TREATMENT OF WASTEWATER FROM SEPARATORS FOR RAINFALL RUNOFF USING ELECTROCHEMICAL OXIDATION PROCESSES

In recent years, industry has increased and with it the amount of oily wastewater, which are considered hazardous waste because they contain various types of heavy metals and oils that endanger the environment and human health. In the last twenty years, there has been increased research on new technologies to treat wastewater as efficiently and environmentally friendly as possible. A recent approach to wastewater treatment is the application of electrochemical processes such as the electro-Fenton process, which belongs to the group of electrochemical advanced oxidation processes and electrocoagulation. The aim of this work was to remove organic contaminants and heavy metals from wastewater originating from oil and grease separators that clean stormwater runoff from traffic areas. The use of stainless steel, iron and aluminum electrodes results in electrooxidation, electroreduction and electrocoagulation. At a current of 15 A the treatment efficiency was 50% for COD and 73% for mineral oil. At a current of 110 A the treatment efficiency was 96% for COD and 90% for mineral oil

STATIC AND DINAMIC REMOVAL OF COPPER (II) IONS BY FOUNDRY WASTE

U ovom radu proučavana je statička i dinamička adsorpcija bakrovih (II) iona iz otpadne vode na ljevaoničkom otpadu. Kao adsorbens je korištena otpadna kalupna mješavina iz ljevaonice željeznog i čeličnog lijeva. Kao otpadna voda korištena je voda iz termoelektrane koja je onečišćena bakrovim(II) ionima. Dobiveni rezultati pokazali su da se ljevaonički otpad može koristiti kao dobar adsorbens za uklanjanje bakrovih iona primjenom statičkog i dinamičkog procesa adsorpcije.In this paper, the static and dynamic adsorption of copper (II) ions from wastewater by waste from foundry was studied. Waste molding mixture from iron and steel foundry was used as adsorbent. Water from thermal power plant was used as water contaminated with copper (II) ions. Obtained results show that the foundry waste may be used as a good adsorbent for the removal of copper ions by using static and dynamic adsorption process

Der Einfluss von physikalischen und chemischen Indikatoren und Metallen auf die Gemeinschaften von Eintagsfliegen, Steinfliegen und Köcherfliegen (EPT)

