Zn In Effluent Research Articles

Ecotoxicological impacts of industrial effluents on irrigation water quality, animal health and the role of calcium alginate in effluents treatment

The effluents discharged from Mansoura Company for Resins and Chemicals Industry were evaluated for drinking and irrigation purposes. Calcium-alginate beads were used for effluents treatment in this study. Young male rats were also allowed to drink effluents at different concentrations (10%, 50%, 100%) and treated 100% effluents with calcium-alginate for 11 weeks. Results indicated high concentrations of some physicochemical parameters and Cd, Co, Fe, Mn, Ni, Pb, and Zn in effluents that exceeded the permissible limits for drinking and irrigation purposes. Treatment by calcium-alginate alleviate heavy metals concentration but did not affect the physicochemical parameters. Depending on effluents concentration, the liver of young male rats showed high accumulation of Fe, Mn, Zn, Pb, Cd, Co, Cu, Cr, and Ni compared to the control group. Serum levels of liver enzymes, total bilirubin significantly increased while total protein, and albumin contents decreased in effluent groups. Liver concentrations of malondialdehyde and protein carbonyl significantly elevated along with significant decrease in superoxide dismutase, catalase, glutathione-S-transferase activities, and glutathione content. Moreover, growth and thyroid hormones were significantly reduced along with significant elevation in thyroid stimulating hormone. This was accompanied by significant decrease in the body weight, especially with 100% effluents concentration compared to control group. Also, histological investigations of both liver and thyroid gland using hematoxylin and eosin showed distortion in the structure of both organs especially with 50% and 100% effluent groups. However, treatment of effluents by calcium-alginate improved these changes. The study revealed that calcium-alginate are effective biosorbents for heavy metals and consequently decrease animal and human health hazards, but further studies are needed to alleviate physicochemical characteristics.

Investigation of intra - event variations of total, dissolved and truly dissolved metal concentrations in highway runoff and a gross pollutant trap – bioretention stormwater treatment train

Metals in stormwater can be toxic to organisms, particularly when occurring in truly dissolved form (fraction <3 kDa). Here, using 153 samples collected during six rains, we investigated intra-events variations of total, dissolved and truly dissolved metal concentrations in highway runoff, and how they were affected by a stormwater treatment train, comprising a gross pollutant trap (GPT) and a bioretention system. Although intra-event variations in metal concentrations were observed in the highway stormwater, the effluent of the GPT and the effluent from the bioretention system, generally no “first flush” was observed. While total Pb, Cu and Zn concentrations were, on average, significantly reduced by the bioretention system (>76%, 79% and 94%, respectively), removal of dissolved metals was lower and truly dissolved Cd and Cu were generally not effectively removed (average removal Cd -11%, Cu 7.7%). Only for truly dissolved Zn was removal 65%. However, as with Cu, effluent Zn concentrations exceeded environmental threshold values. While Cu, Pb and Zn occurred in the highway runoff in particulate form, with average percentages of 86%, >99% and 72%, respectively, the speciation of Cu and Zn in the bioretention effluent shifted towards greater fractions of colloidal and truly dissolved metals. The GPT had no significant effect on metal concentrations and speciation.

In-Water Cleaning and Capture to Remove Ship Biofouling: An Initial Evaluation of Efficacy and Environmental Safety

Biofouling is a long-standing challenge for ships because it can interfere with operations and increases vessel drag, fuel consumption and exhaust emissions. More recently, ship biofouling has also been recognized as a leading vector for global transfers and introductions of marine non-indigenous species. Ship in-water cleaning and capture (IWCC) systems, to remove and collect macrofouling organisms and associated antifouling coating compounds, are now becoming available as a possible solution to both problems. However, independent and rigorous evaluations of IWCC efficacy and environmental safety are needed to facilitate technology maturation, support vessel operator biofouling management decisions, aid IWCC approvals and permitting, and future biosecurity regulations. We developed a formal protocol for evaluating an IWCC system, on two ships with varying biofouling levels and under different environmental conditions, to quantify biofouling removal and capture efficacy as well as impacts on water quality. The IWCC system reduced hull biofouling by 82 - 94%. Concentrations of dissolved and particulate Cu and Zn in effluent from the IWCC onshore processing varied by orders of magnitude between trials, in one case greatly exceeding water quality standards. Our results demonstrate that rigorous, quantitative assessments of IWCC system performance are possible, even under challenging conditions. This initial evaluation also identifies the major factors that impact performance of in-water cleaning, and key needs for future research, to consider in advancing standardized testing and independent evaluations needed for all in-water cleaning systems.

