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1.
Research progress and application prospect of anaerobic biological phosphorus removal.
Yang, F, Zhang, C, Rong, H, Cao, Y
Applied microbiology and biotechnology. 2019;(5):2133-2139
Abstract
Anaerobic biological phosphorus removal has proposed a new direction for the removal of phosphorus from wastewater, and the discovery of phosphate reduction makes people have a more comprehensive understanding of microbial phosphorus cycling. Here, from the perspective of thermodynamics, the bioreduction reaction of phosphate was analyzed and its mechanism was discussed. The research progress of phosphate reduction and the application prospects of anaerobic biological phosphorus removal from wastewater were introduced, pointing out the situation and guiding the further research in this field.
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2.
Biological nitrogen removal from wastewater using sulphur-driven autotrophic denitrification.
Cui, YX, Biswal, BK, Guo, G, Deng, YF, Huang, H, Chen, GH, Wu, D
Applied microbiology and biotechnology. 2019;(15):6023-6039
Abstract
Biological denitrification process in mainstream wastewater treatment often needs dosing supplemental electrons, consequently adding a remarkable operating cost. Organic carbon compounds are nowadays the most intensively used electron sources in full-scale wastewater treatment, corresponding with the well-understood carbon-nitrogen biogeochemistry for heterotrophic denitrification process. In the twenty-first century, the low-carbon technology is on calling to reduce the carbon footprint and relieve climate changing threatens. Autotrophic denitrification is highly recommended for mainstream wastewater treatment. The reduced-sulphur compounds (such as sulphide, elemental sulphur, and thiosulphate) could be utilised as electron donors, to drive sulphur cycle reactions to reduce nitrate and nitrite to dinitrogen gas. Based on the literature review and our own research experiences, this paper presents our perspectives on sulphur-driven autotrophic denitrification. It particularly focuses on the functional enzymes, sulphur bioreactors, and influential operating factors. Overall, this paper provides new insights on sulphur-nitrogen biogeochemistry and application as a low-carbon technology for nitrogen removal during municipal wastewater treatment.
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3.
Dye Removal from Water and Wastewater Using Various Physical, Chemical, and Biological Processes.
Piaskowski, K, Świderska-Dąbrowska, R, Zarzycki, PK
Journal of AOAC International. 2018;(5):1371-1384
Abstract
Synthetic dyes or colorants are key chemicals for various industries producing textiles, food, cosmetics, pharmaceutics, printer inks, leather, and plastics. Nowadays, the textile industry is the major consumer of dyes. The mass of synthetic colorants used by this industry is estimated at the level of 1 ÷ 3 × 105 tons, in comparison with the total annual consumption of around 7 × 105 tons worldwide. Synthetic dyes are relatively easy to detect but difficult to eliminate from wastewater and surface water ecosystems because of their aromatic chemical structure. It should be highlighted that the relatively high stability of synthetic dyes leads to health and ecological concerns due to their toxic, mutagenic, and carcinogenic nature. Currently, removal of such chemicals from wastewater involves various techniques, including flocculation/coagulation, precipitation, photocatalytic degradation, biological oxidation, ion exchange, adsorption, and membrane filtration. In this review, a number of classical and modern technologies for synthetic dye removal from industry-originated wastewater were summarized and discussed. There is an increasing interest in the application of waste organic materials (e.g., compounds extracted from orange bagasse, fungus biosorbent, or green algal biomasses) as effective, low-cost, and ecologically friendly sorbents. Moreover, a number of dye removal processes are based on newly discovered carbon nanomaterials (carbon nanotubes and graphene as well as their derivatives).
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4.
The Potential of Cold Plasma for Safe and Sustainable Food Production.
Bourke, P, Ziuzina, D, Boehm, D, Cullen, PJ, Keener, K
Trends in biotechnology. 2018;(6):615-626
Abstract
Cold plasma science and technology is increasingly investigated for translation to a plethora of issues in the agriculture and food sectors. The diversity of the mechanisms of action of cold plasma, and the flexibility as a standalone technology or one that can integrate with other technologies, provide a rich resource for driving innovative solutions. The emerging understanding of the longer-term role of cold plasma reactive species and follow-on effects across a range of systems will suggest how cold plasma may be optimally applied to biological systems in the agricultural and food sectors. Here we present the current status, emerging issues, regulatory context, and opportunities of cold plasma with respect to the broad stages of primary and secondary food production.
