Environmental Engineering Reference
In-Depth Information
8
Chemical D
rinking Water Parameters
There is nothing in the world softer and weaker than water,
and yet there is nothing better for attacking hard and strong things.
For this reason there is no substitute for it.
—Lao-Tzu (c. BCE 550)
Water, in any of its forms, also … [has] scant respect for the laws of chem-
istry. Most materials act either as acids or bases, settling on either side of
a natural reactive divide. Not water. It is one of the few substances that
can behave both as an acid and as a base, so that under certain conditions
it is capable of reacting chemically with itself. Or with anything else.
Molecules of water are off balance and hard to satisfy. They reach out to
interfere with every other molecule they meet, pushing its atoms apart,
surrounding them, and putting them into solution. Water is the ultimate
solvent, wetting everything, setting other elements free from the rocks,
making them available for life. Nothing is safe. There isn't a container
strong enough to hold it.
Lyall Watson (1988)
Introduction
Water chemical parameters are categorized into two basic groups: inorganic
and organic chemicals. This chapter does not look at each organic or inor-
ganic chemical individually; instead, we look at general chemical parameter
categories such as dissolved oxygen (DO) organics (i.e., biochemical oxygen
demand and chemical oxygen demand), synthetic organic chemicals (SOCs),
volatile organic chemicals (VOCs), total dissolved solids (TDS), fluorides,
metals, and nutrients—the major chemical parameters of concern.
DID YoU KNoW?
Water is the closest thing in nature to the mythical universal solvent.
Whether or not a rock dissolves readily in water determines how rap-
idly it weathers. When substances are dissolved, some of the atoms, or
groups of atoms, dissociate in the liquid into what are called
ions
. The
ions have positive or negative electrical charges (Jacobson, 1991).
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