GENERAL pH

A scientist named Sorensen devised the 0 to 14 pH scale in 1909.  While very important, the actual hydrogen ion concentrations are very small and rather hard to work with.  For example, a neutral pH of 7 represents 0.0000001 grams of hydrogen ions in a liter of water (10^-7 grams).  The definition of pH is the logarithm of one over the hydrogen ion concentration.  Through some mathematical manipulation, Sorensen took the concentration exponent, in this example 7, as his simplified measure of pH.  Like the Richter Scale for earthquakes, each whole number is ten times stronger that the one before.  The acid range is from 0 to 7 units, with 0 being the most acid, and the alkaline range is from 7 to 14, with 14 the most alkaline.   By definition then, a pH of 5 is ten times more acid than a pH of 6, and a pH of 9 is ten times more alkaline that a pH of 8.

Treating domestic water supplies for pH can be pretty straightforward, often requiring little or no equipment.  The water source is usually stable, and therefore predictable, so a fixed device like an in-line filter can provide for small adjustments.  Systems requiring a larger pH change might call for a chemical feed pump (see Basic Chemical Pump Questions and Jar Testing Made Easy).

Practical and effective pH control for wastewater, however, can get complicated.  Industrial wastewater in particular presents some interesting challenges.  We almost always deal with pre-existing collection systems and tankage, so we have to adapt the new pH equipment to work in the old environment.  Individual plant chemistry, solids loading, chemical buffering capacity, mixing capability, flow variations, retention time, periodic chemical fluctuations--all of these things and more effect the pH of your treated water.

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