Articles

Naegleria deaths: desired chlorine level not maintained

Despite tall claims about taking effective measures to keep Naegleria fowleri in check, the civic agencies concerned still have to do a lot of work to save precious lives since a large quantity of water supplied to the city is still shockingly unhealthy and prone to assist the growth of ‘brain-eating’ amoeba,

Water Supply and Sanitation in Pakistan

Drinking water supply and sanitation in Pakistan is characterized by some achievements and many challenges.

WHO guidelines for water contamination

This fourth edition of the World Health Organization’s Guidelines for Drinking-water Quality builds on over 50 years of guidance by WHO on drinking-water quality,

Methods of Water Purification

Water treatment can be defined as any procedure or method used to alter the chemical composition or natural "behavior" of a water supply.

Chlorine in Drinking Water

Exposure to chlorine, hypochlorous acid, and hypochlorite ion through ingestion of household bleach occurs most commonly in children.

Methods of Water Purification

Water treatment can be defined as any procedure or method used to alter the chemical composition or natural "behavior" of a water supply.

Water supplies are classified as either surface water or groundwater. The majority of public or municipal water comes from surface water such as rivers, lakes, and reservoirs. The majority of private water supplies consist of groundwater pumped from wells.

MUNICIPAL OR UTILITY WATER TREATMENT

Most municipal water found in a city or community today has been treated extensively. Specific water treatment methods and steps taken by municipalities to meet local, state, national, or international standards vary but are categorized below.

Screen prefiltration

A coarse screen, usually 50 to 100 mesh (305 to 140 microns), at the intake point of a surface water supply, removes large particulate matter to protect downstream equipment from clogging, fouling, or being damaged.

Clarification

Clarification is generally a multi-step process to reduce turbidity and suspended matter. Steps include the addition of chemical coagulants or pH-adjustment chemicals that react to form floc. The floc settles by gravity in settling tanks or is removed as the water percolates through a gravity filter. The clarification process effectively removes particles larger than 25 microns. The clarification process is not 100% efficient; therefore, water treated through clarification may still contain some suspended materials.

LIME TREATMENT

The addition of lime (Ca) and soda ash (Na2CO3) reduces the level of calcium and magnesium and is referred to as "lime softening." The purpose of lime softening is to...