Leachability and Microstructural Analysis of Clay and Lime Stabilized/Solidified Polluted Sediment – Long-Term Performance

The objective of this study is to enable a better understanding of the effectiveness of solidification/stabilization (S/S) technique in treating polluted sediment, and provide the much needed validation of the longevity of the technology. In this research kaolinite and montmorillonite, with a certain proportion of lime, were used for S/S treatment of sediment polluted with metals. Leachability of metals was examined using the toxicity characteristic leaching procedure (TCLP) and the German standard leaching test (DIN 3841-4 S4) prescribed in national legislative. Results indicated successful S/S treatment using both clays and lime, from the aspect of all leached metals even with pH variations over time and slight changes in structural integrity of specimens. X-ray diffraction (XRD), scanning electron microscope (SEM) analyses and porosity measurement were also performed on the prepared monolithic matrices. XRD qualitative and semi-quantitative analysis proved hydration and pozzolanic product formation with increase in their content and finer crystallites formation over time. SEM analysis confirmed the presence of morphologically dense and stable structures while pore size distribution indicated on mesoporous matrices with ongoing compaction over time. Generally, structural microanalysis indicated the formation of hardened matrices over time and hydration process has been fully completed and further carbonation took place. Unconfined compressive strength measurement gave the satisfying results and matured monolite with 30 % of montmorillonite and 10 % of lime can be considered potentially applicable as non-load-bearing material. In summary, all results indicated that this kind of S/S treatment can achieve satisfactory durability and represent reliable and economically feasible technique for long-term remediation of metal polluted sediment

Assessing the possibility of solidification and stabilization of pyrite cinder by using quicklime and fly ash

The aim of this study was to determine the possibility of using two low-cost binders, quicklime and fly ash for the solidification/stabilization (S/S) of pyrite cinder. Pyrite cinder, used in this study, represents a remnant from sulfuric acid production in fertilizer factory IHP “Prahovo” A.D. (Serbia), and has a very high toxic metal content. High contents and leachability of copper, lead and zinc make this waste material hazardous, representing an extraordinary risk to the environment. In order to determine the leaching behavior of the S/S mixtures, four single-step leaching tests were performed, each one having a different sort of leaching fluid (deionized water, inorganic and organic acidic solutions). X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray analyzer (EDS) were implemented to elucidate the mechanisms responsible for immobilization of Cu, Pb and Zn. Overall, the test results indicated that S/S treatment using both quicklime and fly ash was effective in immobilizing these metals, especially when there is a higher share of binder present. Treated waste can be safe for disposal and even considered for “controlled utilization”. Furthermore, the use of fly ash for S/S treatment of pyrite cinder solves the disposal problems of two waste types, as it also represents a secondary industrial product

Assessing the possibility of solidification and stabilization of pyrite cinder by using quicklime and fly ash

The aim of this study was to determine the possibility of using two low-cost binders,quicklime and fly ash for the solidification/stabilization (S/S) of pyrite cinder.Pyrite cinder, used in this study, represents a remnant from sulfuric acid productionin fertilizer factory IHP “Prahovo” A.D. (Serbia), and has a very high toxicmetal content. High contents and leachability of copper, lead and zinc make thiswaste material hazardous, representing an extraordinary risk to the environment.In order to determine the leaching behavior of the S/S mixtures, four single-stepleaching tests were performed, each one having a different sort of leaching fluid(deionized water, inorganic and organic acidic solutions). X-ray diffraction (XRD),scanning electron microscope (SEM) and energy dispersive X-ray analyzer (EDS)were implemented to elucidate the mechanisms responsible for immobilization ofCu, Pb and Zn. Overall, the test results indicated that S/S treatment using bothquicklime and fly ash was effective in immobilizing these metals, especially whenthere is a higher share of binder present. Treated waste can be safe for disposal andeven considered for “controlled utilization”. Furthermore, the use of fly ash for S/Streatment of pyrite cinder solves the disposal problems of two waste types, as it alsorepresents a secondary industrial product

Experimental design of photo-Fenton process decolorization of Reactive Red 120 by using mathematical statistics models

A statistical design of experiments was used to evaluate the potential use of clay catalyst (CuOFeB) during photo-Fenton process in which the concentration of hydrogen peroxide (H2O2), catalyst loading and pH values were selected as effective experimental factors in the process of dye decolorization. The photo-Fenton oxidation of Reactive Red 120 (RR120) has been investigated using a concentrating solar parabolic reactor with constant solar radiation of 950 W/m2 during summer period of the year. Under the optimal reaction conditions catalyst showed good catalytic activity in the processes with dye removal over 90%. Also, experiment confirmed that decolorization efficiency depends on the pH and concentration of H2O2 , wherein better results were achieved under lower pH values and higher concentration of H2O2

