The Management of Hazardous Waste in Developing Countries

This book chapter discusses the management of hazardous waste in developing countries, with particular emphasis on industrial hazardous waste, medical waste, and household hazardous waste. It seeks to identify the current situation and also aims to provide a review of the existing strategies that are particularly related to hazardous waste management. In developing countries, hazardous waste management systems lack a systematic approach to administer waste management programmes; inability to effectively collect and manage wastes as well as to reduce the negative impacts of those activities. The current regulatory frameworks and regulations do not adequately address hazardous waste treatment and final disposal. There are inadequacies in the implementation of regulations associated with hazardous waste management due to fragmented responsibilities among government departments and local authorities. The chapter provides practical best processes for the management of hazardous waste aimed at improving the current situation

The Generation, Composition, Collection, Treatment and Disposal System, and Impact of E-Waste

The problem of e-waste has forced governments of many countries to develop and implement environmentally sound management practices and collection schemes for E-waste management, with a view to minimize environmental impacts and maximize re-use, recovery and recycling of valuable materials. In developed countries, e-waste management is given high priority countries, while in developing countries, it is exacerbated by completely adopting or replicating the e-waste management of developed countries and several problems including, lack of investment, technological, financial, technically skilled human resources, lack of infrastructure, little available information on the e-waste situation, recovery of valuable materials in small workshops using rudimentary recycling methods, lack of awareness on the impacts of e-waste, absence of appropriate legislations specifically dealing with e-waste, approach and inadequate description of the roles and responsibilities of stakeholders and institutions involved in e-waste management, etc. This chapter provides the definition of e-waste, and presents information on generation of –andcomposition of e-waste, collection, treatment, and disposal systems. It also discusses the overview of e-waste collection schemes in different parts of the world with regional focus, and the best current practices in WEEE management applied indeveloped and developing countries. It outlines the illegal e-waste trade and illegal waste disposal practices associated with e-waste fraction. In this chapter, the terms “WEEE” and “E-waste” are used synonymously and in accordance to the EU, WEEE Directive

A simplified thermoregulation model of the human body in warm conditions

Thermoregulation models of the human body have been widely used in thermal comfort studies. The existing models are complicated and not fully verified for application in China. This paper presents a simplified thermoregulation model which has been statistically validated by the predicted and measured mean skin temperature in warm environments, including 21 typical conditions with 400 Chinese subjects. This model comprises three parts: i) the physical model; ii) the controlled system; and iii) the controlling system, and considers three key questions formerly ignored by the existing models including: a) the evaporation efficiency of regulatory sweat; b) the proportional relation of total skin blood flow and total heat loss by regulatory sweating against body surface area; and c) discrepancies in the mean skin temperatures by gender. The developed model has been validated to be within the 95% confidence interval of the population mean skin temperature in three cases

A method of evaluating the accuracy of human body thermoregulation models

Human Body Thermoregulation Models have been widely used in the field of human physiology or thermal comfort studies. However there are few studies on the evaluation method for these models. This paper summarises the existing evaluation methods and critically analyses the flaws. Based on that, a method for the evaluating the accuracy of the Human Body Thermoregulation models is proposed. The new evaluation method contributes to the development of Human Body Thermoregulation models and validates their accuracy both statistically and empirically. The accuracy of different models can be compared by the new method. Furthermore, the new method is not only suitable for the evaluation of Human Body Thermoregulation Models, but also can be theoretically applied to the evaluation of the accuracy of the population-based models in other research fields

A study of adaptive thermal comfort in a well-controlled climate chamber

This paper aims to critically examine the application of Predicted Mean Vote (PMV) in an air-conditioned environment in the hot-humid climate region. Experimental studies have been conducted in a climate chamber in Chongqing, China, from 2008 to 2010. A total of 440 thermal responses from participants were obtained. Data analysis reveals that the PMV overestimates occupants' mean thermal sensation in the warm environment (PMV > 0) with a mean bias of 0.296 in accordance with the ASHRAE thermal sensation scales. The Bland–Altman method has been applied to assess the agreement of the PMV and Actual Mean Vote (AMV) and reveals a lack of agreement between them. It is identified that habituation due to the past thermal experience of a long-term living in a specific region could stimulate psychological adaptation. The psychological adaptation can neutralize occupants’ actual thermal sensation by moderating the thermal sensibility of the skin. A thermal sensation empirical model and a PMV-revised index are introduced for air-conditioned indoor environments in hot-humid regions. As a result of habituation, the upper limit effective thermal comfort temperature SET* can be increased by 1.6 °C in a warm season based on the existing international standard. As a result, a great potential for energy saving from the air-conditioning system in summer could be achieved

Seasonal variation of thermal sensations in residential buildings in the hot summer and cold winter zone of China

