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1.
Boron nitride-based materials for water purification: Progress and outlook.
Ihsanullah, I
Chemosphere. 2021;:127970
Abstract
Analogous to the carbon family, boron nitride (BN)-based materials have gained considerable attention in recent times for applications in various fields. Owing to their extraordinary characteristics, i.e., high surface area, low density, superior thermal stability, mechanical strength, and conductivity, excellent corrosion, and oxidation resistance, the BN nanomaterials have been explored in water remediation. This article critically evaluates the latest development in applications of BN-based materials in water purification with focus on adsorption, synthesis of novel membranes and photocatalytic degradation of pollutants. The adsorption of various noxious pollutants, i.e., dyes, organic compounds, antibiotics, and heavy metals from aqueous medium BN-based materials are described in detail by illustrating the adsorption mechanism and regeneration potential. The major hurdles and opportunities related to the synthesis and water purification applications of BN-based materials are underscored. Finally, a roadmap is suggested for future research to assure the effective applications of BN-based materials in water purification. This review is beneficial in understanding the current status of these unique materials in water purification and accelerating the research focusing their future water remediation applications.
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2.
Heterogeneous Fenton catalysts: A review of recent advances.
Thomas, N, Dionysiou, DD, Pillai, SC
Journal of hazardous materials. 2021;(Pt B):124082
Abstract
Heterogeneous Fenton catalysts are emerging as excellent materials for applications related to water purification. In this review, recent trends in the synthesis and application of heterogeneous Fenton catalysts for the abatement of organic pollutants and disinfection of microorganisms are discussed. It is noted that as the complexity of cell wall increases, the resistance level towards various disinfectants increases and it requires either harsh conditions or longer exposure time for the complete disinfection. In case of viruses, enveloped viruses (e.g. SARS-CoV-2) are found to be more susceptible to disinfectants than the non-enveloped viruses. The introduction of plasmonic materials with the Fenton catalysts broadens the visible light absorption efficiency of the hybrid material, and incorporation of semiconductor material improves the rate of regeneration of Fe(II) from Fe(III). A special emphasis is given to the use of Fenton catalysts for antibacterial applications. Composite materials of magnetite and ferrites remain a champion in this area because of their easy separation and reuse, owing to their magnetic properties. Iron minerals supported on clay materials, perovskites, carbon materials, zeolites and metal-organic frameworks (MOFs) dramatically increase the catalytic degradation rate of contaminants by providing high surface area, good mechanical stability, and improved electron transfer. Moreover, insights to the zero-valent iron and its capacity to remove a wide range of organic pollutants, heavy metals and bacterial contamination are also discussed. Real world applications and the role of natural organic matter are summarised. Parameter optimisation (e.g. light source, dosage of catalyst, concentration of H2O2 etc.), sustainable models for the reusability or recyclability of the catalyst and the theoretical understanding and mechanistic aspects of the photo-Fenton process are also explained. Additionally, this review summarises the opportunities and future directions of research in the heterogeneous Fenton catalysis.
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3.
Cyanobacterial blooms in wastewater treatment facilities: Significance and emerging monitoring strategies.
Romanis, CS, Pearson, LA, Neilan, BA
Journal of microbiological methods. 2021;:106123
Abstract
Municipal wastewater treatment facilities (WWTFs) are prone to the proliferation of cyanobacterial species which thrive in stable, nutrient-rich environments. Dense cyanobacterial blooms frequently disrupt treatment processes and the supply of recycled water due to their production of extracellular polymeric substances, which hinder microfiltration, and toxins, which pose a health risk to end-users. A variety of methods are employed by water utilities for the identification and monitoring of cyanobacteria and their toxins in WWTFs, including microscopy, flow cytometry, ELISA, chemoanalytical methods, and more recently, molecular methods. Here we review the literature on the occurrence and significance of cyanobacterial blooms in WWTFs and discuss the pros and cons of the various strategies for monitoring these potentially hazardous events. Particular focus is directed towards next-generation metagenomic sequencing technologies for the development of site-specific cyanobacterial bloom management strategies. Long-term multi-omic observations will enable the identification of indicator species and the development of site-specific bloom dynamics models for the mitigation and management of cyanobacterial blooms in WWTFs. While emerging metagenomic tools could potentially provide deep insight into the diversity and flux of problematic cyanobacterial species in these systems, they should be considered a complement to, rather than a replacement of, quantitative chemoanalytical approaches.
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4.
Biomedical Applications of Biomolecules Isolated from Methanotrophic Bacteria in Wastewater Treatment Systems.
