Fungal carbonatogenesis process mediates zinc and chromium removal via statistically optimized carbonic anhydrase enzyme.

INTRODUCTION: With rapid elevation in population, urbanization and industrialization, the environment is exposed to uncontrolled discharge of effluents filled with broad-spectrum toxicity, persistence and long-distance transmission anthropogenic compounds, among them heavy metals. That put our ecosystem on the verge or at a stake of drastic ecological deterioration, which eventually adversely influence on public health. Therefore, this study employed marine fungal strain Rhodotorula sp. MZ312369 for Zn2+ and Cr6+ remediation using the promising calcium carbonate (CaCO3) bioprecipitation technique, for the first time. RESULTS: Initially, Plackett-Burman design followed by central composite design were applied to optimize carbonic anhydrase enzyme (CA), which succeeded in enhancing its activity to 154 U/mL with 1.8-fold increase comparing to the basal conditions. The potentiality of our biofactory in remediating Zn2+ (50 ppm) and Cr6+ (400 ppm) was monitored through dynamic study of several parameters including microbial count, CA activity, CaCO3 weight, pH fluctuation, changing the soluble concentrations of Ca2+ along with Zn2+ and Cr6+. The results revealed that 9.23 × 107 ± 2.1 × 106 CFU/mL and 10.88 × 107 ± 2.5 × 106 CFU/mL of cells exhibited their maximum CA activity by 124.84 ± 1.24 and 140 ± 2.5 U/mL at 132 h for Zn2+ and Cr6+, respectively. Simultaneously, with pH increase to 9.5 ± 0.2, a complete removal for both metals was observed at 168 h; Ca2+ removal percentages recorded 78.99% and 85.06% for Zn2+ and Cr6+ remediating experiments, respectively. Further, the identity, elemental composition, functional structure and morphology of bioremediated precipitates were also examined via mineralogical analysis. EDX pattern showed the typical signals of C, O and Ca accompanying with Zn2+ and Cr6+ peaks. SEM micrographs depicted spindle, spherical and cubic shape bioliths with size range of 1.3 ± 0.5-23.7 ± 3.1 µm. Meanwhile, XRD difractigrams unveiled the prevalence of vaterite phase in remediated samples. Besides, FTIR profiles emphasized the presence of vaterite spectral peaks along with metals wavenumbers. CONCLUSION: CA enzyme mediated Zn2+ and Cr6+ immobilization and encapsulation inside potent vaterite trap through microbial biomineralization process, which deemed as surrogate ecofriendly solution to mitigate heavy metals toxicity and restrict their mobility in soil and wastewater.

Role of Carbonyl Compounds for N-Nitrosamine Formation during Nitrosation: Kinetics and Mechanisms.

N-Nitrosamines are potential human carcinogens frequently detected in natural and engineered aquatic systems. This study sheds light on the role of carbonyl compounds in the formation of N-nitrosamines by nitrosation of five secondary amines via different pathways. The results showed that compared to a control system, the presence of formaldehyde enhances the formation of N-nitrosamines by a factor of 5-152 at pH 7, depending on the structure of the secondary amines. Acetaldehyde showed a slight enhancement effect on N-nitrosamine formation, while acetone and benzaldehyde did not promote nitrosation reactions. For neutral and basic conditions, the iminium ion was the dominant intermediate for N-nitrosamine formation, while carbinolamine became the major contributor under acidic conditions. Negative free energy changes (<-19 kcal mol-1) and relatively low activation energies (<18 kcal mol-1) of the reactions of secondary amines with N2O3, iminium ions with nitrite and carbinolamines with N2O3 from quantum chemical computations further support the proposed reaction pathways. This highlights the roles of the iminium ion and carbinolamine in the formation of N-nitrosamines during nitrosation in the presence of carbonyl compounds, especially in the context of industrial wastewater.

Sulfate radicals-based advanced oxidation processes for the degradation of pharmaceuticals and personal care products: A review on relevant activation mechanisms, performance, and perspectives.

