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Anaerobic digestion (AD) under psychrophilic temperature has only recently garnered deserved attention. In major parts of Europe, USA, Canada and Australia, climatic conditions are more suited for psychrophilic (20 ℃) rather than mesophilic (35 - 37 ℃) and thermophilic (55 - 60 ℃) AD. Low temperature has adverse effects on important cellular processes which may render the cell biology inactive. Moreover, cold climate can also alter the physical and chemical properties of wastewater, thereby reducing the availability of substrate to microbes. Hence, the use of low temperature acclimated microbial biomass could overcome thermodynamic constraints and carry out flexible structural and conformational changes to proteins, membrane lipid composition, expression of cold-adapted enzymes through genotypic and phenotypic variations. Reduction in organic loading rate is beneficial to methane production under low temperatures. Moreover, modification in the design of existing reactors and the use of hybrid reactors have already demonstrated improved methane generation in the lab-scale. This review also discusses some novel strategies such as direct interspecies electron transfer (DIET), co-digestion of substrate, bioaugmentation, and bioelectrochemical system assisted AD which present promising prospects. While DIET can facilitate syntrophic electron exchange in diverse microbes, the addition of organic-rich co-substrate can help in maintaining suitable C/N ratio in the anaerobic digester which subsequently can enhance methane generation. Bioaugmentation with psychrophilic strains could reduce start-up time and ensure daily stable performance for wastewater treatment facilities at low temperatures. In addition to the technical discussion, the economic assessment and future outlook on psychrophilic AD are also highlighted.

The present work reports the frequency dependent dielectric, ac-conductivity study across spin reorientation transition (TSRT) & Raman spectroscopy study across TSRT, Neel temperature (TN,Fe) of polycrystalline SmFeO3 (SFO). Anomalous variation is observed in phonon mode parameters for SFO across TSRT and TN,Fe indicating the presence of spin-phonon coupling similar to that of other RFeO3 compounds. Anomalous behavior is also observed in the temperature variation of dielectric constant and ac-conductivity across TSRT and frequency dispersion is observed at lower temperature side of TSRT.

In this research a new process of harvesting the oleaginous yeast biomass (Yarrowia lipolytica) by flocculation followed by cell wall disruption and lipid extraction with petroleum diesel as a solvent was developed. Alum and calcium chloride along with the extracellular polymeric substance (EPS) as a flocculant were evaluated for lipid bearing biomass settling. The maximum flocculation activity of biomass using calcium chloride (36 mM) in combination with EPS (5.85 mg EPS/g biomass) or Alum (1.2 mM) with EPS (18 mg EPS/g biomass) was 74.3 and 79% and the settling velocity was 2.93 and 1.46 mm/s, respectively. To have a similar efficiency of biomass settling, 3.07 times less dosage of EPS was required in combination with calcium chloride than required with Alum. Further, settled biomass (166 g/L) was treated with N-lauroyl sarcosine (N-LS) to disrupt the cellular structure and release lipid. The released lipid was separated from cell debris and water using petroleum diesel (co-solvent) and maximum lipid recovery efficiency of 94.7 ± 1.2 % (w/w) was observed.

The effect of dissolved oxygen concentration on lipid accumulation in Trichosporon oleaginosus has been investigated. The experiment was performed in 15 L fermenters. The dissolved oxygen concentration varied by adjusting the agitation and aeration. High dissolved oxygen level at 50%–60% enhanced cell growth. Maintaining low dissolved oxygen concentration at 20%–30% during lipogenesis phase led to high final lipid content (51%) in Trichosporon oleaginosus. The consumptions of energy and cost of the process were evaluated. The energy consumption in the dissolved oxygen level optimized process was 41% less than that with dissolved oxygen level at 50%–60%. In addition, the cost was also reduced around one time in the dissolved oxygen level optimized process compared to the one with dissolved oxygen level at 50%–60%. The study provided a feasible way of enhancing lipid accumulation in Trichosporon oleaginosus and reducing the consumption of energy and cost of lipid production from Trichosporon oleaginosus.

