Deposition and coagulation of aerosols from household spray products

This study investigated the dynamics of aerosols emitted from household spray products in terms of deposition rate, deposition velocity, and coagulation. Thirty brands of spray products were selected with respect to their uses. Time variations of particle size distribution and concentrations resulting from aerosol emission from the spray products were measured using the MetOneTM GT 321 particle counter. Deposition rates were estimated as a function of air exchange rate. Coagulation rates of singlet, doublet, and triplet particles were estimated using Smoluchowski’s equation. Average deposition rates for 0.3, 0.5, 1.0, 2.0, and 5.0 µm aerosols were 0.154, 0.157, 0.159, 0.165, and 0.170 min-1 , respectively. The results provide useful information about the fate of aerosols released from the spray products and can be used in indoor air quality modeling and exposure assessment studies

The potentials of waste-to-energy system in Nigeria: A study of pyrolysis conversion of wood residue to bio-oil in major cities of south-western Nigeria

n this study, the potentials of waste-to-energy system in Nigeria had been uncovered by considering the production of bio-oil from wood residue generated in major cities of south-western Nigeria using pyrolysis conversion. The major cities examined were Lagos, Abeokuta, Ibadan, Ilorin, Ado-Ekiti, Akure and Ile-Ife with wood residue generation of 807.7 Ton/day, 1,335.4 Ton/day, 65.5 Ton/day, 69.8 Ton/day, 15.1 Ton/day, 14.4 Ton/day and 8.1 Ton/day respectively. High tonnages generation from Abeokuta and Lagos result from their favourable environmental condition for afforestation, over-population and industrial influences. The potential of producing 1,161,242.4 litres/day of bio-oil using pyrolysis from a total of 2,316 Ton/day of wood residue generated from cities examined was discovered. The liable revenue to be generated from the sale of this bio-oil at ₦50/litre is ₦21.2 billion/year which can equally be used in providing lacking infrastructural facilities in examined cities. However, effective techno-economic analysis of the process is very important to know the capital and operating costs involved. Also, investigations into pyrolysis process optimization of wood residue are necessary to have optimum bio-oil production based on the available resource

Indoor/Outdoor Concentration of Pollutants Around Major Roundabouts in Ilorin Metropolis, Nigeria

The escalation of daily human activities has led to a surge in gaseous pollutants and particulates, with indoor environments often exhibiting higher pollutant levels than outdoor air. This study delves into the intricate relationship between outdoor pollutants and indoor settings near traffic intersections within the Ilorin metropolis. The research focuses on six strategically chosen locations with intensified vehicular and human interactions. Data on particulate concentration were collected at various time intervals.The Met One Aerocet 531s apparatus assessed indoor and outdoor particulate matter concentrations. Additionally, the Crowcon Gas Pro, a versatile multi-gas measurement equipment, facilitated the quantification of gaseous pollutants, including Oxygen, Carbon monoxide, Carbon dioxide, Hydrogen sulfide, and Methane. The assessment of other gaseous pollutants, such as NO, NO2, and NH3, was conducted using the ToxiRAE II apparatus, which offers diverse measurement capabilities. The Kestrel weather tracker contributed to the study by furnishing microclimatic parameters. All measurement instruments were strategically positioned at approximately 1.5 meters above ground level.Vehicular density variation emerged as a pivotal criterion in the evaluation process. Findings revealed elevated outdoor PM10 concentrations during rush hours at the roundabouts, indicating heightened pollutant emissions during peak traffic times. Conversely, intriguingly elevated indoor PM10 concentrations were observed within specific indoor environments during non-rush hour periods. This phenomenon potentially results from the interplay of meteorological fluctuations and indoor activities, underscoring the complexity of pollutant dispersion dynamics.Indoor-to-outdoor concentration ratios emerged as a significant metric, consistently exceeding unity across diverse sites. This observation substantiates the presence of indoor-based pollutant sources, necessitating vigilant monitoring and effective mitigation strategies to mitigate potential health risks for indoor occupants.This research contributes vital insights into the intricate domain of air quality assessment, offering nuanced perspectives on pollutant distribution dynamics, indoor exposure scenarios, and ensuing health implications. By addressing the complex nexus between outdoor and indoor environments, this study emphasizes the imperative of adopting comprehensive strategies to curtail pollutant emissions at their source, foster sustainable urban planning, and enhance the quality of indoor environments. The outcomes resonate with broader endeavours to address the far-reaching consequences of air pollution on both ecological equilibrium and human well-being

Modeling of an activated sludge process for effluent prediction—a comparative study using ANFIS and GLM regression

In this paper, nonlinear system identification of the activated sludge process in an industrial wastewater treatment plant was completed using adaptive neuro-fuzzy inference system (ANFIS) and generalized linear model (GLM) regression. Predictive models of the effluent chemical and 5-day biochemical oxygen demands were developed from measured past inputs and outputs. From a set of candidates, least absolute shrinkage and selection operator (LASSO), and a fuzzy brute-force search were utilized in selecting the best combination of regressors for the GLMs and ANFIS models respectively. Root mean square error (RMSE) and Pearson’s correlation coefficient (R-value) served as metrics in assessing the predicting performance of the models. Contrasted with the GLM predictions, the obtained modeling results show that the ANFIS models provide better predictions of the studied effluent variables. The results of the empirical search for the dominant regressors indicate the models have an enormous potential in the estimation of the time lag before a desired effluent quality can be realized, and preempting process disturbances. Hence, the models can be used in developing a software tool that will facilitate the effective management of the treatment operation

