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The aim of this research was development of appropriate procedure for the treatment of landfill leachate taken from the Visevac, Mraclinska Dubrava and Piskornica sanitary landfills. Due to the complex nature of the effluents a combined treatment approach was applied. The pretreatment step included simultaneous treatment with calcium oxide and electrocoagulation/electrooxidation by stainless steel electrode set. The main treatment included electrocoagulation/electrooxidation using the set of stainless steel, iron and aluminum electrodes. The pretreatment allowed the destruction and/or coagulation of the high molecular weight organic substances as well as optimization of pH values for the formation of reactive oxidative species, and the transformation of NH(4)-N into volatile NH(3)-N. In the presence of added calcium oxide and electrochemically generated coagulant the removal of the fluorides, phosphates and heavy metals occur through the formation of poorly soluble fluorapatite, hydroxyl apatite, and various hydroxides. During the main treatment electrochemically generated reactive oxidative species carried out rapid decomposition of the organic matter and ammonia, resulting in the removal of COD from 74.9% to 94.2%, color from 98.8% to 99.7%, turbidity from 98.4% to 99.3%, suspended solids from 97.1% to 99.3%, and ammonia from 99.6% to 99.7%. Slightly better results for the removal efficiency of color, turbidity and suspended solids were obtained in the case of Piskornica landfill compared with the other two landfills, while the COD removal efficiency decreases in the following order: Piskornica >Mraclinska Dubrava >Visevac. This could be related to the age of the landfill, which increases in the same order. Consequently, with the increasing age of the landfill the degree of degradability of the organic matter reduces significantly. Applied treatment approach resulted in clear, colorless and odorless effluent with the values of all measured parameters significantly lower compared to the upper permissible limit for discharge into the environment.

Spatial distributions of trace elements in the coastal sea sediments and water of Maslinica Bay (Southern Adriatic), Croatia and possible changes in marine flora and foraminifera communities due to pollution were investigated. Macro, micro and trace elements’ distributions in five granulometric fractions were determined for each sediment sample. Bulk sediment samples were also subjected to leaching tests. Elemental concentrations in sediments, sediment extracts and seawater were measured by source excited energy dispersive X-ray fluorescence (EDXRF). Concentrations of the elements Cr, Cu, Zn, and Pb in bulk sediment samples taken in the Maslinica Bay were from 2.1 to over six times enriched when compared with the background level determined for coarse grained carbonate sediments. A low degree of trace elements leaching determined for bulk sediments pointed to strong bonding of trace elements to sediment mineral phases. The analyses of marine flora pointed to higher eutrophication, which disturbs the balance between communities and natural habitats.

Production of the coagulant using bauxite waste (red mud and waste base) as raw material and the results of the testing of this new product in laboratory and field condition (pilot plant, full scale plant) were presented. Results showed that red mud could be used as a low-coast solution for heavy metals removal from its own waste base and other industrial wastewaters after partial dissolution with diluted sulphuric acid and neutralization with the waste base. This coagulant is especially suitable for the treatment of the wastewaters generated from the pressure washing of boats in the marinas. The coagulant produced from the red mud has few advantages compared to the commercial Fe and Al salts:(1) Coagulation/flocculation process could be done in one step without coagulant aid or any other chemical addition.(2) pH measurement during the purification could be avoided due to the negligible pH variations of the treated solution.(3) Allow one step removal of the cationic and anionic species from the wastewater.(4) One dose of coagulant is sufficient for five repeated treatment cycles.(5) Negligible leaching of heavy metals from the waste mud under normal environmentalconditions.(6) Safe for the transport, storage and handling.