The subject of emerging contaminants has attracted wide attention from researchers and society world over due to their emerging as well as potential adverse impacts on the environment. Many attempts have been made to shed light on the importance of the release of these contaminants into various environments and further urge policymakers to take required measures. Nevertheless, the effective long-term strategy for addressing this issue is latent in the modification of current technologies of wastewater/water treatment plants and integrating them into a holistic and circular water management system. The research on the new technologies of water treatment must be realigned to consider the real conditions and meet certain requirements set according to technical and environmental perspectives.

Fluoroquinolones (FQs), the group of broad spectrum antimicrobials, are frequently detected in different environmental compartments, mostly due to incomplete metabolism in the target organism, inefficient wastewater treatment, and disposal of expired FQs directly into the environment. Another group of the contaminants, widely present in water, air, and soils, are the metal ions (Me). In general, FQs can form stable complexes with metal ions and their co-existence with Me in the environment leads to metal complexation. The most stable complexes are formed between FQs and trivalent ions, whereas FQs and alkali-earth metal ions, i.e. Ca2+ and Mg2+, are the least stable composites. This interaction between FQs and metal ions may alter antibiotic properties. Antibacterial activity of metal complexes is generally comparable with the parent compound; however, some FQs-metal complexes are found to exhibit higher antibacterial activity. Moreover, it was proved that FQs-Me complex can display antifungal potency toward Candida albicans. The mobility of FQs in soil and/or water strongly depends on pH, temperature, and type of metal ions, present in the environment. This review provides a brief description of FQs, their properties, and capacity to form complexes with metal ions. It summarizes influence of FQs-Me complexes on microorganisms and their mobility in different media. Further, the review provides a linkage between the presence of these metal ions in the environment and their effect on the chemistry and biology of fluoroquinolone antibiotics.

Immobilization of enzymes on the solid supports can improve the stability as well as catalytic properties of enzymes. In this study, biochar derived from various feedstocks were used as immobilization support considering biochars carbon negative as well as sustainable properties. Partially purified (concentrated) crude laccase was covalently immobilized onto pine wood (BC-PW), pig manure (BC-PM) and almond shell (BC-AS) micro-biochars using optimized 5% w/v glutaraldehyde. Moreover, citric acid pretreatment improved the laccase binding capacity of all the micro-biochars and the highest laccase binding of 40.2 ± 1.8 U g−1 was observed with BC-PM in comparison with raw BC-PM (34.1 ± 1.1 U g−1). The enhanced binding of laccase on BC-PM over wood derived biochars was attributed to the higher surface area (46.1 m2 g−1) of BC-PM. Moreover, feedstock selection as well as a method of production influenced the biochar physicochemical properties such as surface area and consequently, different biochars showed various laccase immobilization efficiencies. BC-PW showed better pH, thermal, storage, and operational stability, compared with BC-AS and BC-PM. While applying the laccase bound micro-biochar, complete removal was observed in 2 h under batch mode with 0.5 g of laccase bound BC-PM at an environmentally relevant concentration of 500 µg L−1 in wastewater effluent. About 40% of the laccase activity was retained with all the laccase-bound micro-biochars after 5 cycles of diclofenac treatment.

A field study was carried out to investigate the sediment in-situ bioremediation by adding microbial activated beads. In this work, Calcium carbonate, silicon dioxide, activated carbon powder, attapulgite powder, sodium alginate, microbial liquid and polyvinyl alcohol were utilized to make the immobilized microbial activated beads. Field experiment results showed that the removal rate of NH4+-N, TN and COD in overlying water reached about 61.8%, 87.5% and 87.1%, respectively. The initial concentration of NH4+-N, TN and COD was 159 mg/L, 6.24 mg/L and 7.28 mg/L, whereas and the final concentration was 58 mg/L, 0.78 mg/L and 0.94 mg/L when water temperature, DO, pH and C/N ratio were 25–30 °C, 2–3 mg/L, 7.0–8.0 and 10–15, respectively. Moreover, under optimal temperature condition (25–30 °C), the removal rate of TOC, TN, heterotrophic bacteria and sulfur bacteria in the river sediment reached to 46.5%, 50.7%, 39.2% and 73.2%, respectively.