The seasonal differences of neutral or acceptable temperatures between summer and winter were revealed by previous researchers, but the studies on the difference of human thermal adaption in transitional seasons are insufficient. To clarify this, this paper analyzes the data from a nationwide field study database, including a year-long survey which was carried out in 505 residential buildings in six cities located in the Hot Summer and Cold Winter (HSCW) zone of China involving 11,524 subjects. Results show a significant difference of adaptive responses in different seasons. Air temperature is found to be the most significant driver for behavioral responses, and a lag of behavioral responses behind climate change in transitional seasons is observed. Occupants not only adjust clothing insulation according to air temperature in different seasons, but also actively control indoor air movement, including closing/opening windows and using fans. The seasonal, monthly and daily neutral temperatures are studied, implying that occupants’ thermal experience history has significant effect on their thermal comfort by behavioral, physiological and psychological paths. Thus, the running mean air temperature method and aPMV model are recommended for thermal comfort evaluation in free-running space. The research results provide comprehensive understanding of the thermal comfort demand which directly affects the energy needs for heating and cooling purpose. The findings provide scientific evidence to the concept that dynamic thermal comfort temperature range should be considered in the evaluation of indoor thermal environment

A modified method of evaluating the impact of air humidity on human acceptable air temperatures in hot-humid environments

This research aims to investigate human thermal responses to air humidity in warm and hot environments and to evaluate the effect of humidity on human thermal comfort. 20 subjects were involved in 12 exposure experiments in a well-controlled climate chamber at three relative humidity levels (40%, 60%, 80%) and four air temperature levels (26 °C, 28 °C, 30 °C, 32 °C) with little indoor airflow. The physical environmental and physiological parameters, as well as subjective questionnaires, were collected simultaneously with the on-going experiments. The results show that in hot environments, particularly when the air temperature exceeds 30 °C, the relative humidity has a significant effect on human thermal responses both physiologically and subjectively. The Standard Effective Temperature (SET) is biased when evaluating human thermal comfort in hot-humid environments without considering human thermal adaptation to humidity. Hence, a humidity correction coefficient eRH is proposed to modify the deviation of the SET under different relative humidity levels, and to quantify the effect of humidity on human acceptable air temperatures. The modified acceptable temperature-humidity zone has been obtained using the modified method

Quantification of personal thermal comfort with localized airflow system based on sensitivity analysis and classification tree model

Although local air movement acts as a critical factor to enhance human thermal comfort and energy efficiency, the various factors influencing such movement have led to inconsistent publications on how to evaluate and design localised airflow systems in practice. This study aims to identify the main impacting factors for a localised airflow system and predict a cooling performance based on machine learning algorithms. Three typical localised airflow forms, i.e. an isothermal air supply (IASN), non-isothermal air supply (NIASN), and floor fan (FF), were deployed. The experiments were conducted under a variety of temperature/humidity/air velocity conditions in a well-controlled climate chamber, and a database including 1305 original samples was built. The primary results indicated that a classification tree C5.0 model showed a better prediction performance (83.99%) for a localised airflow system, with 17 input parameters in the model. Through a sensitivity analysis, 8 feature variables were quantified as having significant main effect responses on subjects’ thermal sensation votes (TSV), and three environmental factors (temperature, air velocity, and relative humidity) were identified as having the most significant effects. Using the 8 sensitive factors, the C5.0 model was modified with 82.30% accuracy for subject TSV prediction. A tree model demonstrating the decision rules in the C5.0 model was obtained, with air velocity (=0 m/s,＞0 m/s) as the first feature variable, and root node and temperature (≤28 °C,＞28 °C) as the second feature variable and leaf node, respectively. The outcomes that provide the most influential variables and a machine learning model are beneficial for evaluating personal thermal comfort at individual levels and for guiding the application of a localised airflow system in buildings

Moisture in clothing and its transient influence on human thermal responses through clothing microenvironment in cold environments in winter

Air humidity produces conditions of varying moisture contents in clothing, which affects the heat and moisture transfer between human body, clothing and environment, as well as the wearers’ comfort. This study was designed to evaluate the moisture effects in clothing in cold environments. A series of wearing experiments were conducted in a climate chamber, simulating transient moisture absorption and desorption in experimental clothes. Totally 20 subjects were involved in three temperature levels (16 oC/20 oC/24 oC) and two relative humidity levels (15% RH/85% RH) during winter, with physiological measurement and subjective evaluation. The results showed that moisture in clothing under 85% RH significantly reduced subject mean skin temperatures(MST) and increased the local blood flow, due to enhanced heat loss by vapour evaporation. The initial skin wettedness was approximately 0.7 at 85% RH and stabilised at 0.33 after 90min exposure. The skin heat loss (Qskin) at 85% RH was almost twice as high as that at 15% RH under the same temperature conditions, owing to larger sensible and evaporative heat loss caused by moist clothing. The inner clothing effective temperature Teff was proposed to relate to TSV that the TSV increased by 1.12 units with an increase of 1 oC of Teff, which quantified the coupled effects of air temperature and humidity in clothing microenvironment on human thermal comfort. The findings address the negative effect of clothing absorbing a large amount of moisture, which should be considered for indoor heating temperature designs in cold-humid environments