Waste coconut shell-derived carbon monolith as an efficient binder-free cathode for electrochemical advanced oxidation treatment of endocrine-disrupting compounds.

Discharge of endocrine-disrupting compounds such as methylparaben (MePa) into natural water bodies deteriorates the aquatic ecosystem. In this regard, electrochemical oxidation (EO) and electro-Fenton (EF) processes are acknowledged as effective methods to eliminate biorecalcitrant compounds from different wastewater matrices. In these systems, the H2O2-producing ability of carbon-based cathodes is put to advantage for producing homogenous hydroxyl radicals by simulating Fenton's reaction, which dramatically augments the contaminant removal efficiency. However, commercial carbon based cathodes are not economically affordable, especially for voluminous treatment. Hence in the present work, waste-derived carbonised coconut shell (CCS) monolith was employed as a cathode in EO and EF treatment of MePa. Almost the entire MePa with initial concentration of 10 mg/L was removed in 60 min by EO and 45 min by EF process at neutral pH, applied current density of 7.5 mA/cm2, NaCl concentration of 1.0 g/L and 10 mg/L of Fe2O3 dosing. The MePa removal efficiency of the CCS cathode-fitted system after 60 min was better than the commercial graphite plate and Ti-based mixed metal oxide employing system due to higher H2O2 electrosynthesis (H2O2 = 9.0 ± 0.6 mg/L after 60 min). Moreover, the same setup was used for treating 10 mg/L of MePa-spiked real sewage and demonstrated MePa and total organic carbon removal efficiency of 80.16 ± 2.31% and 37.42 ± 3.50%, respectively, in 45 min. Further, the CCS-mediated EF treatment achieved >90% removal of MePa for eight continuous batch cycles and recorded a current density drop of just 0.23% per cycle. The degradation pathway and toxicity assessment of the intermediates using the Ecological Structure Activity Relationships (ECOSAR) tool supported the eco-friendliness of the current treatment scheme.

Nickel-iron-driven heterogenous bio-electro-fenton process for the degradation of methylparaben.

Discharge of emerging contaminants such as parabens in natural water bodies is a grievous concern. Among parabens, methylparaben (MP) is most prevalent due to its extensive usage in personal care and food products and has been purported to trigger hormonal-related diseases. In this regard, the bio-electro-Fenton (BEF) process garners attention for remediating refractory compounds because of its ability to generate in situ hydroxyl radicals (•OH) utilising the energy harvested from electroactive microorganisms. In the present investigation, a Ni-Fe-driven heterogenous BEF system (BEF-MFC) was used to degrade MP from different matrices. At neutral catholyte pH, 99.54 ± 0.22% of MP was removed from an initial concentration of 10 mg/L in 240 min of retention time with an estimated treatment cost of about 1.01 $/m3. The removal rate ameliorated when the catholyte pH was dropped to 3.0 and by imposing an external voltage of 0.5 V, requiring just 120 min to achieve comparable MP removal efficiencies. However, catalyst leaching was higher at acidic pH (leaching of Fe ions = 0.44 mg/L and Ni ions = 0.06 mg/L) and applying external voltage increased the treatment cost slightly to 1.08 $/m3. Further, treatment of 10 mg/L MP-spiked real wastewater at pH of 7.0 with the BEF-MFC attained 85.70 ± 3.30% and 56.50 ± 1.70% reduction in MP and total organic carbon, respectively, in 240 min. In addition, a maximum power density of 205.90 ± 2.27 mW/cm2 was harvested in the BEF-MFC; thus, portraying the dual benefit of Ni-Fe heterogeneous catalyst. Even though, Ni-Fe performed reasonably well as Fenton-cum-cathode catalyst, future endeavours should be poised to fine-tune catalysts to accelerate H2O2 and •OH generation, which will reinforce the scalability of this system.

Graphene and biochar-based cathode catalysts for microbial fuel cell: Performance evaluation, economic comparison, environmental and future perspectives.

Microbial fuel cells (MFCs) have been the prime focus of research in recent years because of their distinctive feature of concomitantly treating and producing electricity from wastewater. Nevertheless, the electrical performance of MFCs is hindered by a protracted oxygen reduction reaction (ORR), and often a catalyst is required to boost the cathodic reactions. Conventional transition metals-based catalysts are expensive and infeasible for field-scale usage. In this regard, carbon-based electrocatalysts like waste-derived biochar and graphene are used to enhance the commercialisation prospects of MFC technology. These carbon-catalysts possess unique properties like superior electrocatalytic activity, higher surface area, and high porosity conducive to ORR. Theoretically, graphene-based cathode catalysts yield superior results than a biochar-derived catalyst, though at a higher cost. In contrast, the synthesis of waste-extracted biochar is economical; however, its ability to catalyse ORR is debatable. Therefore, this review aims to make a side-by-side techno-economic assessment of biochar and graphene-based cathode catalyst used in MFC to predict the relative performance and typical cost of power recovery. Additionally, the life cycle analysis of the graphene and biochar-based materials has been briefly discussed to comprehend the associated environmental impacts and overall sustainability of these carbo-catalysts.

