Abstract
Iron precipitating organisms play a significant role in the formation of ferric hydroxide precipitate, which acts as strong adsorbent for toxic metal. In this respect four different iron precipitating cultures were isolated from Hutti gold mine surface winze water sample on citrate agar medium. The best isolate was screened out for metal removal study on the basis of fast visual iron precipitation. The selected isolate was identified as Enterobacter sp. based on routine biochemical tests and Biolog GN microplate results and as Enterobacter cloacae subsp. dissolvens by 16S rRNA gene sequence analysis (GenBank accession number EU429448). Influence of medium composition, medium initial pH, the influence of inoculum size, effect of various media and ferric ammonium citrate concentration were studied on metal removal in shake flask experiments. Under the optimized conditions studied, E. cloacae showed 94 ± 2, 95 ± 2 and 70 ± 2% of cadmium, copper and mercury removal from a simulated waste in shake flask studies. In lab scale column reactor more than 85% of copper and mercury removal was achieved.
Key Words
biosorption; iron precipitation; Enterobacter cloacae; copper; mercury; cadmium
Address
Department of Microbiology and Biotechnology, School of Sciences, Gujarat University, Ahmedabad 380 009. Gujarat, India.
Abstract
The present study primarily focuses on the evaluation of the comparative effect of chemical coagulation and ultrasonication for elimination of aromatic amines (AAs) present in anaerobically pretreated textile wastewater containing different types of dyes including azo dyes. Color and COD reduction was also monitored at the optimized conditions. The production of AAs was measured spectrophotometrically in the form of total aromatic amines (TAAs) and also verified with high performance liquid chromatography (HPLC) selectively. A composite coagulant, magnesium chloride (MC) aided with aluminium chlorohydrate (ACH) in an equal ratio (MC + ACH) was utilized during the coagulation process, which yielded 31% of TAAs removal along with 85% of color and 52% of COD reduction. At optimized power (200 W) and sonication time (5 h), an appreciable TAAs degradation efficiency (85%) was observed along with 51% color reduction and 62% COD removal using ultrasonication. The chromatographic data indicate that sulphanilic acid and benzidine types of aromatic amines were produced after the reductive cleavage of utilized textile dyes, which were effectively mineralized after ultrasonication. The degradation followed the first order kinetics with a correlation coefficient (R2) of 0.89 and a first-order kinetic constant (k) of 0.0073 min-1.
Key Words
aromatic amines degradation; chemical coagulation; UASB reactor effluent; textile dyes; ultrasonication
Address
(1) Akshaya K. Verma:
Department of Civil Engineering, Institute of Technical Education & Research, SOA University Bhubaneswar - 751 030, Odisha, India;
(2) Puspendu Bhunia, Rajesh R. Dash:
Department of Civil Engineering, School of Infrastructure, Indian Institute of Technology Bhubaneswar - 751 013, Odisha, India.
Abstract
Four chickpea cultivars viz. kabuli (Pusa 1088 and Pusa 1053) and desi (Pusa 1103 and Pusa 547) differing in sensitivity to high temperature conditions were analyzed in earthern pot (30 cm) at different stages of growth and development in the year of 2010 and 2011. Pusa-1053 (kabuli type) showed maximum photosynthetic rate and least by Pusa-547 (desi type), whereas maximum cell membrane thermostability were recorded in Pusa-1103 and minimum in Pusa-1088. Among the treatments, the plants grown under elevated temperature conditions had produced 13.01% more significant data in comparison to plants grown under continuous natural conditions. Stomatal conductance were reduced 44.25% under elevated temperature conditions than natural conditions, whereas 35.56%, when plants grown under initially natural conditions upto 30DAS, then 30-60DAS elevated temperature and finally shifted to natural conditions till harvest. In case of Pusa-1103, stomatal conductance was maximum as compared to rest of 2.7% from Pusa-1053, 8.9% from Pusa-1088, and 10.3% in Pusa-547 throughout the study. Plants grown under continuous elevated temperature conditions had produced 15.30% and 15.32% more significant membrane thermostability index in comparison to continuous natural conditions at vegetative stage and 19.40% and 18.44% at flowering stage, while the better response was recorded at pod formation stage. Pusa-1053 had given 2.8% more membrane thermostability index than Pusa-1088 and Pusa-1103 had given 1.6% more membrane thermostability index than Pusa-547 in the present study. The membrane disruption caused by high temperature may alter water ion and inorganic solutes movement, photosynthesis and respiration. Thus, thermostability of the cell membrane depends on the degree of the electrolyte leakage.
Key Words
chickpea; photosynthetic rate; stomatal conductance and cell membrane thermostability index
Address
Indira Gandhi National Open University Regional Centre, Karnal, Haryana, India.
