Water Depollution and Photo-Detoxification by Means of TiO2: Fluoroquinolone Antibiotics as a Case Study

Photocatalysis by semiconductors is considered one of the most promising advanced oxidation processes (AOPs) and TiO2 is the most well-studied material for the removal of contaminants from the aquatic system. Over the last 20 years, pharmaceuticals have been the most investigated pollutants. They re-enter the environment almost unmodified or slightly metabolized, especially in the aquatic environment, since the traditional urban wastewater treatment plants (WWTPs) are not able to abate them. Due to their continuous input, persistence in the environment, and unpleasant effects even at low concentrations, drugs are considered contaminants of emerging concern (ECs). Among these, we chose fluoroquinolone (FQ) antibiotics as an environmental probe for assessing the role of TiO2 photocatalysis in the degradation of recalcitrant pollutants under environmental conditions and detoxification of surface waters and wastewaters. Due to their widespread diffusion, their presence in the list of the most persistent pollutants, and because they have been deeply investigated and their multiform photochemistry is well-known, they are able to supply rich information, both chemical and toxicological, on all key steps of the oxidative degradation process. The present review article explores, in a non-exhaustive way, the relationship among pollution, toxicity and remediation through titanium dioxide photocatalysis, with particular attention to the toxicological aspect. By using FQs as the probe, in depth indications about the different phases of the process were obtained, and the results reported in this paper may be useful in the improvement of large-scale applications of this technology, and—through generally valid methods—they could be deployed to other pharmaceuticals and emerging recalcitrant contaminants.

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Immunogold labeling of CMP-KDO synthetase produced by recombinant E. Coli cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100128900 ◽

1987 ◽

Vol 45 ◽

pp. 924-925

Author(s):

F. A. Durum ◽

R. G. Goldman ◽

T. J. Bolling ◽

M. F. Miller

Keyword(s):

Inclusion Bodies ◽

Large Scale ◽

Recombinant Dna ◽

Test System ◽

Cell Protein ◽

Gram Negative Bacteria ◽

Cytoplasmic Inclusions ◽

Isolation And Purification ◽

E Coli ◽

Low Concentrations

CMP-KDO synthetase (CKS) is an enzyme which plays a key role in the synthesis of LPS, an outer membrane component unique to gram negative bacteria. CKS activates KDO to CMP-KDO for incorporation into LPS. The enzyme is normally present in low concentrations (0.02% of total cell protein) which makes it difficult to perform large scale isolation and purification. Recently, the gene for CKS from E. coli was cloned and various recombinant DNA constructs overproducing CKS several thousandfold (unpublished data) were derived. Interestingly, no cytoplasmic inclusions of overproduced CKS were observed by EM (Fig. 1) which is in contrast to other reports of large proteinaceous inclusion bodies in various overproducing recombinant strains. The present immunocytochemical study was undertaken to localize CKS in these cells.Immune labeling conditions were first optimized using a previously described cell-free test system. Briefly, this involves soaking small blocks of polymerized bovine serum albumin in purified CKS antigen and subjecting them to various fixation, embedding and immunochemical conditions.

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Bottlenecks in the Implementation of On-Site Wastewater Treatment Plants on a Large Scale in The Netherlands

Water Science & Technology ◽

10.2166/wst.1990.0214 ◽

1990 ◽

Vol 22 (3-4) ◽

pp. 291-298

Author(s):

Frits A. Fastenau ◽

Jaap H. J. M. van der Graaf ◽

Gerard Martijnse

Keyword(s):

Wastewater Treatment ◽

The Netherlands ◽

Large Scale ◽

Wastewater Treatment Plants ◽

Housing Stock ◽

Research Work ◽

Field Research ◽

Domestic Wastewater ◽

Research Programme ◽

Definition Of

More than 95 % of the total housing stock in the Netherlands is connected to central sewerage systems and in most cases the wastewater is treated biologically. As connection to central sewerage systems has reached its economic limits, interest in on-site treatment of the domestic wastewater of the remaining premises is increasing. A large scale research programme into on-site wastewater treatment up to population equivalents of 200 persons has therefore been initiated by the Dutch Ministry of Housing, Physical Planning and Environment. Intensive field-research work did establish that the technological features of most on-site biological treatment systems were satisfactory. A large scale implementation of these systems is however obstructed in different extents by problems of an organisational, financial and/or juridical nature and management difficulties. At present research is carried out to identify these bottlenecks and to analyse possible solutions. Some preliminary results are given which involve the following ‘bottlenecks':-legislation: absence of co-ordination and absence of a definition of ‘surface water';-absence of subsidies;-ownership: divisions in task-setting of Municipalities and Waterboards; divisions involved with cost-sharing;-inspection; operational control and maintenance; organisation of management;-discharge permits;-pollution levy;-sludge disposal. Final decisions and practical elaboration of policies towards on-site treatment will have to be formulated in a broad discussion with all the authorities and interest groups involved.

