فهرست مطالب

Environmental Science and Technology - Volume:12 Issue:9, 2015
  • Volume:12 Issue:9, 2015
  • تاریخ انتشار: 1394/08/14
  • تعداد عناوین: 30
  • Impact of various amendments on immobilization and phytoavailability of nickel and zinc in a contaminated floodplain soil
    S. M. Shaheen, J. Rinklebe, M. H. Selim Pages 2765-2776

    The immobilization of toxic metals in soils using amendments is a cost-effective remediation technique for contaminated soils. Therefore, this study aimed to assess the efficiency of various amendments to immobilize nickel (Ni) and zinc (Zn) in soil and reduce their phytoavailability. A greenhouse pot experiment was established with a contaminated agricultural floodplain soil. The soil was treated with activated carbon (AC), bentonite (BE), biochar (BI), cement bypass kiln dust (CBD), chitosan (CH), coal fly ash (FA), limestone (LS), nano-hydroxyapatite (HA), organo-clay (OC), sugar beet factory lime (SBFL), and zeolite (Z) with an application rate of 1 % (0.2 % for HA) and cultivated by rapeseed (Brassica napus). After plant harvesting, the soil was analyzed for water-soluble and geochemical fractions of Ni and Zn. Additionally, both metals were analyzed in the aboveground biomass. Application of the amendments increased significantly the biomass production of rapeseed compared to the control (except for OC, HA, and FA). Water-soluble Ni and Zn decreased significantly after adding the amendments (except OC, Z, and CH). The SBFL, CBD, LS, BE, AC, and BI were most effective, resulting in a 58–99 and 56–96 % decrease in water-soluble Ni and Zn, respectively. The addition of SBFL, CBD, and LS leads to the highest decreasing rate of concentrations of Ni in plants (56–68 %) and Zn (40–49 %). The results demonstrate the high potential of CBD, SBFL, LS, BE, AC, and BI for the immobilization of Ni and Zn in contaminated floodplain soils.

    Keywords: Low, cost immobilizing agents, Nano, hydroxyapatite, Organo, clay, Rapeseed, Remediation, Toxic metals
  • Determination of aerosol deliquescence and crystallization relative humidity for energy saving in free-cooled data centers
    L. Ferrero, L. Dangelo, G. Rovelli, G. Sangiorgi, M. G. Perrone, M. Moscatelli, M. Casati, V. Rozzoni, E. Bolzacchini Pages 2777-2790

    This study examines an innovative application of the aerosol deliquescence and crystallization determination, for corrosion prevention and energy-saving strategies in free-cooled data centers. Aerosol deliquescence and crystallization were investigated by combining standardized aerosol sampling techniques (i.e. EN-14907) with the assessment of the electrical effects of aerosol, while varying relative humidity within a specially designed aerosol exposure chamber. Aerosol samples collected in the Po Valley (Northern Italy) were analysed; a clearly defined hysteresis cycle (deliquescence and crystallization at 60.5 ± 0.8 and 47.9 ± 0.7 % of RH, respectively) was found. Results were applied to a data center designed for the Italian National Oil and Gas Company, making it possible to identify a critical area for direct free cooling at this data center. As a result, aerosol hydration was avoided (thus preventing aerosol from damaging electrical components) and a large amount of energy saved (using free cooling instead of air-conditioning); the potential energy saving achieved in this way was 79 % (compared to the energy consumption of a traditional air-conditioning system): 215 GWh of energy was saved, and 78 fewer kt of equivalent CO2 was emitted per year. Moreover, in order to evaluate whether a real-time estimation of the aerosol hydration state within a data center could be performed, measured deliquescence and crystallization were compared through simulations performed using three different models: two thermodynamic models for deliquescence and a parametric model for crystallization. The results obtained tend to converge in terms of deliquescence, whereas in the case of crystallization, they failed to effectively simulate experimental aerosol behaviour.

    Keywords: Aerosol chamber, Carbon footprint, Conductivity, Energy, Hygroscopicity, Models
  • Removal of organic and inorganic compounds from landfill leachate using reverse osmosis
    I. A. Talalaj Pages 2791-2800

    The main objective of this work was to evaluate an effectiveness of removing organic and inorganic pollutants from landfill leachate in a long-term reverse osmosis (RO) study. Investigations were carried out during the first year of RO exploitation since February till September 2013. Over 20 parameters were analysed both in leachate and permeate samples. In the first 1-year operation, the treatment performance was feasible for most of analysed leachate pollutants. The average removal rate of chemical oxygen demand (COD), electro-conductivity, ammonia nitrogen (N-NH4 +), total inorganic nitrogen, cyanides (CN−), iron (Fe) and chlorides (Cl−) reached 97, 97.2, 98.7, 99, 93, 97.6 and 98 %, respectively. A smaller reduction rate—of 83 and 86 %—was obtained for sulphates (SO4 2−) and sulphides (S−), what is the result of sulphuric acid addition before treatment process in order to decline a pH to a value of 6.0–6.5. Boron was eliminated only by 81 % due to easy transportation through the membrane uncharged species of boric acid B(OH)3, which predominate in leachate. Average reduction of nitrites (NO2 −) and nitrates (NO3 −) was 63.8 %, which is the result of inhibition NO2 − oxidizers by nitrous acid and relatively low ratio of biochemical oxygen demand and COD (BOD/COD). The obtained permeate quality does not meet the Polish discharge standards for S−. It is also foreseen that the concentration of N-NH4 + in maturate leachate will increase in the next years.

