Dissertation/Thesis Abstract

Performance and Health Impact of Decentralized Membrane-Based Water and Wastewater Treatment Technologies
by Sima, Laura, Ph.D., Yale University, 2012, 158; 3535402
Abstract (Summary)

Decentralized membrane-based technologies, coupled with entrepreneurial approaches to water and sanitation services, may provide revolutionary solutions in urban slums, where municipal, centralized approaches frequently fail. Oftentimes, well-engineered systems have been unsustainable in developing countries, because they were not customized to work in developing world contexts or because their implementation was ineffective. The goal of this dissertation is to conduct a comprehensive analysis of the technical, economic, and public health context of decentralized water and wastewater treatment via decentralized membrane technologies in unplanned urban settlements in developing countries.

Small-scale water and sanitation distribution businesses exist, often informally, in many slums. Chapter 1 presents a critical review on the global presence and characteristics of the small-scale water distribution sector. The sector is highly active in most urban slums in developing countries. Due to a paucity of data, quantitative analyses of the economics and environmental impacts of the sector are lacking. Chapter 2 enhances the global understanding of the sector by investigating the market supply and environmental impacts in one developing city, Kisumu, Kenya. Findings indicate that the sector is adaptable to neighborhood-level demand and pricing is dependent on neighborhood-level earnings. Furthermore, embedded energy use is highest for water delivered by trucks, with municipal distribution being ten times more energy efficient. These findings suggest that there is an existing market for water in urban slums. Water in this sector is untreated, and membrane technologies would be significant improvement.

Before membrane-based technologies are deployed in the field, their efficacy must first be validated. Pathogen removal in membrane-based water treatment systems is well documented, but pathogenic virus removal in membrane-based wastewater systems had not been investigated. In chapter 3, the removal of pathogenic viruses by a municipal-scale membrane bioreactor was investigated by quantifying nucleic acid titer in wastewater after each treatment step during a six-month period. Findings indicate that norovirus GI, GII, and GIV as well as adenovirus and sapovirus are all effectively removed by the municipal-scale membrane bioreactor. Removal is highest during the membrane filtration step, with high viral nucleic acid titer identified in the plant biosolid. The reliable efficacy of membrane-based treatment, coupled with their modular design, make them suitable for use in urban slums. Small-scale membrane-based water treatment and refill stations already exist in Southeast Asia and India. Chapter 4 discusses perspectives on these stations, including accepted business models and technologies.

Even if membrane-based entrepreneurial businesses are profitable in low-income areas, and remove pathogens effectively, a number of socioeconomic factors may impede their ability to reduce the burden of diseases in urban slums. Chapter 5 investigates the association between childhood diarrhea and water refill stations, controlling for known diarrheal risk-factors. Results of a longitudinal health study in Jakarta show that consistent purchase of water from refill stations, like the consistent consumption of bottled water, is associated with a reduction in the relative risk of childhood diarrhea in an urban slum.

If money is to be invested for disease control, it is important that the primary causes for disease spread be understood in a given area. The final portion of this work recognizes that diseases are spread by many vectors, and increased access to water is not the only intervention type that may reduce the risk of disease. A structural equation model is used to analyze the relative contribution of various latent risk factors to diarrhea outcomes. Modeling results show that hygiene and food quality are more significant in determining the length of a diarrhea episode than water quality or sanitation factors, likely reflecting the pathogens transmitted via each route.

In summation, entrepreneurial, for-profit membrane-based water and wastewater treatment technologies show promise in slums of developing countries, though their introduction needs to be coupled with other interventions to eliminate the spread of diseases in these areas. Novel contributions of this dissertation include (i) an analysis of market characteristics and embedded energy use of informal water distribution businesses in a developing city, (ii) quantification of the reliable pathogenic virus removal capacity in a municipal membrane bioreactor, (iii) calculation of relative risk reductions associated with consumption of water from decentralized refill stations in an urban and peri-urban area of a developing country, and (iv) development and confirmation of a novel technique to understand contribution of various risk-factors to childhood diarrhea in slums of developing countries.

Indexing (document details)
Advisor: Elimelech, Menachem
Commitee: Desai, Mayur, McCarty, Kathleen, Peccia, Jordan, Zimmerman, Julie
School: Yale University
Department: Chemical and Environmental Engineering
School Location: United States -- Connecticut
Source: DAI-B 74/05(E), Dissertation Abstracts International
Source Type: DISSERTATION
Subjects: Chemical engineering, Civil engineering, Sustainability
Keywords: Decentralized membranes, Diarihea, Membrane-based treatment, Slums, Wastewater treatment, Water refill
Publication Number: 3535402
ISBN: 9781267856821
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