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Hydrogen sulfide is reported as one of the most common odor-producing compounds from sewage treatment plants. The literature review revealed that very little information is available on the emission of H2S from different units of sewage treatment plants. Besides, the removal efficiency as well as dispersion studies of H2S should be explored more. Therefore, the purposes of this study were to measure the emissions of H2S, evaluate the efficiency of odor control unit, and explore the dispersion potential of H2S from a sewage treatment plant in Muscat, Sultanate of Oman. Site survey analysis revealed four sources (tanker discharge area, grit/sand and fog removal channels, pre-aeration basin, and screen building) of H2S in the plant premises. Additionally, measurement analysis showed that the efficiency of odor control unit, which treated the emissions from all sources, except the tanker discharge facility, was 90.2%. The Gaussian plume dispersion modeling studies demonstrated that the allowable concentration of dispersed H2S (1 ppm) was observed > 30 m from the identified sources. Although the combined outlet of the odor control unit was greater than 1 ppm, the plant is complying with the current environmental specifications at the boundaries (≤ 1 ppm) set by the environmental authorities. Hence, a set of recommendations is suggested to improve the efficiency of the system to resolve the odor emission from the plant. [ABSTRACT FROM AUTHOR]

The main objective of this study was to investigate the potential of using spent catalysts produced from the process of refining crude oil as a constituent material in hot mix asphalt (HMA). Two types of spent catalyst; equilibrium catalyst (ECat) and zeolite catalyst (ZCat) were used to partially replace some selected sizes of aggregate in the HMA. Chemical analysis of the raw catalysts indicated that both catalyst types used in this study comprised mainly of Al2O3 and SiO2. Marshall Method of mix design was followed to determine the optimum asphalt content of the aggregate structure containing waste catalyst. Volumetric and stability data indicated that there is a good potential for using spent catalyst in road applications. Environmental analysis and moisture damage potential were also carried out to further characterize the designed mixes. It was observed that the level of all toxic elements in both ECat and ZCat spent catalysts samples were within the acceptable limits. ECat mixes proved to be less susceptible to moisture damage compared to the ZCat mixes. For the amounts of catalyst used in this study, the ZCat mixes failed to meet the moisture resistance requirements of 80% retained strength and hence it is not recommended to be utilized as a filler material. [ABSTRACT FROM AUTHOR]

The only way to dispose of municipal solid waste (MSW) in Oman is in engineered landfills without pre-treatment. An effective waste management system requires a reliable database of solid waste composition, properties, and energy content. Although investigating waste in landfills in Muscat Governorate is challenging and complex, it is essential. In this study, MSW from Muscat Governorate landfills is examined. The MSW samples were collected et al. Amerat and Barka landfills in 2020 in order to determine some of the importance of their physiochemical properties and the ratio of materials (food, plastic, and paper). It was found that approximately 50% of the weight of the disposed waste was recyclable. There were high levels of biodegradable organic material in MSW. In terms of moisture content, MSW ranged from 21.5 to 43.3%. Both the volatility and loss of ignition of MSW were high. It was found that the total oxide ratios ranged from 12.4 to 44.06%. The elemental analysis of Muscat MSW resulted in six chemical formulas for MSW with and without sulfur. Silica is the most influential oxide, followed by calcium oxide. The findings of this study indicate that almost half of Muscat's municipal solid waste can be recycled. Solid waste can be recycled to create renewable materials that can replace oil as a by-product of the recycling industry. Additionally, Muscat MSW has a high moisture content, which enables it to be composted and biodegraded. Moreover, waste-to-energy technologies are feasible due to their high-energy content., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Food waste is a major constituent in municipal solid wastes and its accumulation or disposal of in landfills is problematic, causing environmental issues. Herein, a techno-economic study is carried out on the potential of biogas production from different types of food waste generated locally. The biogas production tests were at two-time sets; 24-h and 21-day intervals and results showed a good correlation between those two-time sets. Thus, we propose to use the 24-h time set to evaluate feedstock fermentation capacity that is intended for longer periods. Our approach could potentially be applied within industry as the 24-h test can give a good indication of the potential substrate gas production as a quick test that saves time, with minimal effort required. Furthermore, polynomial models were used to predict the production of total gas and methane during the fermentation periods, which showed good matching between the theoretical and practical values with a coefficient of determination R 2  = 0.99. At day 21, the accumulative gas production value from mixed food waste samples was 1550 mL per 1 g of dry matter. An economic evaluation was conducted and showed that the case study breaks-even at $0.2944 per cubic metre. Any prices above this rate yield a positive net present value (NPV); at $0.39/m 3 a discounted payback period of six years and a positive NPV of $3108 were calculated. If waste management fee savings are to be incorporated, the total savings would be higher, increasing annual cash flows and enhancing financial results. This economic evaluation serves as a preliminary guide to assess the economic feasibility based on the fluctuating value of methane when producing biogas from food waste via anaerobic digestion, thus could help biogas project developers investigate similar scale scenarios .

