Chapter 2 - Basic Water Chemistry

Abstract

It is useful to have an understanding of the basic concepts in water chemistry and ions commonly found in water. Solubility principles, some common substances found in commercial and industrial water systems, and water-quality guidelines are discussed in this chapter. It gives the reader an appreciation for the types of contaminants and their impacts on water systems. Water is the universal solvent due to its power to dissolve all substances to some extent. The key to this phenomenal ability is its structure. The water molecule consists of two atoms of hydrogen and one atom of oxygen with a slight positive charge near the hydrogen atoms and a slight negative charge near the oxygen atom. This polarity enables the water to dissolve all ionic and polar substances. Non-polar compounds such as hydrocarbons are insoluble in water. For this reason pure water is not found in nature. It always contains impurities, which impart color, clarity, taste, smell and feel. The types of impurities found in water and wastewater can be divided into four groups: dissolved, physical, microbial and radiological. Impurities in natural waters depend on the source of water. Wells and spring waters are classed as ground water while rivers and lakes are known as surface waters. Ground water picks up impurities as it seeps through the rock strata. The natural filtering effect of rock and sand usually keeps water free of suspended matter. Wastewater may contain a myriad of substances depending on the source and can range from inorganic to organic substances.