Technical and economic investigation of chemical scrubber and bio-filtration in removal of H 2 S and NH 3 from wastewater treatment plant

A detailed techno-economic comparison of a chemical scrubber (CS) and a bio-filter (BF) was conducted over a 45-day time period at a municipal wastewater treatment plant (WWTP), Yazd city. The assessment of emissions quantity indicated that odor emissions from the Yazd WWPT mainly consist of hydrogen sulfide (H 2 S) and ammonia (NH 3 ). It was also found that odor gaseous loading changes corresponding to water consumption pattern in society (R 2 = 0.922) for H 2 S and (R 2 = 0.978) for NH 3 . The highest level of 25 and 3 ppm for H 2 S and NH 3 , respectively were detected at specific times during the day. The BF system was continuously supplied with Yazd WWPT's off-gas treatment while the CS was only examined at the times during the day when the gas emissions are at the highest level. The removal efficiency of NH 3 and H 2 S were found to be affected by their respective loading rate. Additionally, among the various oxidants examined in the CS, the NaOCl solution showed the best results in terms of removal efficiency and compatibility. The experiment revealed almost complete removal of NH 3 while the H 2 S removal efficiency remained above 95 for both systems regardless of the operating conditions. This study clearly demonstrates the effectiveness of both systems in treating actual waste gases containing H 2 S and NH 3 . By comparing the gas loading rate of both systems and considering limitations of the BF system, the CS seems to be more efficient applicable odor control technology from a technical viewpoint. From the economic viewpoint, comparisons revealed that chemical usage and operating expenses were costly parts of the CS and the BF, respectively. The economic indexes of 1.58 �.m �3 . h �1 and 2.57 �.m �3 . h �1 were obtained for the BF and CS, respectively, reflecting cost-effectiveness of the BF system. © 201

Ambient air quality standards and policies in eastern mediterranean countries: a review

Objectives: National ambient air quality standards (NAAQS) are critical tools for controlling air pollution and protecting public health. We designed this study to 1) gather the NAAQS for six classical air pollutants: PM(2.5), PM(10), O(3), NO(2), SO(2), and CO in the Eastern Mediterranean Region (EMR) countries, 2) compare those with the updated World Health Organizations Air Quality Guidelines (WHO AQGs 2021), 3) estimate the potential health benefits of achieving annual PM(2.5) NAAQS and WHO AQGs per country, and 4) gather the information on air quality policies and action plans in the EMR countries. Methods: To gather information on the NAAQS, we searched several bibliographic databases, hand-searched the relevant papers and reports, and analysed unpublished data on NAAQS in the EMR countries reported from these countries to the WHO/Regional office of the Eastern Mediterranean/Climate Change, Health and Environment Unit (WHO/EMR/CHE). To estimate the potential health benefits of reaching the NAAQS and AQG levels for PM(2.5), we used the average of ambient PM(2.5) exposures in the 22 EMR countries in 2019 from the Global Burden of Disease (GBD) dataset and AirQ+ software. Results: Almost all of the EMR countries have national ambient air quality standards for the critical air pollutants except Djibouti, Somalia, and Yemen. However, the current standards for PM(2.5) are up to 10 times higher than the current health-based WHO AQGs. The standards for other considered pollutants exceed AQGs as well. We estimated that the reduction of annual mean PM(2.5) exposure level to the AQG level (5 mug m(-3)) would be associated with a decrease of all natural-cause mortality in adults (age 30+) by 16.9%-42.1% in various EMR countries. All countries would even benefit from the achievement of the Interim Target-2 (25 mug m(-3)) for annual mean PM(2.5): it would reduce all-cause mortality by 3%-37.5%. Less than half of the countries in the Region reported having policies relevant to air quality management, in particular addressing pollution related to sand and desert storms (SDS) such as enhancing the implementation of sustainable land management practices, taking measures to prevent and control the main factors of SDS, and developing early warning systems as tools to combat SDS. Few countries conduct studies on the health effects of air pollution or on a contribution of SDS to pollution levels. Information from air quality monitoring is available for 13 out of the 22 EMR countries. Conclusion: Improvement of air quality management, including international collaboration and prioritization of SDS, supported by an update (or establishment) of NAAQSs and enhanced air quality monitoring are essential elements for reduction of air pollution and its health effects in the EMR

A field indoor air measurement of SARS-CoV-2 in the patient rooms of the largest hospital in Iran

The coronavirus disease 2019 (COVID-19) emerged in Wuhan city, China, in late 2019 and has rapidly spread throughout the world. The major route of transmission of SARS-CoV-2 is in contention, with the airborne route a likely transmission pathway for carrying the virus within indoor environments. Until now, there has been no evidence for detection of airborne severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and this may have implication for the potential spread of the COVID-19. We investigated the air of patient rooms with confirmed COVID-19 in the largest hospital in Iran, on March 17, 2020. To collect the SARS-CoV-2 particles, ten air samples were collected into the sterile standard midget impingers containing 20 mL DMEM with 100 μg/mL streptomycin, 100 U/mL penicillin and 1 antifoam reagent for 1 h. Besides, indoor particle number concentrations, CO2, relative humidity and temperature were recorded throughout the sampling duration. Viral RNA was extracted from samples taken from the impingers and Reverse-Transcription PCR (RT-PCR) was applied to confirm the positivity of collected samples based on the virus genome sequence. Fortunately, in this study all air samples which were collected 2 to 5 m from the patients' beds with confirmed COVID-19 were negative. Despite we indicated that all air samples were negative, however, we suggest further in vivo experiments should be conducted using actual patient cough, sneeze and breath aerosols in order to show the possibility of generation of the airborne size carrier aerosols and the viability fraction of the embedded virus in those carrier aerosols. © 2020 Elsevier B.V