    Keywords: Landfill leachate, Pollutants, Reverse osmosis, Treatment
  • Evaluation of bioremediation potential and biopolymer production of pseudomonads isolated from petroleum hydrocarbon-contaminated areas
    A. Goudarztalejerdi, M. Tabatabaei, M. H. Eskandari, D. Mowla, A. Iraji Pages 2801-2808

    Bacteria are diverse and abundant in soils, but only a few bacteria have known to grow on hydrocarboncontaminated areas and utilize complex carbon source such as crude oil for the synthesis of polyhydroxyalkanoate (bioremediation potential and the ability to produce important biopolymers). Among 32 samples collected from several sites of petroleum refinery soil and oily sludge of Iranian southwestern refineries, 45 oil-degrading pseudomonads were identified, and 33 % of the isolated Pseudomonas strains were able to produce polyhydroxyalkanoate using Gachsaran crude oil (2 % v/v) as carbon source. The repeated monomer composition of the copolymer produced from Gachsaran crude oil was determined by gas chromatography/ mass spectrometry. The produced monomers composites contained: C8 (3-hydroxyoctanoate), C10 (3- hydroxydecanoate), C12 (2-hydroxydodecanoate), C14 (3- hydroxytetradecanoate), and C16 (3-hydroxydecahexanoate), which are known as biopolymers. This study indicates oil-contaminated areas can be important sources for polyhydroxyalkanoate producers which can be used for the bioremediation of crude-oil-polluted sites; also polyhydroxyalkanoate has a functional role in bacterial survival and stress tolerance in the toxic environments and poor nutrient availability.

    Keywords: Biopolymers  Bioremediation  Polyhydroxyalkanoate  Pseudomonads
  • Enhanced fluoride removal by hydroxyapatite-modified activated alumina
    G. Tomar, A. Thareja, S. Sarkar Pages 2809-2818

    Fluoride in drinking water is beneficial at low concentrations but is considered harmful for the human health when present at concentrations exceeding 1.5 mg/L. Prevalence of high concentration of fluoride in drinking water, combined with the nonavailability of alternate viable sources, makes the treatment of the contaminated water an essential task. In this study, we report the synthesis and characterization of a hybrid adsorbent; hydroxyapatite-modified activated alumina (HMAA) prepared by dispersing nanoparticles of hydroxyapatite inside activated alumina granules. The composite adsorbent provided a synergy toward fluoride removal from contaminated drinking water. The hybrid adsorbent possesses a maximum adsorption capacity of 14.4 mg F/g which is at least five times higher than the virgin-activated alumina, which has been used extensively for fluoride removal. HMAA was regenerated using six bed volumes of a solution containing commonly available innocuous chemicals. The adsorbent was subjected to multiple numbers of operating cycles within a column, each cycle consisting of one adsorption run followed by regeneration.

    Keywords: Activated alumina, Column run, Fluoride, defluoridation, Hydroxyapatite, modified activated alumina, Nanoparticles, adsorption, Regeneration
  • Biodegradation of di-n-butyl phthalate in sequencing batch reactor bioaugmented with Micrococcus sp. and the bacterial community analysis
    J. Hu, Q. Yang, J. L. Wang Pages 2819-2828

    The feasibility of using Micrococcus sp. to bioaugment a sequencing batch reactor (SBR) for degrading di-n-butyl phthalate (DBP) was investigated. Terminal restriction fragment length polymorphisms (T-RFLP) was used to analyze the changes in sludge microbial community. The experimental results showed that for the bioaugmented reactor, the removal efficiency of DBP degradation of DBP was about 85% as compared with 25% of the control reactor when initial DBP concentration was 100 mg/L. The bioaugmentation not only enhanced the removal efficiency of target compound, but shortened the start-up time of the reactor. The kinetics of DBP degradation conformed to the first-order model in both reactors. The T-RFLP analysis indicated the bacterial community changes of the acclimated activated sludge and the introduced Micrococcus sp. during the operational process.

    Keywords: bacterial community., Bioaugmentation, Biodegradation, phthalate
  • Phytogeographic retrospective in ecotonal areas guided by soil attributes
    T. Monteiro, C. A. Alvares, D. E. Stott, A. M. Da Silva Pages 2829-2840

    Re-establishing deforested ecosystems to pre-settlement vegetation is difficult, especially in ecotonal areas, due to lack of knowledge about the original physiognomy. Our objective was to use a soils database that included chemical and physical parameters to distinguish soil samples of forest from those of savannah sites in a municipality located in the southeastern Brazil region. Discriminant Analysis (DA) was used to determine the original biome vegetation (forest or savannah) in ecotone regions that have been converted to pasture and are degraded. First, soils of pristine forest and savannah sites were tested, resulting in a reference database to compare to the degraded soils. Although the data presented, in general had a high level of similarity among the two biomes, some differences occurred that were sufficient for DA to distinguish the sites and classify the soil samples taken from grassy areas into forest or savannah. The soils from pastured areas presented quality worse than the soils of the pristine areas. Through DA analysis we observed that, from seven soil samples collected from grassy areas, five were most likely originally forest biome and two were savannah, ratified by a complementary cluster analysis carried out with the database of these samples. The model here proposed is pioneer. However, the users should keep in mind that using this technology, i.e., establishing a regional-level database of soil features, using soil samples collected both from pristine and degraded areas is critical for success of the project, especially because of the ecological and regional particularities of each biome.

    Keywords: Ecotone, pristine forest soil, soil database, vegetation re, establishment
  • Investigation of anaerobic biodegradability of real compost leachate emphasis on biogas harvesting
    H. H. Hashemi, A. Ebrahimi, A. Khodabakhshi Pages 2841-2846

    Anaerobic treatability of real compost leachate was assessed using laboratory-scale anaerobic sequencing batch reactor at mesophilic conditions. Interventional study was conducted at wide range of organic loading rate 0.93–25 g l-1 day-1 by varying hydraulic retention times 23 and 12 h. Initial chemical oxygen demand (COD) was 1.85–25 g l-1. pH variations; total, soluble (SCOD), readily biodegradable (rbCOD) chemical oxygen demand; volatile fatty acids degradation; biogas production; and methane fraction were considered in this study. The organic matter removal efficiencies were in the range of 76–81 % depending on loading rates applied. The maximum volumetric methane production rate of 5.7 l CH4 - l-1 day-1 was achieved at the loading rate of 19.65 g l-1 day-1. About 85 % of removed organic matters during the biodegradation were converted to the methane. The results have shown that the anaerobic batch reactor could be an appealing option for changing compost leachate into the useable products such as biogas and other energy-rich compounds, which may play a serious role in meeting the world’s ever-increasing energy requirements in the future.

