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Microalgal bioremediation of food-processing industrial wastewater under mixotrophic conditions: Kinetics and scaleup approach
No full textThe Chlorella microalgae were mixotrophically
cultivated in an unsterilized and unfiltered raw foodprocessing
industrial wastewater. Both inorganic carbon
(CO2-air) and organic carbon (wastewater) were provided
simultaneously for microalgae growth. The aim of the
study is to find out the utilization rates of total organic
carbon (TOC) and chemical oxygen demand (COD) under
mixotrophic conditions for a given waste water. About
90% reduction in TOC and COD were obtained for all
dilutions of wastewater. Over 60% of nitrate and 40% of
phosphate were consumed by microalgae from concentrated
raw wastewater. This study shows that microalgae
can use both organic and inorganic sources of carbon in
more or less quantity under mixotrophic conditions. The
growth of microalgae in food-processing industrial wastewater
with all studied dilution factors, viz. zero (raw), 1.6
(dilution A), and 5 (dilution B) suggests that the freshwater
requirement could be reduced substantially (20%–60%).
The degradation kinetics also suggests that the microalgae
cultivation on a high COD wastewater is feasible and
scalable
cDNA cloning and characterization of tryptophan synthase alpha subunit from Polygonum tinctorium
Get PDFPolygonum tinctorium is a cultivated plant that produces indigo, a natural blue dye. Its leaves contain a large amount of indican (indoxyl-beta-D-glucoside), a colorless precursor of indigo. The enzyme beta-glucosidase, which degrades indican, is present in leaf cells. If the leaves ar
e scratched because of some external factors, indican is enzymatically degraded into indoxyl and glucose. Because of the chemical instability of indoxyl, it is immediately oxidized to indigo by atmospheric oxygen. Beta-glucosidase is located in chloroplasts, whereas the substrate indican is stored in vacuoles. Therefore, indigo is only produced if leaf cells are physically broken. The insoluble indigo may have a negative effect on infectious fungi and bacteria as well as on invasive insects and other animals. We hypothesize that the physiological role of indican as a secondary metabolite is of a defense system against predators. In a previous study, we have shown that indican is synthesized from indoxyl and UDP-glucose by the catalysis of UDP-glucosyltransferase. The substrate indoxyl is probably produced by the hydroxylation of indole catalyzed by cytochrome P450. Indole is an intermediate product in tryptophan syn thesis, which is the final step of
the shikimic acid pathway, a primary metabolic pathway. The tryptophan synthase consists of four subunits: two alpha subunits (TSA) and two beta subunits (TSB). Only TSA catalyzes the synthetic reaction of indole. Subsequently, indole is converted to tryptophan by the action of TSB. The purpose of this study is to uncover the complete indican synthetic pathway and to provide insight into the switching mechanism from primary to secondary metabolism. Here, we report on the cDNA cloning, expression, and characterization of TSA from P. tinctorium. Transcriptome analysis using mRNA from P. tinctorium leaf tissue resulted in a one-fragment sequence that has homology with sequences from other plant TSAs. Based on this sequence, the RACE method was used to get the complete length of the TSA cDNA. The obtained cDNA consisted of 1,469 bp encoding a polypeptide of 315 amino acids. The primary structure contained the consensus sequences of TSAs and the regions for interaction with beta subunits. P. tinctorium TSA, which we named as ptTSA1, showed high homology to some
enzymes from plants; this was the case particularly with TSA from Isatis tinctoria, another indigo plant, which showed 95.7% homology to ptTSA1. To analyze the properties and functions of ptTSA1, the recombinant protein was expressed in Escherichia coli. In addition, the ptTSA1 cDNA was used to examine whether ptTSA1 could complement a TSA deletion in E. coli. ptTSA1 protein expression and mRNA levels in various tissues of P. tinctorium were examined by the Western blot analysis and semi-quantitative RT-PCR. These expression patterns were also compared with those of TSBs. Here, we will further discuss regarding the analysis
of ptTSA1 and the interaction between TSA and TSB
Characterization of Bioaerosols and their Relation with OC, EC and Carbonyl VOCs at a Busy Roadside Restaurants-Cluster in New Delhi
Get PDFMeasurement of biological particles (bioaerosols) in ambient air is of great importance as it is directly linked with the
health issues. However, data on the bioaerosols characterization are scarce. Here we report on the concentration and
characterization of bioaerosols (including bacterial and fungal aerosols) as well as determination of organic and elemental
carbon (OC and EC) in total suspended particulate matter (TSPM) at a busy roadside restaurants-cluster site in New Delhi.