Co-transport of heavy metals in layered saturated soil: Characteristics and simulation

Interest in soil pollution by multiple heavy metals has been growing over the last decades. However, few experiments combining numerical analyses with solute transport in layered soil can be found in the literature. Here, the retention and fate of three coexisting metal ions, Cu, Cd, and Zn, in layered soils were investigated to evaluate soil co-contamination through batch and column experiments. Results showed high amounts of Cu adsorption and retention by soils, followed by Cd and Zn. The partial concentration of Zn in effluent was greater than the input from competition adsorption and the ‘snow plow effect’. These findings indicate the high potential risk of Zn and Cd groundwater pollution when Cu, Cd, and Zn co-exist in the soil. Adsorption isotherms obtained from batch experiments were well described by Freundlich equation. Breakthrough curves (BTCs) obtained from column experiments were well described by standard convection-dispersion equation (CDE) for Br, and Tow-site (TSM) and One-site models (OSM) for metals except for Zn, using the Levenberg-Marquardt nonlinear optimization algorithm. However, the parameters were poorly constrained by the available observational data due to high correlation between parameters, rather than insensitivity to model outputs. The Generalized Likelihood Uncertainty Estimation (GLUE) method did not only qualify the uncertainty of parameters for solute transport in layered medium, but estimate prediction uncertainty. Prediction bounds basically captured the observed Br, Zn and Cd BTCs, while systematically overestimated the effluent Cu concentration.Comparing with the optimization, GLUE method can improve prediction reliability of heavy metal transport in layered soils.

Infiltration behavior of heavy metals in runoff through soil amended with biochar as bulking agent

Biochar as a porous carbon material could be used for improving soil physical and chemical properties, while insufficient attention has been paid to potential risks induced by infiltration of heavy metals in the runoff water flowing through biochar-amended soil. Four different soil-biochar matrices with same volumes were constructed including soil alone (M1), biochar alone (M2), soil-biochar layering (M3) and soil-biochar mixing (M4). Leaching experiments were conducted with Pb, Cu, and Zn contaminated runoff water. Results showed that biochar amendment greatly improved the water permeation, and the infiltration rates in M2, M3, and M4 were 2.85–23.0 mm min−1, being much higher than those in M1 (1.33–4.05 mm min−1), though the rates decreased as the leaching volumes increased. However, biochar induced more Pb, Cu, and Zn infiltrated through soil-biochar matrix. After 350-L leaching, M1 retained about 95% Pb, 90% Cu, and 36% Zn, while M2 only retained 4.80% Pb, 17.4% Cu, and 4.01% Zn; about 30% Pb, 80% Cu, and 15% Zn were retained in M3 and M4. Notably, Zn was trapped first and then re-leached into the filtrate, which resulted in a much higher effluent Zn than the influent Zn at the later stage. However, the unit weight of biochar showed a higher capacity for retaining heavy metals compared to per unit of soil. Under the dynamic water flow, all benefits and disadvantages induced by biochar were weakened with its physical disintegration. Biochar as soil amendment can enhance plant growth via ameliorating soil structure, while it would pose risks to environment because of large penetration of heavy metals. If biochar was compacted to form a denser physical structure, perhaps more heavy metals could be retained.

Evaluation of Pollution Sources of Zinc in Tokyo Bay Based on Zinc Isotope Ratio in Sediment Core

This study evaluated the sources of Zn pollution in Tokyo Bay, Japan, on the basis of δ66Zn in a sediment core. The Zn concentration in sediments in the 1980s-2000s was considerably higher than the background concentration, suggesting that there remain important sources of Zn in the bay. The δ66Zn (+0.51‰) of anthropogenic Zn estimated in the core was significantly higher than those (approximately –0.1‰ - +0.2‰) of treated water from sewage treatment plants and vehicle-related sources. A large number of electroplating plants are located in Tokyo areas. It is assumed that Zn in effluents from electroplating operations is isotopically heavier owing to a negative isotopic effect on Zn electroplating. This tends to support the hypothesis that river bottom sediments, which were contaminated with Zn in the untreated effluents from electroplating plants in the past, are the principal sources of anthropogenic Zn in Tokyo Bay in the 1980s-2000s.

