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Stable partial nitrification in an up-flow fixed-bed bioreactor under an oxygen limiting environment
No full textChalk dustfall during classroom teaching: particle size distribution and morphological characteristics
No full textThe study was undertaken to examine the nature of particulate chalk dust settled on classroom floor during traditional teaching with dusting and non-dusting chalks on two types of boards viz. rough and smooth. Settling chalk particles were collected for 30 min during teaching in glass Petri plates placed in classrooms within 3 m distance from the teaching boards. Particle size distribution, scanning electron microscopic images of chalk dusts and compressive strength of two types of chalks were tested and
evaluated. Results showed that a larger proportion of dusts generated from anti-dusting chalks were of <4.5 and <2.5 μm size on both smooth and rough boards, as compared to dusting chalks. Non-dusting chalks, on an average, produced about 56% and 62% (by volume) of <4.5 μm (respirable) diameter, on rough and smooth boards, respectively, while the corresponding values for dusting chalks were 36%
and 45%. Also, on an average, 83% and 94% (by volume) of the particles were <11 μm (thoracic) in case of non-dusting chalks against 61% and 72% for dusting chalks on rough and smooth boards, respectively. Interestingly, taking into account the mass of chalk dust produced per unit time, which was higher in dusting chalks than non dusting chalks, the former was actually producing higher amount of PM <4.5
and <11 particles from both types of boards. Scanning
electron microscope images revealed that chalk particles had random shape, although in dusting chalks prevalence of elongated particles was observed, apparently due to the longitudinal breaking of the chalks during writing, which was confirmed during compressive strength testing. We could conclude that dusting chalks could be potentially more harmful than anti dusting chalks, as they produced higher amount of potentialy dangerous PM 4.5 and PM 11
Processing of poultry feathers by alkaline keratin hydrolyzing enzyme from Serratia sp. HPC 1383
No full textThe present study describes the production and characterization of a feather hydrolyzing enzyme by Serratia
sp. HPC 1383 isolated from tannery sludge, which was identified by the ability to form clear zones
around colonies on milk agar plates. The proteolytic activity was expressed in terms of the micromoles of
tyrosine released from substrate casein per ml per min (U/mL min). Induction of the inoculum with protein
was essential to stimulate higher activity of the enzyme, with 0.03% feathermeal in the inoculum
resulting in increased enzyme activity (45 U/mL) that further increased to 90 U/mL when 3 d old inoculum
was used. The highest enzyme activity, 130 U/mL, was observed in the presence of 0.2% yeast extract.
The optimum assay temperature and pH for the enzyme were found to be 60 �C and 10.0, respectively.
The enzyme had a half-life of 10 min at 60 �C, which improved slightly to 18 min in presence of 1 mM
Ca2+. Inhibition of the enzyme by phenylmethyl sulfonyl fluoride (PMSF) indicated that the enzyme
was a serine protease. The enzyme was also partially inhibited (39%) by the reducing agent b-mercaptoethanol
and by divalent metal ions such as Zn2+ (41% inhibition). However, Ca2+ and Fe2+ resulted in
increases in enzyme activity of 15% and 26%, respectively. The kinetic constants of the keratinase were
found to be 3.84 lM (Km) and 108.7 lM/mL min (Vmax). These results suggest that this extracellular keratinase
may be a useful alternative and eco-friendly route for handling the abundant amount of waste
feathers or for applications in other industrial processes
Amine loaded zeolites for carbon dioxide capture: Amine loading and adsorption studies
No full textNovel functionalised adsorbents have been synthesized by immobilization of various amines on synthetic
zeolite 13X. Various primary and secondary amines namely monoethanolamine (MEA), ethylenediamine
(ED) and isopropanol amine (IPA) have been immobilized on zeolite 13X. Quantitative estimations of the
amine loadings were undertaken using different analytical techniques namely titrimetric, total organic
carbon and gas chromatography analysis. Fairly good correlation was obtained for amine loadings estimated
using the three techniques. Effect of various parameters like effect of solvent, shaking time, synthesis
temperature, and wetting of pellets prior to amine loadings was also studied. The results revealed
that maximum loading was achieved for methanol-mediated synthesis conducted using previously wetted
pellets at room temperature and with 15 min of shaking time. Preliminary attempts have also been
made to determine the CO2 adsorption capacities of these newly developed materials. The adsorption
capacities obtained were 16.01 mg/g for unmodified zeolite 13X and 19.98, and 22.78 mg/g for zeolite
modified with monoethanol amine, and isopropanol amine
Assaying Baseline Status of Particulate Laden Polyaromatic Hydrocarbon for a Grass Root Level Industrial Project
No full textA study of particulate laden polyaromatic hydrocarbon was conducted at 13 selected locations in a 10 km radial distance of a proposed site for a grass root level industry. Suspended particulate matter samples were
continuously monitored for 24 h over a period of 3 months.
