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Herein, we report a bacteria-based strategy as an efficient, reasonable, benign, and promising methodology for remediating heavy metals fed waterbodies. The contemporary study deals with isolating, screening, and characterizing heavy metal resistive bacteria from metal-rich sites. The transcriptome analysis reveals the identity of the isolated species as Bacillus pumilus and Bacillus cereus. Batch studies put forth the bioremoval results in designed conditions of different pH, concentration, dose, and time. The mechanistic actions are drawn using complementary techniques such as Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The theory of surface adsorption of lead (Pb(II)) and nickel (Ni(II)) is further fostered by the application of adsorption isotherms. The conducted studies establish the bacterial morphological stratagems and multifarious biochemical approaches for countering metallic ions of Pb(II) and Ni(II). The exhibition of significant removal results by the isolated bacterial strains in simulated water samples with remarkable proliferation rates has opened up its favorability for industrial platforms.

Environmental nanotechnology is holding an immense position in modern days’ science and engineering. These advanced ‘nanomaterials’ are being utilized for diverse range of applications but with the ideology of saving environment. Environmental sector is being tackled with the aim of developing sensors for detecting, monitoring and analysing the toxic contaminants so as to protect and remediate environment. In the presented chapter we have tried to illustrate applications of nanofields, and resulting impacts on the four spheres of the earth. Many efforts are being taken to have a check on the negative impacts of the nanotechnology but still there are many prevailing discrepancies that need to be confronted.

The release of untreated wastewater containing biotoxic substances in the form of heavy metals is one of the most crucial environmental and health challenges faced by our community. The recent advances in microbes derived removal has propelled bioremediation as a better and effective alternative to conventional techniques. Present study investigates the detoxification mechanisms evolved by the nickel (Ni(II)) resistant fungal strains, isolated from the industrial drain sites. The molecular detailing of the isolated fungal isolates confirms their identity as Neurospora crassa and Aspergillus flavus. Laboratory-scale experiments have established influence of different ranges of dose, pH, time, and metal concentration on the removal and uptake trends. Further, the variations in the carbon and nitrogen sources and agitation conditions has revealed the best substratum for achieving optimum results for the industrial exploitation of these microbes. SEM micrographs and FTIR spectra elucidates the superficial alterations on the mycelium of the fungal isolates and the involvement of active functional groups in the bioremediation of Ni(II) respectively. Biosorption of Ni(II) on living biomass has followed the Langmuir adsorption model. The findings of the study have provided a promising insight in the simultaneous action of different mechanistic removal approaches to explore a large scale removal of Ni(II) from the waste generating industries.

The ecological toxicity imparted by non-biodegradable organic dyes has been considered as a major risk to handle in front of mankind. In this view, the low-cost zinc oxide nanoparticles (ZnO-NPs) were facially synthesized by coating the surface with surfactant (CTAB) and ionic liquid (BMTF) molecules for the effective removal of Eriochrome Black T (EBT) from aqueous media. Various advanced characterization techniques have given insight into the morphological features, crystalline structure and physio-chemical properties of as-synthesized ZnO-NPs. The systematic analysis of the adsorption isotherms and kinetics models specifies that the adsorption of EBT follow Freundlich model and pseudo-second-order kinetics. The intraparticle diffusion model displayed a linear relationship (R2 = 0.98, 0.97 and 0.94 for BMTF@ZnO, CTAB@ZnO and bare ZnO-NPs), which shows that pore diffusion rate is affected by surface modification and effects the overall EBT adsorption process. Furthermore, after the removal of 87% and 84% of EBT dye by BMTF@ZnO-NPs and CTAB@ZnO-NPs, the fabricated nanoadsorbents of ZnO were successfully regenerated and reused after the treatments up to four times. The adsorption aptitude of ZnO-NPs towards EBT dye was systematically explored in real wastewater samples and interference study of inorganic metallic salts was also performed. The toxicity estimations of the treated dye solutions were made using floral and fungal activities, to ascertain their non-toxic nature before releasing into the environment. These outcomes have supported the immense potential of ZnO-NPs towards the removal of EBT in a cost effective manner.

The aim of the present work is to evaluate the ability of ‘fungi’ for the biodegradation of recalcitrant xenobiotic compound, ‘Atrazine’ in batch liquid cultures. Different parameters like pH (2.0–8.0) temperature (16–32 °C), biomass (1–5 g), and concentration (25–100 ppm) were optimized for the efficient degradation of atrazine. The decomposition behavior of atrazine is analyzed with the help of Fourier Transform Infrared (FTIR) spectroscopy. Herein, we have reported that the Bjerkandera adusta possess high removal efficiency of the xenobiotic compound (atrazine) up to 92%. The fungal strain investigated could prove to be a valuable active pesticide degrading micro-organism, with high detoxification values. These results are useful for improved understanding and prediction of the behavior and fate of B. adusta in the bio-purification of wastewater contaminated with xenobiotics. Thus providing a new and green approach for the remediation of toxicants without altering the environmental components.