Uncontrolled release of hydrocarbons from pipelines results in soil and groundwater contamination. However, due to the geo-environmental properties of the contaminated area, the remediation strategies might vary by light non-aqueous phase liquid (LNAPL) behaviors. In this study, a contaminated area with spilled oil from a pipeline was monitored. In the initial investigation in the 1980s, the contamination was reported in some citizen wells (CIZs), which resulted in drilling of 15 boreholes (BHs) across the Site from February 2001 to February 2007. Additionally, an area of around 0.24 km 2 encompassing the LNAPL was inferred. The extension of plume in 2016-7 was monitored in this study, in which new farms were impacted by the contamination. Further, a conceptual model based on the previous information and current measured data was developed to better understand the behavior of the plume. The model showed that the Site is very complex, dipping towards the south, and the groundwater contains light hydrocarbons. Pumping tests, as a part of LNAPL remedial technology, were conducted by using three pumping wells (PWs), each accompanied by a monitoring well. Accordingly, a risk-based corrective action was implemented to eliminate and control unacceptable risks in a safe and timely manner. From the remediation approach, a monitoring plan in BHs and CIZs was suggested. In the case of receptors (humans and farms), clean-up of wells, tanks, and water channels as well as replacement of contaminated soils were highly regarded. Although the recent investigation and clean up monitoring wells showed that the LNAPL was very minimal, further steps in the receptor side should be taken prior to irrigation applications., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Emission of fugitive iron particles from anthropogenic sources can have significant effects on the human health and the environment. In this study, a regulatory air pollutant dispersion model (AERMOD) was implemented to predict the dispersion and deposition of fugitive iron particles towards a mid-sized residential area in Sultanate of Oman. The performance of the model was validated using air, soil, and dust fall samples. PM 10 was found as the most abundant iron particles in the soil samples. The results showed that the maximum daily concentration level of fugitive iron particles simulated through AERMOD was 7.19 μg/m 3 . Statistical analysis, including fractional bias (FB), normalized mean square error (NMSE), and predicted/observed ratio (Pred./Obs.), showed a reliable agreement in accuracy and precision between the datasets (for air samples FB = 0.024, NMSE = 0.001, Pred./Obs. = 0.976; for dust fall samples FB = -0.004, NMSE = 0.000, Pred./Obs. = 1.004). However, uncertainties and differences were from the external sources, such as other industries in the region. The results presented that the concentration levels were below the national and international guidelines proposed by the US Environmental Protection Agency (USEPA) and Omani Ambient Air Quality Standards (OAAQS). The methodology followed and the developed dispersion model can be generalized to other industries from which the dispersion of fugitive metal particles need to be evaluated as a potential route for human exposure. Graphical abstract ᅟ.

