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Today's trends are focused on investigating the efficiency of oily wastewater treatment with electrochemical processes due to the fact that they do not depend on temperature changes of the influent, do not require the addition of chemicals and do not require pH adjustment during treatment. Among different electrochemical processes, state- of-the-art confirms the high efficiency of electrocoagulation (EC) process. The use of Fe and Al electrodes achieves a relatively high efficiency of oil and grease removal, as well as COD removal. However, there is a need to investigate the efficiency of hybrid processes that combine different electrochemical processes, such as advanced oxidation processes (AOP) and EC. In this paper, oily wastewater from oil and grease separators was used, and the treatment was performed on a pilot plant using a combination of electrochemical AOP and EC processes. Two tests were performed, the first analysing the treatment efficiency of oily wastewater, which was completely mixed without pretreatment, and the second analysing the effect of primary sedimentation (1st stage of treatment) on the overall treatment efficiency. In the treatment of oily wastewater by applied electrochemical processes without primary sedimentation, the removal efficiency of total oil and grease was about 70%, and COD about 50%. With additional primary sedimentation prior to AOP-EC process, the total removal efficiency of total oil and grease was about 90%, and COD about 70%. The results indicate the high efficiency of oily wastewater treatment by a hybrid AOP and EC process, and the application of primary sedimentation has been proven with higher overall treatment efficiency.

U radu je prikazana obrada klaoničkih otpadnih voda kombinacijom termičke predobrade i glavne elektrokemijske obrade uz simultano ozoniranje. Ispitana je učinkovitost uklanjanja karakterističnih pokazatelja te količina generiranog mulja obzirom na vrstu elektroda (nehrđajući čelik, željezo, aluminij), vrijeme obrade (5-30 minuta) i jakost struje (50-100 A). Otpadna voda je karakterizirana vrlo neugodnim mirisom, visokim vrijednostima boje (17400 CoPt), mutnoće (4230 NTU) ukupne suspendirane tvari (1730 mg dm-3), kemijske potrošnje kisika (3720 mg dm-3) te biokemijske potrošnje kisika (1870 mg dm-3) te povišenim vrijednostima amonija (128 mg dm-3) i fosfata (93 mg dm-3). Termičkom predobradom je uklonjeno 98,23% mutnoće, 89,94% boje, 75,14% ukupne suspendirane tvari (UST), 49,73% BPK5 i 36,29% KPK. Set elektroda od nehrđajućeg čelika se pokazao najučinkovitijim u uklanjanju organskih pokazatelja i amonija, a rezultirao je i najmanjim volumenom otpadnog mulja, dok su aluminijeve elektrode najučinkovitije u uklanjanju boje, ali uz najveću produkciju mulja. Najbolji rezultati su dobiveni kombinacijom sve tri vrste elektroda uz istovremeno ozoniranje uz kontaktno vrijeme 20 minuta, jakost struje od 70 A i napon od 10 V. Nakon elektrokoagulacije/elektroksidacije pomoću elektroda od nehrđajućeg čelika, elektrokoagulacije/ozoniranja pomoću željezovih elektroda, elektrokoagulacije/ozoniranja pomoću aluminijevih elektroda te završnog ozoniranja uklonjeno je 100% boje, mutnoće i UST, 99,77% KPK te 99,25% BPK5, 99,98% fosfata, 99,80% amonija i 43,86% ukupne otopljene tvari, a svi mjereni pokazatelji su zadovoljavali uvjete za ispust u okoliš., The paper presents slaughterhouse wastewater treatment implemented as a combination of thermal pre-treatment and main electrochemical treatment, with a simultaneous ozonation. The efficiency of the characteristic indicator removal and the quantity of generated sludge according to electrode types (stainless steel, iron and aluminium), treatment time (5-30 minutes) and amperage (50-100 A) was tested. The wastewater is characterized by a very unpleasant odour, high colouring value (17400 CoPt), turbidity (4230 NTU), total suspended solids (1730 mg dm-3), chemical oxygen demand (3720 mg dm-3) and biochemical oxygen demand (1870 mg dm-3) as well as increased values of ammonium (128 mg dm-3) and phosphates (93 mg dm-3). Thermal pre-treatment removed 98.23% turbidity, 89.94% colour, 75.14% total suspended solids (TSS), 49.73% BOD5 and 36.29% COD. A stainless steel electrode set proved to be the most efficient in the removal of organic indicators and ammonium and the lowest sludge volume, whereas aluminium electrodes were the most efficient in colour removal, although with the highest sludge production. The best results were achieved by a combination of all three electrode types, with a simultaneous ozonation of 20-minute contact time, amperage of 70 A and voltage of 10 V. Following the electrocoagulation / electrooxidation by stainless steel electrodes, electrocoagulation / ozonation by iron electrodes and electrocoagulation / ozonation with aluminium electrodes and the final ozonation, 100% colour, turbidity and TSS were removed as well as 99.77% COD and 99.25% BOD5, 99.98% phosphates, 99.80% ammonium and 43.86% total dissolved solids. All measured indicators complied with the conditions for discharge into the environment.

