Environmental Engineering Reference
In-Depth Information
removal technologies as and when needed to provide the best-tasting (palatable) water
possible.
WaterHealth's award-winning technology, UV Waterworks™ (UVW), is based on a
novel approach to the use of UV light for the inactivation of microbial pathogens (Figure
22.6). WHI's technology has many advantages over preexisting technologies. First, UV
treatment has the advantage that it is free of chemicals and potential carcinogenic and
mutagenic disinfection by-products and environmental pollutants. Unlike conventional
UV technology and other methods, UVW is designed to be highly energy eficient and
work without the need for high pressure (in gravity feed mode), has superior throughput
with high eficacy, and is sustainable from maintenance and cost perspectives even in
remote and challenging environments with little technical infrastructure. In contrast
with boiling water, it is more easily adopted and is not associated with the environmen-
tal degradation that can result from cutting down trees to provide irewood for boiling
water.
In certain geographies, where likelihood of secondary contamination is present, either
during water transportation or during handling, WaterHealth chlorinates the water to
provide some residual disinfection. The chlorine addition, maintained at 0.2-0.5 ppm, is
closely monitored and controlled to make sure it does not adversely impact the taste or
generation of any harmful by-products.
Initial concentration
(CFU/mL)
Posttreatment
(CFU/mL)
Bacteria
Diseases
Escherichia coli
10
7
ND
Bloody diarrhea,
abdominal cramps
Salmonella typhi
10
7
ND
Typhoid fever
Vibrio cholerae
10
7
ND
Cholera
Streptococcus faecalis
10
7
ND
Urinary tract infections,
wound infections
Clostridium perfringens
10
7
ND
Acute food poisoning
Shigella dysenteriae
10
7
ND
Dysentery
Proteus vulgaris
10
7
ND
Urinary tract infections
Klebsiella aerogenes
10
7
ND
Klebsiella terrigena
10
6
ND
Enterobacter cloacae
10
7
ND
Pneumonia
Pseudomonas aeruginosa
(immunotype IV)
10
7
ND
Dermatitis
Initial concentration
(particles/mL)
Vir u se s
Log reduction
Diseases
Poliovirus
10
6
5.0
Polio
Rotavirus
10
6
5.0
Severe diarrhea
Initial concentration
(organisms/L)
Protozoan cysts
Log reduction
Diseases
Cryptosporidium parvum
10
6
>5.1
Diarrhea
FIGURE 22.6
UVW effectiveness against commonly known pathogens.