U ovom smo radu istraživali vezu između broja svojti unutar triju redova vodenih kukaca: vodencvjetova (Ephemeroptera), obalčara (Plecoptera) i tulara (Trichoptera), ukupnog broja svojti (EPT), kao i udjela EPT jedinki u zajednici bentoskih makrobeskralješnjaka (EPT[%]) te metala otopljenih u vodi i fizikalno-kemijskih pokazatelja. Prisustvo EPT zajednice s velikim brojem svojti i velikim udjelom u ukupnoj zajednici bentoskih makrobeskralješnjaka se obično povezuje s dobrom kvalitetom slatkovodnih ekosustava. Svi podaci su prikupljeni u sklopu programa sustavnog praćenja stanja površinskih voda tijekom 8 godina (2010.-2017.). Ukupno je analizirano 247 uzoraka bentoskih makrobeskralješnjaka na 172 postaje uzorkovanja, a svi uzorci prikupljeni su koristeći AQEM metodu uzorkovanja. Voda za određivanje koncentracije otopljenih metala i osnovnih fizikalno-kemijskih pokazatelja uzorkovana je u godini kad je prikupljen uzorak bentoskih makrobeskralješnjaka, a svi navedeni pokazatelji mjereni su standardnim analitičkim metodama za analizu kakvoće površinskih voda (ISO norme). Pronađena je negativna veza EPT zajednice (broj svojti vodencvjetova (E), obalčara (P), tulara (T) i ukupno (EPT), te udio jedinki EPT u ukupnom uzorku (EPT [%]) s fizikalno-kemijskim pokazateljima, kao što su to npr.: temperatura i P = -0,528, električna vodljivost i P = -0,491, ukupna tvrdoća i EPT = -0,493) te slaba negativna veza s alkalitetom i ukupnom suspendiranom tvari. Spearmanov koeficijent korelacije ukazuje i na statistički značajnu negativnu povezanost između i koncentracije mangana s P i T (-0,540, -0,380 slijedom) te arsena s EPT[%] (-0,421). S ostalim metalima (bakar, cink, kadmij, krom, nikal, olovo, živa i željezo) korelacije su slabe do beznačajne. Rezultati ovog istraživanja ukazuju da bi uporaba EPT kao bioindikatora mogla biti važna strategija pri određivanju zagađenja manganom i arsenom u vodenom okolišu.The paper investigates the relationship between the number of taxa within three orders of aquatic insects - Ephemeroptera (mayflies), Plecoptera (stoneflies) and Trichoptera (caddisflies), the total taxa (EPT) and EPT individuals in the benthic macroinvertebrate community (EPT[%]), including dissolved metals in the water and physico-chemical parameters. The presence of EPT community with numerous taxa and a large share in the total macroinvertebrate community is usually associated with good water quality of freshwater ecosystems. All collected data used in this study originate from the national monitoring programme of surface water quality within a period of 8 years (2010 - 2017). In total, 247 samples of benthic macroinvertebrates from 172 sampling stations were analysed. All samples were collected according to the AQEM sampling protocol. The water used for determining the concentrations of dissolved metals and basic physico-chemical parameters was sampled in the same year when the samples of macrozoobenthos were collected, and all mentioned parameters were measured according to standard analytical methods for analysing surface water quality (ISO standards). The statistical analysis showed a significant negative correlation of the EPT assemblage (number of taxa of Ephemeroptera (E), Plecoptera (P), Trichoptera (T) and altogether (EPT), as well as the share of EPT individuals in the sample (EPT [%]) with physico-chemical parameters, such as temperature and (P) = -0.528, electric conductivity and (P) = -0.485, total hardness and EPT = -0.493, including a weak negative correlation with alkalinity and total suspended solids. The Spearman\u27s coefficient of the correlation indicated a statistically significant negative correlation of Manganese with P and T (-0.540 and -0.380, respectively) and of Arsenic with EPT[%] (-0.421). The correlations with other metals (Copper, Zinc, Cadmium, Chrome, Nickel, Lead, Mercury and Iron) were weak to insignificant. The results of the present study suggest that the use of EPT as bioindicators may be an important strategy for detecting Manganese and Arsenic pollution in aquatic environments.In diesem Artikel wurde das Verhältnis untersucht zwischen der Anzahl von Taxa innerhalb drei Ordnungen von Insekten, nämlich Eintagsfliegen (Ephemeroptera), Steinfliegen (Plecoptera) und Köcherfliegen (Trichoptera), der Gesamtzahl von Taxa (EPT), dem Anteil der EPT-Individuen in der Gemeinschaft von Makrozoobenthos (EPT[%]) sowie im Wasser gelösten Metallen und den physikalischen und chemischen Indikatoren. Die Anwesenheit der EPT-Gemeinschaft mit einer großen Anzahl von Taxa und großem Anteil an der Gesamtgemeinschaft von Makrozoobenthos verbindet man gewöhnlich mit sehr guter Qualität von Süßwasserökosystemen. Alle Daten wurden im Rahmen des Programms zur systematischen Überwachung des Zustandes von Oberflächengewässern im Laufe von acht Jahren (2010-2017) gesammelt. Insgesamt wurden 247 Makrozoobenthosproben von 172 Probenstationen analysiert, wobei alle Proben nach der AQEM-Methode gesammelt wurden. Die Wasserproben zur Bestimmung der Konzentration von im Wasser gelösten Metallen und den physikalischen und chemischen Indikatoren wurden im gleichen Jahr wie die Makrozoobenthosproben entnommen. Alle Indikatoren wurden mit den üblichen Methoden zur Analyse der Qualität von Oberflächengewässern (ISO-Normen) gemessen. Der negative Zusammenhang zwischen der EPT-Gemeinschaft (Anzahl von Taxa von Eintagsfliegen (E), Steinfliegen (P), Köcherfliegen (T) und Gesamtzahl (EPT) sowie dem Anteil der EPT-Individuen in der Gesamtprobe (EPT[%]) und den physikalischen und chemischen Indikatoren, z. B. Temperatur und P = -0,528, elektrische Leitfähigkeit und P = -0,491, Gesamthärte und EPT = -0,493 wurde festgestellt sowie der schwache negative Zusammenhang zur Alkalität und Gesamtschwebestoffen. Der Spearman-Korrelationskoeffizient weist auf einen statistisch signifikanten negativen Zusammenhang zwischen der Mangankonzentration und P und T (-0,540 bzw. -0,380) und der Arsenkonzentration und EPT[%] (-0,421) hin. Bei anderen Metallen (Kupfer, Zink, Cadmium, Nickel, Blei, Quecksilber und Eisen) sind die Korrelationen schwach bis insignifikant. Die Ergebnisse dieser Untersuchung zeigen, dass die Anwendung von EPT als Bioindikator eine wichtige Strategie in der Bestimmung von Mangan- und Arsenverschmutzung in Gewässern sein könnte