Svrha ovog rada je razvoj sustava za pročišćavanje procjednih voda starih odlagališta komunalnog otpada simultanom primjenom elektrokemijskih, ultrazvučnih i elektromagnetskih metoda u laboratorijskim uvjetima i pilot postrojenju. Procjedna voda je uzeta s dva sanitarna odlagališta (Piškornica i Tarno) i podvrgnuta elektrokemijskoj obradi primjenom elektroda od nehrđajućeg čelika, željeza i aluminija uz istovremenu obradu ultrazvukom i recirkulaciju kroz elektromagnetsko polje. Reakcije zagađivala iz procjednih voda s elektrokemijski generiranim hipokloritom, kromatima i slobodnim radikalima, kao i termička razgradnja u kavitacijskim mjehurićima su odgovorni za brzo i efi kasno uklanjanje organske tvari i amonija s učinkovitosti uklanjanja KPK, BPK5 i amonijaka preko 99 % nakon 85 minuta obrade. Uklanjanje teških metala do 99,93 % uglavnom je postignuto elektrokoagulacijom pomoću elektroda od željeza i aluminija. Svi mjereni pokazatelji u obrađenoj vodi kako u laboratorijskim uvjetima tako i na pilot postrojenju su bili znatno niži u odnosu na njihove maksimalno dopuštene koncentracije za vode koje se mogu ispustiti u prirodni prijemnik., The purpose of this paper is to develop a treatment system for leachate from old municipal landfills by means of electrochemical, ultrasound and electromagnetic methods in laboratory conditions and at a pilot plant. The leachate was taken from two sanitary landfills (Piškornica and Tarno) and subjected to electrochemical treatment by implementing electrodes made of stainless steel, iron and aluminium, and a simultaneous treatment with ultrasound and recirculation through electromagnetic fi eld. The reactions of pollutants from the leachate with the electrochemically generated hypochlorite, chromates and free radicals as well as thermal decomposition in cavitation bubbles are responsible for fast, efficient removal of organic matter and ammonium. The removal efficiency of COD, BOD5 and ammonium is over 99 % after 85-minute treatment. The removal of heavy metals up to 99.93 % is mostly achieved by means of electrocoagulation with iron and aluminium electrodes. All measured indicators in treated water, both in laboratory conditions and at the pilot plant, were significantly lower with respect to their maximum permitted concentrations in waters that can be discharged into a natural receiving body.

The purpose of this work was development and application of the purification system suitable for the treatment of groundwater used for human consumption as well as watering of the plants in the system for the hydroponic cultivation of tomatoes. For that purpose the well water from the 60 m deep water layer situated near the city of Županja (Eastern Croatia) was processed. Most of the measured parameters exceeded upper permissible limit (UPL) for drinking water. The highest increase over UPL was found for the parameters phosphates (34.7 times), color (14.6 times), iron (8.6 times), arsenic (7.4 times), CODMn (7.4 times), turbidity (5.3 times), ammonia (2.4 times) and manganese (1.5 times). Due to the complex composition of the treated water, the purification system required the combination of electrochemical treatment, using iron and aluminum electrode plates with simultaneous ozonation followed by post treatment with hydrogen peroxide and ozone. The electrocoagulation/ozonation approach was used for the removal of heavy metals, suspended solids, color, turbidity, phosphates and partially organic matter while the rest of the organic contaminants and ammonia were removed by the treatment with sodium peroxide. Following the combined electrochemical treatment and post treatment with hydrogen peroxide and ozone all measured parameters in the treated water were in agreement with regulated values. The combined treatment resulted in total removal of arsenic, turbidity, ammonia and organic contaminants while the removal of other parameters of interest was up to 97.98%.