The aim of this work was the development and application of the pilot plant with the capacity of 1000 L/day for the purification of groundwater used for human consumption characterized with high concentration of arsenic and increased values of organic pollutants, ammonia, nitrites, color and turbidity. For that purpose, groundwater from the production wells supplying the towns Zrenjanin and Temerin (Vojvodina, Serbia) was used. Due to its complex composition, the purification system required the combination of the electroreduction/electrocoagulation, using iron and aluminum electrode plates with/without ozonation, followed by the electromagnetic treatment and the finally by the simultaneous ozonation/UV treatment. The electroreduction was used for the removal of nitrates, nitrites, and Cr(VI), while the removal of arsenic, heavy metals, suspended solids, color and turbidity required the application of the electrocoagulation with simultaneous ozonation. Organic contaminants and ammonia were removed completely in the last treatment step by applying the simultaneous ozonation/UV treatment. All measured parameters in the purified water were significantly lower compared to the regulated values. Under the optimum treatment conditions, the removal efficiencies for color, turbidity, suspended solids, total arsenic, total chromium, Ni(II), total copper, sulfates, fluorides, chemical oxygen demand, ammonia, nitrates, and nitrites were 100%. The removal efficiencies of the total manganese and iron were 85.19% and 97.44%, respectively, whilst the final concentrations were 4 and 7 μg/L, respectively.

Eighteen samples of electroplating sludge were taken from three vertical profiles of waste storage pond of the zinc plating facility. Dry matter and organic matter content, pH value, bulk concentrations and leachate composition were determined. A sludge sample with the highest zinc value in the leachate was treated with calcium oxide (10% to 70%) and the obtained solidificate was repeatedly tested. There were found significant variations of all measured parameters among the profiles of untreated waste. Dry matter content varied from 125 to 455 mgg(-1), organic matter varied from 94.3 to 293.9 mgg(-1), and pH value varied from 3.42 to 5.90 (mean 4.34). Iron content ranged from 38.4 to 191.4 mgg(-1) (mean 136 mgg(-1); RSD 0.25), while zinc ranged from 10.9 to 58.2 mgg(-1) (mean 33.4 mgg(-1); RSD 0.38). According to its DIN38414-S4 leachate composition, this material was not suitable for landfilling of inert waste since zinc and nickel mean values were 10 and 1.5 times higher, respectively, and maximum values 27 and 2.5 times higher, respectively, compared to the upper permissible limit. Maximum values of Cr(VI), Fe, Ni, Cu, and Zn in the DIN38414-S4 leachate were 0.183 mgL(-1), 34.085 mgL(-1), 1.052 mgL(-1), 0.829 mgL(-1) and 107.475 mgL(-1)L, respectively. Following the solidification/stabilization procedure with CaO (sample/CaO = 90/10), concentrations of Cr(VI), Fe, Cu and Zn were reduced 92, 44, 66 and 57 times, respectively, compared to the untreated sample. The addition of 50% of CaO into the sludge reduced zinc and nickel concentrations 79 and 45 times, respectively, in the DIN38414-S4 leachate of the solidified waste compared to the original sludge, thereby converting an hazardous waste into the inert material suitable for landfilling or reuse in the construction processes.

The objective of this study was to chemically characterize the soil samples affected by the dust emission and slag dumping from ferrochromium smelter, as well as uptake of metals by vegetation growing on that soil. There were 38 samples collected altogether, including unpolluted background soil samples, polluted soil samples taken in the vicinity of the factory, slag material, bottom and fly ash. Grass material was also taken from both polluted and unpolluted soil. All samples were analyzed with energy dispersive X-ray fluorescence (EDXRF). The results showed (especially for chromium and manganese) metal concentrations in soil samples taken in the vicinity of the factory increased up to 56 times in relation to normal background soil concentrations. Slag material, fly and bottom ash were highly enriched with chromium, manganese and nickel. There was a significant chromium uptake by vegetation growing on the contaminated soil.

Distributions of trace elements in the coastal sea sediments of Punat Bay in the Northern Adriatic have been investigated. The concentrations of 16 elements (Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Br, Rb, Sr, Y, Zr and Pb) were measured by energy dispersive XRF. Two predominant types of sediments were observed: the first (sediment “A”), which consists of 87% pelitic fraction and the second (sediment “B”), where coarse-grained fraction (0.315–0.1 mm) prevails. Enrichment factors had elevated values in two upper-most segments for the elements Cu, Zn and Pb in sediment “A.” The highest percentage of exchangeable fraction with respect to the total composition was characteristic for Cr, Cu and Zn in both types of sediments. By means of the linear regression analysis it was established that metals present in the antifouling paints were dispersed all over the bay because of an inefficient cleaning mechanism, poor communication with the open sea, and the good mixing of water and suspended mater in the ba...