Histaminergic system in brain disorders: lessons from the translational approach and future perspectives

Histamine and its receptors were first described as part of immune and gastrointestinal systems, but their presence in the central nervous system and importance in behavior are gaining more attention. The histaminergic system modulates different processes including wakefulness, feeding, and learning and memory consolidation. Histamine receptors (H1R, H2R, H3R, and H4R) belong to the rhodopsin-like family of G protein-coupled receptors, present constitutive activity, and are subjected to inverse agonist action. The involvement of the histaminergic system in brain disorders, such as Alzheimer’s disease, schizophrenia, sleep disorders, drug dependence, and Parkinson’s disease, is largely studied. Data obtained from preclinical studies point antagonists of histamine receptors as promising alternatives to treat brain disorders. Thus, clinical trials are currently ongoing to assess the effects of these drugs on humans. This review summarizes the role of histaminergic system in brain disorders, as well as the effects of different histamine antagonists on animal models and humans

Evaluation Of The Possible Options For Reuse Of Ardebil Wastewater Treatment Plant Effluent

Recent advances in wastewater treatment have resulted in production of well-treated effluents which are suitable for use in more different sectors. In fact, these reclaimed wastewaters would be regarded as new water resources in many regions. In this research, the area studied was the city of Ardebil in northwest of Iran. At present, the effluent of Ardebil wastewater treatment plant is discharged into Qaresoo River. In this study, different aspects of Ardebil wastewater reuse have been investigated. Sampling of the effluent was performed in winter 2006 and summer 2007; and parameters indicating the suitability of wastewater discharge and/or reuse were considered in accordance to the recommendations of Iran Department of Environment. All the analyses were accomplished according to the latest edition of standard methods. Results clearly showed that apart from the problem of total and fecal coliforms which were above the standard values (1000 MPN and 400 MPN per 100 mL) the reuse of the treated effluent in agricultural irrigation could be carried out without restriction. But, regarding the discharge of this effluent into surface waters and injection wells, it would be necessary to upgrade treatment processes for further reduction of a few parameters such as nitrate, ammonium and phosphate

Evaluation Of Hollow Fiber Membrane Bioreactor Efficiency For Municipal Wastewater Treatment

The membrane bioreactor technology has been proven to be a single step process in efficient treatment of wastewater, either directly or after pretreatment by reverse osmosis. In this study, a pilot scale experiment was studied to treat a synthetic municipal wastewater sample. The aerobic reactor with a submerged membrane used in this work was continuously aerated for organic matter oxidation, nitrification and phosphorous uptake as well as for fouling control. The mixed liquor was recycled from the aerated zone to the anoxic zone for denitrification. The membrane had a nominal pore size of 0.1 μm and a filtration area of 4.0 m2. The performance of submerged membrane bioreactor was examined in order to determine the removal efficiency of organic compounds and nitrogen in different solid retention times (10, 20, 30, and 40 days) under a continuous inflow of the synthetic municipal wastewater. Results indicated that the submerged membrane bioreactor could efficiently remove the pollutants. Average removal rates of chemical oxygen demand, total Kejeldahl nitrogen removal, total nitrogen and phosphorous reached to as high as 99.3%, 98.1%, 85.5%, and 52%, respectively. Furthermore, concentrations of nitrate and nitrite in the last stage were well reduced and reached to 5.3 and 0.047 mg/L, respectively

Investigation of Existing Status of Hazardous Wastes Management in Central Campus of Tehran University Medical Sciences, Iran

"nBackgrounds and Objectives: Due to having features such as toxicity, corrosiveness, ignitability, reactivity or other similar characteristics, hazardous wastes refer to the wastes that jeopardize man's health and environment. A study was required to identify the hazardous wastes in Tehran University of Medical Sciences (TUMS), since it plays an important role in the development of the country's education. The objective of this research was to provide a review of hazardous wastes production and its management at Tehran University of Medical Sciences."nMaterials and Methods: In this study, four schools that were in the central campus of Tehran University of Medical Sciences, Iran, were selected and the necessary data were gathered using a sampling, questionnaire, interviewing those in charge of the units, and referring to the available documents. The information includes the type and amount of waste, method of temporary storage, frequency of waste discharge, and method of final disposal of wastes."nResults: The obtained results indicate that approximately 2072 Kg of hazardous wastes are produced each year, excluding the uncontrolled wastewater. Moreover, schools of dental, pharmacy, medicine, and public health produced approximately 993, 606, 256, 217 Kg/year, respectively, of hazardous wastes in the central campus. Also, the results show that, of total amount of annual hazardous waste that was 2.72 tons, 954, 848, 475, 427, 245, 49 Kg were wastes that the features infectious, toxicity, ignitability, carcinogenesis, corrosiveness, and reactivity, respectively."nConclusion: It  is to be mentioned that hazardous solid wastes were manage with household solid waste and hazardous liquid waste were discharged into sink without any kind of control. Improper practice is evident from the point of waste production to final disposal