Owing to the rapid development of modern industry, a greater number of organic pollutants are discharged into the water matrices. In recent decades, research efforts have focused on developing more effective technologies for the remediation of water containing pharmaceuticals and personal care products (PPCPs). Recently, sulfate radicals-based advanced oxidation processes (SR-AOPs) have been extensively used due to their high oxidizing potential, and effectiveness compared with other AOPs in PPCPs remediation. The present review provides a comprehensive assessment of the different methods such as heat, ultraviolet (UV) light, photo-generated electrons, ultrasound (US), electrochemical, carbon nanomaterials, homogeneous, and heterogeneous catalysts for activating peroxymonosulfate (PMS) and peroxydisulfate (PDS). In addition, possible activation mechanisms from the point of radical and non-radical pathways are discussed. Then, biodegradability enhancement and toxicity reduction are highlighted. Comparison with other AOPs and treatment of PPCPs by the integrated process are evaluated as well. Lastly, conclusions and future perspectives on this research topic are elaborated.

Climate crisis and recent developments in bio-based restoration of ecosystems.

Over the years, due to the climate crisis, sustainable economic growth and biodiversity protection have been increasingly promoted. Scientists, researchers, and experts in the field of sustainable development highlighted that bio-based restoration of ecosystems and responsible management of existing resources are needed to meet the needs of future generations. This paper discusses some of the latest developments in three main areas of sustainability, i.e., energy, water and environment, that emerged from the "16th Sustainable Development of Energy, Water and Environment Systems Conference - SDEWES 2021". The purpose of this introduction article is to briefly review the articles included in this Virtual Special Issue. As such, it acts as an editorial paper for the virtual special issue of the Journal of Environmental Management, dedicated to the SDEWES 2021 conference.

Effective removal of ammonia from aqueous solution through struvite synthesis and breakpoint chlorination: Insights into the synergistic effects of the hybrid system.

The ever-growing contamination of surface water due to various catchment activities poses threats and stress to downstream water treatment entities. Specifically, the presence of ammonia, microbial contaminants, organic matter, and heavy metals has been an issue of paramount concern to water treatment entities since stringent regulatory frameworks require these pollutants to be removed prior to water consumption. Herein, a hybrid approach that integrates struvite crystallization (precipitation) and breakpoint chlorination (stripping) for the removal of ammonia from aqueous solution was evaluated. To fulfil the goals of this study, batch experimental studies were pursued through the adoption of the well-known one-factor-at-a-time (AFAAT) method, specifically the effects of time, concentration/dosage, and mixing speed. The fate of chemical species was underpinned using the state-of-the-art analytical instruments and accredited standard methods. Cryptocrystalline magnesium oxide nanoparticles (MgO-NPs) were used as the magnesium source while the high-test hypochlorite (HTH) was used as the source of chlorine. From the experimental results, the optimum conditions were observed to be, i.e., Stage 1 - struvite synthesis, 110 mg/L of Mg and P dosage (concentration), 150 rpm of mixing speed, 60 min of contact time, and lastly, 120 min of sedimentation while optimum condition for the breakpoint chlorination (Stage 2) were 30 min of mixing and 8:1 Cl2:NH3 weight ratio. Specifically, in Stage 1, i.e., MgO-NPs, the pH increased from 6.7 to ≥9.6, while the turbidity was reduced from 9.1 to ≤1.3 NTU. Mn removal efficacy attained ≥97.70% (reduced from 174 µg/L to 4 µg/L) and Fe attained ≥96.64% (reduced from 11 mg/L to 0.37 mg/L). Elevated pH also led to the deactivation of bacteria. In Stage 2, i.e. breakpoint chlorination, the product water was further polished by eliminating residual ammonia and TPC at 8:1 Cl2-NH3 weight ratio. Interestingly, ammonia was reduced from 6.51 to 2.1 mg/L in Stage 1 (67.74% removal) and then from 2.1 to 0.002 mg/L post breakpoint chlorination (99.96% removal), i.e., stage 2. Overall, synergistic and complementary effects of integrating struvite synthesis and breakpoint chlorination hold great promise for the removal of ammonia from aqueous solutions thus confirming that this technology could potentially be used to curtail the effects of ammonia in the receiving environments and drinking water.

