Can Urban Grassland Plants Contribute to the Phytoremediation of Soils Contaminated with Heavy Metals.

The main objective of this study was to investigate whether the most common wild plant species of urban grassland can be used for phytoremediation of soils polluted with heavy metals. The study was conducted in the city of Varazdin, in northern Croatia. The content of heavy metals (Cd, Cu, Fe, Mn, Ni, Pb, Zn) was determined in soil samples as well as in unwashed and washed plant samples (Taraxacum officinale, Plantago lanceolata, Trifolium repens). The results show that the most polluted site is the railway station, while most sites are polluted by road traffic. The soils are most enriched with Pb, Cu, Zn and Cd. The bioconcentration factors for all three plant species are <1, indicating the relatively low capacity of phytoextraction. A considerable amount of heavy metals is found in the dust deposited on the plant surface, which is confirmed by a statistically significant difference between washed and unwashed plant samples. In addition, the biomass of each plant species that can be removed (in t/ha year), the mass of specific heavy metal that can be removed (in kg/ha), and the years required for phytoremediation are reported. In conclusion, phytoremediation with only common plant species of urban grassland is not possible within a reasonable period of time.

Soil burden by persistent organochlorine compounds in the vicinity of a coal-fired power plant in Croatia: a comparison study with an urban-industrialized area.

The impact of a coal-fired Plomin Power Plant (PPP) in Croatia on PCB soil burden was examined by comparing the occurrence, levels, and profile of PCBs in soil from the PPP with the values determined in urban-industrialized soil (Varazdin, Croatia). Soil burden by organochlorine pesticides (OCPs) were also investigated at both locations. Topsoil samples were collected at five distances (100-800 m) along a downwind pollution gradient from the PPP and across the city. The total content of PCBs in 100-m soil was nearly 20-fold the levels found in 800-m soil, which pointed to the PPP as a local source of soil contamination. The PPP soils were dominated by indicator PCB congeners, particularly hexa-homologs. A different profile and mass fraction range of PCBs in soils from PPP and Varazdin area indicated the different sources of contamination. Levels of total PCBs in PPP soils (0.25-19.07 µg kg-1) were higher than PCB levels determined in soils from Varazdin (0.29-5.52 µg kg-1), partially as a result of higher OC content in PPP soils. PPP soil burden by PCBs corresponded to a lower end of PCB level ranges reported for cities with high population and heavy industry. OCPs were detected at significantly higher levels in Varazdin soils than in PPP soils, with the highest contribution of the DDT-like compounds (DDX) detected in soils affected by river deposits. The p,p'-DDE/p,p'-DDT ratio in Varazdin soils indicated a fresh atmospheric input of p,p'-DDT. The PPP soil analysis detected a presence of only p,p'-DDE and HCB at levels corresponding to their global environmental presence.

Detection of heavy metals in common vegetables at Varazdin City Market, Croatia.

The present study was aimed at the estimation of heavy metal content in vegetables sold at the city market of one of the densely populated Croatian cities, Varazdin, and to establish the relationship between their levels and possible sources of contamination. Twenty-eight samples of the most common diet vegetables (red and white potato, onion, carrot, common bean, lettuce, and cabbage) were randomly bought at the market in September and October 2013. Using the atomic absorption spectrometry method, concentrations of nine heavy metals (As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn) were measured in the selected samples. The results showed that, in five out of 28 samples analysed, six concentrations exceeded the maximum levels provided for in the regulations: five for Pb and one for Cd. Maximum regulated levels for Pb were exceeded in two samples of red potato, two samples of common bean, and one sample of carrot (17.9 %), and for Cd in a sample of red potato (3.6 %). In conclusion, the cause of the overstepping of the maximum levels for Pb and Cd in the vegetables analysed was most likely the contaminated soil. The possible sources of soil contamination include traffic, nearby industry, floodwaters of rivers and streams, and the use of pesticides and fertilisers in agricultural production.

The assessment of air emissions increase due to the collection of municipal solid waste with old collection vehicles: A case study of Ludbreg (Croatia).