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Analysis and design of suitable model structures for activated sludge tanks with circulating flow

Water Science & Technology ◽

10.2166/wst.1999.0189 ◽

1999 ◽

Vol 39 (4) ◽

pp. 55-60 ◽

Cited By ~ 4

Author(s):

J. Alex ◽

R. Tschepetzki ◽

U. Jumar ◽

F. Obenaus ◽

K.-H. Rosenwinkel

Keyword(s):

Activated Sludge ◽

Large Scale ◽

Wastewater Treatment Plants ◽

Treatment Plant ◽

High Sensitivity ◽

Suitable Model ◽

Model Structure ◽

Analysis And Design ◽

Hydraulic Behaviour ◽

Model Structures

Activated sludge models are widely used for planning and optimisation of wastewater treatment plants and on line applications are under development to support the operation of complex treatment plants. A proper model is crucial for all of these applications. The task of parameter calibration is focused in several papers and applications. An essential precondition for this task is an appropriately defined model structure, which is often given much less attention. Different model structures for a large scale treatment plant with circulation flow are discussed in this paper. A more systematic method to derive a suitable model structure is applied to this case. Results of a numerical hydraulic model are used for this purpose. The importance of these efforts are proven by a high sensitivity of the simulation results with respect to the selection of the model structure and the hydraulic conditions. Finally it is shown, that model calibration was possible only by adjusting to the hydraulic behaviour and without any changes of biological parameters.

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The Role of the Reactive Species Involved in the Photocatalytic Degradation of HDPE Microplastics Using C,N-TiO2 Powders

Polymers ◽

10.3390/polym13070999 ◽

2021 ◽

Vol 13 (7) ◽

pp. 999 ◽

Cited By ~ 1

Author(s):

Aranza Denisse Vital-Grappin ◽

Maria Camila Ariza-Tarazona ◽

Valeria Montserrat Luna-Hernández ◽

Juan Francisco Villarreal-Chiu ◽

Juan Manuel Hernández-López ◽

...

Keyword(s):

Wastewater Treatment Plants ◽

Reaction System ◽

Terrestrial Ecosystems ◽

Degradation Process ◽

Reactive Species ◽

Hazardous Substances ◽

Wide Range ◽

Degradation Behaviors ◽

Environmentally Friendly Process

Microplastics (MPs) are distributed in a wide range of aquatic and terrestrial ecosystems throughout the planet. They are known to adsorb hazardous substances and can transfer them across the trophic web. To eliminate MPs pollution in an environmentally friendly process, we propose using a photocatalytic process that can easily be implemented in wastewater treatment plants (WWTPs). As photocatalysis involves the formation of reactive species such as holes (h+), electrons (e−), hydroxyl (OH●), and superoxide ion (O2●−) radicals, it is imperative to determine the role of those species in the degradation process to design an effective photocatalytic system. However, for MPs, this information is limited in the literature. Therefore, we present such reactive species’ role in the degradation of high-density polyethylene (HDPE) MPs using C,N-TiO2. Tert-butanol, isopropyl alcohol (IPA), Tiron, and Cu(NO3)2 were confirmed as adequate OH●, h+, O2●− and e− scavengers. These results revealed for the first time that the formation of free OH● through the pathways involving the photogenerated e− plays an essential role in the MPs’ degradation. Furthermore, the degradation behaviors observed when h+ and O2●− were removed from the reaction system suggest that these species can also perform the initiating step of degradation.

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Heat Aged Tensile Strength Retention of Poly (p-phenylene terephthalamide) Sewing Thread

Journal of Engineered Fibers and Fabrics ◽

10.1177/155892500800300403 ◽

2008 ◽

Vol 3 (4) ◽

pp. 155892500800300 ◽

Cited By ~ 4

Author(s):

Walter R. Hall ◽

Warren F. Knoff

Keyword(s):