Appraising efficacy of existing and advanced technologies for the remediation of beta-blockers from wastewater: A review.

The discharge of emerging pollutants, such as beta-blockers (BB), has been recognized as one of the major threats to the environment due to the ecotoxicity associated with these emerging pollutants. The BB are prescribed to treat high blood pressure and cardiovascular diseases; however, even at lower concentration, these pollutants can pose eco-toxic impacts towards aquatic organisms. Additionally, owing to their recalcitrant nature, BB are not effectively removed through conventional technologies, such as activated sludge process, trickling filter and moving bed bioreactor; thus, it is essential to understand the degradation mechanism of BB in established as well as embryonic technologies, like adsorption, electro-oxidation, Fenton process, ultraviolet-based advance oxidation process, ozonation, membrane systems, wetlands and algal treatment. In this regard, this review articulates the recalcitrant nature of BB and their associated removal technologies. Moreover, the major advantages and limitations of these BB removal technologies along with the recent advancements with regard to the application of innovative materials and strategies have also been elucidated. Therefore, the present review intends to aid the researchers in improving the BB removal efficiency of these technologies, thus alleviating the problem of the release of BB into the environment.

Evaluating application of photosynthetic microbial fuel cell to exhibit efficient carbon sequestration with concomitant value-added product recovery from wastewater: A review.

The emission of CO2 from industrial (24%) and different anthropogenic activities, like transportation (27%), electricity production (25%), and agriculture (11%), can lead to global warming, which in the long term can trigger substantial climate changes. In this regard, CO2 sequestration and wastewater treatment in tandem with bioenergy production through photosynthetic microbial fuel cell (PMFC) is an economical and sustainable intervention to address the problem of global warming and elevating energy demands. Therefore, this review focuses on the application of different PMFC as a bio-refinery approach to produce biofuels and power generation accompanied with the holistic treatment of wastewater. Moreover, CO2 bio-fixation and electron transfer mechanism of different photosynthetic microbiota, and factors affecting the performance of PMFC with technical feasibility and drawbacks are also elucidated in this review. Also, low-cost approaches such as utilization of bio-membrane like coconut shell, microbial growth enhancement by extracellular cell signalling mechanisms, and exploitation of genetically engineered strain towards the commercialization of PMFC are highlighted. Thus, the present review intends to guide the budding researchers in developing more cost-effective and sustainable PMFCs, which could lead towards the commercialization of this inventive technology.

Maximal Dependence Capturing as a Principle of Sensory Processing.

Sensory inputs conveying information about the environment are often noisy and incomplete, yet the brain can achieve remarkable consistency in recognizing objects. Presumably, transforming the varying input patterns into invariant object representations is pivotal for this cognitive robustness. In the classic hierarchical representation framework, early stages of sensory processing utilize independent components of environmental stimuli to ensure efficient information transmission. Representations in subsequent stages are based on increasingly complex receptive fields along a hierarchical network. This framework accurately captures the input structures; however, it is challenging to achieve invariance in representing different appearances of objects. Here we assess theoretical and experimental inconsistencies of the current framework. In its place, we propose that individual neurons encode objects by following the principle of maximal dependence capturing (MDC), which compels each neuron to capture the structural components that contain maximal information about specific objects. We implement the proposition in a computational framework incorporating dimension expansion and sparse coding, which achieves consistent representations of object identities under occlusion, corruption, or high noise conditions. The framework neither requires learning the corrupted forms nor comprises deep network layers. Moreover, it explains various receptive field properties of neurons. Thus, MDC provides a unifying principle for sensory processing.

A filamentous trio.

Opportunistic infections caused by fungi and unusual bacteria are predominantly encountered in the setting of immunosuppressed host. Co-infections with multiple such organisms can pose multiple challenges even to the astute clinician from establishing the diagnosis to drug interactions during treatment of such infections. We hereby present one such case of a triple opportunistic infection in an immunocompetent host and the difficulties faced in the therapeutic decision making.

A 51-Year-Old Woman With Pellets in the Sputum.

CASE PRESENTATION: A 51-year-old woman with no comorbidities presented with a 3-month history of cough with mucopurulent expectoration and intermittent fever. Over the past 1 month, she complained of streaky hemoptysis and gave history of expectorating "whitish pellets" in the sputum on two occasions. She had developed progressive breathlessness for a week prior to presentation to our hospital. There was no history of chest pain or loss of weight or appetite. She was a nonsmoker and did not consume alcohol. She had received multiple courses of antibiotics at another center with no relief of symptoms.