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This article is part of the special series "Remtech Europe 2021: International Approaches to Contamination Management." The series documents and advances the current state of the practice, with respect to the sustainable management of contaminated sites, high resolution techniques for characterization, disrupting technologies for remediation of soil and groundwater, and risk assessment frameworks.

<p>The aim of this study was to investigate the transport behavior of two selected organophosphorus pesticides (chlorpyrifos-CP and chlorpyrifos-methyl-CPM) through Danube alluvial sediment in the absence and in the presence of microbially inoculated chars originated from sugar beet shreds (biochar produced at 400°C and three hydrochars produced at 180, 200, and 220°C). <em>Bacillus megaterium</em> strain was used for microbial inoculation of investigated carbon-based adsorbents. Column experiments were used to simulate sorption in non-equilibrium conditions. Obtained results were modeled using the advective-dispersive equation (ADE). For column experiments only with alluvial sediment retardation coefficient (<em>R</em><sub>d</sub>) was in the range (<em>R</em><sub>d</sub>=15.5-16) and higher biodegradation was observed for CPM (<em>λ=</em>4.15) than for CP (<em>λ=</em>1.80). The retardation coefficient (<em>R</em><sub>d</sub>) for investigated compounds in column experiments with the addition of inoculated carbon-based materials ranged from (<em>R</em><sub>d</sub>=20-275). The addition of inoculated carbon based materials in a column filled with alluvial sediment significantly increases the retardation coefficient (<em>R</em><sub>d</sub>). This may be a consequence of simultaneous adsorption on the organic matter of the alluvial sediment, on carbon-based materials and results of biosorption. The biodegradation (<em>λ</em>) of the investigated compounds in a column filled with the addition of inoculated adsorbents was in range (<em>λ=</em>0.4-4.5)<em> </em>and was lower compared to the column without the addition of chars. A higher retardation coefficient (<em>R</em><sub>d</sub>) in column experiments with the addition of inoculated chars was observed for biochar than for hydrochars, which is directly correlated with the higher specific surface area (SSA) of the investigated biochar. Generally, the addition of inoculated carbon-based materials to contaminated sediments has the potential as a remediation technique to inhibit the leaching of pollutants to groundwaters and affect their immobilization.</p> <p><strong>Keywords</strong>: transport, biochar, hydrochar, chlorpyrifos, chlorpyrifos-methyl, sugar beet shreds</p> <p><strong>Acknowledgment </strong></p> <p>Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or European Research Executive Agency (REA). Neither the European Union nor the granting authority can be held responsible for them. Grant agreement No. 101059546</p>

<p>Increased pesticide uses over the last few decades raise a serious threat to environment, especially to the groundwater the most important drinking water resource. This work investigates the biodegradation potential of two selected organophosphorus pesticides, OPPs (fenthion and disulfoton) on Danube alluvial sediment in the presence of microbially inoculated biochar (BC). The investigated BC was produced by slow pyrolysis of the <em>Miscanthus giganteus</em> at a temperature of 400°C. <em>Bacillus megaterium</em> BD5 was isolated from the alluvial Danube sediment sample and was successfully immobilized on BC in the form of vegetative cells and endospores. The breakthrough curve of thiourea as a nonsorbing substance was symmetrical, indicating absence of physical nonequilibrium processes in porous media. In general, the results indicate that the <em>R<sub>d</sub></em> coefficient for fenthion (<em>R<sub>d</sub></em>=30) is higher than the <em>R<sub>d</sub></em> for disulfoton (<em>R<sub>d</sub></em>=20), but higher biodegradation was observed for disulfoton (λ=6) than for fenthion (λ=4.5). The highest biodegradation could be a consequence of high adsorption on BC and biosorption. Further enhancement of the biodegradation processes could be achieved by integration with bioelectrochemical remediation system, which will be done in the future experiments.</p> <p><strong>Acknowledgment. </strong>Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or European Research Executive Agency (REA). Neither the European Union nor the granting authority can be held responsible for them. Grant agreement No. 101059546</p>