Ambient noise from off-grid diesel engines electric power generators in an urban environment

Abstract Purpose – The aim of this paper is to investigate the impacts of the noise from the diesel engine power generators used for production activities in an urban environment. Design/methodology/approach – This study has used the Enterprise Edition of NoiseMap 2000 Version 2.7.1 to investigate the impacts of the noise from the diesel engines electric power generators used in a factory in Ikorodu, an urban environment in Lagos, Nigeria. Five sections of the factory with diesel engines electric power generators were considered. The immediate and distant environments covering about 10 km of the factory host environment were considered as receptors to the noise for this study. Findings – It was found out that when all the generators operate simultaneously in the factory, the ambient noise was 30.0-152.5 dB(A) with the minimum contribution within the factory being 70.0-84.4 dB(A) and the maximum contribution of 57.2-70.8 dB(A) outside the factory fence line. Though the maximum noise is 152.5 dB(A), the maximum noise of 70.8 dB(A) beyond the fence line shows a compliance with 70 dB(A) industrial and commercial area limit but breaches the 45 dB(A) and 55 dB(A) residential area limit of the World Bank. Research limitations/implications – As much as it would be desirable ambient noise level could not be measured in all the receptors’ locations covered by the modeling. However, the capability of themodeling software adopted makes this to have no negative impact on the quality of the findings of this study. Practical implications – The study will assist the public to determine the noise level safe region around diesel engine electric power generators. Originality/value – The paper highlights the challenges in which ambient noise from the use of off-grid generators used for industrial purposes could pose to the neighboring receptor environments

Environmental Benefits of Ultra-Low Emission (ULE) Technology Applied in China

Seven scenarios were designed to study the national environmental benefits of ULE in coal-fired power plants (CPPs), ULE in industrial coal burning (ICB) and NH3 emission reduction by using the GEOS-Chem model. The results showed that although the CPPs have achieved the ULE transformation target, the PM2.5 concentration across the country has decreased by 4.8% (1.4 μg/m3). Due to the complex non-linear chemical competition mechanism among nitrate and sulfate, the average concentration of nitrate in the country has increased by 1.5% (0.1 μg/m3), which has reduced the environmental benefits of the power plant emission reduction. If the ULE technology is applied to the ICB to further reduce NOx and SO2, although the PM2.5 concentration can be reduced by 10.1% (2.9 μg/m3), the concentration of nitrate will increase by 2.7% (0.2 μg/m3). Based on the CPPs-ULE, NH3 emissions reduced by 30% and 50% can significantly reduce the concentration of ammonium and nitrate, so that the PM2.5 concentration is decreased by 11.5% (3.3 μg/m3) and 16.5% (4.7 μg/m3). Similarly, based on the CPPs-ICB-ULE, NH3 emissions can be reduced by 30% and 50% and the PM2.5 concentration reduced by 15.6% (4.4 μg/m3) and 20.3% (5.8 μg/m3). The CPPs and ICB use the ULE technology to reduce NOx and SO2, thereby reducing the concentration of ammonium and sulfate, causing the PM2.5 concentration to decline, and NH3 reduction is mainly achieved through reducing the concentration of ammonium and nitrate to reduce the concentration of PM2.5. In order to better reduce the concentration of PM2.5, NOx, SO2 and NH3 emission reduction control measures should be comprehensively considered in different regions of China. By comprehensively considering the economic cost and environmental benefits of ULE in ICB and NH3 emission reduction, an optimal haze control scheme can be determined

Environmental Benefits of Ultra-Low Emission (ULE) Technology Applied in China

Seven scenarios were designed to study the national environmental benefits of ULE in coal-fired power plants (CPPs), ULE in industrial coal burning (ICB) and NH3 emission reduction by using the GEOS-Chem model. The results showed that although the CPPs have achieved the ULE transformation target, the PM2.5 concentration across the country has decreased by 4.8% (1.4 μg/m3). Due to the complex non-linear chemical competition mechanism among nitrate and sulfate, the average concentration of nitrate in the country has increased by 1.5% (0.1 μg/m3), which has reduced the environmental benefits of the power plant emission reduction. If the ULE technology is applied to the ICB to further reduce NOx and SO2, although the PM2.5 concentration can be reduced by 10.1% (2.9 μg/m3), the concentration of nitrate will increase by 2.7% (0.2 μg/m3). Based on the CPPs-ULE, NH3 emissions reduced by 30% and 50% can significantly reduce the concentration of ammonium and nitrate, so that the PM2.5 concentration is decreased by 11.5% (3.3 μg/m3) and 16.5% (4.7 μg/m3). Similarly, based on the CPPs-ICB-ULE, NH3 emissions can be reduced by 30% and 50% and the PM2.5 concentration reduced by 15.6% (4.4 μg/m3) and 20.3% (5.8 μg/m3). The CPPs and ICB use the ULE technology to reduce NOx and SO2, thereby reducing the concentration of ammonium and sulfate, causing the PM2.5 concentration to decline, and NH3 reduction is mainly achieved through reducing the concentration of ammonium and nitrate to reduce the concentration of PM2.5. In order to better reduce the concentration of PM2.5, NOx, SO2 and NH3 emission reduction control measures should be comprehensively considered in different regions of China. By comprehensively considering the economic cost and environmental benefits of ULE in ICB and NH3 emission reduction, an optimal haze control scheme can be determined