The Polyaromatic Hydrocarbons (PAHs) were extracted from the particulate samples and analysed using Gas Chromatograph-Mass Spectrometer. Limit of Quantification
was also established for individual PAHs. Coal combustion and traffic emission were the major contributors for PAHs in the region. The relative contribution of 2, 3, 4, 5, and 6 ring PAHs in particulates of different sampling sites was also investigated and it is observed that 4 ring (29.76%) and 5 ring (29.06%) compounds are prominent in the particulates measured in the region
Fate and Degradation of POP-Hexachlorocyclohexane
No full textHexachlorocyclohexane (HCH) and its isomers are one of the most frequently detected chlorinated contaminants in the environment. In spite of the ban on technical grade HCH and restricted use of γ -HCH (lindane), its residues have not stopped from entering the environment. Its extensive use in the past, present use of lindane in several countries, unused stockpiles of date-expired HCH from earlier manufacturing, as well as leachates from earlier disposal
at dump sites continue to pollute the biosphere. Because HCH is a persistent organic pollution (POP) known to have several toxic and deleterious effects on human health and wildlife, it becomes imperative to remove this substance of serious concern to the global community. A better understanding on the fate and degradation of this POP in the environment will facilitate in drawing measures to
mitigate this chemical and bring about bioremediation of already contaminated sites. This review focuses on the fate, contamination levels, abiotic and biotic degradation of HCH isomers, genes and enzymes involved in microbial degradation, and future research needs in this area
A modified anaerobic baffled reactor for municipal wastewater treatment
No full textA nine-chambered modified anaerobic baffled reactor (MABR) was developed to evaluate its suitability for the treatment of municipal wastewater and to establish the understanding of the relationship between reactor design and operational parameters. The paper presents the configuration of the MABR, its start-up, effect of variation of hydraulic retention time (HRT) on treatment efficiency, and performance evaluation of the MABR while treating the municipal wastewater. To assess the self-inoculation
potential of the MABR, the start-up was carried out without seed sludge at a HRT of 6 d. An acclimatization curve was plotted and indicated that a start-up period of 90 d was required for the MABR. Reactor performance evaluation was carried out for 375 d at 11 different HRTs ranging from 6 d to 3 h. The HRT of 6 h was adjudged to be appropriate for this reactor configuration. At a HRT of 6 h, the efficiencies of reduction in suspended solids (SS), biochemical oxygen demand (BOD), and chemical oxygen demand (COD) were found to be 86%, 87% and 84% respectively. Specific biogas yield and methane content were found to be 0.34 m3CH4/KgCODr and 67% respectively. The study has evaluated the performance pattern of the MABR and identified it as a suitable reactor technology for municipal
wastewater management in India.
Energy efficient—Advanced oxidation process for treatment of cyanide containing automobile industry wastewater
No full textDestruction of cyanide (CN) from an automobile industry wastewater by advance oxidation process (AOP) has been evaluated. The operating conditions (in an digenously designed photoreactor) for three different treatment strategies have been optimized. The treatment strategies involved use of, ultra violet light (UV), hydrogen peroxide (H2O2) and ozone (O3) in various combinations. Treatment of automobile industrywastewater (250 mg/L CN) showed fastest CN destruction, which was significantly (P < 0.05) faster
than that observed with syntheticwastewater (with similar CN concentration). A combined application of H2O2/O3 was found to be the best option for maximum CN destruction. This treatment allows CN to reach the regional/international limit (of 0.02 mg/L) for safe industrial wastewater discharges to the receiving water bodies. The specific energy consumption by the photoreactor following this treatment was comparable to that obtained by conventional treatments, which use photocatalyst. Since the present treatment does not use catalyst, it provides an excellent energy efficient and economical option for treatment and safe disposal of CN containing industrial wastewater.
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Ozonation of reactive dye, Procion red MX-5B catalyzed by metal ions
No full textOzonation of aqueous solution of Procion redMX-5B, a commercial azo reactive dyewas investigated. The effect of various experimental variables on decolorization and degradation of the dye has been studied. Color removal was faster than organic removal. Dye mineralization was evident by the generation of sulphate, chloride, nitrate, oxalic and acetic acid during ozonation. The decolorization and organic removal followed pseudo-first-order kinetics. Among the metal ions studied, manganese catalyzed ozonation
showed better decolorization and organic removal. Fourier transform infrared (FTIR) spectroscopy results indicated the disappearance of bands for aromatics and appearance of bands due to carboxylic acids in the ozonated samples. Acetyl benzoic acid, diethyl phthalate and phthalic anhydride were identified as intermediates by gas chromatography mass spectra (GC/MS). Based on these findings a tentative pathway for the degradation MX-5B was postulated
In situ bioremediation of organochlorine-pesticide-contaminated microcosm soil and evaluation by gene probe
No full textBACKGROUND:Pesticide-formulating industries are contaminatingthe environment through various activities. Bioremediation is the bestmethod for decontamination, as chemical and physicalmethods are not only costly but also not very effective in open field systems. In the present study, in situ bioremediation of organochlorine-contaminated soil was demonstrated by combined biostimulation and bioaugmentation strategies, followed by evaluation using amolecular method.RESULTS: Three parameters were monitored: microbial biomass (colony-forming units (CFU) g−1 soil), residual pesticides after treatment and catabolic genes from microcosm soil. Both the biostimulation and the bioaugmentation treatments showed an initial lag phase of 80 days towards colony-forming units. Gas chromatography of soil samples showed that concentrations of residual pesticides in the soil declined by up to 85–90% after 80 days, indicating their utilisation with time.
On dot-blot hybridisation of the total DNA from the same soil samples, it was observed that catabolic genes tfdC (catechol1,2-dioxygenase) and cm genes (chlorophenol monoxygenase) were predominant, whereas other catabolic genes such as catechol 2,3-dioxygenase (xylE) were negligible.
CONCLUSION: The strategy of in situ bioremediation and its evaluation by gene probe and also by conventional methods was demonstrated for organochlorine-pesticide-contaminated soil in open microcosms. It showed that bioaugmentation alongwith biostimulation was effective, although initial acclimatisation for a period of almost 2–3 months was required in the open field systems