Characterization and kinetic study of magenta printing effluent after homogeneous fenton treatment

The objectives of this study were to determine the physico-chemical characterization of Magenta printing effluent treated with homogeneous Fenton process, as well as kinetic model that best describes degradation process of organic pollutant. Physico-chemical characterization of printing effluent before and after homogeneous Fenton treatment included measurements of pH, electrical conductivity, temperature, turbidity, chemical oxygen demand, biochemical oxygen demand, total organic carbon and toxicity test. Three kinetic models (first-order, second-order, and Behnajady-Modirshahla-Ghanbary) were evaluated in order to best describe Magenta degradation process. Results indicated that dye degradation process is followed with the increase of conductivity and biological oxygen demand due to the formation of various by-products and release of inorganic ions. The obtained results are in accordance with the established dye mineralization degree on the basis of chemical oxygen demand and total organic carbon content. However, treated printing effluent is characterized as nontoxic due to the Vibrio fischeri inhibition of 18.16%

Optimization of homogenous fenton process using definitive screening design applied for flexographic printing wastewater

The treatment of flexographic cyan dye synthetic solution and real printing effluent has been studied by using homogeneous Fenton process with the addition of FeSO4*7H2O as a catalyst. The study demonstrate that applied treatment could significantly reduce dye concentration in the examined aqueous solutions. Operating parameters, such as initial dye concentration, iron dosage, hydrogen peroxide concentration and pH were varied to investigate their influence on decolorization efficiency, as well as their mutual interactions. The optimal conditions, found with definitive screening design (DSD) statistical method, were: dye concentration = 123 mgL-1 , Fe concentration = 60 mgL-1 , H2O2 concentration = 5.44 mM and a pH value = 2. Under these conditions decolorization efficiency resulted with 87% and 37% for cyan synthetic solution and real printing effluent, respectively

Impact assessment wastewater discharge on water quality DTD canal Bečej-Bogojevo

Pressure and impact analysis requires information on the main drivers and changes in conditions. In order to analyze such pressures and impacts, each river basin requires: an analysis of its characteristics, a review of the impact of human activity on the status of the surface water and an economic analysis of water use. Pressure and impact analysis plays a central role in the planning of river basin management. The quality of the stream at any point depends on several major factors: lithology of the basin, weather conditions, climate, and human impacts. Most of the polluters are located in the big cities next to canal DTD Bečej-Bogojevo canal (Odzaci,Vrbas, Srbobran, Becej). Per year, 2900000 m3 of wastewater was discharged into the Bečej-Bogojevo section of the DTD canal: 1,4 tCOD, 0,8 0tBOD, 260 kg of nitrogen, 19 kg of phosphorus and 282 kg of suspended solids. Of the total volume of wastewater, 20% comes from industry and 80% from municipal wastewater. Most of the wastewaters from the studied polluters is discharged untreated or insufficiently treated (only primary treatment). This poor quality wastewater threatens the receipients into which its is discharged. Comparison of the wastewater quality results to the Decree on emission limits and deadlines for their achievement, shows that many polluters exceed the limits for all parameters (COD, BOD, nitrogen, phosphorus, suspended solids). On the basis of the physico-chemical analysis of the water from the DTD Bečej-Bogojevo canal it can be concluded that the water quality is unsatisfactory. According to the national legislation, the water quality exceeds the values for good potential streams for most parameters at all sampling locatio dissolved oxygen, organic matter and nutrients). Thus, we can conclude that the water in the studied section of the DTD Bečej-Bogojevo canal does not meet the criteria for "good ecological potential". The most vulnerable locations are downstream of the Vrbas and downstream of the Bečej, while the best quality canal water is at the furthest upstream location (CS Bogojevo). Risk assessment based on monitoring results indicates that the water of the studied section of the DTD Bečej-Bogojevo canal is probably at risk of failing to meet the objectives of the Water Framework Directive, as 33% of the analyzed parameters to calculate specific risk ratios were greater than 1, and thus fall into the category of pollutants medium risk. In order to achieve the quality (to achieve good status and good potential), there must be a response from industrial producers, which consists primarily of comprehensively understanding the problems and implementing measures to minimize the impact of these problems. [Projekat Ministarstva nauke Republike Srbije, br. TR37004

Interpretation of the results of surface water quality applying multivariate analysis