    Keywords: Batch process  Compost liquid  Methane  Organic load
  • Adsorptive desulfurization of feed diesel using chemically impregnated coconut coir waste
    Md. J. K. Ahmed, M. Ahmaruzzaman Pages 2847-2856

    This study reports the usage of chemically impregnated coconut coir waste (CICCW) as a low-cost adsorbent for the desulfurization of feed diesel. The characterization of the developed adsorbent was focused on quantitative analysis (carbon yield %, proximate, ultimate, carbon surface functionalities, BET surface area and porosity distribution, and particle size analysis), qualitative analysis (FTIR), and optical analysis (SEM). Batch experiments with feed diesel having a total sulfur concentration of 2,050 mg L−1 were conducted to optimize the adsorption parameters such as adsorbent dose, temperature, and contact time. The adsorption process shows an optimum dose of 1 g/20 mL, and the equilibrium is attained in 3 h. The adsorption of sulfur onto the adsorbent at optimum temperature 293 K is regulated by external mass transfer (diffusion into mesopores) followed by a steady adsorption phase with intra-particle diffusion in micropores. A Fickian mechanism controls the diffusion of sulfur molecules from the solution onto the surface of the adsorbent. Freundlich adsorption isotherm illustrates the equilibrium adsorption data very well. The negative value of ΔG° (−27.61 kJ mol−1) and ΔS° (−44.56 J K−1 mol−1) indicates the feasibility, spontaneity of the adsorption process and justified the decrease in the randomness of adsorbed sulfur molecules onto the adsorbent surface, respectively. The exhausted CICCW can be effectively regenerated by methanol and reutilized for three adsorption–desorption cycles. The approximate cost of preparation of the adsorbent was USD 10.714 per kg. These results clearly proved the feasibility of the developed low-cost adsorbent (CICCW) as a good candidate for the desulfurization of feed diesel.

    Keywords: Adsorption, Batch experiments, Freundlich isotherm, Sulfur
  • The ability of immobilized bacterial consortia and strains from river biofilms to degrade the carbamate pesticide methomy
    C. S. Chen, T.-W. Wu, H.-L. Wang, S.-H. Wu, C.-J. Tien Pages 2857-2866

    Complex microbial communities from river biofilms might contain microorganisms capable of degrading xenobiotic pollutants such as pesticides (e.g. methomyl, which is commonly detected in rivers). Therefore, this study was used to determine the methomyl degradation potential of bacteria consortia and single bacterial strains acclimatized and isolated from natural river biofilms to provide biomaterials for bioremediation of water that is contaminated with methomyl. Natural river biofilms were culture enriched with methomyl as the sole carbon source to obtain acclimatized bacterial consortia and single bacterial strains. The microbial consortium on the ceramic discs was able to remove 91 % of added methomyl (50 mg l−1) in 7 days. The longer-acclimatized bacterial consortium on loofah sponges removed methomyl more quickly than the shorter-acclimatized consortium, but both had similar removal capabilities (i.e. 92.4 and 92.2 %). This finding suggested that the former might contain more methomyl degraders than the latter. However, after preservation at 25, 4 and −20 °C for 1 or 3 months, the methomyl degradation ability of the bacterial consortia decreased significantly, indicating loss of methomyl degraders during preservation. Three bacterial species were isolated from acclimatized river biofilms, and only one species, identified as Sphingomonas sp., was able to remove methomyl, with a 7-day removal rate of 44.7 % when sugar was added and of 32.5 % when no sugar was added. These results suggested that an additional carbon source might slightly improve the ability of Sphingomonas sp. to degrade methomyl. Acclimatized bacterial consortia have a higher potential for treating methomyl-contaminated water than isolated bacterial species.

    Keywords: Bacteria, Degradation, Methomyl, Preservation, River biofilm
  • Chemical modification of Byrsonima crassifolia with citric acid for the competitive sorption of heavy metals from water
    J. Monroy, Figueroa, D. I. Mendoza, Castillo, A. Bonilla, Petriciolet, M. A. PÉrez, Cruz Pages 2867-2880

    This study reports the chemical modification of the Byrsonima Crassifolia biomass with citric acid to improve its sorption properties for the removal of cadmium and nickel ions from aqueous solutions under competitive sorption conditions (i.e., multicomponent solutions). The best operating conditions of the chemical modification process were identified using the signal-to-noise ratio to enhance the metal uptakes and to reduce the competitive sorption effects during the simultaneous removal of these metals using the modified biomass. Results indicated that both the sorption capacity and selectivity for heavy metal removal can be improved in multicomponent metal solutions. This improvement in sorption properties of Byrsonima crassifolia biomass is mainly related to an increment of the acidic functional groups on the biomass surface caused by the chemical reaction between citric acid and this lignocellulosic material. The methodology reported in this study can be used to increase the sorption properties of other biomasses for the effective removal of toxic pollutants from multicomponent solutions and for the synthesis of sorbents with tailored sorption properties.