In addition, 14 carbonyl volatile organic compounds (carbonyl VOCs) were also measured and their relationship with
bioaerosols and OC/EC is assessed. The culturable airborne bacterial and fungal concentrations (CAB and CAF) at
restaurant area varied significantly in different seasons ranging from 1.7 × 104–9.8 × 104 (averaged 6.3 × 104 ± 2.6 × 104
cfu m–3) and 3.5 × 102–9.5 × 103 (3.9 × 103 ± 3.1 × 103 cfu m–3) cfu m–3, respectively. Major concentration peaks of TSPM,
OC, EC as well as bacterial and fungal aerosols were found in winter and spring seasons. These peaks can be attributed to
the low atmospheric boundary layer (ABL) height and favourable meteorological conditions for microbial growth in
winter and spring seasons in New Delhi. Good correlations (R2 > 0.5) were observed between CAB, CAF, TSPM and OC.
On the other hand, CAB and CAF were not found to be correlated with carbonyl compounds (R2 < 0.2) indicative of their
diverse sources. The bacterial identification was done by 16s rDNA sequencing and the identified strains were Bacillus sp.,
Bacillus firmus, Bacillus licheniformis, Bacillus cereus, Bacillus pumilus, Acinetobacter sp. and Acinetobactor radioresistens
gene. Predominant fungal genera identified were Aspergillus, Cladosporium, Alternaria and Fusarium, which are known
for adverse health effects causing numerous allergic and pathogenic inflammations
Study of Valuable and Hazardous Metals from Capacitors of Personal Computer
Get PDFDesktop personal computer (PC) is one of the major contributors of the waste electrical and electronic equipment’s
(WEEE) generated worldwide. Composition of a typical desktop PC is complex and consists of hundreds of
different materials which may be valuable, precious as well as hazardous in nature. Due to globalization and
changing economic scenario, huge amount of E-waste is generated and its management has become a challenging
task. The present paper highlights the various metals that can be recovered and recycle from the capacitors
obtained from the printed circuit boards (PCB) of Central Processing Unit (CPU). Capacitors contain valuable
(Aluminum, iron, copper, zinc, magnesium, manganese, nickel, etc.), hazardous (lead, chromium) and precious
(silver) metals. The study of capacitors has been broadly undertaken following various systematic steps, which
includes study of different types of capacitors present on the PCBs, its quantification, and characterizations
studies. Effect of surface area on metal leaching efficiency was studied. It was observed that the electrolytic
capacitors are present in higher quantity followed by solid electrolytic capacitors. Most of the valuable and
hazardous metals were found in ceramic, film and solid electrolytic capacitors, also the metal leaching rate
enhances by increasing surface area
Thermodynamic modeling and experimental study of rice husk pyrolysis
Get PDFPyrolysis of agricultural waste is a promising route for waste to energy generation. Rice husk is a type of agro-waste that is available in plenty in India. It can be used as feed for pyrolysis to produce different products such as (solid) coke and silica, (liquid) tar and other organics and syngas. HSC Chemistry computer aided code for thermodynamic modeling was used to predict the products of rice-husk pyrolysis in this research study. The pyrolysis of rice husk was carried out between 100-1200°C in the pressure range of 1 – 15 bar. The pyrolysis products predicted by HSC calculations were mainly solid coke, gases like H2, CO2,
CO, CH4, with small quantity of aromatic compounds like C6H6, C7H8, C8H10 (ethyl benzene), C8H10 (xylenes) and C6H5 –OH. An experimental study for product validation was also done and the results are presented
Highly photoactive anatase foams prepared from lyophilized aqueouscolloids of peroxo-polytitanic acid
No full texttPeroxo-polytitanic acid foams annealed at temperature above 500◦C lose volatile components and excessof oxygen providing anatase in the form of thin leaves consisting of intergrown nanocrystalline anataseparticles which transform at temperatures above 850◦C to rutile. The size and shape of the initialleaflets forming the foam is preserved up to ∼900◦C. We observed that the annealed material is highlyphotoactive, owing to highly anisotropic shape of anatase aggregates and their perfect crystallinity. Out-standing photocatalytic activity determined by measuring the kinetics of degradation of Methylene Blue(MB) and 4-chlorphenol (4-CP) as well as measuring the formation of hydroxyl radical spin adductsby EPR spectroscopy was observed. All three methods demonstrated significantly higher activity incomparison with the Degussa P25 photocatalyst. Both methods used for photoactivity tests providedsimilar results, the activity increased with increasing annealing temperature in order 500◦C < DegussaP25 < 600◦C < 850–950◦C. Results of measurement of formation of •OH radicals by EPR also confirmedthe unusually high activity of our materials. In comparison with the Degussa P25, the sample annealedat 950◦C showed significantly higher production of•OH radicals
Understanding carbon regulation in aquatic systems - Bacteriophages as a model
Get PDFThe bacteria and their phages are the most abundant constituents of the
aquatic environment, and so represent an ideal model for studying carbon
regulation in an aquatic system. The microbe-mediated interconversion of
bioavailable organic carbon (OC) into dissolved organic carbon (DOC) by the
microbial carbon pump (MCP) has been suggested to have the potential to
revolutionize our view of carbon sequestration. It is estimated that DOC is the
largest pool of organic matter in the ocean and, though a major component of
the global carbon cycle, its source is not yet well understood. A key element of
the carbon cycle is the microbial conversion of DOC into inedible forms. The
primary aim of this study is to understand the phage conversion from organic to
inorganic carbon during phage-host interactions.
