Industrialization and excessive use of pesticides for boosting agricultural production have adversely affected the ecosystem, polluting natural water reserves. Remediation of contaminated water has been an area of concern with numerous techniques being applied to improve the quality of naturally available water to the level suitable for human consumption. Most of these methods, however, generate by-products that are sometimes toxic. Heterogenous photocatalysis using metal oxide nanostructures for water purification is an attractive option because no harmful by-products are created. A discussion on possible methods to engineer metal oxides for visible light photocatalysis is included to highlight the use of solar energy for water purification. Multifunctional photocatalytic membranes are considered advantageous over freely suspended nanoparticles due to the ease of its removal from the purified water. An overview of water remediation techniques is presented, highlighting innovations through nanotechnology for possible addressing of problems associated with current techniques. 相似文献
The rising occurrence of emerging contaminants in sludges both inhibits the anaerobic digestion of sludges and induces health issues when sludges are recycled in agriculture, calling for methods to remove contaminants. Here we review emerging pollutants in wastewater treatment plants, before and after anaerobic digestion. We present their inhibitory effects and remediation methods to alleviate inhibition. Pharmaceuticals have been detected in about 50% of the sludge samples. Sewage sludge contaminants include 19% of diuretics, 16–21% of lipid-modifying agents, hydrochlorothiazide, diclofenac, furosemide, clarithromycin, atorvastatin, and carbamazepine. Levels of antibiotics, azithromycin, ciprofloxacin, and estrone range from 500 to 600 ng/g in sludges from wastewater treatment plants. Remediation methods comprise electrooxidation, ultrasonication, thermal hydrolysis, ozonation, and bioaugmentation. Fermenting the sludges with acidogenic bacteria reduces the level of emerging pollutants in the supernatant. Nonetheless, liquid digestates still contains emerging pollutants such as sunscreen octocrylene at 147 ug/L and acetaminophen at 58.6 ug/L. As a result, pretreatment of sludge containing emerging pollutants is required.
Pharmaceuticals and personal care products (PPCPs) have been regarded as an emerging problem in the surface water environment in the past few decades. In China, although related studies were initiated several years ago, an increasing number of studies on this topic have been conducted in recent years. These studies have expanded knowledge of their occurrence, behavior and associated risk in the surface water environment in China. This review compiles the most recent literature related to the studies of PPCPs in the surface water environment in China. It includes PPCP occurrence in surface water and sediments, their geographical distribution, and outcomes of the associated risk assessment. It shows that antibiotics have received much more attention in both surface water and sediments than other PPCPs. Compared to other countries; most antibiotics in the collected sediments in China showed higher contamination levels. Many more study areas have been covered in recent years; however, attention has been given to only specific areas. Environmental risk assessment based on risk quotients indicated that sulfamethoxazole presents the most significant environmental risk to relevant aquatic organisms; followed by ofloxacin, ciprofloxacin, enrofloxacin, 17α-ethynylestradiol, ibuprofen and diclofenac. Despite limited research on the environmental risk assessment of PPCPs in sediments, higher risks posed by PPCPs in the sediments rather than surface water were identified highlighting the need for further risk assessment of PPCPs in sediment samples.
Increasing water pollution by microbes has become a source of serious health concern across the globe. Production of potentially
carcinogenic disinfection by-products has marred credibility of traditional water purification techniques like chlorination.
Photocatalysis has emerged as a promising alternative technique for the disinfection of water with minimal risk of harmful
by-products. The process involves a wide band gap semiconductor material which, upon irradiation of light, produces electrons
and holes with high redox potential to degrade organic contaminants and microbes. In this review, we analyze the research
trends in photocatalytic inactivation of water borne microorganisms. This report analyzes the major factors that affect the
disinfection efficiency using this process. The discussion also includes plausible mechanisms of microbial degradation as
well as a kinetic model of the inactivation process. Different approaches, like doping of semiconductors or energy band engineering
or plasmon coupling, have been reported for the enhancement and utilization of ambient solar light. Photocatalysis could be
a cost-effective and environmentally friendly water purification technique though further research is required to enhance
its efficiency with the use of solar light. 相似文献
Tetracycline antibiotics are one of the primarily antibiotics groups used for veterinary purposes, for human therapy and for agricultural purposes. Amongst the different antibiotics used, more attention is paid to tetracycline’s as it exhibits serious environmental problems including ecological risks and human health damages. Due to their extensive usage, most of the actual evidence suggests that tetracycline antibiotics are omnipresent compounds found in different ecological compartments. After medication, more than 70 % of tetracycline antibiotics are excreted and released in active form into the environment via urine and feces from humans and animals. Their highly hydrophilic character and low volatility have resulted in significant persistence in the aquatic environment. Very few studies describe the fate and toxicity of tetracycline antibiotics in the environment. Here, we review several important issues with regard to: (1) the toxicity of these compounds on aquatic and terrestrial organisms; (2) their estrogenic effects; (3) their behavior in different ecological systems and; (4) the by-products generated during water treatment. These antibiotics residues promote the development of antibiotic resistant microorganisms, which can induce adverse effect to human health by increasing the risk of certain infections. Based on recent research results, the occurrence of tetracycline antibiotics in the environment inhibits the growth of some terrestrial and aquatic species. Besides, the residual concentrations of such drugs could affect steroidogenic pathway and consequently may cause endocrine disruption of aquatic species. Most of the wastewater treatment plants are not capable of removing effectively the tetracycline antibiotics. Therefore, there is a need to develop alternative processes to remove them from waters. Advanced oxidation processes have been proposed as alternative methods to ensure higher degradation and mineralization of tetracycline antibiotics are present in waters. 相似文献