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5.
Magnetic water treatment-A review of the latest approaches.
Chibowski, E, Szcześ, A
Chemosphere. 2018;:54-67
Abstract
Understanding of magnetic field (MF) effects observed during and after its action on water and aqueous solutions is still a controversial issue although the effects have been reported for at least half of century. The purpose of this paper was a brief review of the literature which deals with the magnetic force treatment effects. However, it is especially focused on the latest approaches, published mostly in the last decade which have developed our understanding of the mechanisms accompanying the field action. Generally, the changes in water structure via hydrogen bonding changes, as well as in intraclusters and between interclusters were taken into account, but the most remarkable progress was achieved in 2012 by Coey who applied the non-classical theory of nucleation mechanism of the formation of dynamically ordered liquid like oxyanion polymers (DOLLOP) to explain the magnetic field action. His criterion for the magnetic field effect to occur was experimentally verified. It was also proved that the gradient of the magnetic field is more important than the magnetic field strength itself. Some interesting approaches explaining an enhanced evaporation rate of water by MF are also discussed. More experimental results are needed for further verification of the DOLLOP theory to achieve a more profound understanding of the MF effects.
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6.
Carbon, nitrogen and phosphorus removal mechanisms of aerobic granules.
Sarma, SJ, Tay, JH
Critical reviews in biotechnology. 2018;(7):1077-1088
Abstract
Aerobic granules are the potential tools to develop modern wastewater treatment technologies with improved nutrient removal efficiency. These granules have several promising advantages over conventional activated sludge-based wastewater treatment processes. This technology has the potential of reducing the infrastructure and operation costs of wastewater treatment by 25%, energy requirement by 30%, and space requirement by 75%. The nutrient removal mechanisms of aerobic granules are slightly different from that of the activated sludge. For instance, unlike activated sludge process, according to some reports, as high as 70% of the total phosphorus removed by aerobic granules were attributed to precipitation within the granules. Similarly, aerobic granule-based technology reduces the total amount of sludge produced during wastewater treatment. However, the reason behind this observation is unknown and it needs further explanations based on carbon and nitrogen removal mechanisms. Thus, as a part of the present review, a set of new hypotheses have been proposed to explain the peculiar nutrient removal mechanisms of the aerobic granules.
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7.
A review on experimental design for pollutants removal in water treatment with the aid of artificial intelligence.
Fan, M, Hu, J, Cao, R, Ruan, W, Wei, X
Chemosphere. 2018;:330-343
Abstract
Water pollution occurs mainly due to inorganic and organic pollutants, such as nutrients, heavy metals and persistent organic pollutants. For the modeling and optimization of pollutants removal, artificial intelligence (AI) has been used as a major tool in the experimental design that can generate the optimal operational variables, since AI has recently gained a tremendous advance. The present review describes the fundamentals, advantages and limitations of AI tools. Artificial neural networks (ANNs) are the AI tools frequently adopted to predict the pollutants removal processes because of their capabilities of self-learning and self-adapting, while genetic algorithm (GA) and particle swarm optimization (PSO) are also useful AI methodologies in efficient search for the global optima. This article summarizes the modeling and optimization of pollutants removal processes in water treatment by using multilayer perception, fuzzy neural, radial basis function and self-organizing map networks. Furthermore, the results conclude that the hybrid models of ANNs with GA and PSO can be successfully applied in water treatment with satisfactory accuracies. Finally, the limitations of current AI tools and their new developments are also highlighted for prospective applications in the environmental protection.
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8.
The role of operating parameters and oxidative damage mechanisms of advanced chemical oxidation processes in the combat against antibiotic-resistant bacteria and resistance genes present in urban wastewater.