Abstract
Eight trace metals, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn, were measured in the urban soil of Guwahati City, Assam, India from 31 sites representing five different types of land use, residential, commercial, industrial, public utilities, and roadside. Cd and Co occurred in very low concentrations (Cd << Co) in all types of land use without any significant variation from one type of land use to another. Ni concentrations were more than those of Co, and the concentrations depended on land use pattern. Average Cr and Cu concentrations were ≥ 100 mg/kg, but Cr had a significantly higher presence in industrial land use. Pb concentrations showed similar trends. The two metals, Mn and Zn, were present in much larger amounts compared to the others with values ≥ 300 mg/kg. Industrial and roadside soil contained much more Mn while commercial soil was enriched with Zn. Toxicity Characteristic Leaching Procedure (TCLP) was used for elucidating the mobility characteristics of the eight heavy metals. Mn suffered the highest leaching from commercial land (9.9 mg/kg on average) and also from other types of land. Co, Cu and Pb showed higher leachability from commercial soils but the leached concentrations were less than those of Mn. The two metals, Zn and Ni, were leached from residential land in considerable amounts. The TCLP showed Mn to be the most leachable metal and Cr the least.
Key Words
heavy metal accumulation; TCLP; leaching; urban soil; Cd; Co; Cr; Cu; Mn; Ni; Pb; Zn
Address
Department of Chemistry, Gauhati University, Guwahati 781014, Assam, India.
Abstract
The determination of the effectiveness of the immobilization of blasting dust (waste generated in galvanic activities) in cement matrix, as well of mechanical, physical and microstructural properties of concrete paving blocks produced with partial replacement of cement was the objective of this work. The results showed that blasting dust has high percentage of silica in the composition and very fine particle size, characteristics that qualify it for replacement of cement in manufacturing concrete blocks. The replacement of Portland cement by up to 5% residues did not cause a significant loss in compressive strength nor increase in water absorption of the blocks. Chemical tests indicated that there is no problem of leaching or solubilization of contaminants to the environment during the useful life of the concrete blocks, since the solidification/stabilization process led to the immobilization of waste in the cement mass. Therefore, the use of blasting dust in the manufacture of concrete paving blocks is promising, thus being not only an alternative for proper disposal of such waste as well as a possibility of saving raw materials used in the construction industry.
Key Words
blasting dust; concrete paving block; stabilization; solidification
Address
Chemical Engeneering Department, State University of Maringa, 5790 Colombo Avenue, City of Maringa, Brazil.
Abstract
The present study has been performed on one year old tree saplings of Azadirachta indica (L.), Cassia siamea (L.), Dalbergia sissoo (Roxb.), Eucalyptus rostrata (L.), Mangifera indica (L.) and Schyzygium cumini (L.) in order to assess the effect of exposure of SO2-NO2, alone and combination of two gases. Tree saplings have been exposed to an average of 495 μg m-3 SO and 105 μg m-3 NO2 for 40 d at the rate of 4 h d-1 during 10:00 am to 01:00 pm in OTC. Total chlorophyll, specific leaf area (SLA), nitrate reductase (NR) activity, foliar protein, free proline content and free amino acids (AAs) of foliage have been the plant parameters, taken into consideration to evaluate the effect of gaseous exposure. Exposure of two gases has caused reduction in total chlorophyll content (P < 0.05, 0.01). Physiological and biochemical process has been seemed to be altered noticeable due to the combined effect of SO2 + NO2 followed by SO2 alone (P < 0.05, 0.01). NO2 mediated stress has produced, stimulatory and inhibitory responses in tree saplings. Results reveal that tree saplings have been attempted to absorb the NO2 through N assimilation pathway. E. rostrata, C. siamea have been emerged as moderate tolerant to SO2 mediated stress followed by A. indica. Response pattern of S. cumini, M. indica and D. sissoo set them as good indicators of SO2-NO2 exposure. Effects of two gases on tree saplings have been found to be synergistic.
Key Words
Open Top Chamber (OTC); SO2; NO2; stimulatory-inhibitory response; tree saplings
Address
Institute of Environment Management & Plant Sciences, School of Studies in Botany, Vikram University Ujjain 132001, India.
Abstract
In this study, we investigated a life cycle assessment (LCA) of six roof-waterproofing systems [asphalt (C1), synthetic polymer-based sheet (C2), improved asphalt (C3), liquid applied membrane (C4), Metal sheet with asphalt sheet (N1), and liquid applied membrane with asphalt sheet (N2)]for reinforced concrete building using an architectural model. To acquire accurate and realistic LCA results, minimum units of material compositions for life cycle inventory and real data for compositions of waterproofing materials were used. Considering only materials and energy demands for waterproofing systems per square meter, higher greenhouse gas (GHG) emissions could be generated in the order of C1 > N2 > C4 > N1 > C2 > C3 during construction phase. However, the order was changed to C1 > C4 > C3 > N2 > N1 > C2, when the actual architecture model was applied to the roof based on each specifications. When an entire life cycle including construction, maintenance, and deconstruction were considered, the amount of GHG emission was in the order of C4 > C1 > C3 > N2 > C2 > N1. Consequently, N1 was the most environmental-friendly waterproofing system producing the lowest GHG emission. GHG emissions from maintenance phase accounted for 71.4%~78.3% among whole life cycle.
Key Words
life cycle assessment; GHG emission; roof-waterproofing system; reinforced concrete building; architectural model
Address
Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291Daehak-ro, Yuseong-gu, Daejeon, 305-701, Republic of Korea.
