Catalytic Pyrolysis of Municipal Solid Waste: Effects of Pyrolysis Parameters

Burning municipal solid waste (MSW) increases CO2, CH4, and SO2 emissions, leading to an increase in global warming, encouraging governments and researchers to search for alternatives. The pyrolysis process converts MSW to oil, gas, and char. This study investigated catalytic and noncatalytic pyrolysis of MSW to produce oil using MgO-based catalysts. The reaction temperature, catalyst loading, and catalyst support were evaluated. Magnesium oxide was supported on active carbon (AC) and Al2O3 to assess the role of support in MgO catalyst activity. The liquid yields varied from 30 to 54 wt% based on the experimental conditions. For the noncatalytic pyrolysis experiment, the highest liquid yield was 54 wt% at 500 °C. The results revealed that adding MgO, MgO/Al2O3, and MgO/AC declines the liquid yield and increases the gas yield. The catalysts exhibited significant deoxygenation activity, which enhances the quality of the pyrolysis oil and increases the heating value of the bio-oil. Of the catalysts that had high deoxygenation activity, MgO/AC had the highest relative yield. The loading of MgO/AC varied from 5 to 30 wt% of feed to the pyrolysis reactor. As the catalyst load increases, the liquid yield declines, while the gas and char yields increase. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Nanoparticles Synergistic Effect with Various Substrate Pretreatment and their Comparison on Biogas Production from Algae Waste

Algae waste is one of the potential substrates for biogas and biohydrogen production and can comprehend multiple benefits of waste treatment and resource utilization. In view of the key bottlenecks such as low substrate degradation rate and poor productivity of algae waste production process, this study analyzes the combined effect of two metallic and metallic oxide nanoparticles with different substrate pretreatment methods (autoclave, ultrasonic, and microwave methods) to investigate the effect of anaerobic digestion of green algae (Enteromorpha). The results showed that out of the three pretreatment methods, microwave pretreatment and nanoparticles' synergistic effect significantly increases biogas production. The microbial community composition at the phylum level was analyzed. It was observed that the Firmicutes were most abundant across all samples. The relative abundance of Firmicutes for control, Ni NPs + MW, Co NPs + MW, and Fe3O4 NPs + MW groups were 51.78, 70.37, 75.77, and 83.93%,      respectively. The second most abundant was of Bacteroidetes that also contributes to hydrogen production. This relatively high abundance of Firmicutes and Bacteroidetes promises its potential applications in a hydrogen production facility. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Prospects and State of the Glass Industry in Saudi Arabia and a preliminary assessment of the quality of Glass and Glass-Ceramics Fabrication

Although the economic value of glass products and its importance to the Saudi National Economy is vast, not much information is available about the current state of the art of the industry. Likewise little information is available about the geography, potential sites for mining sand as well as the evaluation of sand quality. This paper attempts to bridge this gap by presenting a feasibility study of fabricating normal glass and glass ceramics from Saudi Arabia’s domestically available raw materials. It discusses the current status of glass industry in Saudi Arabia and the Middle East region. It also gives a brief explanation about the sand topography in Saudi Arabia. In order to determine the feasibility of fabricating glass using these raw materials, experimental data on the fabrication of normal glass and glass-ceramics from indigenously available raw materials was obtained and reported as part of the findings of this paper Firstly, normal transparent glass were able to be fabricated without any apparent large defects using sand collected from Ar-Rayis region in Saudi Arabia. Four nano-sized crystallization catalysts, namely VC, WC, TiC and Y2O3, were added to the constituents of the glass in 3 wt.%.  For VC, the crystallization process was limited. The glass ceramics of WC consisted of multi-dimensional edges crystals which covered all the matrix. Gray crystalline whiskers were obtained by addition of TiC. The Y2O3- glass ceramics consisted of multi-directionally rosette crystals. Finally, the microhardness values of the added crystallization catalysts glass ceramics were obtained and found to be much higher compared to normal glass. The results show that glass of high quality can be produced specifically for Ar—Rayis region which would be of interest to researchers, glass industry personnel and potential investor

