adel mokammel

The initial step in managing methane emissions is quantification. This study aims to comprehensively investigate the methods for estimating and measuring methane gas emissions in municipal solid waste landfills.

This systematic review includes studies published in English and Farsi between January 2005 and May 2023. English-language articles were included from  PubMed, Web of Science, and Scopus databases, while Persian-language articles were included from SID, Majiran and Google Scholar.

After evaluating the studies, 90 studies providing information on methods for measuring and estimating methane gas emissions in urban landfills were selected. The results showed that emission estimates based on widely used models like LandGEM and IPCC, despite being lower in cost and providing faster results, are often associated with relatively high uncertainty. Therefore, quantitative and qualitative methods of direct measurement are preferred for accurately determining methane emissions from landfills. The most commonly used methods for measuring greenhouse gases, especially methane from landfills, include direct reading equipment and closed flux determination chambers.

Estimating greenhouse gas emissions from primary sources allows responsible authorities to understand the current status of methane emissions and to formulate reduction strategies. The findings of estimated methane emissions from landfills can differ significantly from the actual measurements in some situations. Therefore, while these estimation methods are  useful, fast and cost-effective tools, their inherent uncertainties should be considered when using them.

The current study was designed to investigate PM2.5 status in Tehran from 2011 to 2022.

Hourly data of particulate matter (PM2.5) concentrations in the air of Tehran city were examined from all air quality monitoring stations belonging to the Department of Environmental and the Air Quality Control Company. The health effects of this air pollutant were estimated, including the number of attributed deaths, using BenMAP-CE and the latest version of AirQ+ software. Additionally, the economic costs associated with health impacts were calculated using the Value of Statistical Life approach.

During the 12-year period under study (from 2011 to the end of 2022), PM2.5 concentrations in of Tehran city consistently exceeded the established standards by a significant margin. The annual values were approximately 5 to 8 times higher than the new guidelines of the World Health Organization and 2.5 to 3.5 times higher than the national standards. As a result, the citizens of Tehran have been exposed to a considerably high level of this cancer-causing risk factor. The number of deaths attributed to PM2.5 in the year 2022 reached around 9,241 (with a range of 8,583 to 9,647) in individuals over 25 years of age. Furthermore, the economic loss resulting from these deaths due to PM2.5 in the ambient air of Tehran in the year 2022 were estimated to be around 2.5 billion dollars.

Considering the undesirable air quality in Tehran city, planning and implementing scientific and practical programs to reduce air pollutant concentrations in this city are considered vital necessities.

Background and Antibiotics have worldwide uses and they can enter water sources through different ways. Due to their different inappropriate effects, they have created a major concern in environmental control practices. Metronidazole (MTN) is an example of these antibiotics. This study was performed to investigate the efficiency of ozonation process (SOP) in MTN removal from aqueous solutions. The solution pH (3-12), reaction time and initial MTN concentration (1-40 mg/L) were investigated for their effects on efficiency of the removal process. The MTN concentration was analyzed by HPLC. Biodegradability improvement and mineralization rate were studied by BOD5/COD and TOC tests, respectively. The optimum pH for SOP was 10. The best compatibility for drug degradation kinetic was found with pseudo-second order (liner type II) model. The BOD5/COD increased from 0.09 in SOP influent to 0.33 in SOP effluent and the MTN mineralization rate was about 68%. Higher ozone decomposition in alkaline pH increased the radical production and improved removal efficiency. Moreover, higher mineralization rate reduced the environmental risks of effluent discharges.