Environmental Engineering Reference
In-Depth Information
water. Their survival in the environment is prolonged at low temperatures and in the sediments onto which
they easily absorb (Jin et al., 2004). In contaminated surface water, levels of 1-100 culturable enteric
viruses per liter are common. In less polluted surface water, their numbers are closer to 1-10 per 100 liters
(Health Canada, 2004).
The conditions that are used to accomplish indicator bacteria inactivation based on chlorination/
dechlorination are relatively ineffective for control of waterborne viruses, as compared to UV radiation
(WERF, 2005), and viruses are one of the most resistant targets for UV disinfection. Adenoviruses are
the most resistant to UV disinfection and are found in high concentrations in municipal wastewater
(Geosyntec, 2008). While ozone is particularly effective against viruses, little information is available
regarding the effectiveness of ozone on the inactivation of Caliciviruses and enteric adenoviruses
(Geosyntec, 2008).
T able 9.13 Summary of pathogen disinfection efficiencies for the various disinfection methods
Pathogen Ozonation Ultraviolet Chlorination/dechlorination
E. coli 4 log a , 1.3 log-4.5 log b 4 log h > 4 log h
Pseudomonas aeruginosa 2 log b 4 log h > 4 log h
Salmonella 4 log a 3-4 log j Not available
Enterococci Not available Not available More resistant than E. coli h
Cryptosporidium 0.57 log-2.67log b 3 log c 0.2 log-3 log a
Giardia 1.57 log-2.7 log b 2 log j 0.5 log a
Total Enteric Viruses 5 log b 0.32 log-3.61 log h 5 log d
Calicivirus 2 log e 4 log g 2 log e
Adenovirus 4 log i 1 log-4 log f 2-4 log k
Note : A 1 log reduction is a 90% reduction, a 2 log reduction is a 99% reduction, and so on (after Geosyntec, 2008)
References: (a) USEPA (1999b); (b) Paraskeva and Graham (2002); (c) Clancy (2004); (d) Nelson et al., undated;
(e) Health Canada (2004); (f) Gerba et al. (2002); (g) Thurston-Enriquez et al. (2003b); (h) WERF (2005); (i)
Thurston-Enriquez et al. (2005); (j) Chang et al. (1985): and k) Thurston-Enriquez et al. (2003a)
9.5 Sediment Contamination
Most toxic heavy metals and complex hydrocarbons, such as petroleum hydrocarbons, Polycyclic Aromatic
Hydrocarbons (PAHs), Polychlorinated Biphenyls (PCBs), and organochlorine pesticides, have a high
affinity for sediments. For example, Terstriep et al. (1982) reported the following percentages of absorption
to sediment in urban runoff for heavy metals: lead and nickel—100%, iron—98%, manganese —73%,
and copper—68%; and Harremoes (1982) reported 95% of petroleum hydrocarbons adsorbed to sediment
in urban runoff.
The list of toxic metals includes: aluminum, arsenic, beryllium, bismuth, cadmium, chromium, cobalt,
copper, iron, lead, manganese, mercury, nickel, selenium, strontium, thallium, tin, titanium, and zinc
(Masters, 1991, p. 114). The complex hydrocarbons either are toxic or carcinogenic, particularly the PCBs,
PAHs, and organochlorine pesticides. The presence of these compounds can negatively impact the benthic
community and then higher forms of life all the way to man through the food chain. The process of toxic
or carcinogenic compounds moving through the food chain is known as bioaccumulation. For example,
PCBs are efficiently adsorbed on phytoplankton, and, thus, the fate of PCBs is also strongly tied to the
behavior of phytoplankton, which provide a direct route into the food chain. PCBs become progressively
concentrated as they move up the food chain from phytoplankton to zooplankton, forage fish, and
predator fish. As a result, many of the large fish in Green Bay (Lake Michigan, U.S.), such as lake trout,
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