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Bioremediation of synthetic high–chemical oxygen demand wastewater using microalgal species Chlorella pyrenoidosa
No full textThe microalgal species Chlorella pyrenoidosa was cultivated in synthetic wastewater of initialchemical oxygen demand (COD), nitrate, and phosphate concentrations of 5000, 100, and 40 mg/L,respectively. The aim of the study was to find out the tolerance of microalgae to different COD concentrations and the extent of COD degradation at those concentrations. Three dilutions of wastewater (initial COD concentrations 5000, 3000, and 1000 mg/L) and three inoculum sizes (0.1,0.2, and 0.3 g/L) were considered for the study. The experimental parameters such as total organic
carbon, total inorganic carbon, COD, optical density, total solids, nitrate, and phosphate were measured on a daily basis. Biodegradation kinetics was determined for all cases using first-order reaction and Monod degradation equations. Optimal results showed that up to 90% reduction in TOC was obtained for 1000 COD wastewater while only 38% reduction in total organic carbon (TOC)was achieved for 5000 COD wastewater. Over 95% reduction in nitrate and nearly 90% removal of phosphate were obtained with the lowest microalgal inoculum concentration (i.e., 0.1 g/L) for all COD dilutions. This study showed that microalgal species C. pyrenoidosa can successfully degrade the organic carbon source (i.e., acetate) with significant removal efficiencies for nitrate and phosphate
Graphene-based materials supported advanced oxidation processes for water and wastewater treatment: a review
No full textAdvanced oxidation processes (AOPs) received
much attention in the field of water and wastewater treatment
due to its ability to mineralize persistent organic pollutants
from water medium. The addition of graphene-based materials
increased the efficiency of all AOPs significantly. The present
review analyzes the performance of graphene-based materials
that supported AOPs in detail. Recent developments in this
field are highlighted. A special focus has been awarded for the
performance enhancement mechanism of AOPs in the presence of graphene-based materials
Recycling E-Waste for Sustainable Management of Natural Resources
Get PDFElectronic waste (E-waste) which consists of old, end-of life, discarded electrical and
electronic equipment’s (EEE), is the most rapidly growing MSW stream worldwide. The toxic
and hazardous materials present in it can lead to severe environmental and occupational
hazards, if not handled properly. However, presence of significant quantity of valuable
recoverable material makes it a potential secondary resource for metal extraction. Composition
of E-waste is complex with 38% ferrous material, 28% non-ferrous material, 19% plastic, 4%
glass, 11% other (wood, rubber, ceramic, etc.). Although the precious materials are only 1% by
weight, it accounts to nearly 80% of the total intrinsic value. Around $ 21 billion of Au and Ag
are used in various EEE per annum.Along with precious metals it also contains various rare
earth metals such as Platinum, Gallium, Indium, Lithium, etc. Primary metal extraction from
mining has significant negative environmental impact due to substantial natural resources
consumed and low recovery efficiency; comparatively extraction from E-waste is 50 times
greater which is much more economical with lesser ecological foot printand the energy savings
are considerable: aluminium 95%, copper 85%, iron and steel 74%, plastics 80%. This is the reason why E-waste recycling which is also called as “Urban Mining” can facilitate in
sustainable management and conservation of rapidly depleting natural resources
Control of Multidrug-Resistant Gene Flow in the Environment Through Bacteriophage Intervention
No full textThe spread of multidrug-resistant (MDR) bacteria is an emerging threat to the
environment and public wellness. Inappropriate use and indiscriminate release of antibiotics
in the environment through un-metabolized form create a scenario for the emergence of
virulent pathogens and MDR bugs in the surroundings. Mechanisms underlying the spread
of resistance include horizontal and vertical gene transfers causing the transmittance of MDR
genes packed in different host, which pass across different food webs. Several controlling
agents have been used for combating pathogens; however, the use of lytic bacteriophages
proves to be one of the most eco-friendly due to their specificity, killing only target bacteria
without damaging the indigenous beneficial flora of the habitat. Phages are part of the natural
microflora present in different environmental niches and are remarkably stable in the environment.
Diverse range of phage products, such as phage enzymes, phage peptides having
antimicrobial properties, and phage cocktails also have been used to eradicate pathogens along
with whole phages. Recently, the ability of phages to control pathogens has extended from the
different areas of medicine, agriculture, aquaculture, food industry, and into the environment.