Michael-Kordatou, I, Karaolia, P, Fatta-Kassinos, D
Water research. 2018;:208-230
Abstract
An upsurge in the study of antibiotic resistance in the environment has been observed in the last decade. Nowadays, it is becoming increasingly clear that urban wastewater is a key source of antibiotic resistance determinants, i.e. antibiotic-resistant bacteria and antibiotic resistance genes (ARB&ARGs). Urban wastewater reuse has arisen as an important component of water resources management in the European Union and worldwide to address prolonged water scarcity issues. Especially, biological wastewater treatment processes (i.e. conventional activated sludge), which are widely applied in urban wastewater treatment plants, have been shown to provide an ideal environment for the evolution and spread of antibiotic resistance. The ability of advanced chemical oxidation processes (AOPs), e.g. light-driven oxidation in the presence of H2O2, ozonation, homogeneous and heterogeneous photocatalysis, to inactivate ARB and remove ARGs in wastewater effluents has not been yet evaluated through a systematic and integrated approach. Consequently, this review seeks to provide an extensive and critical appraisal on the assessment of the efficiency of these processes in inactivating ARB and removing ARGs in wastewater effluents, based on recent available scientific literature. It tries to elucidate how the key operating conditions may affect the process efficiency, while pinpointing potential areas for further research and major knowledge gaps which need to be addressed. Also, this review aims at shedding light on the main oxidative damage pathways involved in the inactivation of ARB and removal of ARGs by these processes. In general, the lack and/or heterogeneity of the available scientific data, as well as the different methodological approaches applied in the various studies, make difficult the accurate evaluation of the efficiency of the processes applied. Besides the operating conditions, the variable behavior observed by the various examined genetic constituents of the microbial community, may be directed by the process distinct oxidative damage mechanisms in place during the application of each treatment technology. For example, it was shown in various studies that the majority of cellular damage by advanced chemical oxidation may be on cell wall and membrane structures of the targeted bacteria, leaving the internal components of the cells relatively intact/able to repair damage. As a result, further in-depth mechanistic studies are required, to establish the optimum operating conditions under which oxidative mechanisms target internal cell components such as genetic material and ribosomal structures more intensively, thus conferring permanent damage and/or death and preventing potential post-treatment re-growth.
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9.
Opportunities for groundwater microbial electro-remediation.
Pous, N, Balaguer, MD, Colprim, J, Puig, S
Microbial biotechnology. 2018;(1):119-135
Abstract
Groundwater pollution is a serious worldwide concern. Aromatic compounds, chlorinated hydrocarbons, metals and nutrients among others can be widely found in different aquifers all over the world. However, there is a lack of sustainable technologies able to treat these kinds of compounds. Microbial electro-remediation, by the means of microbial electrochemical technologies (MET), can become a promising alternative in the near future. MET can be applied for groundwater treatment in situ or ex situ, as well as for monitoring the chemical state or the microbiological activity. This document reviews the current knowledge achieved on microbial electro-remediation of groundwater and its applications.
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10.
Analogies and differences among bacterial and viral disinfection by the photo-Fenton process at neutral pH: a mini review.
Giannakis, S
Environmental science and pollution research international. 2018;(28):27676-27692
Abstract
Over the last years, the photo-Fenton process has been established as an effective, green alternative to chemical disinfection of waters and wastewaters. Microorganisms' inactivation is the latest success story in the application of this process at near-neutral pH, albeit without clearly elucidated inactivation mechanisms. In this review, the main pathways of the combined photo-Fenton process against the most frequent pathogen models (Escherichia coli for bacteria and MS2 bacteriophage for viruses) are analyzed. Firstly, the action of solar light is described and the specific inactivation mechanisms in bacteria (internal photo-Fenton) and viruses (genome damage) are presented. The contribution of the external pathways due to the potential presence of organic matter in generating reactive oxygen species (ROS) and their effects on microorganism inactivation are discussed. Afterwards, the effects of the gradual addition of Fe and H2O2 are assessed and the differences among bacterial and viral inactivation are highlighted. As a final step, the simultaneous addition of both reagents induces the photo-Fenton in the bulk, focusing on the differences induced by the homogeneous or heterogeneous fraction of the process and the variation among the two respective targets. This work exploits the accumulated evidence on the mechanisms of bacterial inactivation and the scarce ones towards viral targets, aiming to bridge this knowledge gap and make possible the further application of the photo-Fenton process in the field of water/wastewater treatment.