Nanotechnology has revolutionized plethora of scientific and technological fields; environmental safety is no exception. One of the most promising and well- developed environmental applications of nanotechnology has been in water remediation and treatment where different nanomaterials can help purify water through different mechanisms including adsorption of heavy metals and other pollutants, removal and inactivation of patho- gens and transformation of toxic materials into less toxic compounds. For this purpose, nanomaterials have been produced in different shapes, integrated into various composites and functionalized with active components. Nanomaterials have also been incorporated in nanostructured catalytic membranes which can in turn help enhance water treatment. In this article, we have provided a succinct review of the most common and popular nanomaterials (titania, carbon nanotubes (CNTs), zero-valent iron, dendrimers and silver nanomaterials) which are currently used in environmental remediation and particularly in water purification. The catalytic properties and functionalities of the mentioned materials have also been discussed. 相似文献
The increasing quantities of polluted waters are calling for advanced purification methods. Flocculation is an essential component of the water purification process, yet flocculation is commonly not optimal due to our poor understanding of the flocculation process. In particular, there is little knowledge on the mechanisms ruling the migration of pollutants during treatment. Here we have created the first tensor diagram, a mathematical framework for the flocculation process, analyzed its properties with a deep learning model, and developed a classification scheme for its relationship with pollutants. The tensor was constructed by combining pixel matrices from a variety of floc images, each with a particular flocculation period. Changing the factors used to make flocs images, such as coagulant dose and pH, resulted in tensors, which were used to generate matrices, that is the tensor diagram. Our deep learning algorithm employed a tensor diagram to identify pollution levels. Results show tensor map attributes with over 98% of sample images correctly classified. This approach offers potential to reduce the time delay of feedback from the flocculation process with deep learning categorization based on its clustering capabilities. The advantage of the tensor data from the flocculation process improves the efficiency and speed of response for commercial water treatment.
Heterogeneous photocatalysis using the semiconductor titanium dioxide (TiO2) has proven to be a promising treatment technology for water purification. The effectiveness of this oxidation technology for the destruction of pharmaceuticals has also been demonstrated in numerous studies. This review highlights recent research on TiO2 photocatalytic treatment applied to the removal of selected pharmaceuticals. The discussions are tailored based on the therapeutic drug classes as the kinetics and mechanistic aspects are compound dependent. These classes of pharmaceuticals were chosen because of their environmental prevalence and potential adverse effects. Optimal operational conditions and degradation pathways vary with different pharmaceutical compounds. The main conclusion is that the use of TiO2 photocatalysis can be considered a state-of-the-art pharmaceutical wastewater treatment methodology. Further studies are, however, required to optimize the operating conditions for maximum degradation of multiple pharmaceuticals in wastewater under realistic conditions and on an industrial scale. 相似文献
Conventional mathematical programming methods, such as linear programming, non linear programming, dynamic programming and
integer programming have been used to solve the cost optimization problem for regional wastewater treatment systems. In this
study, a river water quality management model was developed through the integration of a genetic algorithm (GA). This model
was applied to a river system contaminated by three determined discharge sources to achieve the water quality goals and wastewater
treatment cost optimization in the river basin. The genetic algorithm solution, described the treatment plant efficiency,
such that the cost of wastewater treatment for the entire river basin is minimized while the water quality constraints in
each reach are satisfied. This study showed that genetic algorithm can be applied for river water quality modeling studies
as an alternative to the present methods. 相似文献
Rapid and sensitive pathogen detection methods are essential for the effective functioning of the water treatment industry, yet for many pathogens, effective detection and removal methods are still lacking. Cryptosporidium parvum oocysts and Giardia lamblia cysts are two of the most common waterborne pathogens currently infecting the water supply. In this study, a new method was developed for the detection of Cryptosporidium parvum oocysts and Giardia lamblia cysts. The method includes multi-steps as coagulation concentration of (oo)cysts in water, the dissolution of the resulting flocs into a small volume using acid, filtration of the (oo)cysts solution, and DNA extraction, purification, and examination using real-time PCR. The method was tested using spiked tap water and reservoir water as references, and the mean recovery ranged from 19.6% to 97.6% for oocysts, and from 51.4% to 98.7% for cysts. The method is economical and convenient, and is especially suitable for relatively high turbidity surface water. 相似文献