Techno-Economic Analysis of Formate Assisted Pyrolysis

The purpose of this study is to determine the capital and operating cost for producing liquid fuel from biomass by using Formate-Assisted Pyrolysis (FAsP) process. Many studies have been published about producing liquid fuel from biomass by using fast pyrolysis. Fast pyrolysis produces bio-oil with 60% mass yield; however, the bio-oil is unstable, has a high amount of oxygen (35 wt%) and requires high capital cost to upgrade it. Formate-Assisted Pyrolysis (FAsP), a new method being developed at the University of Maine, produces a bio-oil that is more stable and has less amount oxygen. FAsP uses the same operating conditions as fast pyrolysis (500 °C and atmospheric pressure), but also integrates the thermal decomposition of formate salts. Typical FAsP oil has (15 wt%) oxygen and 40% energy yield. Experiments were done by another student using different calcium formate/biomass ratios. An Aspen Plus® process model has been developed for a 2000 dry metric ton of biomass per day FAsP plant. The model includes feedstock sizing and drying, pyrolysis, hydrogen production and hydrotreatment of FAsP oils, and recycle of calcium. The char is used to provide heat for the kiln reactor. Other gases from upgrading and pyrolysis are used to produce hydrogen which is necessary for bio-oil upgrading. The bio-oil is upgraded to reach a final 18% gasoline/diesel mass yield and 42% energy yield based on the dry biomass fed. The total capital investment for a grass-roots plant was estimated to be US$276 million with an annual cost of manufacturing of US$171 million. With a 20 year project life, a minimum selling price for hydrocarbon fuel was determined to be US$3.91 per gallon with a 15% return on investment

CH₄ oxidation catalysts evaluated in a monolith reactor

Unburned CH₄ from natural gas vehicle (NGVs) exhausts limits the use of natural gas as a vehicle fuel. CH₄ is a potent greenhouse gas with a high C-H bond strength (~435 kJ mol⁻¹) making it difficult to oxidize in catalytic converters. This study is focused on the assessment of the activity and stability of selected catalysts placed in a monolith reactor with the goal of improving NGV emission control. Firstly, the washcoat formulation was investigated with the activity and stability of PdO/AlOOH/Al₂O₃, PdO/Ce/AlOOH/Al₂O₃ and Pt-PdO/Ce/AlOOH/Al₂O₃ monolith catalysts for CH₄ oxidation in the presence of H₂O, CO, CO₂ and SO₂ reported. Secondly, the effect of adding a washcoat overlayer to improve the performance of the monolith catalyst was investigated. The monolith catalysts were prepared using a cordierite (2MgO.2Al₂O₃.5SiO₂) mini-monolith (400 cells per square inch (CPI), 1 cm diameter x 2.5 cm length; ~52 cells) that was washcoated using a Al₂O₃ suspension combined with boehmite (AlOOH), followed by sequential deposition of Ce and Pd(Pt) by wet impregnation. The initial activity of the mini-monolith catalyst was measured by temperature-programmed CH₄ oxidation (TPO) at a GHSV of 36000 h⁻¹. Time-on-stream (TOS) tests were used to quantify the stability of the catalysts at 425 and 550°C using a feed gas with 10 vol % H₂O. The results showed that the composition of the washcoat plays a major role in the stability of the catalysts, with both AlOOH or CeO₂ enhancing the stability of the PdO/Al₂O₃ catalyst in the presence of H₂O. Moreover, a washcoat overlayer applied to the PdO(Pt/CeO₂)/AlOOH/Al₂O₃ monolith catalysts, is shown to enhance CH₄ oxidation activity and stability at low temperature (< 500°C) in the presence of H₂O and SO₂. Three recent kinetic models of CH₄ oxidation reported in the literature and based on Langmuir-Hinshelwood kinetics have been applied to the data measured herein using the mini-monolith reactor. Data obtained in dry feed gas and with 2 and 5% H₂O in the feed gas were analysed. The results of the models show that adding CeO₂ or the washcoat overlayer decreases H₂O adsorption, which leads to enhanced catalyst activity.Applied Science, Faculty ofChemical and Biological Engineering, Department ofGraduat

Using Reciprocal Teaching Strategies to Improve Reading Comprehension For English as a Second Language Students With Learning Disabilities