    Keywords: Byrsonima crassifolia, chemical modification., Heavy metals, sorption, Wastewater treatment
  • Kinetic study of the gas-phase reactions of hydroxyl radicals and chlorine atoms with cis-3-hexenylformate
    D. Rodrnguez, A. Rodrnguez, I. Bravo, A. X. A. Garzo N., A. Aranda, Y. Diaz, De, Mera, A. Notario Pages 2881-2890

    Recently, it has been demonstrated that grass and cut grass are important sources of C6 esters’ emissions into the atmosphere. The esters emitted as part of the wound defense mechanisms are responsible for the smell of freshly cut grass and are also highly photochemically reactive. Thus, these grass emissions should be included in models of urban photochemical pollution so that accurate smog predictions can be obtained. In this work, we have carried out a kinetic study of the gas-phase reactions of chlorine atom and hydroxyl radical with cis-3-hexenylformate (HCO2CH2CH2CH=CHC2H5) for the first time. This was performed in a Teflon static reactor at room temperature and atmospheric pressure of nitrogen or air using gas chromatography with flame ionization detection. Kinetic rate coefficients obtained for cis-3-hexenylformate were (in units of cm3 molecule−1 s−1) (2.45 ± 0.30) × 10−10 and (4.61 ± 0.71) × 10−11 for chlorine and hydroxyl radical reactions, respectively. The reaction between the ester and chlorine atoms is very fast, approaching the collision-controlled regime; nevertheless, the rate constant for the reaction with hydroxyl radical is lower. In addition, the rate coefficients for the reactions of cis-3-hexenylformate with different atmospheric reactive species were estimated through a Quantitative Structure–Activity Relationship model in which High Occupied Molecular Orbital energy of the formate is used as a theoretical molecular descriptor. Tropospheric lifetimes, based on the homogeneous sinks of the cis-3-hexenylformate, are estimated from the kinetic data obtained in the present work. The relatively short atmospheric lifetimes of the ester indicate that the compound will be oxidized near its anthropogenic origin source.

    Keywords: Atmospheric lifetimes, Chlorine atoms, Cis, 3, hexenylformate, Hydroxyl radicals, Rate coefficients, Smog chamber
  • Conceptualizing a decentralized stormwater treatment system for an urbanized city with improper stormwater drainage facilities
    A. S. Arora, A. S. Reddy Pages 2891-2900

    Urbanization involving replacement of previous areas with impervious surfaces and drainage channel modifications results in increased runoff volume leading to flooding and also in deteriorating the quality of the stormwater runoff. An effective and efficient stormwater management is needed in the urban areas for mitigating the impacts and overcoming the problems associated with the urban stormwater. An attempt has been made in the present study to investigate the relationships between stormwater quality and five different land uses for the Patiala city of Punjab State. Stormwater samples collected from these locations, between April 2010 and March 2011, were analyzed for various organic and inorganic water quality parameters and heavy metals. Inter-parameter relationships studied provided vital information in deciding upon the treatment units most likely to be suitable for that particular sub-watershed. Multiple regression modeling helped in assessment of water quality parameters and predicting the quality well before actually analyzing the parameters and thus aided in developing treatment schemes suitable for taking care of the stormwater quality even under worst set of conditions. The outcomes of the research study effectively contributed toward conceptualizing a decentralized stormwater treatment system that would be capable of coping with the stormwater runoff-associated problems faced by the city and can serve as a model for other under-developed and developing cities having improper stormwater management facilities.

    Keywords: Decentralized stormwater treatment, Multiple regression analysis, Sub, watershed, Urban stormwater quality
  • Utilization of neutralized spent sulfuric acid pickle liquor from metal treatment in cement production
    E. Jarosz, Krzemiska, E. Helios, Rybicka, M. Gawlicki Pages 2901-2908

    The research addresses the issue of utilization of neutralized spent sulfuric acid pickling liquor, deposited in 1.62 ha lagoons, derived from steel industry, in cement production. Physical–chemical characteristics of the investigated waste revealed low levels of contaminants with the exception of sulfate anions. However, the presence of CaSO4·2H2O revealed a new utilization option for the investigated waste. A key part of the research involved studying the usability of stored waste as a substitute of natural gypsum, acting as a set retarder in cement production. Cement was prepared by grinding Portland clinker with the addition of waste gypsum and then was subjected to the examinations of initial setting time, specific surface, water demand and compressive strength. The analysis of mechanical and physical properties revealed that the tested cement with the addition of waste meets standard requirements for Portland cement. Furthermore, the study of natural radioactivity of the waste did not reveal a rise in the level of radionuclides, thus confirming that the investigated waste can be used for the production of construction materials used in buildings intended for human residence. Utilization of the deposited wastes can help eliminate the environmental hazards regarding sulfuric acid pickle liquor waste and can also provide a low-cost resource of waste gypsum, which can be widely used in the production of construction materials.

    Keywords: By, product gypsum Cement Portland clinker Spent pickling liquor Set retarder
  • Assessing groundwater vulnerability to contamination in an arid environment using DRASTIC and GOD models
    R. Ghazavi, Z. Ebrahimi Pages 2909-2918

    Groundwater is vulnerable to contamination by anthropological activities. Vulnerability mapping is considered as a fundamental aspect of groundwater management. The aim of this study was to estimate aquifer vulnerability by applying the DRASTIC and GOD models in Abarkooh plain, Yazd province, center of Iran. The DRASTIC model uses seven environmental parameters (depth to water, net recharge, aquifer media, soil media, topography, impact of vadose zone, and hydraulic conductivity) to characterize the hydrogeological setting and evaluate aquifer vulnerability. GOD is an overlay and index method designed to map groundwater vulnerability over large regions based on three parameters (groundwater confinement, overlying strata, and depth to groundwater). The information layers for models were provided via geographic information system. The overlap techniques were used to provide and produce the vulnerability map of the study areas considering weight coefficients of each layer. Accuracy of the models was evaluated using linear regression between observations values of nitrate and estimated vulnerability to pollution in the measured wells. A significant correlation was observed between measured nitrate and pollution potential evaluated by DRASTIC model (P.01), but no significant correlation was observed for GOD model (P.05). The results showed that the DRASTIC model is better than GOD model to estimate groundwater vulnerability to pollution in the measured wells. For DRASTIC model, the correlation coefficient between vulnerability index and nitrate concentration was 68 % that was substantially higher than 28 % obtained for the GOD model. We can conclude that nitrate concentration should be a suitable parameter to investigate the accuracy of the DRASTIC and GOD models.

