Impurities in raw water
To discuss the various unit operations configured in a water purification system we need to know impurities present in raw water. The nature, type, and concentration of various impurities should define the water purification system.
Definition of water purification is techniques required to produce the desired water quality. Raw water supplies to pharmaceutical water purification systems must meet the National Primary Drinking Water Regulation (NPDWR) as defined by the U.S. EPA or a similar agency.
The requirements for feed water to a compendial water system are set forth in the current applicable USP Official Monograph. It is important to recognize the different potential sources of feed water to facilities. Raw feed water may be from a municipal supply or a dedicated private supply for the facility. It should be obvious that the nature and concentration of various impurities in raw water supplies will be a function of the ultimate source of the water.
Sources may include reservoirs, lakes, streams, rivers, and groundwater. Groundwater supplies may be influenced by surface water supplies depending on the topography and depth of the aquifer.
The U.S. EPA National Primary and Secondary Drinking Water Regulations are defined (40CFR141 and 40CFR142). The regulations are periodically updated to reflect available treatment technology, analytical detection capability, and ongoing research associated with the health effects of impurities. The Surface Water Treatment Rule defines specific requirements for municipal facility treatment of both surface water supplies and groundwater influenced by surface water supplies. The Disinfection By-products Rule outlines specific limits for undesirable by-products produced by the reaction of disinfecting agents with naturally occurring organic material (NOM). While impurities in raw water are discussed in subsequent post, specific limits for impurities are defined by the U.S. EPA and may change periodically.
I will post details of following Impurities in details:
- Particulate Matter
- Ionic Material
- Dissolved Gases
- Bacterial Endotoxins
- Organic Material
- Residual Disinfectant
- Disinfection By-Products