The subject of this research was the characterization and the treatment of the acid mine drainage (AMD) originating from the sulfide ore mining and metallurgical activities in the Bor copper mining and smelting complex, Serbia. The AMD from the Bor mining complex (Bor-Krivelj-Cerovo) and smelting /refining of copper was characterized by low pH value (usually below 4) and high concentrations of heavy metals whose concentrations vary depending on the source. If entire complex was considered 7 different sources of the wastewaters could be defined. The treatment of the AMD included pretreatment/pH adjustment with CaO until pH 8 followed by electrocoagulation using iron (I = 50 A ; U = 10 V ; t =5 min.) followed by aluminum electrode sets (I = 50 A ; U = 10 V ; t =10 min.). Each electrode set contained of ten quadratic, one millimeter thick plates (75 x 250 mm) in the parallel arrangement, separated by an electro insulator. The distance between plates was 10 mm in both electrode sets. In the end of electrochemical treatment the suspension was recirculated in strong electromagnetic field for 10 minutes and subjected to slow mixing for another 15 minutes while the settlement time was 30 minutes. Waste sludge from the combined treatment process could be reused for another cycle of the pH adjustment/pretreatment of the acid mine drainage instead of CaO, and afterwards, due to its inertness, it could be used for overlaying layer of the flotation waste heap during its recovery work.

During last twenty years, the antifouling paints based on toxic tributhyltin are being replaced with less toxic compounds. To prevent fouling to boat’s hulls thus minimizing boat transport costs, people invented several possible solutions. Use of paints based on heavy metals is one of them. Annually, boats are being washed using high pressure wash machines thus generating approximately 100 L of wastewater that contains various types of heavy metals. The aim of this study was to test toxicity of such wastewater on human peripheral blood lymphocytes (HPBLs) and Salmonella typhimurium strains TA98 and TA100. In order to test cytotoxicity we have performed differential acridine orange and ethidium bromide vital staining on HPBLs. The results showed significant decrease in cell viability after both 4 h and 24 h exposure period. Genotoxic potential of tested wastewater was evaluated on HPBLs using comet assay. Similar results are observed for both exposure periods, where the percentage of migrated DNA resulted with 2.31-fold increase after 4 h and 1.86-fold increase after 24 h exposure period, compared to vehicle control samples. As models for mutagenicity testing S. typhimurium strains TA98 and TA100 were used. Interestingly, the wastewater failed to induce any significant, reproducible increase either in the presence or absence of metabolizing system S9 mix. The possible explanation of high genotoxicity could be either due to effective repair processes, or relatively high cytotoxicity of tested sample thus not inducing mutagenicity in S. typhimurium strains. In order to give possible solution for this potentially toxic wastewater, we have purified it using ozonation/electrocoagulation treatment processes. The same set of tests was done on purified wastewater where the level of some heavy metals decreased up to 100%. In that manner, the cytotoxicity, genotoxicity, and mutagenicity tests resulted with the same results as detected in vehicle control samples. Taken together, boat washing is potentially hazardous source of heavy metals leaching into sea water. Because of large number of boats and boatyards along the sea coasts it could present threat to environment, marine organisms, and humans, if not treated adequately.

Groundwater of the Pannonian basin which covers the parts of Hungary, Romania, Croatia, Serbia and Slovakia represents the complex system with elevated to high values of heavy metals and arsenic, color, turbidity, suspended solids, ammonia, and other nutrients as well as natural organic matter. When considering the human health risk, among the mentioned contaminants, arsenic is of the highest importance. The purpose of this work was development of the pilot plant purification system and its application onto groundwater taken from the production well water in the Vinkovci County (Eastern Croatia). The highest increase of the parameters over upper permissible limit UPL was found for the arsenic (13.8 times), phosphates (11.7 times), color (6.2 times), mercury (4.7 times), turbidity (3.3 times), ammonia (2.4 times), nickel (1.8 times) and iron (1.5 times). Due to the complex composition of the treated water, the purification system consisted of the combined electrochemical treatment, using iron and aluminum electrode plates with simultaneous ozonation followed by post treatment with UV, ozone and hydrogen peroxide. The combined treatment resulted in the total removal of arsenic, phosphates, color, turbidity, suspended solids and ammonia while the removal of other contaminants of interest was up to 96.7%.

