Cost Minimization for Coal Conversion Pollution Control: A Mixed Integer Programming Model

A mixed integer program was structured to identify the least cost combination of recycling and treatment alternatives that can be used to control the liquid, solid, and gas waste streams produced from a 750-megawatt coat fired steam electric power plant. The model compared methods of liquid stream recycle and waste discharge treatment to meet given air and water quality standards. The model was then used to study the effects on the optimal solution of changes in capital, operation and maintenance, and energy and water costs. In addition, the effects on optimum system design of changes in particulate and sulfur oxide emission standards and stream discharge standards were evaluated. Nonlinear cost functions for system components were structured with binary integer variables to define the ordinate intercept and with continuous variables to define the slopes of total cost curve segments. The binary and continuous variables were associated with each other in pairs to approximate nonlinear total cost functions of alternative pollution control units. The optimal plant design was sensitive to increases in capital, operation and maintenance, and energy costs as well as air emission standard changes. The model indentified the optimal treatment until alternatives and their sizes when segments of the total costs and environmental standards were changed. The optimal solutions always indentified water recycle, rather than stream discharge, as the optimal production strategy

Mapping Urban aerosolized fungi: Predicting spatial and temporal indoor concentrations

© 2018, Society for Human Ecology. All rights reserved. The prediction of bioaerosols, specifically airborne fungi, can be achieved using various mapping techniques, potentially enabling the determination of ambient indoor concentrations within environments where people spend most of their time. The concentration and composition of indoor air pollutants are determined by a multitude of variables, with building ventilation type being the most predominant factor in most scenarios. A predictive statistical model-based methodology for mapping airborne fungi was developed utilizing satellite-based technology. Mapping was carried out for total aerosolized fungal spores and the diversity of aerosolized fungi in Sydney, Australia, over four seasons. Corresponding data for a range of environmental parameters known to influence airborne fungi were also used, notably green space density, land cover, altitude, meteorological variables, and other locally determined factors. Statistical models previously developed from the combined meteorological and environmental variable data were used to establish spatiotemporal models for airborne fungi across the study area for each season. Results showed that the models produced reasonable predictions of monitored aeromycota concentrations; although, the accuracy of these predictions for individual survey periods was variable. Using known indoor/outdoor (I/O) ratios of airborne fungi for the area, the prevalence and concentrations of indoor aeromycota were modeled for buildings with both natural and mechanical ventilation. As accurate manual assessment of the aeromycota is labor, time, and cost intensive, the current findings should assist in the prediction of fungal aerosols in both urban and indoor environments. Additionally, understanding the indoor microbiome has great importance for the health and well-being of the occupants concerned

Understanding the impacts of air pollution on human experience: Two case studies

In the months that preceded the global spread of COVID-19, a series of airborne events transformed the atmosphere of the Indo-Pacific region; the bushfire smoke on the East coast of Australia, the tear gas used in the Santiago de Chile and Hong Kong protests, the Indian Supreme Court ruling on Delhi’s pollution failures, and activists covering iconic statues with respirators across Johannesburg and Pretoria. All these incidents map the political struggles taking place in the region’s air, triggering a proliferation of masked faces avant la lettre. The publication Folk Costumes, Indo-Pacific Air is an account of the region’s masked state. It brings together culturally and geographically diverse case studies exploring air’s effects on the body to describe the emergent wearable architectures it produces. Considered as folk costumes, these wearables are socio-technical constructions that mediate our relationship with the environment—they negotiate our daily struggles, emancipatory efforts, and emotional inner-lives. Discussing air as a political matter, the book collects contributions by scientists, writers, historians, architects, photographers, and dilettantes, encouraging readers to fly freely between visual and conceptual affinities to create a map of a region in the making

Bench-Study of Green-Wall Plants for Indoor Air Pollution Reduction

Potted-plants have the potential for improving indoor air quality (IAQ), however there has been little research on the performance of green-walls as indoor biofilters. The aim of this investigation was to compare rates of air pollutant reduction with two commonly used indoor species, and to assess the effects of added substrate airflows on the capacity of green-wall modules to remove two prevalent indoor airborne contaminants - particulate matter (PM), and volatile organic compounds (VOCs), using benzene as model. The species tested were Chlorophytum comosum (Spider Plant) and Epipremnum aureum (Pothos). The results showed that each species could significantly reduce increasing doses of PM, with or without augmented substrate airflow, however benzene removal rates decreased with increasing aeration. The findings provide a first assessment of the ability of green-wall plants to reduce indoor air pollution, and responses to two types of pollutant, particulate and gaseous

