Pollutant gas and particulate material emissions in ethanol production in Brazil: social and environmental impacts

Evaluation of the efficiency of a Venturi scrubber in particulate matter collection smaller than 2.5 µm emitted by biomass burning

Energy demand has increased worldwide, and biomass burning is one of the solutions most used by industries, especially in countries that have a great potential in agriculture, such as Brazil. However, these energy sources generate pollutants, consisting of particulate matter (PM) with a complex chemical composition, such as sugarcane bagasse (SB) burning. Controlling these emissions is necessary; therefore, the aim was to evaluate PM collection using a rectangular Venturi scrubber (RVS), and its effects on the composition of the PM emitted. Considering the appropriate use of biomass as an industrial fuel and the emerging need for a technique capable of efficiently removing pollutants from biomass burning, this study shows the control of emissions as an innovation in a situation such as the industrial one with the use of a Venturi scrubber in fine particle collection, in addition to using portable and representative isokinetic sampling equipment of these particles. The pilot-scale simulation of the biomass burning process, the representative sampling of fine particles and obtaining parameters to control pollutant emissions for a Venturi scrubber, meets the current situation of concern about air quality. The average collection efficiency values were 96.6% for PM_{> 2.5}, 85.5% for PM_1.0-2.5, and 66.9% for PM_{< 1.0}. The ionic analysis for PM_{< 1.0} filters showed potassium, chloride, nitrate, and nitrite at concentrations ranging from 20.12 to 36.5 μg/m³. As the ethanol and sugar plants will continue to generate electricity with sugarcane bagasse burning, emission control technologies and cost-effective and efficient portable samplers are needed to monitor particulate materials and improve current gas cleaning equipment projects.

Climate Risk Mitigation and Adaptation Concerns in Urban Areas: A Systematic Review of the Impact of IPCC Assessment Reports

Urban areas continue to be the center of action for many countries due to their contribution to economic development. Many urban areas, through the urbanization process, have become vulnerable to climate risk, thereby making risk mitigation and adaptation essential components in urban planning. The study assessed the impacts of IPCC Assessment Reports (ARs) on academic research on risk mitigation and adaptation concerns in urban areas. The study systematically reviewed literature through searches of the Web of Science and Scopus databases; 852 papers were retrieved and 370 were deemed eligible. The results showed that the East Asia and Pacific, and Europe and Central Asia regions were most interested in IPCC ARs, while Sub-Saharan Africa showed little interest. Several urban concerns, including socio-economic, air quality, extreme temperature, sea level rise/flooding, health, and water supply/drought, were identified. Additionally, studies on negative health outcomes due to extreme temperatures and air pollution did not appear in the first four IPCC ARs. However, significant studies appeared after the launch of the AR5. Here, we must state that climate-related problems of urbanization were known and discussed in scientific papers well before the formation of the IPCC. For instance, the works of Clarke on urban structure and heat mortality and Oke on climatic impacts of urbanization. Though the IPCC ARs show impact, their emphasis on combined mitigation and adaptation policies is limited. This study advocates more combined risk mitigation and adaptation policies in urban areas for increased resilience to climate risk.

Numerical analysis on a novel CGPFs for improving NOx conversion efficiency and particulate combustion efficiency to reduce exhaust pollutant emissions

Improving the NOx conversion efficiency and particulate combustion efficiency under cold-start conditions (low-temperature conditions) is still the main challenge faced by catalytic gasoline particulate filter systems (CGPFs). In this study, the physical and mathematical models of novel CGPFs are proposed based on the computational fluid dynamics software. Then, the models are validated based on experiments, and the performances of conventional and novel CGPFs are analyzed comparatively. The comparison conclusions indicate that the NOx conversion efficiency of the novel CGPFs increases by 3.2% and the particulate combustion efficiency increases by 2.7% under the same operating condition. Finally, the effects of exhaust flow v_f, exhaust oxygen mass fraction C_o, exhaust NO mass fraction C_NO, and electric heating power P_e on the NOx conversion efficiency and particulate combustion efficiency are investigated. The weights of each influencing parameter on the NOx conversion efficiency and particulate combustion efficiency are explored by orthogonal tests. The conclusions show that the NOx conversion efficiency is increased by 3.6% and the particulate combustion efficiency is increased by 16.7% compared to the initial condition. This study has an important reference value for improving the purification efficiency of vehicle emission under cold-start conditions.