A pilot plant study of the treatment of electroplating wastewaters using elctroreduction with iron electrode plates, electrocoagulation/ozonation using aluminium electrode set followed by ozonation was presented. The initial effluent was highly enriched in heavy metals and elevated levels of organic contaminants. The concentrations of Cr6+, Fe, Ni, Cu, Zn, Pb, TOC, and COD exceeded the upper permissible limits of 63, 220.2, 1.1, 7, 131.3, 1.7, 12.3 and 11.4 times, respectively. The heavy metal removal was forced either by the coagulation/flocculation using Fe2+, Fe3+, and Al3+ ions released into the treated solution by electrochemical corrosion of the sacrificial iron and aluminium electrodes, precipitation of the metal hydroxides as well as co-precipitation with iron and aluminium hydroxides. The principle mechanisms of the organic matter destruction were oxidation by ozone and the indirect oxidation with chlorine/hypochlorite formed by the anodic oxidation of chloride already present in the wastewater. Following the combined treatment, the removal efficiencies of the parameters Cr6+, Fe, Ni, Cu, Zn, Pb, TOC, and COD were 99.94%, 100.00%, 95.86%, 98.66%, 99.97%, 96.81%, 93.24%, 93.43%, and 77.78%, respectively. All the parameters in the final effluent were in agreement with regulated values.

The maintenance and repair of reinforced concrete structures, especially those submerged in the sea-water, requires effective inspection and monitoring techniques for assessing the state of corrosion in reinforcement material. An underwater inspection system was developed which is able to monitor the reinforcement corrosion. The system is remotely operating vehicle (ROV) equipped with the sealed tube neutron generator (NG). By rotating the NG and by using the associated alpha particle technique it is possible to measure the concrete cover depth together with the reinforcing bar diameter. The possibility to estimate the carbon and chloride content in the concrete was investigated. Iron plates of different thickness, covered by 6 cm thick concrete block, were successfully detected and the thickness of the concrete cover was estimated. In addition, reinforced bar of one and three centimeters in diameter was identified and measured.

The purpose of this work was development and application of the purification system suitable for the treatment of groundwater used for human consumption. The system should satisfy the following basic criteria: (a) no need for external addition of the chemicals (coagulants/flocculants, adsorbents, acids, basis) ; (b) applicable for simultaneous removal of wide range of contaminants present in the treated water (microbiological, inorganic, organic) ; (c) low sensitivity to the changes in the composition of the treated water ; (d) high quality of treated water with regard to all measured parameters. For that purpose Eastern Slavonia groundwaters with elevated values of heavy metals, color, turbidity, suspended solids, ammonia and organic contaminants were used. Due to the complexity of the composition of the treated water the purification system required electrochemical treatment using appropriate elctrochemical reactors followed by simultaneous ozonation/UV treatment. All measured parameters in the purified water were significantly lower compared to regulated values. Under the optimum treatment conditions removal efficiency of color, turbidity, suspended solids, nickel and arsenic was 100%. Removal efficiency of Fe, Mn, Cr, Zn, Cu, COD and ammonia was 99.4%, 95.7%, 98.2%, 74.0%, 99.1%, 93.8% and 94.0% respectively and increased with increasing initial concentration.

The aim of this research was development of appropriate procedure for the treatment of landfill leachate taken from the Piškornica, Mraclinska Dubrava and Viševac sanitary landfills. Due to the complex nature of the effluent 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. Pretreatment allows the destruction of the humic and fulvic acids and optimization of pH values for the formation of reactive oxidative species, as well as the transformation of NH4-N into volatile NH3-N. This pretreatment allows the softening of the water and 100% removal of the bacteria, between 90 and 96% removal of color, turbidity and suspended solids, approximately 65% removal of NH3-N and more than 98% removal of fluorides, phosphates and heavy metals, while the hardly biodegradable organic matter decomposes into more easily degradable carboxylic acids. In the presence of added calcium oxide and electrochemically generated coagulant the removal of the fluorides, phosphates and heavy metals occur trough 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 up to 98%, color and turbidity up to 99% and ammonia up to 97%. Following the electrochemical treatment the suspension was passed through an electromagnet in order to speed the separation of the sludge from the treated water. 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.