The usage of old equipment (over 10-year-old diesel-fuelled waste collection vehicles, WCVs) for municipal solid waste (MSW) collection in Ludbreg for longer than a decade has had a negative environmental impact, which has been reduced by replacing an old diesel WCV with a new diesel WCV. This study aims to assess the share of air emissions of two old WCVs (FAP 1990 and MAN 2003) and one new (MAN 2015), expressed in CO2 emissions. In addition, these vehicles have been found easily to reach the limit of 100 dB, which can cause hearing damage in their surroundings. Furthermore, their average fuel consumption is more than 80 l per 100 km, which makes them ineffective in terms of fuel consumption. Generally, higher fuel consumption results in more emissions and for a more eco-friendly operation, the MAN 2003 from Ludbreg WCV fleet should be technically amended and adjusted, and the FAP 1990 should be retired. Although the MAN 2015 is diesel fuelled, the best solution for replacement, according to Maimoun et al. (Waste Management 33: 1079-1089, 2016), would be the use of hydraulic-hybrid vehicles, which provide the best environmental benefits over other alternatives. According to Maimoun et al., hybrid is better environmentally, diesel is the best environmental-economical option and landfill gas-sourced natural gas is the best alternative when accessible because it significantly (up to 80%) reduces emissions of hazardous gases as well as noise levels (50-98%).

Minimization of organic content in simulated industrial wastewater by Fenton type processes: a case study.

Pre-treatment of simulated industrial wastewaters (SIM1, SIM2 and SIM3) containing organic and inorganic compounds (1,2-dichloroethane, sodium formate, sodium hydrogen carbonate, sodium carbonate and sodium chloride) by oxidative degradation using homogeneous Fenton type processes (Fe2+/H2O2 and Fe3+/H2O2) has been evaluated. The effects of initial Fe2+ and Fe3+ concentrations, [Fe2+/3+], type of iron salt (ferrous sulfate vs. ferric chloride), initial hydrogen peroxide concentration, [H2O2], on mineralization extent, i.e., total organic content (TOC) removal, were studied. Response surface methodology (RSM), particularly Box-Behnken design (BBD) was used as modelling tool, and obtained predictive function was used to optimize the overall process by the means of desirability function approach (DFA). Up to 94% of initial TOC was removed after 120 min. Ferrous sulfate was found to be the most appropriate reagent, and the optimal doses of Fe2+ and H2O2 for reducing the pollutant content, in terms of final TOC and sludge production were assessed.

Decolourization and mineralization of commercial reactive dyes by using homogeneous and heterogeneous Fenton and UV/Fenton processes.

The oxidative decolourization and mineralization of three reactive dyes in separately prepared aqueous solutions C.I. Reactive Yellow 3 (RY3), C.I. Reactive Blue 2 (RB2) and C.I. Reactive Violet 2 (RV2) by using homogeneous and heterogeneous Fenton and UV/Fenton processes have been investigated. The effects of H(2)O(2), Fe(2+) and Fe(0) concentrations, Fe(2+)/H(2)O(2) and Fe(0)/H(2)O(2) molar ratios at pH 3 and T=23+/-1 degrees C have been studied. Optimal operational conditions for the efficient degradation of all three dye solutions (100 mg L(-1)) were found to be Fe(2+)/H(2)O(2)=0.5mM/20mM and Fe(0)/H(2)O(2)=2mM/1mM. The experimental results showed that the homogeneous Fenton process employing UV irradiation was the most effective. By using this process, the high levels of mineralization (78-84%) and decolourization (95-100%) were achieved. Pseudo-first-order degradation rate constants were obtained from the batch experimental data.

Advanced oxidation processes in azo dye wastewater treatment.

The chemical degradation of synthetic azo dyes color index (C.I.) Acid Orange 7, C.I. Direct Orange 39, and C.I. Mordant Yellow 10 has been studied by the following advanced oxidation processes: Fenton, Fenton-like, ozonation, peroxone without or with addition of solid particles, zeolites HY, and NH4ZSM5. Spectrophotometric (UV/visible light spectrum) and total organic carbon measurements were used for determination of process efficiency and reaction kinetics. The degradation rates are evaluated by determining their rate constants. The different hydroxyl radical generation processes were comparatively studied, and the most efficient experimental conditions for the degradation of organic azo dyes solutions were determined.

Influence of iron on degradation of organic dyes in corona.

In this work application of AOPs such as Fenton process, aqueous phase high voltage electrical discharge (corona) and their combination have been studied for colored wastewater treatment. Experiments were conducted on water solutions of four different organic dyes, two azo dyes C.I. Mordant Yellow 10 (MY10) and C.I. Direct Orange 39 (DO39), and two reactive of azo type C.I. Reactive Red 45 (RR45) and C.I. Reactive Blue 137 (RB137). The efficiency of studied AOPs has been estimated on the bases of UV-vis spectrophotometric and TOC measurements. The rate constants in the kinetic model have been determined. Experimental data have been compared with the developed mathematical model.