Comparison of the effects and distribution of zinc oxide nanoparticles and zinc ions in activated sludge reactors

ABSTRACTZinc Oxide nanoparticles (ZnO NPs) are being increasingly applied in the industry, which results inevitably in the release of these materials into the hydrosphere. In this study, simulated waste-activated sludge experiments were conducted to investigate the effects of Zinc Oxide NPs and to compare it with its ionic counterpart (as ZnSO4). It was found that even 1 mg/L of ZnO NPs could have a small impact on COD and ammonia removal. Under 1, 10 and 50 mg/L of ZnO NP exposure, the Chemical Oxygen Demand (COD) removal efficiencies decreased from 79.8% to 78.9%, 72.7% and 65.7%, respectively. The corresponding ammonium (NH4+ N) concentration in the effluent significantly (P < 0.05) increased from 11.9 mg/L (control) to 15.3, 20.9 and 28.5 mg/L, respectively. Under equal Zn concentration, zinc ions were more toxic towards microorganisms compared to ZnO NPs. Under 50 mg/L exposure, the effluent Zn level was 5.69 mg/L, implying that ZnO NPs have a strong affinity for activated sludge. The capacity for adsorption of ZnO NPs onto activated sludge was found to be 2.3, 6.3, and 13.9 mg/g MLSS at influent ZnO NP concentrations of 1.0, 10 and 50 mg/L respectively, which were 1.74-, 2.13- and 2.05-fold more than under Zn ion exposure.

Removal of Pb and Zn from industrial effluent using humic acid

The present work was conducted to remove Pb and Zn from industrial effluents by coagulating the ions with humic acids. Seven types of effluents were collected from textile, tannery and pharmaceutical industries. Two commercially available humic acids one in a liquid state and another one in a semi-solid state, humic acid extracted from peat were used to remove Pb and Zn from industrial effluents as well as synthetic waste water. Optical property, carbon concentration and coagulation threshold of humic acids were studied. Same carbon concentration (1 x 10-5 g L-1) of all the sources was maintained at neutral pH. The values of water soluble Pb and Zn in effluents were 0.000 - 0.0711 ?g/mL and 0.002 - 0.024 ?g/mL, respectively. Results indicated that liquid humic acid having E4: E6 ratio of 1.2 removed 100% Pb and Zn only from pharmaceutical effluent whereas humic acid extracted from peat having E4: E6 ratio of 3.18 completely (100%) removed these metals from pharmaceutical and tannery effluents. Semi-solid humic acid having the lowest E4: E6 ratio of 1.07 did not form coagulation with the metals. The performance of humic acid extracted from peat was better than that of commercially available humic acids. Bangladesh J. Sci. Ind. Res. 51(4), 279-284, 2016

Removal of Zn(II) from simulated wastewater using an algal biofilm.

An algal biofilm was employed as a novel kind of adsorbing material to remove Zn(II) from simulated wastewater. The algal biofilm system formed by Oedogonium sp. was operated in a dynamic mode for a period of 14 days with an initial Zn(II) concentration of 10 mg/L. The average effluent Zn(II) concentration was 0.247 mg/L and the average removal efficiency reached 97.7%. The effects of Zn(II) on key algal physiological and biochemical indices such as chlorophyll content, nitrate reductase and superoxide dismutase activity, extracellular polysaccharides (EPS), and soluble protein levels were studied. Our results showed that the algal biofilm could adapt to the simulated wastewater containing Zn(II). Scanning electron microscope and Fourier transform infrared spectroscopy analyses of algal biofilm revealed the presence of carboxyl, amino, and sulphonate groups, which were the main functional groups of EPS and proteins, and these were likely responsible for biosorption of the Zn(II) ions.