    Keywords: Abarkooh plain  DRASTIC  GOD  Groundwater contamination  Nitrate
  • Organic amendments: effects on cereals growth and cadmium remediation
    I. Ahmad, M. J. Akhtar J. Akhtar, Z. A. Zahir, B. Mitter Pages 2919-2928

    Cadmium (Cd) is one of the toxic metals that adversely affect plant growth. Organic amendments may not only enhance nutrient status of soil, but they may also form complexes with Cd and reduce its availability to plants. This experiment was conducted to determine whether organic amendments (compost and biogas-slurry) could stabilize/extract Cd and alleviate the adverse effects of Cd on the growth of two cereals, wheat and maize. Organic amendments along with four varying levels of Cd (0, 5, 20, 50 mg kg-1 soil) were prepared with soil. Effect of these amendments on tolerance indices, root/shoot dry biomass, tissue Cd concentration, Cd uptake and translocation were studied. Biogas-slurry caused maximum increase in tolerance indices of wheat and maize (100-112 and 117-133%, respectively as compared to control) whereas compost caused significant increase in their dry biomass. Negative correlation between root dry biomass of wheat (r = -0.37) and maize (r = -0.53) to Cd revealed its suppressive effects. Dry biomass of plant correlated with organic amendments in wheat (r = 0.83-0.98) whereas weak correlation was observed in maize (r = 0.30-0.40). Compost significantly reduced Cd uptake in wheat and maize however, it increased Cd translocation in plants. Based on the results of this study, root was the major sink of Cd when soil was amended with or without organic amendments. Biogas-slurry removed 97% Cd from artificially polluted water after 13 h at pH 6. The additions of compost in soil and biogas-slurry in wastewater are recommended to stabilize/extract Cd.

    Keywords: biogas, slurry, Bioremediation, Biosorption, cadmium stress, Compost, maize., wheat
  • Chemical fractions and phytoavailability of copper to rape grown in the polluted paddy soil
    H. F. Yang, Y. B. Wang, Y. J. Huang Pages 2929-2938

    This paper focuses on the phytoaccumulation and translocation of copper (Cu) in rape grown in the Cu-polluted paddy soil. Pot experiments were conducted in greenhouse conditions to examine the Cu availability and uptake by rape in a paddy soil. The soil was spiked with different concentrations of Cu (0, 100, 300, 500 and 1,000 mg kg−1 soil, added as CuSO4) to simulate soil Cu contamination. After 8 months of growth, plant shoots, stems, pod shells and rapeseeds were harvested for analysis. The concentrations of Cu in the roots and aerial parts of the rape and available Cu in soils were then extracted and determined. Chemical fractions of Cu in the paddy soil of rape were also investigated by sequential extraction techniques. The findings showed that Cu in the clean paddy soil was mainly distributed in residual fractions. However, the most drastic increase was observed in Fe–Mn oxides-bound fractions and organic-bound fractions with increasing soil Cu concentrations. Exchangeable fractions played a more important role than other fractions in controlling the mobility and phytoavailability of Cu. Rape growth was stimulated by low concentrations of Cu, but inhibited by high concentrations. Compares to the aerial parts, the roots were more sensitive to Cu toxicity. The correlation analysis showed that Cu in exchangeable fractions made the greatest contribution on the accumulation of Cu in rapes. The factor analysis results showed that the exchangeable fractions in roots can be indicator of Cu availability. Meanwhile, the bio-concentration factors and the translocation factors of Cu in rape were determined and the results showed that Cu had lower accumulation in the edible parts of the rape.

    Keywords: Brassica napus L., Chemical fractionation, Copper accumulation, Factor analysis, Phytoaccumulation
  • Residues from single-stage dry de-dusting and desulphurization of sinter plant off-gas: enabling partial recirculation by air classification
    C. Lanzerstorfer, R. Neuhold Pages 2939-2946

    In iron ore sinter plants, the process off-gas is de-dusted by electrostatic precipitators which are installed upstream of the fan. For further reduction of emissions, a second cleaning stage can be installed. This stage usually comprises a sorption process for removal of acid gases and polychlorinated dibenzo(p)dioxins and furans, followed by a fabric filter. The residue from the first de-dusting stage can be recirculated to the sintering process. The residue from the second cleaning stage has to be disposed of in landfill sites. A new single-stage off-gas cleaning concept for sinter plants comprises an entrained flow sorption process and a fabric filter, installed upstream of the fan. In this way, the investment costs for the off-gas cleaning system can be reduced significantly. However, it would become necessary to dispose of most of the residue. In this work, air classification of a residue equivalent to that of a single-stage off-gas cleaning unit was investigated with the aim of producing a fraction of this residue with reduced sulphur and chloride concentrations which can then be recycled. The results confirm that air classification is a suitable process. In order to maintain raw mixture targets for chlorine or to avoid chlorine enrichment in the raw feed, the recommended dust recycling rate is 66 % with air classification which is an improvement over the allowed rates without air classification of 42 %.