A competitive model for determining air pollution in urban areas: The potential for vegetation for air pollution mitigation

Over the past few decades, the relationship between air pollution and urban forestry has been receiving increasing consideration as global cities have undergone rapid transformation. Urbanisation has resulted in population densification and increased air pollution due to the increased anthropogenic sources. Consequently, urban forestry has been proposed as one of the solutions as it has the potential to mitigate and ameliorate urban air pollution. This research investigated the spatial extent of four air pollutant concentrations and urban forestry to determine the relationship between air pollution concentrations and urban forestry across Sydney, Australia. Ambient air pollutant concentrations and other variables such as land cover, population density, dwelling density, were combined to create a Land Use Regression (LUR) model to develop predictive models for urban CO, NO₂, SO₂, and PM₁₀ concentrations. Differences in pollutant concentrations were assessed with ArcGIS and analysis of covariance across various land cover types; active vegetation, non-active vegetation and bare ground. The relative influence of predictor variables for pollutant concentrations were determined using a stepwise multiple linear regression. An inverse relationship between urban forestry and air pollution was observed and quantified in the land cover model. Furthermore, tree canopy cover was negatively correlated with all four air pollutants and urban indicators of pollution including dwelling density, population density and traffic count was positively correlated with the pollutants. This LUR model established a statistically significant spatial relationship between urban forestry and air pollution mitigation and amelioration. These findings confirm urban forestry’s capabilities to mitigate and ameliorate air pollution on a city-wide scale. Furthermore, these findings could be incorporated in to or used to develop urban planning and greening policies whilst promoting urban forestry uptake in Sydney

A Field Technique Measuring Virus Decay and Potential Aerosol Hazard from Wastewater Sprinkler Irrigation

The increased use of domestic wastewater for irrigation purposes has stimulated a growing practice of sprinkler irrigating from oxidation ponds and other domestic wastewaters. Aerosols generated from these sprinkler irrigation systems may contain potentially hazardous pathogens. Subsequently, the aerosols can contain infective viruses which can be carried through the air to surrounding populations. Thus, a public health hazard can be created by sprinkler irrigating domestic wastewater. This study is an investigation of a means by which the virus decay rate of viruses in aerosols and the potentials hazard of sprinkler irrigation aerosol clouds may be examined. A means of injection of a human and animal virus stimulant, MS-2 bacteriophage, is described. In addition, the factors which are known to effect the survival of viruses in aerosols are discussed. The ambient air factors that are known to effect virus survival and which are discussed include relative humidity, air temperature, solar radiation, and aerosol age. The suspending fluid factors that are known to effect virus survival and which are discussed include dissolved inorganic salt contact, dissolved organic content, filterable solids and pH. The decay rate of the aerosolized MS-2 was measured with an all-glass impinger (AGI-30) when the wind velocity and distance of the sampler from the sprinkler system, and the initial and final concentrations of aerosolized MS-2 virus were known. The aerosol hazard of a domestic wastewater sprinkler irrigation system is defined in terms of the likelihood of infective aerosol particles to be inhaled and penetrate the human lung. Thus, the aerosol hazard is a function of aerosol particle size. The aerosol particle size distribution of the infective aerosol cloud was measured wit the Andersen sampler. A high and homogeneous concentration of the virus in the wastewater was insured by using pressure differentials in the sprinkler irrigation delivery line. By injecting the MS-2 virus into the line at a constant rate along with a tracer, Bacillus subtilus var niger (Bacillus globigii) spores, the decay rate of the virus during airborne exposure to environmental factors could be determined. The decay rate was determined assuming the environmental factors had no affect on the concentration of the tracer. It was proposed that the environmental engineer, after knowing the virus decay rates under varying environmental conditions, can define buffer zones which would be required around sprinkler irrigation sites. The buffer zone would reduce the possibility of contaminating humans by prohibiting access. The usefulness of the filed technique was demonstrated and the MS-2 was found to undergo a 33.3 percent decay per minute in the dark (no solar radiation) at 33 percent relative humidity, 70.6 percent dissolved organic material, 29.4 percent dissolved inorganic salts, 30.1 mg/1 filterable solids, and 17 degree C air temperature. The aerosol cloud resulting from the spray irrigation process appeared potentially hazardous because the Andersen sampler collected 84.2 percent of the virus infective droplets in the size range that could be inhaled

The evolution of botanical biofilters: developing practical phytoremediation of air pollution for the built environment