An update on sustainabilities and challenges on the removal of ammonia from aqueous solutions: A state-of-the-art review.

An insightful attempt has been made in this review and the primary objective was to meticulously provide an update on the sustainabilities, advances and challenges pertaining the removal of ammonia from water and wastewater. Specifically, ammonia is a versatile compound that prevails in various spheres of the environment, and if not properly managed, this chemical species could pose severe ecological pressure and toxicity to different receiving environments and its biota. The notorious footprints of ammonia could be traced to anoxic conditions, an infestation of aquatic ecosystems, hyperactivity, convulsion, and methaemoglobin, popularly known as the "blue baby syndrome". In this review, latest updates regarding the sustainabilities, advancements and challenges for the removal of ammonia from aqueous solutions, i.e., river and waste waters, are briefly elucidated in light of future perspectives. Viable routes and ideal hotspots, i.e., wastewater and drinking water, for ammonia removal under the cost-effective options have been unpacked. Key mechanisms for the removal of ammonia were grossly bioremediation, oxidation, adsorption, filtration, precipitation, and ion exchange. Finally, this review denoted biological nutrient removal, struvite precipitation, and breakpoint chlorination as the most effective and promising technologies for the removal of ammonia from aquatic environments, although at the expense of energy and operational cost. Lastly, the future perspective, avenues of exploitation, and technical facets that deserve in-depth exploration are duly underscored.

Multiple Roles of Dissolved Organic Matter in Advanced Oxidation Processes.

Advanced oxidation processes (AOPs) can degrade a wide range of trace organic contaminants (TrOCs) to improve the quality of potable water or discharged wastewater effluents. Their effectiveness is impacted, however, by the dissolved organic matter (DOM) that is ubiquitous in all water sources. During the application of an AOP, DOM can scavenge radicals and/or block light penetration, therefore impacting their effectiveness toward contaminant transformation. The multiple ways in which different types or sources of DOM can impact oxidative water purification processes are critically reviewed. DOM can inhibit the degradation of TrOCs, but it can also enhance the formation and reactivity of useful radicals for contaminants elimination and alter the transformation pathways of contaminants. An in-depth analysis highlights the inhibitory effect of DOM on the degradation efficiency of TrOCs based on DOM's structure and optical properties and its reactivity toward oxidants as well as the synergistic contribution of DOM to the transformation of TrOCs from the analysis of DOM's redox properties and DOM's transient intermediates. AOPs can alter DOM structure properties as well as and influence types, mechanisms, and extent of oxidation byproducts formation. Research needs are proposed to advance practical understanding of how DOM can be exploited to improve oxidative water purification.

Sustainable development in period of climate crisis.

The ongoing process of climate change has shown that sustainable development of humankind is a necessity. Existing resources need to be used in a form of a circular economy, and no more in a linear economy as has been the case until now. Resources need to be better managed to meet the needs of future generations. Therefore, energy, water and environment systems need to be integrated in order to slow down their overexploitation. This paper discusses some of the latest developments in three main areas of sustainability, i.e., energy, water and environment, that emerged from the four "Sustainable Development of Energy, Water and Environment Systems" (SDEWES) Conferences that took place in 2020. The purpose of this review introduction article is to provide a brief introduction to the field and the articles included in this Virtual Special Issue. As such, it acts as an editorial paper for the virtual special issue of the Journal of Environmental Management, dedicated to the SDEWES 2020 conferences.

Where do we stand to oversee the coronaviruses in aqueous and aerosol environment? Characteristics of transmission and possible curb strategies.

