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Bioaugmentation and phytoremediation of heavy metal from leachate contaminated soil / Jayanthi Barasarathi
Get PDFEnvironment contaminated with heavy metals pose a significant problem, mainly due to the toxic effects of these metals throughout the food chain. Landfilling contributes to high volume of leachate generation. In Malaysia, the daily generation of leachate from landfills is about 6 million litres. Landfill leachate is highly heterogeneous and contains heavy metals. Improper waste management allows lateral flow of leachate into soil and cause serious contamination and it later reaches surface and groundwater sources. This posed risks to human health and the environment. Therefore, it is necessary to find solution for the removal of heavy metal from metal contaminated soil. This study aimed to characterize soil and leachate of two selected landfills in Malaysia and further isolate, identify and screen potential microbes for the removal of heavy metals from leachate contaminated soil. The microbes were then formulated into seven different treatments for bioaugmentation of leachate contaminated soil. The effect of inoculum concentration was also evaluated while the field trials were conducted using the best consortia. Phytoremediation to remove heavy metals from the leachate contaminated soil was also carried out using four different plant species. Characterization of both landfill soil and leachate indicated that Pb, Cu, Al, As, Mn, Cr, Zn, Fe and Ni contents were higher than the prescribed limits. Eighteen bacterial species were isolated from the leachate contaminated soil and were further screened for heavy metal sensitivity using the clear zone method. Among the isolates, Burkholderia vietnamiensis demonstrated the highest tolerance for metals (>20ppm). The best remediation results on soil collected from Taman Beringin landfill showed the reduction of 61%, 87%, 47%, 75%, 59% and 61% for As, Al, Mn, Fe, Ni and Cr, respectively by Proteo-bacteria group. Similarly, Proteo-bacteria also removed Al (87%), Mn (49%), Cu (65%), Fe (86%), Ni (78.7%) and Cr (67%) from soil from Bukit Beruntung Landfill. Increasing the inoculum concentration from 10% to 30% v/w showed increased capacity of metal removal from the contaminated soil. Results from the 100 days field trials at Taman Beringin landfill revealed that significant reduction of Pb, Mn, Fe, Al, Cu, Cr and Zn occurred when proteo-bacteria consortia was administered to the contaminated plots. The metal concentration was much lower in the microbe amended plots as compared to control plots. Phytoremediation studies revealed that Cordyline sp. is the most promising plant and the highest percentage of removal was was for Cu (94.35%), Pb (63%), Ni (88.9%), As (85%), Zn (77.55%), Cr (75%) and Al (67.5%) from the soil collected from Taman Beringin Landfill. For phytoremediation of contaminated soil from Bukit Beruntung Landfill, Tradescantia spatachea was the most prominent species with the highest percentage of metal removal for As (87.7%), Cu (81.5%), Fe (48.5%) and Chlorophylum comosum for Al (60%), Zn (73%), Cr (54%) and Pb (78.6%). Hence, bacterial isolates, especially those that belong to Proteo bacteria showed higher metal removal from contaminated soil, while Cordyline sp., T. Spatachea and C. comosum have high potential to be used for phytoremediation of heavy metal
Bioremediation of landfill gas using methanotrophic microorganisms / Jayanthi Barasarathi
Get PDFMethane (CH4) is an important greenhouse gas with a global warming potential 25 times higher than carbon dioxide (CO2). Landfill is a one of the major contributor to
global CH4 emission and is estimated to be 500-800 Mt CO2 eq/year. Previous studies have shown that microbial oxidation of CH4 in landfill cover soil can be enhanced
using substrates that are rich in organic matter, such as compost. Methanotrophs are group of bacteria that utilize CH4 as its sole carbon and energy source. Therefore this
study is aimed to characterize the physiochemical properties of biocover material,while identifying the potential methanotrophic bacteria from landfill cover soil. It is also intended to evaluate a comparative assessment of the CH4 efficiency of the biocover material under controlled conditions for bottle and column experiments with
the addition of potential methanotrophic bacteria. Compost has been identified as best biocover material based on the associated physiochemical properties and their ability
to oxidize 4% of CH4 within 4 days. Three types of methanotrophic bacteria were isolated from landfill soil and identified as Methylomonas sp, Methylococcus sp 1 and
Methylococcus sp 2. Methylococcus sp 1 showed the highest CH4 oxidation capacity when compared to Methylomonas sp and Methylococcus sp 2 which took only 24 hours for complete CH4 oxidation. Batch experiment with addition of individual
cultures and mixed cultures to the compost carried out at different parameters indicated higher CH4 oxidation capacity at 35˚C and 40˚C, pH 6 and at 60% v/v moisture level. Addition of Methylococcus sp 1 showed the highest CH4 oxidation activity at the rate of 8.33 X 103 μg g-1h-1 while the CH4 oxidation rate with addition of Methylomonas sp was 4.16 X 103 μg g-1h-1. Addition of Methylococcus sp 2
iii showed 75% lower activity compared to Methylococcus sp 1 and 50% lower activity compared to Methylomonas sp. Bacterial count at end of the experiment showed
highest count for Methylomonas sp and Methylococcus sp 1. Statistical analysis (P <0.05) showed significant increase in CH4 oxidation with the addition of Methylomonas sp and Methylococcus sp 1 to the compost at optimum temperature,
moisture and pH when compared to the control. Column experiment carried out with addition of potential methanotrophic bacteria to the compost at different column
height showed highest CH4 oxidation activity at 60cm with the addition of Methylomonas sp and Methylococcus sp 1 and the comparison with control also showed 50% increase in the CH4 oxidation activity. The experiment carried out at
different incubation temperature and moisture content showed highest CH4 oxidation at the temperature of 35˚C to 40˚C and 60% moisture level which are similar to batch
experiment. Kinetic studies using Michaelis Menten equation for batch experiment at optimum parameters showed highest potential CH4 oxidation rate with the addition of
Methyloccocus sp 1. Addition of methanotrophic bacteria to compost showed an enhancement and significant increase in the CH4 oxidation under optimum parameters which are also similar to tropical conditions. A biocover with 60cm column height is potentially the best height for optimal CH4 oxidation
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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