Heterostructured α-Bismuth zinc oxide (α-Bi2O3–ZnO) photocatalyst was fabricated by a facile and cost-effective, ultrasound assisted chemical precipitation method followed by hydrothermal growth technique. As synthesized α-Bi2O3–ZnO photocatalyst showed enhanced photocatalytic performance for the MB dye degradation in contrast to pure ZnO and α-Bi2O3. Light emitting diodes (UV-LED) were used in the experimental setup, which has several advantages over conventional lamps like wavelength selectivity, high efficacy, less power consumption, long lifespan, no disposal problem, no warming-up time, compactness, easy and economic installation. XRD study confirmed the presence of both the lattice phases i.e. monoclinic and hexagonal wurtzite phase corresponding to α-Bi2O3 and ZnO in the α-Bi2O3–ZnO composite photocatalyst. FESEM images showed that α-Bi2O3–ZnO photocatalyst is composed of dumbbell like structures of ZnO with breadth ranging 4–5 μm and length ranging from 10 to 11 μm respectively. It was observed that α-Bi2O3 nanoparticles were attached on the ZnO surface and were in contact with each other. Low recombination rate of photo-induced electron-hole pairs, due to the migration of electrons and holes between the photocatalyst could be responsible for the 100% photocatalytic efficiency of α-Bi2O3–ZnO composite. In addition, photocatalyst was also observed to show the excellent antimicrobial activity with 1.5 cm zone of inhibition for 1 mg L−1 dose, against the human pathogenic bacteria (S. aureus).

Almost all the compartments of the environment have been severely polluted by heavy metals anthropologically, rendering its intrinsic values. In this approach, the present work has been aimed at developing a consortium of heavy metal resistant bacteria isolated from various wastewater sites. The designed bioaugmentation was aimed to specifically remove lead (Pb 2 + ) and nickel (Ni 2 + ) metal ions from the aqueous solutions. From the total 17 different industrial collection sites, 2 strains viz. Bacillus cereus and Bacillus pumilus have shown remarkable removal of Pb 2 + (95.93%) and Ni 2 + (95.54%) ions from the wastewater samples. The influential parameters like pH, incubation time, inoculum size, and initial metal concentration have been monitored for better insight into the interactional mechanism. The mechanism of heavy metals removal involves uptake of metal ions (Pb 2 + and Ni 2 + ) by means of complex formation, crystallization, and surface adsorption; invigorated with intracellular uptake and stabilization. The obtained results witness the hauling potential of the B. cereus and B. pumilus against the removal of bioavailable fractions of heavy metals thus projects of their practice on a commercial level.

Heavy metals like chromium (Cr(VI)) and cadmium (Cd(II)) which are supposed to be indigenous components of rocks, are no longer bound to their place of origin thus manifesting significant toxic impacts on living beings. In the present study, the metal tolerance capacity of highly resistant microorganisms was harnessed individually and in the form of consortium, to remediate conundrum of pollution. These fungal strains were isolated from contaminated sites and screened under various processed conditions. Results of secondary screening had evinced more than 70% of removal percentage for Cr(VI) with the fungi Aspergillus flavus (FS4) and Aspergillus fumigatus (FS6), in the liquid medium. Similarly, one Cd (II) tolerant fungal isolate FS9, identified as Aspergillus fumigatus, showed removal up to 74%. The developed microbial consortium had also enhanced the removal of heavy metals in different industrial effluents. The metal acceptance quality that this fungal consortium possess, may specify its ability as an effective biosorbent for the environment contaminated with heavy metals.

Green chemistry-assisted biocompatible copper (Cu), silver (Ag), and iron oxide (Fe2O3) nanoparticles (NPs) synthesis along with surface modification using Koelreuteria apiculata is demonstrated in this research, for the first time. Appropriate analytical techniques were utilized to confirm the preparation, spherical morphology, and crystalline structure of each of the NPs. The antioxidant nature of synthesized NPs was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging. Besides, the antimicrobial activity was also performed using bacterial strains of Staphylococcus aureus, Escherichia coli, and Salmonella typhi. Aspergillus sp. was designed as marker specie for the antifungal studies. The outcomes of NPs exposure, analyzed with reference to Chlorella sp. of the algal family exhibit the numerical values around 833% for AgNPs, 497% of CuNPs, and 456% for Fe2O3NPs. Phytotoxicity assay performed on the seeds of Vigna radiata and Cicer arietinum further validate the accordant nature of NPs towards vivacity. Allium cepa was also used as a test model to ascertain the genotoxic effects of the NPs wherein the mitotic index (MI) was calculated for AgNPs, CuNPs, and Fe2O3NPs as 42.1, 51.7, and 54.2% respectively. The outcomes of this research proved the suitability and affordability of our NPs developed using green synthesis for new industrial applications of in-situ reduction of carcinogenic compounds from water and soil.