By 17 October 2020, the severe acute respiratory syndrome coronavirus (SARS-CoV-2) has caused confirmed infection of more than 39,000,000 people in 217 countries and territories globally and still continues to grow. As environmental professionals, understanding how SARS-CoV-2 can be transmitted via water and air environment is a concern. We have to be ready for focusing our attention to the prompt diagnosis and potential infection control procedures of the virus in integrated water and air system. This paper reviews the state-of-the-art information from available sources of published papers, newsletters and large number of scientific websites aimed to provide a comprehensive profile on the transmission characteristics of the coronaviruses in water, sludge, and air environment, especially the water and wastewater treatment systems. The review also focused on proposing the possible curb strategies to monitor and eventually cut off the coronaviruses under the authors' knowledge and understanding.

Green development challenges within the environmental management framework.

Green development of energy, water and environment systems is essential as these three systems represent the basic life needs of humankind. Therefore, environmental problems arising from each of these three systems need to be carefully addressed to preserve the energy, water and environment resources for future generations. This paper discusses some of the latest developments in three main areas of sustainability themes, namely energy, water and environment, that emerged from the 14th Sustainable Development of Energy, Water and Environment Systems (SDEWES) Conference held in 2019. As such, it acts as an editorial paper for the virtual special issue of the Journal of Environmental Management, dedicated to the SDEWES 2019 conference.

Environmental problems arising from the sustainable development of energy, water and environment system.

Integration of energy, water and environment systems is essential in the multidisciplinary concept of sustainable development, as they represent the basic life needs of mankind. Therefore, problems arising from the sustainable development concept need to be carefully addressed to preserve the energy, water and environment resources for future generations. This article discusses some of the latest developments in three main areas of sustainability themes, namely energy, water and environment, that emerged from three Sustainable Development of Energy, Water and Environment Systems (SDEWES) conferences held in 2018. As such, it acts as an editorial paper for the virtual special issue of the Journal of Environmental Management, dedicated to the SDEWES2018 conferences.

Bioflocculant production using palm oil mill and sago mill effluent as a fermentation feedstock: Characterization and mechanism of flocculation.

This study was conducted to examine the production of bioflocculants using agricultural wastewater as a fermentation feedstock under different temperatures and incubation times. The mechanism of flocculation was studied to gain a detailed understanding of the flocculation activity. The highest bioflocculant yield (2.03 g/L) at a temperature of 40 °C was produced in a palm oil mill effluent medium (BioF-POME). Bioflocculant produced from a fermented SME medium (BioF-SME) showed the highest activity. The flocculation tests for colour and turbidity removal from lake water indicated that BioF-SME and BioF-POME performed comparably to commercial alum. Analyses of the bioflocculants using liquid chromatography-mass spectrometry (LC-MS) found that the bioflocculants contained xylose and glucose. The mechanism study showed that flocculation occurred through charge neutralization and interparticle bridging between the bioflocculant polymer and the particles in the lake water. Thus, agricultural wastewater can be used as a fermentation feedstock for high-quality bioflocculants.

Special Issue: "New Trends in Membrane Preparation and Applications".

This Special Issue aims to provide a collection of recent advancements in the field of membrane science [...].

Heatable carbon nanotube composite membranes for sustainable recovery from biofouling.

Membrane filtration is one of the most reliable methods for water treatment. However, wider application is limited due to biofouling caused by accumulation of microorganisms on the membrane surface. This report details a heatable carbon nanotube composite membrane with self-cleaning properties for sustainable recovery from biofouling. Microfiltration polycarbonate/carbon-nanotubes hybrid membranes were fabricated using drawable nanotubes that maintained the porosity and provided electrical conductivity to the membrane. Less than 25 V potential and 2-3 W power increase membrane temperature to 100°C in ~10 s. This temperature is above what most microbial life, bacteria and viruses can handle. When this membrane was employed, filtered Escherichia coli collected on its surface were successfully annihilated within 1 min. Ohmic heating of this membrane could be an effective solution to combat biofouling and complications associated with membrane-based filtration. This is a novel and highly desirable approach to combat biofouling, due to its simplicity and economic advantage.

Environmental management as a pillar for sustainable development.