Salem, R, ElDyasti, A, Audette, GF
Biomolecules. 2021;(8)
Abstract
Wastewater treatment plants and other remediation facilities serve important roles, both in public health, but also as dynamic research platforms for acquiring useful resources and biomolecules for various applications. An example of this is methanotrophic bacteria within anaerobic digestion processes in wastewater treatment plants. These bacteria are an important microbial source of many products including ectoine, polyhydroxyalkanoates, and methanobactins, which are invaluable to the fields of biotechnology and biomedicine. Here we provide an overview of the methanotrophs' unique metabolism and the biochemical pathways involved in biomolecule formation. We also discuss the potential biomedical applications of these biomolecules through creation of beneficial biocompatible products including vaccines, prosthetics, electronic devices, drug carriers, and heart stents. We highlight the links between molecular biology, public health, and environmental science in the advancement of biomedical research and industrial applications using methanotrophic bacteria in wastewater treatment systems.
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5.
Water Treatment: Are Membranes the Panacea?
Landsman, MR, Sujanani, R, Brodfuehrer, SH, Cooper, CM, Darr, AG, Davis, RJ, Kim, K, Kum, S, Nalley, LK, Nomaan, SM, et al
Annual review of chemical and biomolecular engineering. 2020;:559-585
Abstract
Alongside the rising global water demand, continued stress on current water supplies has sparked interest in using nontraditional source waters for energy, agriculture, industry, and domestic needs. Membrane technologies have emerged as one of the most promising approaches to achieve water security, but implementation of membrane processes for increasingly complex waters remains a challenge. The technical feasibility of membrane processes replacing conventional treatment of alternative water supplies (e.g., wastewater, seawater, and produced water) is considered in the context of typical and emerging water quality goals. This review considers the effectiveness of current technologies (both conventional and membrane based), as well as the potential for recent advancements in membrane research to achieve these water quality goals. We envision the future of water treatment to integrate advanced membranes (e.g., mixed-matrix membranes, block copolymers) into smart treatment trains that achieve several goals, including fit-for-purpose water generation, resource recovery, and energy conservation.
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6.
Microbial assisted phytodepuration for water reclamation: Environmental benefits and threats.
Riva, V, Riva, F, Vergani, L, Crotti, E, Borin, S, Mapelli, F
Chemosphere. 2020;:124843
Abstract
Climate changes push for water reuse as a priority to counteract water scarcity and minimize water footprint especially in agriculture, one of the highest water consuming human activities. Phytodepuration is indicated as a promising technology for water reclamation, also in the light of its economic and ecological sustainability, and the use of specific bacterial inocula for microbial assisted phytodepuration has been proposed as a further advance for its implementation. Here we provided an overview on the selection and use of plant growth promoting bacteria in Constructed Wetland (CW) systems, showing their advantages in terms of plant growth support and pollutant degradation abilities. Moreover, CWs are also proposed for the removal of emerging organic pollutants like antibiotics from urban wastewaters. We focused on this issue, still debated in the literature, revealing the necessity to deepen the knowledge on the antibiotic resistance spread into the environment in relation to treated wastewater release and reuse. In addition, given the presence in the plant system of microhabitats (e.g. rhizosphere) that are hot spot for Horizontal Gene Transfer, we highlighted the importance of gene exchange to understand if these events can promote the diffusion of antibiotic resistance genes and antibiotic resistant bacteria, possibly entering in the food production chain when treated wastewater is used for irrigation. Ideally, this new knowledge will lead to improve the design of phytodepuration systems to maximize the quality and safety of the treated effluents in compliance with the 'One Health' concept.
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7.
Successive use of microorganisms to remove chromium from wastewater.
Elahi, A, Arooj, I, Bukhari, DA, Rehman, A
Applied microbiology and biotechnology. 2020;(9):3729-3743
Abstract
Heavy metal pollution is a direct consequence of the extensive utilization of heavy metals in various industrial processes. The persistence and nondegradability of heavy metals cause them to bioaccumulate in nature, and when they come in direct contact with the pristine environment, they not only contaminate it severely but also pose dire consequences to the health of all living forms on earth, including humans. Chromium (Cr) is one of the heavy metals which has been extensively used in various industrial processes such as mining, alloy manufacturing, tanning of hides and skins, pigment production, etc. However, it is regarded as a priority pollutant due to its highly toxic, teratogenic, mutagenic, and carcinogenic nature, and the U.S. Environmental Protection Agency (EPA) also categorized it into group "A" human carcinogen. In contrast to water-soluble hexavalent chromium (Cr6+), its reduced form, trivalent chromium (Cr3+), is relatively benign and readily precipitated at environmental pH. Thus, bioremediation of Cr6+ through microorganisms including bacteria, yeast, and algae provides a promising approach to decontaminate a metal-polluted environment. This review describes an overview of the microbial reduction of Cr6+, resistance mechanism, and the antioxidant profiling exhibited by these microorganisms when exposed to Cr6+. It also describes the pilot-scale study of the successive use of bacterial, fungal, and algal strains and the subsequent use of microbially purified water for the cultivation of plant growth. Multiple metal-resistant microorganisms are a good bioresource for green chemistry to eradicate environmental Cr6+. KEY POINTS • Hexavalent chromium (Cr6+) is highly toxic for living organisms including humans. • Microbial Cr resistance is mediated at the genetic, proteomic, and molecular levels. • Successive use of microorganisms is the best strategy to exterminate Cr6+from the environment.