To avoid the arrival of pre-antibiotic epoch, phage intervention proves to be a potential option
to eradicate harmful pathogens generated by the MDR gene flow which are uneasy to cure by
conventional treatments
Comparative analysis of antioxidant response by Pteris vittata and Vetiveria zizanioides towards arsenic stress
No full textAntioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione peroxidase (GPX) reportedly allow plants to combat toxic metal stress. Hydroponic experi- ment was conducted to study the response of antioxidant enzymes under arsenic (As) stress in the fronds and roots of an Indian ecotype of Pteris vittata (As hyperaccumulator) and Vetiveria zizanioides (As non hyperaccumulator). These plants were exposed to different As levels (0, 10, 20, 30 & 50mg As L−1) for 10 days in green house. In P. vittata and V. zizanioides, total As accumulation in biomass increases with increase in As concentrations. Arsenic accumulation was more in the fronds than in the roots of P. vittata, though not in case of V. zizanioides. Arsenic accumulation in total plant biomass of P. vittata and V. zizan- ioides was 879 mg and 785 mg As kg−1 respectively. Enzymatic antioxidants response in P. vittata under As stress showed increased activity in different parts in comparison to control. All enzyme activity was higher in fronds as compared to roots which corresponded to more As accumulation in fronds. Results indicate that enhanced activities of the antioxidant enzymes play a significant role in As tolerance and hyperaccumulation by P. vittata whilst changes in these enzyme activities did not show a specific trend in V. zizanioides under As stress. The results indicate that P. vittata has evolved mechanisms for As detox- ification and hyperaccumulation while V. zizanioides does not, but sustains a moderate level of As stress presumably as excluder
Performance of Natural Coagulant Extracted from Plantago ovata Seed for the Treatment of Turbid Water
No full textPresent study investigates the coagulation ability of Plantago ovata (P. ovata) seed extracts for turbidity removal. The active coagulant agents were successfully extracted from P. ovata seeds using different solvents such as distilled water (PO-DW), tap water (PO-TW), NaCl (PO-NaCl), and ammonium acetate (PO-AA). Experiments were conducted in batch mode for initial turbidity such as 500 NTU (high), 150 NTU (medium), and 50 NTU (low). Results demonstrated that P. ovata extracts are less efficient in low turbidities, while PO-NaCl was found to provide high coagulation activity in all initial turbidity concentrations compared to other extracts. PO-NaCl was able to remove 98.2, 94.9, and 80.2% of turbidity from water having in initial turbidities of 500, 150, and 50 NTU, respectively. Coagulation activity of the extract was the best when the extraction was performed for 50 min at room temperature. Jar test procedure with the coagulation time of 1 min and flocculation time of 30 min was optimized, irrespective of the initial turbidity. The optimum settling time for 500, 150, and 50 NTU water samples were 20, 30, and 90 min, respectively. PO-NaCl was used in different pH turbid solutions and it was found to be working very efficiently in alkaline conditions. The coagulation efficiency of the coagulant stored in refrigerator was higher than that stored at room temperature. Thus, the natural coagulants extracted from P. ovata seeds revealed to be effective for turbidity removal
Fundamentals of Infrared Heating and its application in drying of food materials: A review
No full textDrying is an energy-intensive unit operation in chemical, food and allied industries.
It is always desired to have low energy consumption for drying operation
without compromising the quality of products. In this review, fundamental
aspects of infrared heating are described in detail with the focus on its application
to the drying of food materials. The modeling techniques are explained in detail to
get emphasis on the design of large-scale infrared dryers. This review also contains
the investigations carried out by several researchers by experimentation and/or
modeling to describe the infrared drying, infrared–convective drying, infrared–
microwave drying and infrared–freeze drying. The present work describes the
author’s views regarding the capability and applicability of infrared source for
drying of food materials. After going through a literature survey, it can be seen
that infrared source especially in the far-IR range has been widely used in convective
hot air dryer than other types of dryers
Evaluation of Fenton and Ozone Treatment Process for the Degradation of Psychiatric Drugs Carbamazepine (CBZ) and Oxcarbazepine (oxCBZ) in Simulated Waste Water (SWW)
No full textThe current research focuses on the evaluation of two advanced oxidation processes (AOPs) viz. Fenton and ozone treatment for the degradation of recalcitrant antipsychiatrics carbamazepine (CBZ) and oxcarbazepine (oxCBZ) in simulated wastewater. The parameters for Fenton reactions viz. pH, Fenton dosage, contact time and Fe2+/H2O2 were optimized using Response Surface Methodology. The optimum conditions obtained were (pH 2.0, Fenton dosage 1.61 g/dm3, Fe2+/H2O2 0.427 and contact time of 25 minutes) which yields a COD destruction of 92.49%. A pseudo-first order rate constant of 0.6185 min-1 and 0.0676 min-1 was observed for the ozonation of CBZ and oxCBZ respectivel
Adsorption of Hexavalent Chromium using Levigated Alumina GRM-1909
Get PDFUse of commercially available levigated alumina GRM-1909 for adsorption of Hexavalent chromium is investigated. In this study,
the adsorption of Cr(VI) was carried out in a batch mode and rate of adsorption was evaluated at varying conditions viz. pH,
adsorbent dose, initial concentration and contact time. The maximum removal of Cr(VI) (98%) was observed at pH 4 with an
adsorbent dose 1 gm/100 ml and chromium concentration of 10 mg/l. The adsorption study revealed that pH and adsorbent dose
play significant roles towards Cr(VI) adsorption. Langmuir and Freundlich adsorption isotherm models were applied. The
Langmuir isotherm fitted the equilibrium adsorption data better with a correlation coefficient of R2 = 0.971. The present study
reveals that the commercially available levigated alumina can be an ideal candidate for the removal of chromium (VI) metal ions
from waste water
Metagenomic approach to characterize soil microbial diversity of Phumdi at Loktak Lake
No full textLoktak, one of the largest freshwater lakes of India, is known for floating islands (Phumdi), being made
up of a heterogeneous biomass of vegetation and soil. This ecological site represents an exclusive
environmental habitat wherein the rhizospheric microbial community of Phumdi plays a key role in
biogeochemical cycling of nutrients. A culture-independent whole genome shotgun sequencing
based metagenomic approach was employed to unravel the composition of the microbial community
and its corresponding functional potential at this environmental habitat. Proteobacteria (51%) was
found to be the most dominant bacterial phylum followed by Acidobacteria (10%), Actinobacteria (9%)
and Bacteroidetes (7%). Furthermore, Loktak metagenome data were compared with available
metagenomes from four other aquatic habitats, varying from pristine to highly polluted eutrophic
habitats. The comparative metagenomics approach aided by statistical analysis revealed that
Candidatus Solibacter, Bradyrhizobium, Candidatus Koribacter, Pedosphaera, Methylobacterium,
Anaeromyxobacter, Sorangium, Opitutus and Acidobacterium genera are selectively dominant at this
habitat. Correspondingly, 12 different functional categories were found to be exclusively prevalent at
Phumdi compared to other freshwater habitats. These differential features have been attributed to the
unique habitat at Phumdi and correlated to the phenomenon of bioremediation at Loktak Lak