Chlortetracycline (CTC) is widely used as a veterinary antibiotic and is considered as a recalcitrant pollutant. In this study, spiked CTC (2 mg L−1) in wastewater was degraded using laccase from the white rot fungi, Trametes Versicolor combined with ultrasonication (UlS). Over 60% of CTC was removed in 2 h by UlS assisted laccase (UAL) treatment where laccase treatment alone took 2 days to degrade 87% of CTC under similar CTC concentration (2 mg L−1), laccase dose (0.5 IU) and pH 6.0 conditions. UAL treatment showed 5.3 folds higher CTC degradation rate compared to laccase alone treatment at pH 6.0. Further, pH optimization of UAL treatment was done and pH 4.5 was found to be optimum wherein 80% of CTC degradation was obtained which is 2.6 folds higher compared to degradation at pH 6.0. The UAL treatment with optimized pH was not only increased CTC degradation efficiency (∼80%) but also reduced the degradation time to 2 h. The obtained results highlighted the enhanced degradation rate, efficiency and unaltered stability of laccase during UAL treatment which can be used for oxidizing other tetracycline groups of antibiotics. Moreover, laccase and UAL treatments showed similar degradation products and no estrogenic activity.

Nanotechnology-inspired biocatalytic systems attracted attention for many applications since nanosized supports for enzyme immobilization can improve efficiency-determining factors e.g. enhancing the surface area and loading capacity and reducing the mass transfer resistance. Among the nanomaterials, nanobiochar has unique features as a support for enzyme immobilization i.e. high surface to volume ratio, porous structure, and presence of functional groups on its surface. However, the performance of the immobilization is highly dependent on the immobilization conditions and the properties of the enzyme and the support material. In this research, crude laccase was covalently immobilized onto functionalized nanobiochar using a two-step method of diimide-activated amidation. The effect of different parameters was investigated. The optimal conditions were found to be 14 mg/mL of laccase concentration, 5 mg/mL of nanobiochar, 8.2 mM of cross-linker and 3 h of contact time. For investigating the pH, thermal, storage, and operational stability, the sample obtained from the optimized conditions was used. The results showed the higher stability of immobilized laccase against temperature and pH variation compared to free laccase. In addition, immobilized laccase maintained its catalytic performance up to seven cycles of utilization and showed more than 50% of initial activity after two months of room temperature storage.

In recent years, biodiesel production has grabbed significant attention due to the awareness of fossil fuel exhaustion. Microalgae become interested feedstock candidate of biodiesel production as they have rapid growth rate and high oil content compared to crops. Efforts have been made to increase microalgae productivity and oil content. To investigate the potential of microalgae for biodiesel production, it is essential to knowledge if the microalgae oil is qualified as possible feedstock oil. Moreover, what would be the energy and environmental effect of the production? And whether the production cost would be reasonable? This paper compared the properties of microalgae oil with traditional biodiesel production oils (vegetable oils); the properties of the biodiesel produced from microalgae and vegetable oils; reviewed the net energy ratio (energy output to energy input), GHG emissions, and economic analysis of the process of biodiesel production from microalgae; as well as discussed the factors which would influent the energy, environment, and cost of the process.

The co-contamination of ciprofloxacin (CIP) with metal ions results in alteration of CIP mobility, antimicrobial activity and distribution/development of the antibiotic-resistance genes. In this study, the stability of five CIP-Me complexes [Me = Al(III), Co(II), Cu(II), Fe(III), Mg] was investigated in the presence of humic substances (HS) at two temperatures 18 ± 2 °C and 4 ± 1 °C for seven days period. The most stable complexes were CIP-Al, CIP-Cu, and CIP-Co with the stability constants (K) at 18 °C 35.5 ± 1.4 11.5 ± 1.5 and 11.7 ± 1.5 respectively. At lower temperature (4 °C), the stability constants decreased: 1-fold for CIP-Al, 14-fold for CIP-Co and 2-fold for CIP-Cu. The presence of humic substances decreased the stability of complexes. The chemical reactions of Fe3+ in water at circumneutral pH resulted in stability alteration. The formation of CIP-Mg complexes at lower temperatures and in the presence of HS was limited. In ultrapure water, CIP-Me complexes exhibit higher toxicity towards Gram-negative Enterobacter aeruginosa (ranged between 0.125 and 0.5 μg/ml). However, the presence of HS reduced the antimicrobial activity of CIP-Me complexes by at least 2-fold. Gram-positive representative, Bacillus subtilis was not affected by the presence of metal ions and/or HS. The toxicity toward B. subtilis for the complexes was equal to toxicity of CIP alone (MIC = 0.25 μg/ml). This suggested the different susceptibility to CIP and its complexes.