There is a growing concern about how to minimize the impact of human activities on the environment. Already nowadays, in some places adaptation efforts are needed in order to avoid the irreversibility of negative human activities. Due to climate changes, and corresponding environmental and social changes, there is a great need for a more sustainable development of mankind. Over the years, research studies that analyzed the sustainable development of different communities with a multi-disciplinary approach, stressed the necessity of preserving the environment for next generations. Therefore, responsible and conscientious management of the environment is a pillar of the sustainable development concept. This review introduction article provides an overview of the recent top scientific publications related to sustainable development that mostly originated from previous SDEWES conferences.

Peracetic acid activated by nickel cobaltite as effective oxidizing agent for BPA and its analogues degradation.

The presented research concerns the use of nickel cobaltite nanoparticles (NiCo2O4 NPs) for the heterogeneous activation of peracetic acid and application of NiCo2O4-PAA system for degradation 10 organic micropollutants from the group of bisphenols. The bisphenols removal (initial concentration 1 µM) process was optimized by selecting the appropriate process conditions. The optimal amount of catalyst (115 mg/L), peracetic acid (PAA) concentration (7 mM) and pH (7) were determined using response surface analysis in the Design of Experiment. Then, NiCo2O4 NPs were used to check the possibility of reuse in subsequent oxidation cycles. The work also attempts to explain the mechanism of oxidation of the studied micropollutants. The participation of the sorption process on the catalyst was excluded and based on the experiments with radical scavengers it can be concluded that the oxidation proceeds in a radical pathway, mainly with participation of O2•- radicals. Experiments conducted in real water matrices exhibit low impact on degradation efficiency. Toxicity tests with green alga Acutodesmus obliquus and aquatic plant Lemna minor showed that post-reaction mixture influenced growth and the content of photosynthetic pigments in concentration dependent manner.

Enhancing photocatalytic wastewater treatment: investigating the promising applications of nickel ferrite and its novel nanocomposites.

Water contamination ranks highest among the challenges posed by the rapidly increasing environmental contamination, which is thought to be the most pressing issue globally. The development of innovative techniques for the successful removal of diverse types of undesirable pollutants from wastewater would therefore yield a huge return on investment. Nowadays, the removal of many organic and synthetic pollutants from the environmental matrix is anticipated to be possible by photocatalytic degradation, owing to its low energy consumption, high catalytic activity, and low overall cost. In this context, magnetic nanoparticles received greater attention as photocatalytic materials from the scientific community in wastewater treatment for the removal of different kinds of pollutants due to their specific properties. The present study provides an overview of the recent advances in water treatment using nickel ferrite nanoparticles and their nanocomposites as photocatalysts. Furthermore, a proposed mechanism for these photocatalysts to generate active free radicals under visible and ultraviolet light has been described. The review concludes that photocatalysts based on NiFe2O4 have potential applications in water purification technologies. However, more research is still needed to determine their practical application in water treatment facilities.

Achieving realistic ozonation conditions with synthetic water matrices comprising low-molecular-weight scavenger compounds.

Ozonation is used worldwide for drinking water disinfection and increasingly also for micropollutant abatement from wastewater. Identification of transformation products formed during the ozonation of micropollutants is challenging due to several factors including (i) the reactions of both oxidants, ozone and hydroxyl radicals with the micropollutants, as well as with intermediate transformation products, (ii) effects of the water matrix on the ozone and hydroxyl radical chemistry and (iii) the generation of oxidation by-products. In this study, a simple approach to achieve realistic ozonation conditions in the absence of dissolved organic matter has been developed. It is based on composing synthetic water matrices with low-molecular-weight scavenger compounds (phenol, methanol, acetate, and carbonate) that mimic the chemical interactions of ozone and hydroxyl radicals with real water matrices. Synthetic waters composed of only four low-molecular-weight compounds successfully replicated two lake waters and two secondary wastewater effluents, matching instantaneous ozone demand, ozone and hydroxyl radical exposures in the initial phase, as well as the ozone evolution in the second phase of the ozonation process. The synthetic water matrices also reproduced the effects of temperature and pH changes observed in real waters. The abatement of two micropollutants, bezafibrate and atrazine, and the formation of the corresponding transformation products during ozonation were in agreement for synthetic and real waters. Furthermore, the kinetics and extent of bromate formation during ozonation in synthetic water were comparable to real lake water and wastewater. This supports the robustness of the proposed approach because bromate formation is very sensitive to the interplay of ozone and hydroxyl radicals. Furthermore, with the novel reaction system, a significant effect of hydroxyl radicals scavenging by carbonate on bromate formation was demonstrated. Overall, the herein-developed approach based on synthetic water matrices allows to perform realistic ozonation studies including both oxidants, ozone and hydroxyl radicals, without the constraints of using dissolved organic matter.

