Waste Water pH - How to Measure It
By Richard Runion

While treating contaminated water it is necessary to maintain proper pH level else the treatment is affected and it takes longer than usual. In the paragraphs below, I explain the basic process and the apparatus setup necessary, to accurately measure waste water pH.

pH Of Wastewater

pH for contaminated water is known as the measure of the level of acidity or basicity of the waste water. The acidic conditions in waste water can be established by determining its pH. Unlike waste water, pure water contains more free ions. At a base temperature of 25 degrees C, when this water is in a state of equilibrium, it's condition can be represented as
(H^+) (OH^-) = Kw = 1.01 x 10^-14.

In the above mentioned equation, the Hydrogen Ion (H^+) = Diatomic Anion (OH^-) = 1.005 x 10^-7.

But going by the definition of pH, it is equal to the value -log10AH^+, where the value AH^+ represents the actions of
the Hydrogen Ion. Variations in temperature can change the value of the waste water pH hence any test done should involve ideal temperature conditions.

The following are some values of waste water pH at different temperatures.
At a temperature of 0 degree C, the value is 7.5,
at a temperature of 25 degrees C, the value is 7.0,
at a temperature of 60 degrees C, the value is 7.5.
The pH of wastewater varies with increase or decrease in temperature.

By measuring the potential difference or the voltage at two electrodes, where one is a standard Hydrogen electrode while the other electrode is used for reference, the actions of the Hydrogen (H^+) ions can be measured. A Hydrogen H^+ electrode can present difficulties during tests, hence sometimes a glass electrode is used instead. Whenever glass electrode is used in the testing apparatus in place of Hydrogen, the apparatus has to be re-calibrated potentiometrically to adjust to the properties of the glass electrode.