Der Einfluss von physikalischen und chemischen Indikatoren und Metallen auf die Gemeinschaften von Eintagsfliegen, Steinfliegen und Köcherfliegen (EPT)

U ovom smo radu istraživali vezu između broja svojti unutar triju redova vodenih kukaca: vodencvjetova (Ephemeroptera), obalčara (Plecoptera) i tulara (Trichoptera), ukupnog broja svojti (EPT), kao i udjela EPT jedinki u zajednici bentoskih makrobeskralješnjaka (EPT[%]) te metala otopljenih u vodi i fizikalno-kemijskih pokazatelja. Prisustvo EPT zajednice s velikim brojem svojti i velikim udjelom u ukupnoj zajednici bentoskih makrobeskralješnjaka se obično povezuje s dobrom kvalitetom slatkovodnih ekosustava. Svi podaci su prikupljeni u sklopu programa sustavnog praćenja stanja površinskih voda tijekom 8 godina (2010.-2017.). Ukupno je analizirano 247 uzoraka bentoskih makrobeskralješnjaka na 172 postaje uzorkovanja, a svi uzorci prikupljeni su koristeći AQEM metodu uzorkovanja. Voda za određivanje koncentracije otopljenih metala i osnovnih fizikalno-kemijskih pokazatelja uzorkovana je u godini kad je prikupljen uzorak bentoskih makrobeskralješnjaka, a svi navedeni pokazatelji mjereni su standardnim analitičkim metodama za analizu kakvoće površinskih voda (ISO norme). Pronađena je negativna veza EPT zajednice (broj svojti vodencvjetova (E), obalčara (P), tulara (T) i ukupno (EPT), te udio jedinki EPT u ukupnom uzorku (EPT [%]) s fizikalno-kemijskim pokazateljima, kao što su to npr.: temperatura i P = -0,528, električna vodljivost i P = -0,491, ukupna tvrdoća i EPT = -0,493) te slaba negativna veza s alkalitetom i ukupnom suspendiranom tvari. Spearmanov koeficijent korelacije ukazuje i na statistički značajnu negativnu povezanost između i koncentracije mangana s P i T (-0,540, -0,380 slijedom) te arsena s EPT[%] (-0,421). S ostalim metalima (bakar, cink, kadmij, krom, nikal, olovo, živa i željezo) korelacije su slabe do beznačajne. Rezultati ovog istraživanja ukazuju da bi uporaba EPT kao bioindikatora mogla biti važna strategija pri određivanju zagađenja manganom i arsenom u vodenom okolišu.The paper investigates the relationship between the number of taxa within three orders of aquatic insects - Ephemeroptera (mayflies), Plecoptera (stoneflies) and Trichoptera (caddisflies), the total taxa (EPT) and EPT individuals in the benthic macroinvertebrate community (EPT[%]), including dissolved metals in the water and physico-chemical parameters. The presence of EPT community with numerous taxa and a large share in the total macroinvertebrate community is usually associated with good water quality of freshwater ecosystems. All collected data used in this study originate from the national monitoring programme of surface water quality within a period of 8 years (2010 - 2017). In total, 247 samples of benthic macroinvertebrates from 172 sampling stations were analysed. All samples were collected according to the AQEM sampling protocol. The water used for determining the concentrations of dissolved metals and basic physico-chemical parameters was sampled in the same year when the samples of macrozoobenthos were collected, and all mentioned parameters were measured according to standard analytical methods for analysing surface water quality (ISO