Eco-friendly Strategy for Producing Bio-based Silver Nanoparticles (AgNPs) Employing Sepioteuthis lessoniana ink, in Addition to Biological and Degradation of Dye Applications.

The squid, Sepioteuthis lessoniana, is a remarkable fishery product which is exported by many nations for use in industrial production or human consumption. This study focused on the synthesis of silver nanoparticles (AgNPs) from squid ink (SI) and its wide range of applications. The formation of the nanoparticles was confirmed through UV-Visible spectroscopy, FTIR, XRD, SEM with EDX, DLS, and zeta potential analysis. The results showed a strong absorbance peak at 407 nm, the presence of various functional groups, a nanocrystalline structure with a crystalline size of 17.56 nm, spherical-shaped particles with an average size of 76 nm, and the presence of the highest % mass of Ag and uniformly dispersed particles, respectively. The bioactivity of the synthesized squid ink silver nanoparticles was analyzed through antibacterial, antioxidant, anticancer, and toxicity studies. The dye degradation assay was also analyzed as a means of wastewater treatment for different industrial dyes. The antibacterial activity showed the highest zone of inhibition of 24 mm at a concentration of 100 µg/ml against Escherichia coli, followed by other tested strains. The nitric oxide radical scavenging assay showed the highest antioxidant activity (92%) at a concentration of 100 µg/ml. The cytotoxic ability of SI-AgNPs against the MDA-MB-231 breast cancer cell line revealed an IC50 value of 4.52 µg/ml. The toxicity study revealed a dose and time-dependent activity with the LC50 value of 5.090 and 3.303 mg/ml for 24 and 48 h, respectively. The successful degradation of dyes by SI-AgNPs is attributed to the cooperative action of the electron relay system with Ag as a catalyst and SI as a catalytic support. These findings indicate that SI-AgNPs are a novel potential product that should be further studied to improve its pharmacological, biomedical, and environmental applications.

State-of-the-art progress on tamarind seed polysaccharide (Tamarindus indica) and its diverse potential applications, a review with insight.

Tamarind seed polysaccharide (TSP) is a biocompatible, non-ionic polymer with antioxidant properties. Its uses include drug delivery, food industry, and wastewater treatment. TSP has various hydroxy functional groups, one of the most favorable sites for graft copolymerization of different monomers. Hence, various chemical methods for TSP modification were developed to satisfy increasing industrial demand. Of particular interest in scientific community are the methods of graft copolymerization because of their ability to alter the physicochemical properties of TSP, including pH sensitivity and the swelling index, leading to improvements in the adsorption efficiency of hazardous heavy metals and dyes from wastewater effluents. Moreover, in recent years, TSP has been used for controlled drug delivery applications due to its unique advantages of high viscosity, broad pH tolerance, non-carcinogenicity, mucoadhesive properties, biocompatibility, and high drug entrapment capacity. In light of the plethora of literature on the topic, a comprehensive review of TSP-based graft copolymers and unmodified and modified TSP important applications is necessary. Therefore, this review comprehensively highlights several synthetic strategies for TSP-grafted copolymers and discusses unmodified and modified TSP potential applications, including cutting-edge pharmaceutical, environmental applications, etc. In brief, its many advantages make TSP-based polysaccharide a promising material for applications in various industries.