Treatment of zinc-contaminated water using a multistage ferrihydrite sorption system

Previous studies demonstrated the environmental and economic benefits of treating lead(II)-contaminated water streams with ferrihydrite in multiple equilibrium sorption stages. In this work, multistage ferrihydrite sorption systems were evaluated for their effectiveness in reducing single-solute zinc(II) (Zn(II)) concentrations in contaminated water streams to very low levels. As for lead(II) (Pb(II)), experimental data and modeling results indicate that a multistage sorption system can significantly reduce Zn(II) effluent concentrations for the same total amount of sorbent or, alternatively, dramatically lower total sorbent consumption for the same effluent Zn(II) concentration. Compared to Pb(II), however, Zn(II) removal requires on the order of 10 times more sorbent to achieve the same target effluent concentration for the same pH and number of stages. Model predictions were made using a steady-state, multistage, equilibrium adsorber model that was previously developed for and integrated into OLI Systems' Environmental Simulation Program (ESP). The modified triple-layer model was used to simulate Zn(II) surface-liquid equilibria within the adsorber model. Engineering screening evaluations again indicate that a 2- to 3-stage sorption process can provide significant economic savings when compared to a 1-stage process operating with the same target effluent Zn(II) concentration. Additional equilibrium stages beyond 2 or 3 provide diminishing economic returns. The major economic driver for multiple contacting stages is reduced capital investment and operating costs for sludge handling, dewatering, and disposal.

Optimization of metal sulphide precipitation in fluidized-bed treatment of acidic wastewater

Sulphate-reducing biofilm and suspension processes were studied for treatment of synthetic wastewater containing sulphate, zinc and iron. With lactate supplemented wastewater with 170–230 mg/l Zn and 58 mg/l Fe, the following precipitation rates were obtained: 250 and 350 mg/l d for Zn in fluidized-bed (FBR) and upflow anaerobic sludge blanket reactors, respectively, and 80 mg/l d for Fe in both reactors with hydraulic retention time of 16 h. The effluent Zn and Fe concentrations remained at less than 0.1 mg/l. The alkalinity produced in lactate oxidation increased the initial pH of 2.5–3, resulting in effluent pH of 7.5–8.5. The highest sulphate reduction rate was over 2000 mg/l d. In terms of sulphate reduction, hydrogen sulphide production and effluent alkalinity, the start-up of the FBR with the 10% fluidization rate was superior to the FBRs with 20–30% fluidization rates. With increased loading rates, high recycling rate became an advantage. After process failure caused by intentional overloading, the sulphate reduction partially recovered within 2 weeks. Metal precipitates in the reactors were predominantly FeS 2, ZnS and FeS. The metal mass balance was as follows: 73–86% of Zn and Fe accumulated into the reactors and water level adjustors, 14–23% of the metals were washed out as precipitates and 0.05–0.15% remained as soluble metals. Biomass yield in the sulphate-reducing processes was 0.039–0.054 g dry biomass (VS or VSS) per g of lactate oxidized or 0.035–0.074 g dry biomass per g of sulphate reduced. The results of this work demonstrate that the lactate supplemented sulphate-reducing processes precipitated the metals as sulphides and neutralized the acidity of the synthetic wastewater.

Role of acute metal toxicity in structuring seagrass fauna near a lead smelter

Field acute toxicity tests over 21 d periods demonstrate that 2 species of vagile epibenthic seagrass fauna (the fish Neoodaxsp. and the crustacean Cyrnodoce longicaudata) are acutely affected by Cd, Cu, Pb or Zn in the effluent from a lead smelter. By comparison with the laboratory LCSo data in the literature for other marine fishes and crustaceans it appears that Zn is the metal mainly responsible for these effects. Although C. longicaudata is acutely affected by the metals, its abundance is normal in some parts of the highly contaminated area. A third species (the fish Helotes sexlineatus), whilst not acutely affected by the metals in these experiments, was shown by a previous survey to be reduced in abundance in the highly contaminated area. Since the distribution of these latter 2 common species cannot be explained by the results of acute toxicity tests it is unlikely that acute toxicity of these metals is the major determinant of community structure in the highly contaminated area even though the concentrations of Zn in the smelter effluent appear to be near laboratory-derived LCS, concentrations for other marine species. Outside the highly contaminated area acute toxicity of these metals is unlikely to have any effect on community structure. It is concluded that acute toxicity plays only a minor role in structuring the seagrass fauna1 communities of the contaminated area and that acute toxicity tests using dissolved metals are unable to predict ecological effects. Therefore, such tests are probably unsuitable as bases for determining water quality criteria for protection of seagrass fauna.