Environmental Engineering Reference
In-Depth Information
24
Light-Activated Nanotechnology for
Drinking
Water Puriication
Mark D. Owen and Tom Hawkins
Puralytics, Beaverton, Oregon, USA
CONTENTS
24.1 Introduction ........................................................................................................................ 467
24.2 Developing World and Crises .......................................................................................... 469
24.3 Developed-World Water Problems .................................................................................. 470
24.4 Strengths/Limitations of Current Water Treatment Technologies ............................. 471
24.5 Photochemical Water Puriication ................................................................................... 472
24.6 Puralytics Process .............................................................................................................. 473
24.6.1 Photocatalytic Oxidation ...................................................................................... 473
24.6.2 Photocatalytic Reduction ...................................................................................... 474
24.6.3 Photoadsorption ..................................................................................................... 474
24.6.4 Photolysis ................................................................................................................ 474
24.6.5 Photodisinfection ................................................................................................... 475
24.7 Product Implementation ................................................................................................... 475
24.7.1 Shield ....................................................................................................................... 475
24.7.2 SolarBag ................................................................................................................... 476
24.8 Test Results ......................................................................................................................... 476
24.9 Conclusions ......................................................................................................................... 477
References ..................................................................................................................................... 478
24.1 Introduction
Nearly 1 billion people lack access to any form of improved water supply within 1 km of
their home [1] (Figure 24.1). The poorest 4 billion people collectively spend more than $20
billion per year on water collection and treatment. This consists of collecting water from
surface sources often polluted with unknown amounts of animal waste, chemicals, heavy
metals, and biological agents; partially treated piped water; shared community resources,
individual water puriiers, and mobile water vendors [2].
The United Nations has asserted access to safe water as a basic human right [3]. The
World Health Organization (WHO) has deined safe water as when people have access
to an improved water source, when the germs are killed or removed, and when toxins
are reduced to acceptable levels [4]. The United Nations (UN) Millennial 15-year goal
from 2000 to 2015 was to provide access to improved water sources, and most people who
remain without access are in more remote areas [5]. An improved water source can mean a
467
