INTRODUCTION OF WATER TREATMENT PROCESSES

Modern technologies have greatly reduced the spread of waterborne diseases such as cholera and typhoid fever. These diseases are not much a concern now for public health as they were before. The main key for this advancement is the recognition that human wastes are the source of contamination of public water and it could be eliminated by effective water treatment strategies and waste disposal systems. 

In 1802 the filtration of drinking water was practiced in Paisly, Scotland. It was used by water vendors in London, England in 1828. In U.S the filtration of drinking water was first used in 1872 by the city of Poughkeepsie, New York. In this century the technology to make water safe for drinking has becoming widespread in Europe and North America. 

There are four classes of water treatment:

Class A  

In this class no treatment is required for some borehole water Occasional upland water

Class B

In this class borehole water or occasional water is used in public water supply. Disinfection is practiced to maintain the purity along the water pipelines. Chlorination with chlorine has been very debated. The alternative of chlorine has been searching out. Sometimes in this class aeration is used to remove the hydrogen sulphide odors and taste and to increase the level of oxygen in water. 

Class C

It is known as standard water treatment and it is used for lowland rivers and reservoirs.

Class D

Class D is special water treatment. It is used when the source is downstream of urban developments or when high quality water is required by the industries. Th other processes include: membrane technology, iron and manganese removal, chemical oxidation and carbon adsorption. 

Water treatment is designed to provide the standard quality water at taps. Four considerations are used in this:

• Source Selection
• Water Quality Protection
• Treatment method to be used
• prevention of re contamination

Precautions used to avoid groundwater and surface water pollution are:

• Prohibition of discharge of sanitary and storm sewers close to water reservoir
• installing fences to avoid pollution from recreational use of water
• restriction on application of fertilizers and pesticides in areas that drain to reservoirs

Screening, coagulation, flocculation, filtration and disinfection are used to surface water treatment.

These plants have the task to remove:

• Particulate substances such as sand and clay, organic matter, bacteria and algae
• dissolved substances causing color and hardness
• Pathogenic bacteria and viruses