standards). The statistical analysis showed a significant negative correlation of the EPT assemblage (number of taxa of Ephemeroptera (E), Plecoptera (P), Trichoptera (T) and altogether (EPT), as well as the share of EPT individuals in the sample (EPT [%]) with physico-chemical parameters, such as temperature and (P) = -0.528, electric conductivity and (P) = -0.485, total hardness and EPT = -0.493, including a weak negative correlation with alkalinity and total suspended solids. The Spearman\u27s coefficient of the correlation indicated a statistically significant negative correlation of Manganese with P and T (-0.540 and -0.380, respectively) and of Arsenic with EPT[%] (-0.421). The correlations with other metals (Copper, Zinc, Cadmium, Chrome, Nickel, Lead, Mercury and Iron) were weak to insignificant. The results of the present study suggest that the use of EPT as bioindicators may be an important strategy for detecting Manganese and Arsenic pollution in aquatic environments.In diesem Artikel wurde das Verhältnis untersucht zwischen der Anzahl von Taxa innerhalb drei Ordnungen von Insekten, nämlich Eintagsfliegen (Ephemeroptera), Steinfliegen (Plecoptera) und Köcherfliegen (Trichoptera), der Gesamtzahl von Taxa (EPT), dem Anteil der EPT-Individuen in der Gemeinschaft von Makrozoobenthos (EPT[%]) sowie im Wasser gelösten Metallen und den physikalischen und chemischen Indikatoren. Die Anwesenheit der EPT-Gemeinschaft mit einer großen Anzahl von Taxa und großem Anteil an der Gesamtgemeinschaft von Makrozoobenthos verbindet man gewöhnlich mit sehr guter Qualität von Süßwasserökosystemen. Alle Daten wurden im Rahmen des Programms zur systematischen Überwachung des Zustandes von Oberflächengewässern im Laufe von acht Jahren (2010-2017) gesammelt. Insgesamt wurden 247 Makrozoobenthosproben von 172 Probenstationen analysiert, wobei alle Proben nach der AQEM-Methode gesammelt wurden. Die Wasserproben zur Bestimmung der Konzentration von im Wasser gelösten Metallen und den physikalischen und chemischen Indikatoren wurden im gleichen Jahr wie die Makrozoobenthosproben entnommen. Alle Indikatoren wurden mit den üblichen Methoden zur Analyse der Qualität von Oberflächengewässern (ISO-Normen) gemessen. Der negative Zusammenhang zwischen der EPT-Gemeinschaft (Anzahl von Taxa von Eintagsfliegen (E), Steinfliegen (P), Köcherfliegen (T) und Gesamtzahl (EPT) sowie dem Anteil der EPT-Individuen in der Gesamtprobe (EPT[%]) und den physikalischen und chemischen Indikatoren, z. B. Temperatur und P = -0,528, elektrische Leitfähigkeit und P = -0,491, Gesamthärte und EPT = -0,493 wurde festgestellt sowie der schwache negative Zusammenhang zur Alkalität und Gesamtschwebestoffen. Der Spearman-Korrelationskoeffizient weist auf einen statistisch signifikanten negativen Zusammenhang zwischen der Mangankonzentration und P und T (-0,540 bzw. -0,380) und der Arsenkonzentration und EPT[%] (-0,421) hin. Bei anderen Metallen (Kupfer, Zink, Cadmium, Nickel, Blei, Quecksilber und Eisen) sind die Korrelationen schwach bis insignifikant. Die Ergebnisse dieser Untersuchung zeigen, dass die Anwendung von EPT als Bioindikator eine wichtige Strategie in der Bestimmung von Mangan- und Arsenverschmutzung in Gewässern sein könnte