With rapid urbanization and economic growth, many developing countries have faced a greater share of air pollutants in recent years. An increasing number of exposure studies on air pollutants have been reported lately. However, due to lack of strict regulations and monitoring stations among developing countries, such as Gulf Cooperation Council (GCC) countries, limited air pollution and exposure assessment studies have been conducted in this region. Thus, the objective of this critical review was to identify the major sources of air pollutants in the region with hot and arid/semiarid climate for the main categories contributing to specific pollutants. Finally, a summary of the limitations and knowledge gaps were discussed. Additionally, the current available regulations, emission inventories and source apportionment studies in this region were discussed. In this study, the concentration levels of carbon dioxide (CO 2 ), carbon monoxide (CO), particulate matter (PM), metal elements, nitrogen oxides (NO x ), ozone (O 3 ), sulfur dioxide (SO 2 ), volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), and persistent organic pollutants (POPs) were reviewed. Due to lack of scientific studies, various databases and indexed journals from early 2000 (sometimes prior that time) were considered. The review findings clearly indicated that the sand, dust (natural and anthropogenic, such as cement, metal, stone cutting industries), chemical industries (refinery, petrochemical, etc.) and transportation activities were the major contributors to the overall air pollution in the GCC countries. Besides, the study recommended that the difference between anthropogenic pollution and natural events in dust formation should be explored extensively. Furthermore, possible suggestions for future researches in the region were proposed., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Papers reviewed herein present a general overview of radioactive waste related activities around the world in 2016. The current reveiw include studies related to safety assessments, decommission and decontamination of nuclear facilities, fusion facilities, transportation. Further, the review highlights on management solutions for the final disposal of low and high level radioactive wastes (LLW and HLW), interim storage and final disposal options for spent fuel (SF), and tritiated wastes, with a focus on environmental impacts due to the mobility of radionuclides in ecosystem, water and soil alongwith other progress made in the management of radioactive wastes.

This review includes works published in the general scientific literature during 2016 on the production of bioenergy and biofuel from waste residues generated during bioethanol and biodiesel production with a brief overview of current and emerging feedstocks. A section of this review summarizes literature on culturing algae for biofuels including bioreactors and open pond cultivation systems with the utilization of inorganic and organic sources of nutrients. New methods applicable to the mass culture of algae are highlighted. Algal cell harvesting and oil extraction techniques are discussed along with policies and economics.

A review of the literature published in 2016 on topics relating to the treatment alternatives for wastewater from the textile industries is presented. This review is divided into the following sections: a brief introduction on the implementation of the Best Available Techniques into textile industry, a review of the more promising treatment technologies distinguished into physico-chemical, biological and combined processes.

This review covers research papers and scientific literature published in the year 2016 on the effects of anthropogenic pollutants on freshwater organisms. In the first, the review begins with two broad sections thate are mainly focused on research reviews and broad field studies and surveys. This is followed by reviews of research categorized in sections to reflect the pollutant class. These sections include wastewater, stormwater and non-point source pollution, nutrients, sediment cap materials and suspended clays, botanical extracts, surfactants, metals, persistent organic pollutants, pharmaceuticals, endocrine disruptors, pesticides, petroleum hydrocarbons and polycyclic aromatic hydrocarbons (PAHs), ionic liquids, and nanomaterials. The final section of the review highlights the research published on describing innovations in the field of freshwater pollution research.

Air quality modeling plays an important role in prediction of air pollutants in urban areas. Moreover, it is also an essential component to make crucial decisions in environmental management. In this study, environmental protection agency (EPA) regulatory model (AERMOD) was implemented in order to assess the urban air quality in the city of Muscat, Sultanate of Oman. Dispersion modeling was employed for the prediction of hydrogen sulfide (H 2 S) emissions, a neighborhood claimed issue, from Al-Ansab sewage treatment plant (STP). Meteorological, elevation data, and H 2 S survey results were implemented into the model. From the site survey study, four different H 2 S emission sources were identified as sewage tanker connection points, biofilter, old odor control unit (OCU), and open channels of raw sewage. It was observed that based on maximum 24-h analysis, the ground level concentration outside the STP exceeded the concentration limit, 40 μg/m 3 , recommended by the local regulating agency in Oman. By applying a sensitivity analysis study, the locations with the highest predicted H 2 S levels were identified. The most affected area in the worst-case scenario was the nearby expressway with 450.9 μg/m 3 of H 2 S. The highest ground level concentration of H 2 S was detected in March, while the lowest was measured in December. The model also predicted that the impact of odor nuisance is greater at the summer season than that of other seasons due to the elevated temperatures. The study revealed an adverse environmental impact from the STPs on urban air quality, which may pose a threat to the public health.

A review of the literature published in 2015 on topics relating to the treatment alternatives for wastewater from the textile industries is presented. This review is divided into the following sections: a brief introduction on the implementation of the Best Available Techniques into textile industry, a review of the more promising treatment technologies distinguished into physico-chemical, biological and combined processes.

