31 research outputs found
Development of Antibiotic Resistance in Wastewater Treatment Plants
Get PDFAntibiotic resistant bacteria and antibiotic resistance genes have been of the emerging contaminant threatening human health. The overuse of antibiotics, both in human patients and, importantly, in livestock, has led to an explosion of antibiotic-resistant bacteria, both in the U.S. and around the world. The prediction from the World Health Organization (WHO) is that, if nothing changes, the future will look a lot like the past—where people die from minor injuries that become infected. One of the goals should be a long-term sustainable balance with everything in our environment, including bacteria to promote human health. Different microbial techniques have been employed to study the occurrence and spread of antibiotic resistance in the environment, preventing us from returning to a pre-antibiotic era. Dissemination of antibiotic resistance genes to the environment is an important factor causing an increased prevalence of resistant pathogens. Their spread to multidrug-resistant pathogens is one of the most emerging clinical challenges
Macrocycles: Recent Advances in Synthesis, Reactivity, and Medicinal Chemistry
Get PDFIntroduction: A cyclic compound is common motif in natural product structures. Cyclic peptides, a vast subset of natural products, display a wide variety of biological activities. Owing to their size, cyclic peptides are particularly attractive scaffolds for interrogating challenging biomolecular interactions, such as those at protein–protein interfaces.
Methods and Results:
This review takes an overview of the literature for the synthesis of peptide and non-peptide macrocycles, concentrating on advances in the last five years up to the end of 2017. These methods are clustered by strategies for preparation and further derivatization of preformed macrocycle-containing building blocks. Examples of the use of macrocycles in medicinal chemistry are reported, including a collation of macrocycle derivatives appearing in recent patents for medicinal chemistry applications.
Conclusions:
This review aims to provide an overview of the extensive recent studies involving macrocycles in synthesis and medicinal chemistry and to highlight the continuing challenges
Strategies to Combat Antibiotic Resistance in the Wastewater Treatment Plants
No full textThe main goal of this manuscript is to review different treatment strategies and mechanisms for combating the antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs) in the wastewater environment. The high amount of antibiotics is released into the wastewater that may promote selection of ARB and ARGs which find their way into natural environments. Emerging microbial pathogens and increasing antibiotic resistance among them is a global public health issue. The propagation and spread of ARB and ARGs in the environment may result in an increase of antibiotic resistant microbial pathogens which is a worldwide environmental and public health concern. A proper treatment of wastewater is essential before its discharge into rivers, lake, or sewage system to prevent the spread of ARB and ARGs into the environment. This review discusses various treatment options applied for combating the spread of ARB and ARGs in wastewater treatment plants (WWTPs). It was reported that low-energy anaerobic–aerobic treatment reactors, constructed wetlands, and disinfection processes have shown good removal efficiencies. Nanomaterials and biochar combined with other treatment methods and coagulation process are very recent strategies regarding ARB and ARGs removal and need more investigation and research. Based on current studies a wide-ranging removal efficiency of ARGs can be achieved depending on the type of genes present and treatment processes used, still, there are gaps that need to be further investigated. In order to find solutions to control dissemination of antibiotic resistance in the environment, it is important to (1) study innovative strategies in large scale and over a long time to reach an actual evaluation, (2) develop risk assessment studies to precisely understand occurrence and abundance of ARB/ARGs so that their potential risks to human health can be determined, and (3) consider operating and environmental factors that affect the efficiency of each treatment mechanism
Treatment of algal toxins in drinking water with UV/Cl2 and UV/H2O2 advanced oxidation: toxicity of transformation products and effect on disinfection byproduct formation
No full textThis project evaluated treatment alternatives for water resources contaminated with algal toxins. An established advanced oxidation process (UV/H2O2) was compared with an emerging one (UV/Cl2) in terms of (a) effectiveness for detoxifying the three most common variants of algal hepatotoxin microcystin (LR, RR and YR), and (b) potential to increase the formation of regulated disinfection byproducts [four trihalomethanes (THMs) and nine haloacetic acids (HAAs)] and an unregulated nitrogenous byproduct (NDMA) due to the interaction of the process with algal organic matter and nitrate in the water. The toxicity of the products was assessed with a protein phosphatase inhibition assay (PP2A). Products were also analyzed with HPLC/MS/MS. Disinfection byproducts were assessed using the corresponding EPA methods (551.1, 552.3 and 521) with any modifications described in the report. The results shown that both methods are effective against the three microcystins; however, microcystin LR is also highly susceptible to reaction with chlorine and UV/Cl2 offers an additional advantage of direct chlorine reaction. The PP2A assay was not able to conclusively determine whether the transformation products retain any residual hepatotoxicity; however, HPLC/MS/MS analysis indicated that ADDA group of the molecule that is considered to be responsible for microcystin toxicity is a susceptible reaction site in both advanced oxidation and direct chlorination, and the resulting products are likely non-toxin. More work needs to be done to determine it with certainty, which may include conducting PP2A assays in pure water samples to avoid matrix interference with the analysis, or performing ADDA-specific assays (e.g. ELISA). Addition of nitrate or algal DOM to the sample matrix did not significantly affect the formation of THMs and HAAs, with the exception of chloroform. However, the effect on chloroform, while statistically significant, is unlikely to affect the regulatory compliance for utilities. On the other hand, NDMA formation was considerably increased by both nitrate and algal DOM. NDMA remained below 10 ng/L which is set as advisory level in some states in all samples. The amounts of nitrate and algal DOM used in the experiments were on the high end of environmentally relevant range. However, formation of nitrogenous DBPs warrants additional investigation.Urban Water Consortiu
POST-TREATMENT OF LEACHATE BY MICROWAVE-FENTON PROCESS USING OFAT ANALYSIS METHOD
No full textIndustrial and economic development along with changes in lifestyle over recent
decades in most countries has resulted in considerable growth of different
waste. Since biodegradable organic materials constitute approximately 60\% of
the total municipal solid waste in developing countries, leachate treatment is
considered as a big concern for solid waste management in these areas.