Time studies of phage-host interactions under controlled conditions reveal their
impact on the total carbon content of the samples and their interconversion of
organic and inorganic carbon compared to control samples. A total organic
carbon (TOC) analysis showed an increase in inorganic carbon content by
15-25 percent in samples with bacteria and phage compared to samples with
bacteria alone. Compared to control samples, the increase in inorganic carbon
content was 60-70-fold in samples with bacteria and phage, and 50-55-fold for
samples with bacteria alone. This study indicates the potential impact of
phages in regulating the carbon cycle of aquatic systems
Utilization of coconut shell carbon in the anode compartment of microbial desalination cell (MDC) for enhanced desalination and bio-electricity production
No full textMicrobial desalination cell (MDC) is an emerging bio-electrochemical system. This is considered as one of
the promising technologies for clean water and energy production. MDC technology is a derivative of the
microbial fuel cell (MFC). This study reports bench-scale laboratory desalination using MDC loaded with
granular coconut shell carbon, as a new electrode material in the anode compartment. Control
experiments were performed without granular coconut shell carbon to evaluate the effect of carbon. Two
different initial salt concentrations (20,000 and 30,000 mg L�1) were investigated. The experimental
MDC (with carbon) for an initial concentration of 20,000 mg L�1 NaCl, produced the highest voltage of
461
�9 mV at the same time removing about 84.2% of sodium and 58.25% of chloride in a single
desalination cycle. The control MDC (without carbon) at the same time produced 261 mV and 68.2%
removal of sodium and 50.7% removal of chloride. The SEM analysis of the bio-film showed meager
coverage of rod shaped microorganisms and molecular pili (nanowires) structure. In the current study,
nanowires as observed in SEM may be the potential electron transfer pathways. These results
demonstrate for the
first time the possibility of using activated carbon from a biomass waste, as electrode
material for enhanced water desalination and power production in a MDC
Identification and monitoring of nitrification and denitrification genes in Klebsiella pneumoniae EGD-HP19-C for its ability to perform heterotrophic nitrification and aerobic denitrification
No full textMicrobes capable of performing heterotrophic
nitrification and aerobic denitrification simultaneously
have application in nitrogen level management in effluent
treatment plants. Klebsiella pneumoniae EGD-HP19-
C is a metabolically versatile bacterium capable of
utilising NH3–N, NO2–N and NO3–N as sole sources of
nitrogen. The annotation was done for the genes involved
in N-assimilation and N-dissimilation pathways
from the draft genome sequences of this bacterium
(NCBI GenBank accession no. AUTW02000000.1). The
sequence data also suggested possible existence of plasmid
associated with this bacterium. Multiple gene sequence
alignments of glutamine synthetase (gln), hydroxylamine
reductase (har), nitrite reductase (nir), nitric
oxide reductase (nor), assimilatory nitrate reductase
(nas) and respiratory nitrate reductase (nar) genes from
EGD-HP19-C genome were performed to compare sequence
identities with that of closely related bacterial
species. The metabolic pathways were mapped using
KAAS and 3D structures for representative enzyme
sub-units were also elucidated. The study suggested that
the organism, though it has incomplete nitrification and
denitrification pathways still removes the inorganic nitrogen
content from the system via ammonification reaction
Synthesis Optimization and Fluoride Uptake Properties of High Capacity Composite Adsorbent for Defluoridation of Drinking Water
No full textA novel low cost composite adsorbent has been successfully
synthesized from waste eggshell (ES), alum, and chitin
for removal of excess fluoride from drinking water. Synthesis
of chitin based adsorbent (CBA) was optimized by varying
different synthesis parameters such as alumina loading,
ES:chitin ratio, calcination temperature, calcination time,
shaking time, drying temperature, and washing time. CBA is
a composite type material having heterogeneous phases of
Ca(OH)2, Al(OH)3, Al2O3 encapsulated with carbon,
Al(OH)3 and Al2O3 deposited on carbon and Al2O3. Presence
of multiple phases with prominent presence of crystalline as
well as amorphous phases of alumina has been substantiated
by using XRD and SEM analysis. The elemental composition
of material and EDX also suggests composite nature of material
with different phases. The SEM image of CBA reveals the
presence of both coarse and fine particles with irregularly
shaped particles of alumina agglomerates adhering to calcite
particles of ES. Defluoridation performance was systematically
studied for CBA, which has outperformed several
reported adsorbents with its higher adsorption capacity of
30.3 mg g21. No significant influence on the percent fluoride
removal was observed in presence of Cl2, SO24
and NO23
ions, whereas the fluoride removal decreases significantly by
36, 24.84 and 24% in presence of HCO3
2, CO23
and PO24
ions, respectively. CBA follows pseudo second order kinetic
and fluoride adsorption mechanism was rather complex one,
wherein both intraparticle diffusion and surface diffusion
are involved in the rate-limiting step. Negligible leaching of
Al13 ions was observed