Carbamazepine (CBZ) is one of the most detected pharmaceutical compounds around the world, with adverse human and animal health impacts in wastewater effluents. Recently, biocatalytic degradation using ligninolytic enzymes such as laccase along with redox mediators provides a promising approach for their removal from water and wastewater. However, the effects of operational parameters on biotransformation need to be investigated in order to design a robust and efficient process. In this research, central composite design was performed and analyzed using response surface methodology to study the effects of temperature, pH, enzyme concentration and mediator concentration. The adequacy of the developed model was confirmed by the coefficient of multiple regression (R2 = 75.97%) indicating a reasonable model for practical implementation. The results showed that performing the biotransformation at 35 °C, pH 6, with 60 U/L of enzyme concentration and 18 μM of mediator concentration resulted in 95% removal of CBZ. 10,11-Dihydro-10,11-dihydroxy-CBZ and 10,11-dihydro-10,11-epoxy-CBZ were identified as the major metabolites of CBZ oxidation by laccase. The estrogenicity tests indicated that the CBZ with an initial concentration of 4 μM and its biotransformation products had no estrogenic effect. The successful transformation of CBZ demonstrated the potential of the laccase-mediator system for the removal of recalcitrant micro-contaminants.

Due to its wide occurrence in water resources and toxicity, pharmaceuticals and personal care products are becoming an emerging concern throughout the world. Application of residual/waste materials for water remediation can be a good strategy in waste management as well as in waste valorization. Herein, this dataset provides information on biochar application for the removal of emerging contaminant, diclofenac from water matrices. The data presented here is an extension of the research article explaining the mechanisms of adsorption diclofenac on biochars (Lonappan et al., 2017 [1]). This data article provides general information on the surface features of pine wood and pig manure biochar with the help of SEM and FTIR data. This dataset also provides information on XRD profiles of pine wood and pig manure biochars. In addition, different amounts of biochars were used to study the removal of a fixed concentration of diclofenac and the data is provided with this data set. Keywords: Adsorption, Diclofenac, Biochar, Characterization

Water contains environmental isotopes, which can act as tracers to study the source, origin, and distribution of water in the hydrological cycle. Recently, the environmental isotopes have been widely applied in hydrological investigations and it is established that the spatio-temporal variations in isotopic abundance provide valuable information to enhance the qualitative and quantitative understanding of hydrological processes such as mixing of different flow components and recharge rate, identify origin of water, delineation of groundwater recharge zones, geothermal dynamics, paleo-recharge and many others. Here, a review of case studies is presented to highlight the impact of isotope applications in water resource management in India. Along with a review of studies across India, a study is carried out for the assessment of groundwater interactions using isotopes of water (18O, 2H and 3H) in dry/semi-arid region (Jaipur) and wet/humid region (Guwahati). The major outcome of the study is the formulation of groundwater baseline for Guwahati (post-monsoon in 2017 and 2018: δ D= 4.98 δ 18O + 7.50) and Jaipur (post-monsoon and pre-monsoon in 2018: δ D= 4.85 δ 18O – 9.49). The results indicate that tritium has strong negative correlation (R2 = 0.59) with depth in Jaipur, indicating increasing groundwater age with depth. In Guwahati, the tritium shows weak positive (R2= 0.25) relationship which might be because of the presence of sandyclay layers in the shallow zone limiting vertical recharge to aquifer. Moreover, based upon the review and isotope results of the two study sites, a novel integrated framework for isotope hydrology application for India is proposed, incorporating the principles of environmental sustainability, economic efficiency and social equity. The isotopic techniques in hydrological investigations not only complements the traditional methods used in water resource management but also provides new insights and an enhanced understanding of the hydrological systems.