Indoor air quality is of emerging importance due to the rapid growth of urban populations that spend the majority of their time indoors. Amongst the public, there is a common perception that potted plants can clean the air of pollutants. Many laboratory based studies have demonstrated air pollution phytoremediation with potted plants. It has, however, been difficult to extrapolate these removal efficiencies to the built environment and, contrary to popular belief, it is likely that potted plants could make a negligible contribution to built environment air quality. To overcome this problem, active green walls have been developed which use plants aligned vertically and the addition of active airflow to process a greater volume of air. Although a variety of designs have been devised, this technology is generally capable of cleaning a variety of air pollutants to the extent where comparisons against conventional air filtration technology can be made. The current work discusses the history and evolution of air phytoremediation systems from potted plants through to practical botanical air filtration

Grey to Green Transition: mapping a way forward for green walls

Youtube: https://www.youtube.com/watch?v=-3KUUGyUwAg Urbanisation and densification continue to present a unique set of environmental challenges, as declining urban green spaces are intrinsically linked with population growth, urban sprawl and development. Consequently, the loss of green space also comes with increased air pollution, elevated levels of noise pollution, loss of biodiversity and the increase in urban heat island effect. Further, space limitations are characteristically an issue faced in urban areas as green space is often in competition with other land uses or socioeconomic priorities. Despite these issues, many global cities aim to achieve sustainability targets or green goals in the near future. For example, the City of Sydney’s current goal is to have 40% green cover by 2050, while the cities of Melbourne and Brisbane aim to achieve their 40% green cover targets by 2040 and 2031 respectively. But, it is unknown if it can be achieved with the cities’ current structures and designs. Increasingly, green walls (GWs) have been considered an adaptive environmental solution to space-limited urban areas while potentially improving the sustainability and regreening of cities. Therefore, evaluation methods are required to allow for appraisal to see if existing walls can be retrofitted with GWs. Furthermore, there is a lack of feasibility studies aimed at quantifying the potential for retrofit suitability of GWs across large urban areas or cities. This study developed a preliminary evaluation tool for GW suitability in high density urban areas. Using the tool, the quantity of walls across five major Australian cities that could potentially incorporate GWs was determined. Each wall was analysed using a set of criteria that assessed and ranked the wall based on its suitability. Interestingly, major cities across Australia varied in terms of greening potential with the cities of Sydney and Brisbane recording the greatest proportional length of walls suitable for GW implementation, with approximately 34%. Comparatively, the cities of Perth and Adelaide had the least greening potential, with less than 5% for each city, as many walls were excluded due to the prevalence of glazed facades and heritage buildings. Furthermore, Australian cities had very few GWs present with less than 1% of surveyed walls already greened. These results indicate that cities like Sydney and Brisbane could realistically achieve their targets if they incorporated urban forestry vertically. Though, Perth and Adelaide may need to consider other greening options such as green roofs. These results also highlight the importance of green walls and green roofs as a solution to the space-constrained areas that are characteristic of our urban cityscapes and they offer a green alternative to urban parklands and forestry that may not be viable in the future. Additionally, the accessibility of this tool will allow interested individuals, communities and organisations to assess the retrofit suitability of an area for GW implementation with minimal requirements in terms of training or resources, and could be applied globally. Subsequently, the outcomes of this study emphasised the need for more governmental support and incentives to encourage GW uptake, and this tool could play a pivotal role in the expansion of green infrastructure and urban forestry

Testing the single-pass VOC removal efficiency of an active green wall using methyl ethyl ketone (MEK)

© 2017, The Author(s). In recent years, research into the efficacy of indoor air biofiltration mechanisms, notably living green walls, has become more prevalent. Whilst green walls are often utilised within the built environment for their biophilic effects, there is little evidence demonstrating the efficacy of active green wall biofiltration for the removal of volatile organic compounds (VOCs) at concentrations found within an interior environment. The current work describes a novel approach to quantifying the VOC removal effectiveness by an active living green wall, which uses a mechanical system to force air through the substrate and plant foliage. After developing a single-pass efficiency protocol to understand the immediate effects of the system, the active green wall was installed into a 30-m3 chamber representative of a single room and presented with the contaminant 2-butanone (methyl ethyl ketone; MEK), a VOC commonly found in interior environments through its use in textile and plastic manufacture. Chamber inlet levels of MEK remained steady at 33.91 ± 0.541 ppbv. Utilising a forced-air system to draw the contaminated air through a green wall based on a soil-less growing medium containing activated carbon, the combined effects of substrate media and botanical component within the biofiltration system showed statistically significant VOC reduction, averaging 57% single-pass removal efficiency over multiple test procedures. These results indicate a high level of VOC removal efficiency for the active green wall biofilter tested and provide evidence that active biofiltration may aid in reducing exposure to VOCs in the indoor environment