280
H. S. Weinberg
Zumstein and Buffie (1989) studied the seasonal evolution of NOM in a river
and lake system. Increases in the dissolved organic carbon (DOC) and UV values
were observed in the Grenet River (Switzerland) after heavy rainfalls. These
increases can be attributed to increased leaching of soil organic matter during high
river discharges. Zumstein and Buffie (1989) also found that the DOC values in
the upper layers of Lake Bret (Switzerland) - which is a eutrophic lake - during
the period from May to September, were at a maximum. The epilimnetic DOC
increases in spring and summer were ascribed to the biological activity of the lake.
3.3 Algae
In addition to humic substances, algae can be a source of DBP precursors. Hoehn
and colleagues (1980) found that algae - both their biomass and their extracellular
products - react readily with chlorine to produce THMs. These researchers
observed that the algal extracellular products, upon reaction with chlorine,
generally yielded greater quantities of chloroform from the available TOC than
did the algal biomass. Furthermore, they observed that high-yielding THM
precursors were liberated by algae in greater abundance during the late
exponential phase of growth than at any other time during the algal life cycle.
Algae are a source of amino acids. Trehy and Bieber (1981) found that the
chlorination of certain amino acids - as well as humic acid - resulted in the
formation of haloacetonitriles (HANs). Algae are also the source of some of the
major taste and odor problems associated with surface water supplies. Rather than
be faced with the expense of pilot-testing a specific set of operations to remove
the chemicals generated by algae, management of raw water resources and control
of algal growth makes much more economical and ecological sense. Copper
sulfate is sometimes added to reservoirs to control seasonal growth, or upstream
chlorination is practiced to prevent the organisms from reaching the treatment
plant and compromising subsequent treatment operations.
3.4 Bromide
Sources of bromide include saltwater intrusion, connate water (ancient,
geologically trapped seawater), oil-field brines, and industrial and agricultural
chemicals (Krasner et al. 1994). The concentration of bromide can be seasonally
related (e.g., wet-weather versus dry-weather conditions) (Singer 1994). Krasner
and coworkers (1994) found significant variations in bromide concentrations in
California State Project water (SPW) that were related to the extent of saltwater
intrusion. Such a phenomenon was highly affected by seasonal variability in
rainfall and was most pronounced during drought years.
Bromine chemistry in DBP formation first involves the oxidation of bromide
to hypobromous acid (HOBr) by disinfectant. Symons and colleagues (1993)
found that the ratio of bromide to the average free available chlorine controls
H. S. Weinberg
Zumstein and Buffie (1989) studied the seasonal evolution of NOM in a river
and lake system. Increases in the dissolved organic carbon (DOC) and UV values
were observed in the Grenet River (Switzerland) after heavy rainfalls. These
increases can be attributed to increased leaching of soil organic matter during high
river discharges. Zumstein and Buffie (1989) also found that the DOC values in
the upper layers of Lake Bret (Switzerland) - which is a eutrophic lake - during
the period from May to September, were at a maximum. The epilimnetic DOC
increases in spring and summer were ascribed to the biological activity of the lake.
3.3 Algae
In addition to humic substances, algae can be a source of DBP precursors. Hoehn
and colleagues (1980) found that algae - both their biomass and their extracellular
products - react readily with chlorine to produce THMs. These researchers
observed that the algal extracellular products, upon reaction with chlorine,
generally yielded greater quantities of chloroform from the available TOC than
did the algal biomass. Furthermore, they observed that high-yielding THM
precursors were liberated by algae in greater abundance during the late
exponential phase of growth than at any other time during the algal life cycle.
Algae are a source of amino acids. Trehy and Bieber (1981) found that the
chlorination of certain amino acids - as well as humic acid - resulted in the
formation of haloacetonitriles (HANs). Algae are also the source of some of the
major taste and odor problems associated with surface water supplies. Rather than
be faced with the expense of pilot-testing a specific set of operations to remove
the chemicals generated by algae, management of raw water resources and control
of algal growth makes much more economical and ecological sense. Copper
sulfate is sometimes added to reservoirs to control seasonal growth, or upstream
chlorination is practiced to prevent the organisms from reaching the treatment
plant and compromising subsequent treatment operations.
3.4 Bromide
Sources of bromide include saltwater intrusion, connate water (ancient,
geologically trapped seawater), oil-field brines, and industrial and agricultural
chemicals (Krasner et al. 1994). The concentration of bromide can be seasonally
related (e.g., wet-weather versus dry-weather conditions) (Singer 1994). Krasner
and coworkers (1994) found significant variations in bromide concentrations in
California State Project water (SPW) that were related to the extent of saltwater
intrusion. Such a phenomenon was highly affected by seasonal variability in
rainfall and was most pronounced during drought years.
Bromine chemistry in DBP formation first involves the oxidation of bromide
to hypobromous acid (HOBr) by disinfectant. Symons and colleagues (1993)
found that the ratio of bromide to the average free available chlorine controls