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Air Pollution And Control Technologies By Anjaneyulu Pdf 29



Air pollution became a widespread problem in the United States (US) and, according to the Environmental Protection Agency (EPA), it is estimated that over 100 million individuals are routinely exposed to levels of air pollution that exceed one or more of their health-based standards [1]. The major air pollutants include oxides of sulfur and nitrogen, suspended particulate matter, oxides of carbon, hydrocarbons, lead. These gases are released into the atmosphere from either stationary sources such as industrial point sources or mobile sources like vehicular pollution. These pollutant gases will also produce secondary pollutant like surface Ozone, which has great oxidative capacity and is the primary component of urban smog. Criteria Pollutants Ozone and particulate matter (PM10 and PM2.5) are main focus now as they manly drive the AQI (which is based on five criteria pollutants CO, NO2, SO2, O3, PM). These pollutants can affect our health in many ways, with irritation to the eyes, nose and throat and more serious problems such as chronic respiratory disease and cardiovascular diseases. Understanding the long-term (yearly, decadal) trends of these criteria air pollutants is important for assessing chronic exposure to population and the efficacy of control strategies, emissions changes, and the year to- year influence of meteorology.




air pollution and control technologies by anjaneyulu pdf 29



Pollutants in the atmosphere undergo transportation and dispersion, whose characteristics are dependent on the prevailing atmospheric conditions. Pollutants can be transported across the continents due to globally circulating winds on time scale of months to years, e.g. intercontinental transport of dust from Sahara desert in Northwest Africa and the Gobi desert in East Asia and dispersed over a few hundreds of miles in a few days under the influence of local scale wind circulations. While wind is primarily responsible for transportation and dispersion, topography and atmospheric stability also play an important role. Horizontal and vertical motions arise due to atmospheric pressure gradients and stability conditions. Atmospheric pressure, defined as the weight of the air column above a point, varies due to differential surface heating. Heating and cooling of the earth surface is dependent on the type of surface, for e.g. water bodies have larger specific heat capacity and so takes longer time to get heated or cooled as compared to land surface. Different surfaces have different heating/cooling rates, e.g. asphalt surface gets heated/ cooled faster than vegetation surface; heating/ cooling at the surface causes lower/ higher density vertical columns leading to lower/ higher pressures. As air tends to move from denser to lighter regions, atmospheric wind gets established as movement from high pressure regions to low pressure regions. Similarly vertical motions are dependent on atmospheric stability. Heating at surface causes air to rise mixing with cooler and denser air at higher levels leading to instability and most of the mixing takes place in the lowest part of the atmosphere referred to as atmospheric boundary layer. This is characterized by turbulent fluctuations of wind velocity, temperature and moisture due to energy exchange with earth surface capped by an infinitesimal transition layer below the free atmosphere with lower/ higher stability conditions associated with stronger/ weaker vertical mixing. Since the pollutants originate near the earth surface, characteristics of the atmospheric boundary layer play an important role in the dispersion of pollutants. This is the reason why winter nights which are cooler with higher stability have stagnation of pollutants causing health hazards. Atmospheric dispersion on the scale of a few days (synoptic time scale) is influenced by the transient surface low and high pressure systems. Moderate to intense low pressure systems characterized by winds > 5m/s, mass convergence, higher instability and upward motions contribute to dispersion over wider horizontal extent ranging up to few thousand kilometers thus reducing the pollution effect through mixing with larger environment volume. Conversely, high pressure systems with calm winds, subsiding downward motion and higher atmospheric stability contain dispersion to smaller volume enhancing the pollution effects. These emphasize the role of atmospheric stability criteria and prevailing atmospheric circulation on the atmospheric dispersion of pollutants. In the absence of synoptic forcing, mesoscale and local circulations developed due to topography and land use variations and with synoptic forcing admixture of synoptic scale and mesoscale circulations control the pollutant dispersion.


One of the most relevant articles of the MC to the Indian situation is Article 8, which recommends controlling and, where feasible, reducing emissions of mercury and its compounds to the atmosphere. The article also obliges the parties to the convention to prepare and implement a national action plan (NAP) for managing mercury emissions, as soon as practicable but no later than 10 years after the entry-into-force of the MC. The NAP interventions for mercury pollution management and control, depending on the national circumstances, include establishing a coordinating mechanism and organization process; developing a national overview of the ASGM sector (including baseline estimates of mercury use and practices); setting goals, national objectives and reduction targets; formulating an implementation plan; and developing an evaluation mechanism for the NAP [36]. To do so, some of the suggested measures are to control emissions from point sources such as coal-fired power plants, coal-fired industrial boilers, smelting and roasting processes used in the production of non-ferrous metals, waste incineration facilities, and cement clinker production facilities. In fact, these are the major sources of mercury emissions in India and account for more than 50% of the total mercury emissions to the environment. If effectively implemented, the already existing relevant Indian regulations will play an important role in reducing such large mercury emissions. The Air (Prevention and Control of Pollution) Act, 1981, in India confers and assigns power and functions to Pollution Control Boards (at the National and State level) for the prevention, control, and abatement of air pollution. Under the provisions of this Act, the Central Pollution Control Board (CPCB) sets national ambient air quality standards and is responsible for both testing air quality and assisting the government in policy implementation to meet set standards. In addition to the Air Act, the Environment (Protection) Act, 1986, in India serves as an umbrella act for a variety of environmental issues and empowers the central government to establish authorities charged with the mandate of preventing environmental pollution in all its forms and tackle specific environmental problems nationwide [37]. Article 9 of the MC concerns controlling and reducing the release of mercury and its compounds to land and water. The relevant Indian regulation to manage and control mercury released to the water resources in India is the Water (Prevention and Control of pollution) Act, 1974. This regulation aims to prevent and control water pollution in any form and to maintain/restore wholesomeness of water in India by establishing Pollution Control Boards at the National and State levels which monitor and enforce policies and water quality standards in this regard.