    Keywords: Air classification, Gas cleaning residue, Recycling, Sinter plant
  • Investigation of removal possibilities of chromium(III) oxide from water solution in the presence of albumins
    K. Szewczuk, Karpisz, M. Winiewska Pages 2947-2956

    System destabilization is a highly desirable phenomenon during colloidal impurity removal from sewages and wastewaters. Therefore, in this study, the stability of chromium(III) oxide suspension in the absence and presence of albumins [bovine serum albumin (BSA), ovalbumin (OVA), human serum albumin (HSA)] was investigated. Based on the analysis of experimental results, i.e., measurements of adsorption amount, electrokinetic potential, and metal oxide surface charge density as well as system stability, the mechanism of the suspension stabilization/destabilization was proposed. The examined system without the albumins is relatively stable at pH 3, 4.6, and 9 (TSI = 34.8, 36.6, 34.22, respectively), which is associated with the electrostatic stabilization phenomenon. In turn, the least stable is the suspension at pH 7.6 (TSI = 55.43). This is the result of the adsorbent zero surface charge. Regardless of solution pH, the BSA, OVA, or HSA adsorption causes an increase in the system stability (17.55 < TSI < 30). Probably, the steric stabilization is involved in this phenomenon, which results from the mutual repulsion of the adsorption layers formed on the solid surface. Thus, it can be concluded that the albumin presence in the industrial wastewaters impedes the chromium(III) oxide removal.

    Keywords: Albumin adsorption, Colloids, Electrostatic, steric stabilization, Zeta potential
  • Adsorption of anionic azo dye from aqueous solution using Strychnos potatorum Linn seeds: isotherm and kinetic studies
    M. Kirupa Sankar, K. Muthu Kumar, B. V. Ranganathan Pages 2957-2964

    Dyes from several industry effluents are major concern of environmental pollution. In this study, the efficiency of a cost-effective natural adsorbent Strychnos potatorum Linn (Fam: Loganiaceae) seeds on removing reactive orange-M2R dye from aqueous solution was investigated using batch adsorption isotherms at 30 ± 1 °C and 120 rpm. The efficacy of the adsorbent system was also studied at various parameters viz. contact time, pH, adsorbent dosage and initial dye concentration. Maximum adsorption (q e = 9 mg/g) was observed at pH 2.0, equilibrium time 6 h, initial dye concentration of 100 mg/L and adsorbent dosage of 0.2 g/100 mL. The unit adsorption of dye, q e (mg/g) increased with increase in contact time and initial dye concentration, while it decreased with increase in adsorbent dosage. The adsorption kinetic studies revealed that it follows pseudo-second-order reaction model. Equilibrium adsorption data followed both Langmuir and Freundlich isotherms with good agreement. These investigations suggest that Strychnos potatorum Linn seeds (SPS) could be used as a low-cost adsorbent in treating textile effluents for dye removal applications. The adsorbent (SPS) was also characterized using Fourier transform infrared spectroscopy, powder X-ray diffraction, and scanning electron microscopic technique.

    Keywords: Adsorption, Dye removal, Environment, Linn seeds, Reactive orange, M2R, Strychnos potatorum
  • Study of continuous lead removal from aqueous solutions by marble wastes: efficiencies and mechanisms
    A. Mlayah, S. Jellali Pages 2965-2978

    Lead removal from synthetic solutions and real wastewater by Bianco Gioia marble wastes as abundant, renewable and eco-friendly materials was studied under different experimental conditions in a continuous stirring tank reactor. These marble wastes were found to be very efficient in removing lead for several experimental situations. Indeed, for initial aqueous pH values higher than 3.6, a lead removal efficiency of about 100 % was achieved even for high aqueous concentrations (200 mg L−1), important feeding flow rates (60 mL min−1) and low marble waste dosage (2 g L−1). The best removal capacity (175.7 mg g−1) was obtained for an initial lead concentration of 200 mg L−1, a marble waste dose of 5 g L−1 and an aqueous pH of 5. Even using the real wastewater with low aqueous pH (1.1), lead was also completely removed using 20 g L−1 of the tested marble wastes. According to the energy-dispersive spectroscopy and X-ray diffraction analyses, lead removal seems to be controlled by both precipitation as cerussite (PbCO3) and hydrocerussite (Pb3(CO3)2(OH)2), and adsorption onto the surface particles through cation exchange and complexation. The proposed low-cost material efficiently removes lead present in synthetic solutions and real wastewaters and constitutes an interesting environmental management option.

    Keywords: Dynamic mode, Mineral adsorbents, Precipitation, Wastes management, Water pollutants
  • Double aluminum recovery and its reuse in wastewater treatment
    C. Barrera, Diaz, V. Varela, Guerrero, N. Gonzalez, Rivas, F. Urena, Nunez Pages 2979-2986

    This work evaluates the use of aluminum contained in the aluminum–polyethylene films as anodic electrodes using the electrocoagulation technique to reduce the pollutant contents of industrial wastewater quickly and effectively. Thermal treatment at 500 °C produces pure aluminum (according to TGA and SEM/EDS analysis) which is used to construct aluminum disks (applying 6 tons/cm2 of pressure). Aluminum disks are used as cathodes and anodes in an electrochemical cell. The current density applied in the recovered Al electrodes was 12 mA cm−2, and the maximum COD reduction of wastewater was 77 % at 25 min of treatment. The color and turbidity reductions are 87 and 90 %, respectively. The resulting sludge of wastewater treatment was thermally treated and a second aluminum recovery was reached; since the organic material present in the sludge was removed by the high temperature, the obtained aluminum was pure enough for its reuse. The use of aluminum–polyethylene films as electrodes in the electrocoagulation process contributes to the pollutant removal without the addition of chemical reagents or changing the pH, so it is both effective and environmentally friendly.

    Keywords: Electrocoagulation, Material recuperation, Tetra pak, Waste management
  • Inhibition of bacteria by photocatalytic nano-TiO2 particles in the absence of light
    A. Erdem, D. Metzler, D. Cha, C. P. Huang Pages 2987-2996

    The potential eco-toxicity of fourteen different nanosized titanium dioxide (TiO2) particles was studied using Gram-positive Bacillus subtilis and Gram-negative Escherichia coli (ATCC K12) as test organisms. These photosensitive nanoparticles (NPs) were found to be harmful to the organisms studied at different degrees; the antibacterial activity increased with primary particle size, reached the maximum level in the range of 16–20 nm, and then decreased as the primary particle size increased. The presence of light played a significant role on the eco-toxicity of the nano-TiO2 particles under most conditions studied, presumably due to the generation of reactive oxygen species (ROS). However, bacterial growth was inhibited also under dark condition, indicating that mechanisms other than photocatalytic ROS were responsible for the toxic effect. Results highlight the need for caution during the use and disposal of manufactured NPs as to prevent unintended environmental impacts, as well as the importance of further research on the mechanisms and factors that control the toxicity of NPs toward aquatic organisms.