Hydrolytic Degradation ◽

Oxidative Degradation ◽

Thermal Exposure ◽

Strength Loss ◽

Degradation Process ◽

Downstream Processing ◽

Kink Bands ◽

Sewing Thread ◽

Continuous Filament ◽

Strength Retention

The strength retention after exposure to elevated temperature in air of continuous filament and staple spun PPTA sewing thread and the precursor yarns was determined. For both types, the process of converting the greige yarn to thread reduced the amount of strength retained after thermal exposure. The continuous filament products retained more strength than the staple products. The data was fitted to a kinetic rate model in which two strength loss processes occurred. The first process occurred within about the first 5 minutes of thermal exposure and is hypothesized to be hydrolytic degradation. The estimated secondary degradation process activation energy suggests this to be thermo-oxidative degradation. Optical microscopy of filaments indicates a higher level of kink banding and other damage in continuous filament versus staple products and in finished thread versus the precursor yarns. The kink bands and damage are believed to be caused by the staple manufacturing process and the downstream processing of precursor yarn to finished sewing thread. The kink bands and damage are hypothesized to be responsible for the differences in strength retention.

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Global phosphorus dynamics in terms of phosphine

npj Climate and Atmospheric Science ◽

10.1038/s41612-020-00154-7 ◽

2020 ◽

Vol 3 (1) ◽

Author(s):

Wanyi Fu ◽

Xihui Zhang

Keyword(s):

Wastewater Treatment ◽

Human Activities ◽

Wastewater Treatment Plants ◽

Global Climate ◽

Global Scale ◽

Phosphorus Cycle ◽

Natural Ecosystems ◽

Driving Cycles ◽

Global Cycles ◽

Urban Wastewater Treatment

AbstractSince the detection of phosphine in the wastewater treatment plants in 1988, more and more investigations revealed that phosphine is closely related to ecological activities on a global scale. Here, we present perspectives on the whole dynamic cycles of phosphorus, particularly in terms of phosphine and its interactions with natural ecosystems, as well as the impacts from human activities. It may conclude that the phosphine-driving cycles of phosphorus depend on the coordination of human activities with natural ecosystems. Most importantly, the extensive recovery of phosphorus in numerous urban wastewater treatment plants may seriously obstruct its global cycles to catch up with the ecological needs in natural ecosystems. Phosphine gas plays an important role in the biogeochemical phosphorus cycle. Phosphorus might be one of the important elements participating in the global climate change together with carbon and nitrogen.

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Localized corrosion of (lean) duplex stainless steels in immersion units of urban wastewater treatment plants

Materials and Corrosion ◽

10.1002/maco.202112298 ◽

2021 ◽

Author(s):

Nicolas Larché ◽

Benoit Emo ◽

Audrey Allion ◽

Elisabeth Johansson ◽

Dominique Thierry

Keyword(s):

Wastewater Treatment ◽

Stainless Steels ◽

Wastewater Treatment Plants ◽

Duplex Stainless Steels ◽

Localized Corrosion ◽

Urban Wastewater ◽

Urban Wastewater Treatment

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Degradation Mode of PBAT Mulching Film and Control Methods During Its Degradation Induction Period

Mini-Reviews in Organic Chemistry ◽

10.2174/1570193x18666210813142022 ◽

2021 ◽

Vol 18 ◽

Author(s):

Runmeng Qiao ◽

Xin Wang ◽

Guangjiong Qin ◽

Jialei Liu ◽

Aocheng Cao ◽

...

Keyword(s):

Research And Development ◽

Biodegradable Polymers ◽

Large Scale ◽

Degradation Process ◽

Future Research ◽

Plastic Film ◽

Plastic Mulching ◽

Controllable Degradation ◽

Mulching Film ◽

Agricultural Film

: The plastic film plays an important role in China's agricultural production. However, the large-scale use of plastic film has also produced a very serious problem of agricultural film pollution. Biodegradable polymers have attracted much attention because of the environmental pollution caused by traditional plastic mulching film. The most typical one is poly (butylene adipate co butylene terephthalate, PBAT). Poly (Butylene Adipate-co-Terephthalate) (PBAT) is a kind of aliphatic–aromatic polyesters with excellent biodegradability and mechanical processing properties. Therefore, it has been rapidly developed and widely used in the industry. However, there are clear requirements for the degradation period of agricultural film. At present, the degradable materials available on the market are difficult to meet the requirements of all crops for their degradation period. In this paper, the basic properties，degradation process and ways to delay the degradation of PBAT are reviewed to improve the degradation period of plastic film prepared by using this kind of material. Among them, the degradation process includes photodegradation, biodegradation and hydrolysis. The ways to delay the degradation include adding chain extender, light stabilizer, anti-hydrolysis agent and antibacterial agent. These can provide a theoretical basis for the research and development of biodegradable film with controllable degradation cycle. The future research and development of biodegradable polymers mainly focus on controllable degradation rate, stable degradation cycle, new materials and reducing research and development costs.

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