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8.
Current Trends in the Application of Nanomaterials for the Removal of Emerging Micropollutants and Pathogens from Water.
Kokkinos, P, Mantzavinos, D, Venieri, D
Molecules (Basel, Switzerland). 2020;(9)
Abstract
Water resources contamination has a worldwide impact and is a cause of global concern. The need for provision of clean water is becoming more and more demanding. Nanotechnology may support effective strategies for the treatment, use and reuse of water and the development of next-generation water supply systems. The excellent properties and effectiveness of nanomaterials make them particularly suitable for water/wastewater treatment. This review provides a comprehensive overview of the main categories of nanomaterials used in catalytic processes (carbon nanotubes/graphitic carbon nitride (CNT/g-C3N4) composites/graphene-based composites, metal oxides and composites, metal-organic framework and commercially available nanomaterials). These materials have found application in the removal of different categories of pollutants, including pharmaceutically active compounds, personal care products, organic micropollutants, as well as for the disinfection of bacterial, viral and protozoa microbial targets, in water and wastewater matrices. Apart from reviewing the characteristics and efficacy of the aforementioned nanoengineered materials for the removal of different pollutants, we have also recorded performance limitations issues (e.g., toxicity, operating conditions and reuse) for their practical application in water and wastewater treatment on large scale. Research efforts and continuous production are expected to support the development of eco-friendly, economic and efficient nanomaterials for real life applications in the near future.
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9.
Potential of enzymatic process as an innovative technology to remove anticancer drugs in wastewater.
Pereira, CS, Kelbert, M, Daronch, NA, Michels, C, de Oliveira, D, Soares, HM
Applied microbiology and biotechnology. 2020;(1):23-31
Abstract
Anticancer drugs are a class of pharmaceutical compounds that have been found in hospital, domestic, and industrial wastewaters and also in surface waters. They have been showing recalcitrance to conventional wastewater treatment technologies and present a potential risk to environment and human health, since they exhibit cytotoxic, teratogenic, and carcinogenic among other effects in higher organisms, even at low concentrations. The presence of these compounds in the environment is a recent challenge for wastewater treatment and some alternative strategies to remove them were already studied, such as white-rot fungi (WRF) technologies. Despite promising results, processes involving fungi are complex, have high reaction times, and require nutrient addition for fungus growth and maintenance. Due to this potential, strategies to make the technology feasible were studied, such as the possibility for direct application of enzymes secreted by WRF. Enzymatic processes were studied in the removal of other pharmaceuticals such as antibiotics, anti-inflammatory, and steroid hormones; however, to the best of our knowledge, there is a gap on literature about their direct action on anticancer drugs.
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10.
High-strength wastewater treatment using microbial biofilm reactor: a critical review.
Abdelfattah, A, Hossain, MI, Cheng, L
World journal of microbiology & biotechnology. 2020;(5):75
Abstract
Biofilm reactors retain microbial cells in the form of biofilm which is attached to free moving or fixed carrying materials, thus providing a high active biomass concentration and automatic liquid and solid separation. Nowadays, microbial biofilm reactors have been widely used in high-strength wastewater treatment where very high pollutant removal efficiency is required, which usually requires excessive space and aeration energy for conventional activated sludge-based treatment. This paper provides an overview of microbial biofilm reactors developed over the last half-century, including moving bed biofilm reactor (MBBR), trickling filter (TF) reactor, rotating biological contactor (RBC), membrane biofilm reactor (MBfR), passive aeration simultaneous nitrification and denitrification (PASND) biofilm reactor, for their applications in high-strength wastewater treatment of not only removing carbon, nitrogen, sulphur but also a variety of oxidized contaminants including perchlorate and bromate. Despite the advance of biofilm reactor that exhibits high resistance to excessive pollutants loading, its drawbacks both from engineering and microbiological point of view are reviewed. The future prospects of biofilm reactor are also discussed in this review paper.