Titanium Ions Release from an Innovative Titanium-Magnesium Composite: an in Vitro Study

Svrha: U ovom radu istraživala su se korozijska svojstva inovativnog titanij-magnezijeva (Ti-Mg) kompozita proizvedenog metodom metalurgije praha (P/M). Materijal i metode: Ispitivane su dvije grupe eksperimentalnog materijala – s 1 masenim udjelom (mass% Ti-1Mg) i 2 masena udjela (mass% Ti-2Mg) magnezija u titanijskoj osnovi te su uspoređene s komercijalno čistim titanijem (CP Ti). Test uranjanja i kemijska analiza četiriju otopina: umjetne sline, umjetne sline pH 4, umjetne sline s dodatkom fluora i Hankove otopine, provedeni su nakon 42 dana uranjanja metodom masene spektrometrije induktivno spregnutom plazmom (ICP – MS) kako bi se ustanovila količina otpuštenih iona titanija (Ti). Za određivanje svojstava površine korištene su analize SEM i EDS. Rezultati: Razlika u rezultatima između različitih ispitivanih otopina procjenjivana je ANOVA-om i Newman-Keulsovim testom na razini značajnosti od p < 0,05. Utjecaj prediktorskih varijabli utvrđivan je multiplom regresijskom analizom. Rezultati ovog istraživanja pokazuju nisku stopu korozije titanija u ispitivanoj skupini Ti-Mg. Uočeno je do 46 puta, odnosno 23 puta manje otapanje iona titanija iz Ti-1Mg i Ti-2Mg u usporedbi s kontrolnom skupinom. Između ispitivanih otopina, umjetna slina s dodatkom fluora pokazala je najveći korozijski učinak među svim ispitivanim uzorcima. SEM-analiza pokazala je sačuvanu dvofaznu strukturu površine, a EDS-analiza upozorila je na moguća bioaktivna svojstva površine. Zaključak: Ti-Mg kompozit proizveden metodom P/M-a sugerira se kao materijal boljih korozijskih svojstava u usporedbi s čistim titanijem (CP Ti).The innovative titanium-magnesium composite (Ti-Mg) was produced by powder metallurgy (P/M) method and is characterized in terms of corrosion behavior. Material and methods: Two groups of experimental material, 1 mass% (Ti-1Mg) and 2 mass% (Ti-2Mg) of magnesium in titanium matrix, were tested and compared to commercially pure titanium (CP Ti). Immersion test and chemical analysis of four solutions: artificial saliva; artificial saliva pH 4; artificial saliva with fluoride and Hank balanced salt solution were performed after 42 days of immersion, using inductively coupled plasma mass spectrometry (ICP-MS) to detect the amount of released titanium ions (Ti). SEM and EDS analysis were used for surface characterization. Results: The difference between the results from different test solutions was assessed by ANOVA and Newman-Keuls test at p<0.05. The influence of predictor variables was found by multiple regression analysis. The results of the present study revealed a low corrosion rate of titanium from the experimental Ti-Mg group. Up to 46 and 23 times lower dissolution of Ti from Ti-1Mg and Ti-2Mg, respectively was observed compared to the control group. Among the tested solutions, artificial saliva with fluorides exhibited the highest corrosion effect on all specimens tested. SEM micrographs showed preserved dual phase surface structure and EDS analysis suggested a favorable surface bioactivity. Conclusion: In conclusion, Ti-Mg produced by P/M as a material with better corrosion properties when compared to CP Ti is suggested

Effect of bismuth and rare earth elements on graphite structure in different section thicknesses of spheroidal graphite cast iron castings

Effects of additions of 0.00064, 0.001 and 0.0042 wt.% Bi on the graphite structure in the section thicknesses of 3, 12, 25, 38, 50, 75 and 100 mm of spheroidal graphite cast iron castings containing 2.11 wt.% Si and rare earth (RE) elements (Ce + La + Nd + Pr + Sm + Gd) in the range from 0.00297 to 0.00337 wt.% were analyzed in this paper. Addition of Bi was not necessary for obtaining high nodule count and nodularity higher than 80% in section thicknesses of 3, 12 and 25 mm. RE elements showed a beneficial effect on the nodule count and nodularity in these sections. Nodularity was below 80% in section thicknesses of 38 , 50, 75 and 100 mm when Bi was not added. Detrimental effect of RE elements on graphite morphology in these sections was neutral- ized by adequate addition of Bi. Addition of 0.001 wt.% Bi (ratio of RE/Bi = 3.27) was enough to achieve nodularity above 80% in the section thickness of 38 mm. Nodularity was increased above 80% in section thicknesses of 50, 75 and 100 mm by addition of 0.0042 wt.% Bi (ratio of RE/Bi = 0.78). At the same time, Bi significantly increased the nodule count. Nodularity above 80% and the high nodule count in the section thicknesses of 75 and 100 mm were also achieved by using an external metallic chill in the mold. In this case, addition of Bi was not required