Students who have problems comprehending textual material tend to experience failing grades, peer rejection, and even social isolation. Furthermore, students with poor reading comprehension demonstrate poor academic performance in all subjects, not due to difficulty in learning specific subject content (i.e., math, history, etc.), but rather their inability to comprehend reading passages related to that subject knowledge. Reciprocal teaching (RT) is an effective tool for teaching children with Learning Disabilities (LD) to improve their reading comprehension abilities. These multiple cognitive strategies can meet the needs of many students in terms of more deliberate, directed, and self-regulated learning through students’ interaction with reading texts. Still, gaps in the research warrant further investigation as many studies on this topic were published over 20 years ago. Additionally, most studies that looked at reciprocal teaching strategies have not investigated the impact of these strategies with English as a Second Language (ESL) students with LD. This research study investigated the effectiveness of using RT for a group of ESL students with LD and reading comprehension delays for whom English is a second language. A multiple-probe design across three different types of reading texts was used to assess the effectiveness of the RT interventions

The Impact of CeO₂ Loading on the Activity and Stability of PdO/γ-AlOOH/γ-Al₂O₃ Monolith Catalysts for CH₄ Oxidation

This study reports on the activity and stability of PdO/γ-AlOOH/γ-Al₂O₃ monolith catalysts, promoted with varying amounts of CeO₂, for CH₄ oxidation. Although the beneficial effects of CeO₂ have been reported for powdered catalysts, this study used a cordierite (2MgO.2Al₂O₃.5SiO₂) mini-monolith (400 cells per square inch, 1 cm diameter × 2.5 cm length; ~52 cells), washcoated with a suspension of γ-Al₂O₃ combined with boehmite (γ-AlOOH), followed by sequential deposition of Ce and Pd (0.5 wt.%) by wetness impregnation. The monolith catalysts’ CH₄ oxidation activity and stability were assessed in the presence of CO, CO₂, H₂O and SO₂ at low temperature (≤550 °C), relevant to emission control from lean-burn natural gas vehicles (NGVs). The CeO₂ loading (0 to 4 wt.%) did not significantly impact the adhesion and thermal stability of the washcoat, but CeO₂ reduced the inhibition of CH₄ oxidation by H₂O and SO₂. The catalyst activity, measured by temperature-programmed methane oxidation (TPO) in a dry feed gas with 0.07 vol.% CH₄, showed that adding CeO₂ to the γ-AlOOH/γ-Al₂O₃ washcoat suppressed the activity of the catalysts; whereas, CeO₂ improved the catalyst activity when H₂O (2 and 5 vol.%) was present in the feed gas. Moreover, adding CeO₂ decreased catalyst deactivation that occurred in the presence of 10 vol.% H₂O and 5 ppmv SO₂ at 500 °C, measured over a 25 h time-on-stream (TOS) period. The highest catalyst activity and stability for CH₄ oxidation in the presence of H₂O was obtained by adding 2 wt.% CeO₂ to the washcoat.Applied Science, Faculty ofNon UBCChemical and Biological Engineering, Department ofReviewedFacult

Physicochemical Characterization of Natural Rocks and Their Applications for Wastewater Treatment

Arid countries such as Arabian Gulf countries are suffering from a water shortage, especially with the recent high-water demand. The best solution for this shortage is the management of currently available water resources, through the reuse of treated wastewater for irrigation purposes. This solution also solves the problem of regularization of wastewater discharge, with positive impacts on the environment. This study aimed to apply an innovative, advanced method for treating wastewater with a favorable environment, low economic cost, and less energy consumption. The research investigated the possibility of using natural rocks such as volcanic and zeolite for advanced treatment of wastewater effluent. The research methodology relied on an experimental work in the lab scales and applied on materials available in Saudi Arabia. The experiments included a leaching batch test to first examine what leaches out from these rocks into water. Then, the materials were tested with wastewater effluent. The main mechanism of treatment was based on the absorption process. The results exhibited significant improvement in the water quality of treated wastewater. On the other hand, the results of the leaching tests showed many ions being dissolved from both rocks into water; thus, it is recommended to soak and flush these solid materials with clean water before using them for the treatment process. Further research is required to determine the best pretreated methods to be applied on these rocks to improve their performance as absorbents