    Keywords: Bacillus subtilis, Eco, toxicity, Escherichia coli (K12), Nano, particles, Particle size, Photocatalysts, TiO2
  • Ambient air concentrations of PCDD/Fs, coplanar PCBs, PBDD/Fs, and PBDEs and their impacts on vegetation and soil
    Y., C. Kuoy., C. Chenm., Y. Linl., H. Youngh., T. Hsus., H. Liout., N. Wul., C. Wang Pages 2997-3008

    The impact of persistent organic pollutant (POP) concentration in ambient air on vegetation and soil is investigated in the present study. Ambient air, vegetation, and soil samples were collected from the vicinity of an industrial complex. For each collected sample, the polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), coplanar polychlorinated biphenyls (coplanar PCBs), brominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs), and polybrominated diphenyl ethers (PBDEs) concentrations were analyzed. Principal component analysis (PCA) was adopted to explore the relationships between the concentration of each POP type in ambient air with those in soil and vegetation. Results show that particle-phase PCDD/Fs, PBDD/Fs, and PBDEs, respectively, account for 60.6, 98.3, and 75.7 % of the total concentration in the air, which are much higher than that of coplanar PCB (5.2 %). Results obtained by PCA suggest that PCDD/Fs in vegetation are contributed by atmospheric gas-phase PCDD/Fs, whereas in soil they are contributed by particle-phase PCDD/Fs. Coplanar PCBs concentrations in both vegetation and soil are contributed by atmospheric gas-phase coplanar PCBs. PBDD/Fs concentrations are both contributed by particle phase. PBDEs in vegetation are contributed by both gas- and particle-phase PBDEs, while soil PBDEs are contributed mainly by the particle phase. In confirmation of these results, the researchers found that the above results are consistent with those obtained from theoretical calculations and previous studies. Therefore, it is concluded that the results obtained from the present study would provide useful information for assessing the fate of ambient air POP concentration.

    Keywords: Ambient air, Gas phase, Particle phase, Persistent organic pollutants (POPs), Soil, Vegetation
  • Quantification of effective concentrations of 1,2-dimethyl phthalate (DMP) to rice seedlings
    D., M. Yuex., Z. Yuy., H. Li Pages 3009-3016

    Dimethyl phthalate (DMP) is one of the most widely used plasticizers. Due to its anthropogenic inputs, DMP has become a serious contaminant in soils and water. Hydroponic experiments were conducted focusing on phytotoxic responses of rice seedlings (Oryza sativa L. cv. XZX 45) to 1,2-dimethyl phthalate. Relative growth rate (RGR) and water use efficiency (WUE) were measured as response endpoints to quantify the effective concentrations (ECs) of DMP to rice seedlings. As a comparison, acute phytotoxicity of dimethyl sulfoxide (DMSO) used as solvent media was also determined. Results showed that acute toxicity of DMP to rice seedlings was evident, but selected endpoints had different responses to DMP exposure. RGR of rice seedlings was more sensitive to change of DMP than WUE. EC-48 h values for 10, 20 and 50 % inhibition of the RGR were estimated to be 6.18, 38.41 and 329.41 μΜ for rice seedlings exposed to DMP, respectively, while smaller ECs were obtained for 96 h exposure. Results from phytotoxicity of DMSO demonstrated that the doses of DMSO used for dissolving DMP had a negligible effect on rice seedlings. In conclusion, DMP is problematic at relatively low concentrations for rice seedlings, and inhibitory effects are highly dependent on response endpoints and the duration of exposure period.

    Keywords: Dimethyl phthalate, Effective concentration, Relative growth rate, Rice, Toxicity, Water use efficiency
  • Interactions between spray drift and sprayer travel speed in two different apple orchard training systems
    M. Lesnik, D. Stajnko, S. Vajs Pages 3017-3028

    Trials were carried out in apple orchards of two different training systems to assess the relationship between spray drift and parameters of spraying with an emphasis on the sprayer’s travel speed when applying different solutions, such as pesticides or fertilizers, onto the apple trees. The assessments were based on the following factors: per cent of spay drift, two sprayers (axial- and radial-fan sprayer), two training systems (super spindle and modified slender spindle), spray droplet size (fine or coarse droplets) and the sprayer’s travel speed (5 vs. 10 km h−1). The studies were conducted in the spring and summer seasons under similar external weather conditions to test any seasonal effects that might occur. In this paper, all tested factors and interactions were found to have a significant effect on the spray drift during spray application. For instance, the increase in sprayer speed reduced the spray drift percentage. Other factors, such as sprayer type (axial fan and radial fan) and tree training system, had an impact on spray drift as well.