It was already shown in the previous work that the tagged neutron inspection system (TNIS), which uses the associated particle imaging (API) technique, was able to detect explosive in a sea-going cargo container filled with an iron matrix with density 0.2 g/cm3 [1]. It was also shown the possibility of TNIS to detect the explosive in the organic matrix with density ≤ 0.25 g/cm3 [2]. In this work the possibility of TNIS to identify materials hidden behind or in front of dense organic goods is investigated. A paper target, which is a good explosive simulant, is put close to the flour surroundings. A triangle diagram is made from the number of counts in the carbon peak, number of counts in the oxygen peak and the number of counts in the transmitted neutron peak. Identification of the paper target is possible if some appropriate knowledge about the surroundings is known.

The purpose of this work was the development and testing of a simple cost-effective treatment of waste waters originated from electroplating processes using waste Fe(II)-sulfate and wood fly ash. Ferrous-sulfate was employed for Cr(VI) reduction whereas neutralization and heavy metal removal from EWW was performed using wood fly ash. Optimum amount of ferrous sulfate and wood fly ash needed for successful treatment of EWW, optimum pH value of the treated solution and mixing time were determined. Various leaching tests were conducted on the remaining waste mud, which bound heavy metals from the waste water in order to determine a safe way to its permanent disposal. Heavy metals 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. Reported new procedure is technically simpler, cheaper and requires less space compared to the classical methodology because all reactions (chromate reduction, neutralization and heavy metals removal) could be conducted in only one container. Significant improvement in waste water treatment lies in the fact that both reagents (ferrous-sulfate and fly ash) are used in their original form (solid state) whereby any sort of preliminary processing isn’ t needed.

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 neutralisation 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 cycles of heavy metals removal, 5. negligible leaching of the heavy metals from the waste mud under normal environmental conditions, 6. safe for the transport, storage and handling.

Electroplating wastewaters have significantly contributed to the pollution of agricultural soil and water in Croatia. A total of 104 registered electroplating facilities existed in the year 2002. In most cases, EWW having a pH below 2 and metal levels few hundred to thousand times higher than the allowed values have been discharged directly into the surrounding agricultural soil and local streams. The aim of this work was to present a new, simple cost-effective system for the treatment of waste waters from electroplating and other surface processes highly enriched in heavy metals (Cr (VI), Zn, Ni, Fe) using other waste materials such as waste Fe(II)-sulfate and wood fly ash. The former was employed as a reducing agent and the latter was a neutralizing agent as well as a coagulant. Removal efficiency for analyzed elements ranged from 97.500% for copper to 99.973% for zinc. Satisfying results can be achieved already at the pH 8. The method is suitable for the purposes of wastewater 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.

Long-term observations of soil water content as well as determination of physical and chemical properties of different types of soils in Croatia were made in order to provide the necessary background information for landmine explosive detection. Soil water content is the key attribute of soil as a background in neutron backscattering technique (NBT) landmine detection application. If the critical value of the soil water content is reached, the detection of landmine explosives is not possible. It is recommended that soil moisture content for NBT application does not exceed 0.1 kg.kg-1 [1]. Nineteen representative samples of different soil types from different parts of Croatia were collected in order to establish soil bank with the necessary physical and chemical properties determined for each type of soil. In addition soil water content was measured on daily and weekly basis on several locations in Croatia. This procedure also included daily soil moisture measurements in the test field made of different types of soils from several locations in Croatia. This was done in order to evaluate the behavior of different types of soils under the same weather conditions.

Neutron Backscattering (NB) sensors have been proposed for Humanitarian De-mining applications. Recently, an hand held system integrating a NB sensor in a Metal Detector has been developed within the DIAMINE Contract(IST-2000-25237). Results obtained in term of performance of the NB systems and limitations in its use are presented.