Monitoring of surface water, through the analysis of physical-chemical and chemical parameters is a very important factor in the control of water quality and the health of living beings. Surface water quality is largely determined by the nature (atmospherics) and anthropogenic processes (discharge of municipal and industrial waste water). The results of monitoring of surface water are usually too expensive and difficult for correct interpreting, due to the spatial and temporal variations in water quality. By applying Multivariate statistical analysis can achieve significant reductions of the ampleness of the available data and the better interpretation of the obtained results about the quality and ecological status/potential of water. In this paper, were analyzed selected results of the analysis of surface water in AP Vojvodina in 2011 year by using multivariate statistical analysis (cluster analysis and principal components analysis). These techniques allow the interpretation of the results of the monitoring program of investigated surface water bodies and simultaneous identification of registered influence and potential sources of pollution on the quality of the given water bodies. With both methods applied and the division of water bodies tested in the same manner at the origin (natural and artificial) and on the basis of territorial belonging monitoring stations (Banat and Bačka). Individual variations are discussed in corresponding differences in individual measuring stations in relation to others. Application of the given method, a grouping of the examined indicators of water quality in the following factors: hydro-chemical factor, ecological factor, the factor point pollution and diffusion. The obtained results confirm the initial hypothesis that the use of different statistical methods can identify the main factors that have an impact on the ecological status and ecological potential of water bodies and to improve the existing monitoring. In addition, analysis of the extracted surface water bodies where it is necessary to implement simultaneous monitoring of the biological quality elements to determine whether chemical parameters ensure the functioning of ecosystems. [Projekat Ministarstva nauke Republike Srbije, br. ОI-172013 i br. III43005

The Impact of Public Policy Measures during the COVID-19 Pandemic on the Characteristics of Urban Wastewater in the Republic of Serbia

The change in the way of life caused by the introduction of social restriction measures (closures, the restriction of working hours, and restriction of movement) by governments and thus, the resulting changes in people’s behavior, have affected all aspects of life, i.e., social activities, business, the environment and the performance of the infrastructure of the water supply system. Social distancing policies around the world in response to the pandemic have led to spatio-temporal variations in water consumption and therefore, to changes in the flow of wastewater, creating potential problems in the infrastructure, operation and quality of services. The goal of this work was to examine how these changes and how the pandemic itself affected the characteristics of municipal wastewater. Data on the quantity and quality of municipal wastewater in four settlements of different sizes in the Republic of Serbia in the period from 2015 to 2022 were collected. The data indicated an increase in the amount of wastewater generated in 2020, which may be a consequence of excessive water use. An increase in the mean concentrations of most parameters in 2020 compared to the previous five-year average was also observed. The most significant changes were observed concerning the concentrations of organic matter (2–124%), nitrogen (6–80%), phosphorus (14–91%), suspended matter (8–308%), fats and oils (97–218%) and surfactants (12–110%). Changes in terms of increasing concentrations were also noticed after the peak of the pandemic, i.e., in the period from 2021 to 2022. In addition, an increase in the COD/BOD ratio from around 2 to around 4 in the year 2020 was also observed (COD—Chemical Oxygen Demand; BOD—Biological Oxygen Demand). This is very important and should be taken into account in wastewater treatment procedures in order to achieve high efficiency in the operation of the plant itself

Photocatalytic Degradation of Magenta Effluent Using Magnetite Doped TiO2 in Solar Parabolic Trough Concentrator

Due to population growth and industrial development consumption of non-renewable energy sources, and consequently pollution, has increased. In order to reduce energy utilisation and preserve the environment, developed and developing countries are increasingly trying to find solutions based on renewable energy sources. Cost-effective wastewater treatment methods using solar energy would significantly ensure effective water source utilisation, thereby contributing towards sustainable development goals. In this paper, special emphasis is given to the use of solar energy as the driving force of the process, as well as the use of highly active magnetic TiO2-based catalysts. Therefore, in this study, we investigated the possibility of photocatalytic degradation of aqueous magenta graphic dye using titanium dioxide as a catalyst and DSD model in order to achieve the best process optimisation. TiO2 was successfully coated with magnetic nanoparticles by one step process and characterized using different techniques (BET, SEM/EDS, FTIR, XRD). Based on DSD statistical method optimal reaction conditions were pH = 6.5; dye concentration 100 mg/L; TiO2–Fe3O4 0.6 g/L, at which the highest degree of magenta dye decolourisation was achieved (85%). Application of solar energy coupled with magnetic TiO2 catalyst which could be recovered and reused makes this approach a promising alternative in green wastewater treatment