    Keywords: Adjacent areas, Application of pesticides, Pollution
  • Kinetic studies on anaerobic co-digestion of ultrasonic disintegrated feed and biomass and its effect substantiated by microcalorimetry
    R. Priyadarshini, L. Vaishnavi, D. Murugan, M. Sivarajan, A. Sivasamy, P. Saravanan, N. Balasubramanian, C. Lajapathi Rai Pages 3029-3038

    Studies were carried out on anaerobic co-digestion of primary and secondary excess sludge obtained from tannery effluent treatment plant. Anaerobic biomass collected from a treatment plant was used as the source of microorganisms. The optimum feed to microorganism ratio was evaluated as 0.7 on the basis of volatile solids reduction cum gas production. Both feed and anaerobic biomass was subjected to ultrasonic pre-treatment in order to enhance the digestion process. Experiments carried out on batch mode showed significant increase in the gas production for pre-treated feed and biomass. Optimum pre-treatment durations were evaluated as 5 minutes for feed and 3 minutes for anaerobic biomass. Heat flow analyses of the anaerobic biomass using isothermal microcalorimetry throw light on different stages of digestion process. The effect of ultrasonic pre-treatment on anaerobic biomass was also substantiated using this technique. The heat energy released by pre-treated and untreated anaerobic biomass was evaluated as 16.3 and 7.6 kJ/kg respectively. Kinetic analysis revealed that the overall rate constant of digestion process increased by 1.5 times due to pre-treatment. However, the initial lag time increased by about 20% for the optimally pre-treated sample compared to untreated sample. Modified Gompertz equation was used to model and the parameters were evaluated. The significance of this work lies on energy production (bio gas) and at the same time increasing the maintenance metabolism rate thereby minimizing excess sludge biomass generation.

    Keywords: Activated sludge, Anaerobic digestion, Isothermal microcalorimetry, Ultrasonic pre, treatment
  • Iron flocculation stimulates biogas production in Microthrix parvicella-spiked wastewater sludge
    S. K. Pradhan, E. Torvinen, H. M. P. Siljanen, M. Pessi, H. Heinonen, Tansk Pages 3039-3046

    Municipal wastewater sludge has been used for fertiliser and biogas production for several decades. Chemical compounds such as iron and aluminium are common coagulants used in wastewater treatment plants to remove suspended solids, phosphorus and micro-organisms. This laboratory study explores whether ferric chloride (FeCl3 as PIX-111) or aluminium chloride (AlCl3 as PAX-18) flocculation could stimulate biogas production in wastewater sludge contaminated with Microthrix parvicella. In a fermentation process run in three replicates, cumulative methane production was in average about 25 % higher using the iron flocculated sludge than using the aluminium flocculated sludge; this difference was statistically significant (P < 0.05) in the subsequent runs of the semi-continuous process. In all runs, the iron flocculated sludge produced less (P < 0.05) hydrogen sulphide in the biogas than the aluminium flocculated sludge. The numbers of M. parvicella stayed at the similar levels throughout the process. It is concluded that biogas production is higher and more stable with iron coagulant in comparison with aluminium coagulant, presumably due to the reduced formation of hydrogen sulphide. Thus, iron coagulants seem to be better than aluminium coagulants to stimulate the methane production process. Both coagulants significantly suppressed multiplication of M. parvicella in the biogas reactor, i.e. they did not evoke foaming in this experiment.

    Keywords: Aluminium, Biogas, Iron, Microthrix, Sludge, Wastewater
  • Production of glass- ceramics from heavy metal gypsum and pickling sludge
    D. A. Pan, L. J. Li, J. Yang, J. B. Bu, B. Guo, B. Liu, S. G. Zhang, A. A. Volinsky Pages 3047-3052

    The aim of this investigation was to propose a preparation method of glass–ceramics derived from heavy metal gypsum and pickling sludge, as well as stabilization of Pb, Zn, Cd, As, Hg, Cr and Ni heavy metals. The process consists of the following two stages: the desulfurization of heavy metal gypsum and the preparation of glass–ceramics. Heavy metal gypsum was desulfurized by excess glass powder at 1,473 K and formed calcium silicate and silicon dioxide as intermediate products. The intermediate products, pickling sludge and small amounts of CaO and MgO were used as major raw materials for preparing parent glass. Glass–ceramics was produced by conventional heating method, which included a nucleation stage (973 K, 2 h) and a crystallization stage (1,173 K, 1 h). The main crystalline phase of the obtained glass–ceramics is akermanite (Ca2MgSi2O7). A high microhardness of 5.3 GPa and a bending strength of 206 MPa, as well as a water absorption lower than 0.13 % were obtained. The leaching of toxic elements in glass–ceramics was much lower than the Environmental Protection Agency 1311 method requirement.

    Keywords: Desulfurization, Glass–ceramics, Heavy metal gypsum, Pickling sludge
  • The effects of carbon/phosphorus ratio on polyphosphateand glycogen-accumulating organisms in aerobic granular sludge
    A. Muszynsk, A. Miobedzka Pages 3053-3060

    A laboratory-scale granular sequencing batch reactor, fed with acetate, was operated at two different ratios of chemical oxygen demand to phosphorus—15:1 and 100:1. Smaller aerobic granules, but with better settleability, were obtained at the lower ratio. High ratio of phosphorus release to uptake of dissolved organic carbon (0.42 mol/mol) coincided with high percentage of polyphosphate-accumulating organisms (up to 70 % of all bacteria) and implied high metabolic activity of these bacteria. Polyphosphate-accumulating organisms belonged mainly to Accumulibacter and Tetrasphaera (46 and 23 %, respectively). Despite significant abundance, Tetrasphaera-related microorganisms were not detected by oligoprobes Actino-221 and Actino- 658, but by broader oligoprobes Tet2-892 and Tet3-654. Low abundance (1 %) of Halomonas phosphatis indicated a minor role of these bacteria in the laboratory-scale reactor fed with synthetic wastewater. When the ratio of chemical oxygen demand to phosphorus was increased to 100:1, deterioration of settling properties was observed, caused by growth of filamentous organisms from Thiothrix/021N group. The higher ratio favoured Competibacter and was selected against all groups of polyphosphate-accumulating organisms. However, a significant percentage (10 %) of polyphosphate-accumulating organisms in the granular sludge with concomitant low ratio of phosphorus release to the uptake of dissolved organic carbon (0.01 mol/mol) suggested shift in the overall population metabolism. Under phosphorus limitation in wastewater, polyphosphate-accumulating organisms no longer synthesized poly-P and behaved as glycogen-accumulating organisms.

    Keywords: Biological phosphorus removal  Competition  Microbial community  Molecular biology