This review includes works published in the general scientific literature during 2015 on the effects of anthropogenic pollutants on freshwater organisms. It begins with two broad sections: research reviews and broad field studies and surveys. This is followed by reviews of research categorized in sections to reflect the pollutant class. These sections include wastewater, stormwater and non-point source pollution, nutrients, sediment cap materials and suspended clays, botanical extracts, surfactants, metals, persistent organic pollutants, pharmaceuticals, endocrine disruptors, pesticides, petroleum hydrocarbons and polycyclic aromatic hydrocarbons (PAHs), ionic liquids, and nanomaterials. The final section includes works describing innovations in the field of freshwater pollution research.

Papers reviewed herein present a general overview of radioactive waste activities around the world in 2015. These include safety assessments, decommission and decontamination of nuclear facilities, fusion facilities, transportation and management solutions for the final disposal of low and high level radioactive wastes (LLW and HLW), interim storage and final disposal options for spent fuel (SF), and tritiated wastes, with a focus on environmental impacts due to the mobility of radionuclides in water, soil and ecosystem alongwith other progress made in the management of radioactive wastes.

This review includes works published in the general scientific literature during 2015 on the production of bioenergy and biofuel from waste residues generated during bioethanol and biodiesel production with a brief overview of current and emerging feedstocks. A section of this review summarizes literature on culturing algae for biofuels including bioreactors and open pond cultivation systems with the utilization of inorganic and organic sources of nutrients. New methods applicable to the mass culture of algae are highlighted. Algal cell harvesting and oil extraction techniques tested and developed for algae discussed alongwith policies and economics are also provided.

Papers reviewed herein present a general overview of radioactive waste activities around the world in 2014. These include safety assessments, decommission and decontamination of nuclear facilities, fusion facilities, transportation and management solutions for the final disposal of low and high level radioactive wastes (LLW and HLW), interim storage and final disposal options for spent fuel (SF), and tritiated wastes, with a focus on environmental impacts due to the mobility of radionuclides in water, soil and ecosystem alongwith other progress made in the management of radioactive wastes.

A review of the literature published in 2014 on topics relating to the treatment alternatives for wastewater from the textile industries is presented. This review is divided into the following sections: a brief introduction on the implementation of the Best Available Techniques into textile industry, a review of the more promising treatment technologies distinguished into physico-chemical, biological and combined processes.

This review includes works published in the general scientific literature during 2014 on the production of bioenergy and biofuel from waste residues generated during bioethanol and biodiesel production with a brief overview of current and emerging feedstocks. Anothersection of this review summarizes literature on culturing algae for biofuels including bioreactors and open pond cultivation systems with the utilization of inorganic and organic sources of nutrients. New methods applicable to the mass culture of algae are highlighted. Algal cell harvesting and oil extraction techniques tested and developed for algae are also discussed.

This review includes works published in the general scientific literature during 2014 on the effects of anthropogenic pollutants on freshwater organisms. It begins with two broad sections: research reviews and broad field studies and surveys. This is followed by reviews of research categorized in sections to reflect the pollutant class. These sections include wastewater, stormwater and non-point source pollution, nutrients, sediment cap materials and suspended clays, botanical extracts, surfactants, metals, persistent organic pollutants, pharmaceuticals, endocrine disruptors, pesticides, petroleum hydrocarbons and polycyclic aromatic hydrocarbons (PAHs), ionic liquids, and nanomaterials. The final section includes works describing innovations in the field of freshwater pollution research.

Waste spent catalyst is generated in Oman as a result of the cracking process of petroleum oil in the Mina Al-Fahl and Sohar Refineries. The disposal of spent catalyst is of a major concern to oil refineries. Stabilized spent catalyst was evaluated for use in road construction as a whole replacement for crushed aggregates in the sub-base and base layers and as a partial replacement for Portland cement in masonry blocks manufacturing. Stabilization is necessary as the waste spent catalyst exists in a powder form and binders are needed to attain the necessary strength required to qualify its use in road construction. Raw spent catalyst was also blended with other virgin aggregates, as a sand or filler replacement, for use in road construction. Compaction, unconfined compressive strength and leaching tests were performed on the stabilized mixtures. For its use in masonry construction, blocks were tested for unconfined compressive strength at various curing periods. Results indicate that the spent catalyst has a promising potential for use in road construction and masonry blocks without causing any negative environmental impacts., (Copyright © 2012 Elsevier B.V. All rights reserved.)