The issue of mercury-containing waste management is as important and challenging as the mercury emissions from large industries. India generates about 5500 tonnes of e-waste per day, of which only 1.5% is recycled [50]. The collection and recycling of e-waste is mostly done by the informal sector, which is largely unorganized and often bypasses the waste management policies and guidelines. In such a situation, it becomes difficult to recover mercury from e-wastes due to improper handling and dismantling of waste by low-cost techniques and poorly skilled workers, ultimately leading to serious environmental burdens and health implications. The environmental imprints of such activities have been shown in a recent study which demonstrates high mercury contamination levels (up to 16 mg/kg) in soils from e-waste dismantling, shredding, and dumping sites in four major Indian cities [22]. Over time, continuous accumulation of pollutants including mercury at such dumping sites turns them into the category of designated contaminated sites. These contaminated sites receive recognition from the Ministry of Environment, Forest and Climate Change (MoEFCC), which initiated projects on the remediation of hazardous waste-contaminated dumpsites in the country with CPCB as an executing agency under the National Clean Energy Fund. One of the challenges in managing and remediating such contaminated sites is in terms of mercury pollution control. The CPCB of India concisely lists severely contaminated sites and provides guidelines for their remediation, but the scope of these guidelines is broad and does not provide specifications for individual pollutants including mercury. In particular, these guidelines and regulations for waste management in India appeared rather ineffective in handling accidents such as the Kodaikanal mercury poisoning. It took around one and half decade to do justice to the affected environment and people impacted by the mercury emissions from the thermometer factory in Kodaikanal in Tamil Nadu: the State Pollution Control Board recommended remediation of the soil at the contaminated site in Kodaikanal, however, concerns were raised about the target remediation standard (20 mg/kg) that was accepted in the process of de-contaminating this site, which is 20 times higher than what would have been required in many developed countries. In addition, former workers of the thermometer factory who were exposed to the toxic mercury vapor were given compensations by the employer in the form of financial support and benefits of long-term health and well-being [43]. This incident typically highlights the corporate negligence regarding pollution management and environmental justice in developing countries like India. The case not only illustrated the lack of coherence between corporations and the regulatory system, but also failed to gain the support of systematic research studies monitoring mercury contamination in the environment and human population residing in this area. Overall, to better manage labeled contaminated sites, it is necessary to upgrade existing guidelines by specifying the baseline conditions (of contamination levels and risks to the environment and the human population) and by providing a systematic scheme to prioritize and remediate the contaminated sites. In addition, a scheme for proper channelization of funds especially for better infrastructure, development and adoption of appropriate technology to remediate the contaminated sites, training facilities for waste-handlers at each level, and developing and implementing strategies to transform the unorganized and informal waste management sector into an organized and formal sector should be well established [51]. This calls for cooperation with developed nations and international agencies in terms of transfer of expertise, technology and policy advisory, providing financial aid, and eliminating double-standards for waste management practices including waste offloading in developing countries. Several incidences of illegal waste inflow to developing countries including India have been reported in the past [52, 53]. The implementation of the MC demands phasing-out of mercury-containing health-care equipment and proper management of bio-medical waste that contains traces of mercury from either disposed health-care instruments or pharmaceuticals and personal care products. In India, the amount of bio-medical wastes generated (an estimate of about 520 tonnes per day in 2016) is by several orders of magnitude smaller than the MSWs and e-wastes [54]. Nevertheless, it is a substantial source of mercury pollution due to the significant use of mercury in healthcare instruments, dentistry, and pharmaceuticals in India. Considering the seriousness of the matter, the MoEFCC of the Government of India amended the bio-medical waste management rules in 2016. However, the amendment is not specially focused on the mercury pollution from bio-medical wastes, but more on the structure and capacity of the existing bio-medical waste management system in India. The new rules have simplified the categorization of the bio-medical wastes and authorization system to improve the coverage, collection, segregation, transport, and disposal of bio-medical waste. In the context of mercury management, the rules do not provide specific strategies for handling mercury-containing bio-medical wastes, for example specification about the standards for mercury emissions at Common Bio-Medical Waste Treatment Facility (CBMWTF) are missing. This leaves a further scope to manage mercury emissions from CBMWTF, ultimately requiring steps to eliminate mercury sources and to adopt alternatives of mercury-based products (including alternate dental fillings) in health care facilities. This is especially relevant for the dental-care facilities in India. It was estimated that in India annually about 66 tonnes of mercury waste can be generated as a result of removal of mercury containing dental fillings [55]. Managing mercury waste from dental-care units requires different approaches for rural and urban settings in India, considering that the rural areas lack awareness of mercury toxicity, modern dental care facilities, and availability of mercury-free alternatives. Moreover, the appropriate handling of bio-medical waste should be carried out by the dental practitioners, which can be achieved through regular monitoring and training programs for practitioners, adequate resource availability for the handling, segregation, collection and disposing of bio-medical waste [56,57,58]. 350c69d7ab


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