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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.

Boat Pressure Washing Wastewater Treatment with Calcium Oxide and/or Ferric ChlorideThe aim of this study was to investigate the efficiency of (1) chemical precipitation by calcium oxide, (2) coagulation/flocculation by ferric chloride (FC), and (3) the combination these two methods in reducing the toxicity of wastewater generated by boat pressure washing. All three methods gave satisfactory results in the removal of colour, turbidity, Cr, Fe, Cu, Zn, and Pb. The concentrations of heavy metals were lowered below national limits with 1 g of CaO, 2.54 mg of Fe3+ in the form of FeCl3x6H2O, and the combination of 0.25 g of CaO and 5.08 mg of Fe3+ per 50 mL of wastewater. Both CaO (1.50 g per 50 mL of wastewater) and FC proved efficient, but their combination yielded a significantly better performance: 99.41 %, 100.00 %, 97.87 %, 99.09 %, 99.90 %, 99.46 % and 98.33 % for colour, turbidity, Cr, Fe, Cu, Zn, and Pb respectively. For colour, Cr, Cu, Zn, and Pb removal efficiencies increased in the following order: FC

This paper presents a new treatment procedure applied on phosphogypsum transport water. Untreated transport water is highly acidic (pH 1.79), having fluoride content of 1540 mg/L and elevated values of phosphates (215 mg/L) and heavy metals (Fe = 25.8 mg/L ; Zn = 5.7 mg/L ; Mn = 2.7 mg/L, V = 1.7 mg/L). Neutralization/purification of the transport water was carried out with wood fly ash, otherwise a rich source of calcium, composed of calcite, dipotassium calcium carbonate and hydroxylapatite. Maximum removal efficiency of fluoride was observed at pH 7 (99.99%) and phosphate at pH 9 (96.29%). The removal of fluorides was a consequence of the formation of fluorite and fluorapatite mineral phases derived from the reaction of calcium (released from the fly ash minerals) and fluorides (from the transport water). The removal of phosphates resulted from the formation of fluorapathite and hydroxilapatite. At the optimum conditions removal efficiencies for the elements Pb, V, Cr(VI), Mn, Fe, Ni, Cu, and Zn were 95%, 98.14%, 91.11%, 100%, 99.71%, 96.33%, 97.24%, and 99.65%, respectively. Optimal heavy metal removal occurred in major cases at pH 7.

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.

A new procedure for electroplating waste water treatment using waste by-product (ferrous-sulfate) and waste (wood fly ash) is presented. Ferrous-sulfate was employed for Cr(VI) reduction whereas neutralization and heavy metals removal from electroplating waste waters was performed using wood fly ash. Heavy metal removal efficiency varied from 97.5% for Cu to 99.973% for Zn. Satisfying results can be achieved already at the pH 8. The method is suitable for the purposes of waste water treatment and disposal in compliance with environmental laws. Furthermore, it is technically simple, cost-efficient and requires less space compared to the classical methodology. According to the composition of its water extractable fraction remaining waste ash could be safely deposited on domestic waste repositories.

Soil samples were collected at 112 locations on Croatian island Krk in the northern Adriatic sea. The collected samples were analyzed for 14 chemical elements (Ca, Ti, Mn, Fe, Ni, Cu, Zn, As, Br, Rb, Sr, Y, Zr, Pb) by using EDXRF as an analytical tool. For all of the measured elements concentration maps for the island are produced using kriging gridding methodology. This is done in order to relate geochemical variations in soils to underlying differences in geology, soil type, local environment, prevalent use, and antropogenic influences. Concentration maps for the chemical elements measured could be also used in the evaluation of chemical elements transfer from soils to plants, and eventually through food chain to the inhabitants of the island.

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.

In this study we compared three methods for the treatment of electroplating sludge highly loaded with zinc and iron: (1) calcium oxide-based solidifi cation/stabilisation; (2) conversion into inert material by adsorption of organic and inorganic pollutants onto activated carbon; and (3) conversion of mobile waste components into insoluble phosphates. All three methods proved highly effi cient in the conversion of hazardous waste into inert material. Under optimum treatment conditions zinc concentration in the leachate of solidifi ed waste was reduced by 99.7 % compared to untreated sludge. Zinc retention effi ciency in the waste treated with activated carbon and phosphoric acid was 99.9 % and 98.7 %, respectively. The advantages of electroplating sludge treatment with activated carbon over the other two methods are high sorption capacity, insignifi cant pH and volume changes of the sludge, and simple use.

The aim of this research was development of appropriate procedure for treatment of landfill leachate taken from old sanitary landfill Piskornica (Koprivnica, Croatia). Due to complex nature of the effluent a combined treatment approach was applied. Samples were treated with calcium oxide followed by ferric chloride and finally with clinoptilolite. The optimum amount of treating agents and contact time were determined. Application of calcium oxide (25 g/L, 20 min. contact time) resulted in the reduction of color, turbidity, suspended solids and ammonia for 94.50%, 96.55%, 95.66% and 21.60%, respectively, while the removal efficiency of Cr (VI), Fe, Ni, Cu, Zn and Pb was 75.00%, 95.34%, 56.52%, 78.72%, 73.02% and 100.00%, respectively. After addition of ferric chloride (570 mg Fe(3+)/L, 20 min. contact time) removal efficiency of color, turbidity, suspended solids and ammonia increased to 96.04%, 99.27%, 98.61%, and 43.20%, respectively. Removal of ammonia (81.60%) increased significantly after final adsorption onto clinoptilolite (25 g/L, 4 h contact time). Removal of COD after successive treatment with calcium oxide, ferric chloride and clinoptilolite was 64.70%, 77.40% and 81.00%, 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 purpose of this work was development of an appropriate procedure for the neutralization/purification of electroplating wastewater (EWW) with alkaline solid residue (ASR) by-product of the alkaline extraction of zinc and lead from electric arc furnace dust (EAFD). Removal efficiency of ASR at optimum purification conditions (pH 8 and mixing time; 20 minutes) for the elements Pb, Cr (VI), Cr (III), Fe, Ni, Cu and Zn were 94.92%, 97.58%, 99.59%, 99.48%, 97.25% and 99.97%, respectively. The concentrations of all elements in the purified wastewater were significantly lower in relation to the upper permissible limit for wastewaters suitable for discharge into the environment. The remaining waste mud was regenerated in the strong alkaline medium and successfully applied once again for the neutralization/purification of EWW. Removal efficiencies of heavy metals accomplished with regenerated waste mud were comparable to these achieved by original ASR. Elemental concentrations in the leachates of the waste mud were in accordance with regulated values.

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...

Proposal for coagulant production using red mud and waste base as row material, by-products of abandoned alumina factory near Obrovac in Croatia, is described. Basic physico-chemical characteristics of red mud and waste base were also given. Elemental concentrations of red mud, waste base and wastewaters before and after treatment were measured using tube excited EDXRF method. Coagulant production consist of partial dissolution of red mud with diluted sulphuric acid (30% wt), separation of liquid from residual red mud by centrifugation or filtration through the filter press, and neutralisation of acid red mud (pH = 0) with the waste base to pH = 8. This process of red mud neutralisation results in heavy metals removal and also neutralisation of waste base to pH = 8, which could be, after treatment, discharged directly into the environment. Resulting red mud, after neutralisation, is in gel-like state and is suitable for heavy metals and turbidity removal from industrial wastewaters. As an example, wastewaters from pressure washing of boats coated with antifouling paints were used and promising results were obtained. With one dose of coagulant (activated red mud), five cycles of heavy metals removal could be done.