Application of biological processes is one of common method in leachate
treatment. However, due to presence of refractory pollutants, biological process alone cannot treat leachate on its own. In order to enhance the quality of leachate to the discharge standards, post treatment of biologically treated leachate is essential. One appropriate solution for complementary treatment of leachate and removal of refractory materials is the application of advanced oxidation rocesses. The Fenton process is one of homogenous advanced oxidation processes has been applied for leachate treatment. However, this method is time-consuming and expensive. In order to improve the performance and reagent utilization efficiency, in this paper microwave enhanced Fenton process was utilized for post-treatment of composting leachate. Batch laboratory scaled experiments were employed on effluent of leachate treatment plant of a composting factory in Iran. Initial experiments were conducted and then the effects of variables were determined separately by one factor at a time (OFAT) method. The effects of factors such as pH, ratio of concentration of to initial COD, ratio of concentration of to , and Microwave irradiation power on the microwave enhanced Fenton process efficiency were investigated. According to obtained results the maximum removal efficiency of Microwave enhanced Fenton process was obtained at pH=3, ratio of H2O2 concentration to initial COD equals to 3.75, ratio of concentration to concentration of 3, and Microwave irradiation power of 170W. The experimental results indicated that, under this optimum conditions, the removal of COD, total nitrogen, color, and turbidity were 72\%, 70\%, 75\% and 88\% respectively. Results of this research addresses that, applied process is unable to reduce organic load of the leachate in a way that it could be discharge in receiving environment. However, the ratio of was elevated from 0.01 to 0.25, representing substantial improvement in biodegradability. By so doing, a common biological process such as activated sludge could be hopefully utilized to reduce remaining organic load to the limits set by the standard
Traditional uses, chemistry and pharmacology of Ruscus genus (“Murd esfarm” in traditional Persian medicine); a review
No full textBackground and objectives: Ruscus genus from Asparagaceae (popularly called Butcher`s broom) are perennial rhizomatous evergreen herbs and grows in Europe and south western Asia. They are generally used as anti-inflammatory, diaphoretic, diuretic, mildly laxative, and vasoconstrictive agents in many countries. Ruscus hyrcanus Woronov is widely distributed in north of Iran. It is known as “Murd esfarm” in Persian traditional medicine (TPM). Based on TPM, Iranian physicions applied “Murd esfarm” for various disorders such as epilepsy, diarrhea, expulsion of intestinal worms and for increasing milk secretion. This study aimed to identify “Murd esfarm” a drug used in TPM and develop its therapeutic aspects and introduce a novel species for treatment of chronic vein disease. Methods: This study was conducted using the electronic databases (e.g., Pubmed, Web of science) and important Iranian traditional medicine books such as the Canon of medicine, Makhzan-ol advie, Tuhfat al-Mu’minin. Results: Extracts of these plants were effective in increasing venous tone because of their anti-inflammatory and astringent properties, which is attributed to saponin glycosides. Ruscogenin and neoruscogenin are compounds that constrict and strengthen veins and promote circulation from the lower extremities in both species. Conclusion: R. hyrcanus is a unique species of Ruscus in Iran.Due to the similarity of the Butcher`s broom with the plant mentioned in TPM books, this species can be used for the treatment of many diseases related to vascular insufficiency, including varicose veins and hemorrhoids
System of multi-layered environmental media for the removal of antibiotics from wastewater
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