerow index: 2.02-3.78) indicate the quality of the groundwater at the landfill is degrading over time, with PAH16, TOC, Cr, Cu, Pb and Zn as the substances of greatest concern. Heavy metals Hg (Igeo≤3.14), Pb (Igeo≤2.22), Cr (Igeo≤3.31) and Cu (Igeo≤2.16) represent the worst soil contamination. Hg has moderate (52.9) to very high (530.0) potential ecological risk, demonstrating the long-term potential effects of bioaccumulation and biomagnification. The results of this work indicate that Cr and Cu should possibly be added to the EU Watch List of emerging substances. This proposition is substantiated by relevant state and alike environmental information from nations in the region. This study demonstrates the need to develop a model for prioritization of landfill closure and remediation based on environmental risk assessment.

Influence of Electric Field Operation Modes on Nickel Migration during Electrokinetic Treatment

ABSTRACT Nickel-contaminated sediment can be remediated by electrokinetic techniques. In practical application, nickel may migrate into deep layers and potentially pollute unpolluted layers. In this study, the influence of different types of electric field operation modes on nickel migration in sediment layers was studied. The following experiments were conducted: without current application (NC), with horizontal electric field (HEF), with vertical electric field (VEF), and 2D electric field (horizontal and vertical). The following Ni overall removal efficacies were achieved: 48.9, 49.4, 55.7, and 58.1 after VEF, NC, 2D, and HEF, respectively. Using a vertical electric field in 2D and VEF resulted in less Ni found in the vertical sediment bed (25% and 60%, respectively). The available Ni content in a contaminated sediment bed decreased significantly after using the electrokinetic treatments: 46%, 62%, and 79% after HEF, VEF, and 2D, respectively. Vertical electric field is the most efficient for Ni removal in terms of the amount of Ni that migrated into deeper layers of sediment bed and its amount in mobile form. Thus, the vertical electric field is a promising and practical method for the remediation of nickel-contaminated sediments. Risk analysis indicated the efficiency of EK treatment as available Ni content was reduced after the applied treatments to a degree that poses no risk for the environment.

Potential application of nanomaterials in the treatment of contaminated sediment

In the conducted research nano zero valent iron has been used as the immobilization agent in the remediation treatment of dredged sediment, as well as the treatment that is performed on-site (in-situ). Study aims to find a better understanding of the behavior of metals in sediments and to determine their potential mobility, bioavailability and potential toxicity based on sequential extraction procedures. In order to evaluate the extraction potential of toxic metals and the effectiveness of the treatment applied, three single-step leaching tests were performed. When applying nanomaterial, as the immobilization agent in sediment treatment, using two remediation options (ex situ and in – situ), high stability of the metals is achieved in treated sediment.