Impact of Gravel Pits on Water Quality in Alluvial Aquifers

Gravel pits are considered potentially hazardous in terms of groundwater quality protection as they represent an open part of the aquifer system, increasing the aquifer’s vulnerability to contamination from the surface. The aim of this research was to determine the biogeochemical processes in gravel pits that have a positive effect on the groundwater quality in the alluvial aquifer in NW Croatia. The aquifer is situated below developed agricultural land, with high groundwater nitrate concentrations having been recorded over the last decades. The differences between two gravel pits and the surrounding groundwater were studied using in situ, hydrochemical, and isotopic parameters (δ15N-NO3 and δ18O-NO3), together with existing microbial data. The analyses of nitrogen species indicated that nitrate attenuation processes take place in gravel pits. Bacterial denitrification and nitrate uptake by algae were responsible for significant decreases in nitrate concentration. These processes were more effective in the inactive gravel pit, which has a longer water residence time and during warm periods, when microbial biomass, abundance, and activity were high. The seasonally variable microbial activity also affected trace metals, removing them from groundwater, possibly through the biosorption of metal ions. The presented research shows that the observed biogeochemical processes are associated with seasonal changes that affect the types and number of microbial communities and the chemical composition of water, resulting in gravel pits being groundwater remediation points

Recycling Electric Arc Furnace Slag into Fertilizer: Effects of &ldquo;Waste Product&rdquo; on Growth and Physiology of the Common Bean (Phaseolus vulgaris L.)

The aim of this study was to investigate if electric arc furnace (EAF) slag generated during steel production could have an application as a soil enhancer in agriculture. For that purpose, a greenhouse experiment was conducted on common beans (Phaseolus vulgaris) cultivated in soil enriched with EAF slag (at 1% and 2% level), synthetic fertilizer (NPK), combined EAF slag and synthetic fertilizer, or in control (untreated) soil. The beans were exposed to test soils until maturity (for 8 weeks). Following that period, physico-chemical properties of the soils, as well as nutrient status, growth, photosynthetic and oxidative stress parameters of bean plants were determined. EAF slag improved the mineral status of the soil and significantly increased Fe, Mg, N, P and K in different bean plant organs. EAF slag and/or NPK increased plant height. EAF slag, especially at lower levels, positively affected dry weight of leaf and seed. Soil supplementation with a lower level of EAF slag, as well as with a combination of EAF slag and NPK, led to significant improvement in gas exchange parameters (net photosynthetic rate, intercellular CO2 concentration and stomatal conductance) and nitrate reductase activity, indicating a positive influence on bean plants. Potential phytotoxicity of EAF slag was not detected, as evidenced by the oxidative stress parameters. Thus, EAF slag applied at a low level shows promising potential as an efficient soil enhancer, and as a valuable source of nutrients essential to plants, with an equal or even better performance compared to synthetic fertilizer

Recycling Electric Arc Furnace Slag into Fertilizer: Effects of “Waste Product” on Growth and Physiology of the Common Bean (<i>Phaseolus vulgaris</i> L.)

The aim of this study was to investigate if electric arc furnace (EAF) slag generated during steel production could have an application as a soil enhancer in agriculture. For that purpose, a greenhouse experiment was conducted on common beans (Phaseolus vulgaris) cultivated in soil enriched with EAF slag (at 1% and 2% level), synthetic fertilizer (NPK), combined EAF slag and synthetic fertilizer, or in control (untreated) soil. The beans were exposed to test soils until maturity (for 8 weeks). Following that period, physico-chemical properties of the soils, as well as nutrient status, growth, photosynthetic and oxidative stress parameters of bean plants were determined. EAF slag improved the mineral status of the soil and significantly increased Fe, Mg, N, P and K in different bean plant organs. EAF slag and/or NPK increased plant height. EAF slag, especially at lower levels, positively affected dry weight of leaf and seed. Soil supplementation with a lower level of EAF slag, as well as with a combination of EAF slag and NPK, led to significant improvement in gas exchange parameters (net photosynthetic rate, intercellular CO2 concentration and stomatal conductance) and nitrate reductase activity, indicating a positive influence on bean plants. Potential phytotoxicity of EAF slag was not detected, as evidenced by the oxidative stress parameters. Thus, EAF slag applied at a low level shows promising potential as an efficient soil enhancer, and as a valuable source of nutrients essential to plants, with an equal or even better performance compared to synthetic fertilizer