4. Water treatment. Flashcards
- What ingredients found in water after its taste and odor?
Dissolved gases and minerals or organic substances in solution after the taste and odor of water.
- What type of water cause staining of plumbing fixtures and laundry?
Water containing iron, called “red water”. and manganese, known as “black water”, stains plumbing fixtures and laundry.
- What causes of odor of rotten eggs in some waters?
This disagreeable odor is caused by hydrogen sulphide.
- What are some of the undesirable characteristics of water from common sources of supply which make treatment necessary?
Some of the characteristics of water which make treatment desirable are: hardness, turbidity, acidity, iron and manganese content, organic growths including bacteria and algae, and gas content including hydrogen sulphide, carbon dioxide, and oxygen.
- What is the main purpose of the “aeration” process in a water treatment plant?
The aeration process removes noxious gases (odors) from the water.
- In what direction does water flow through the zeolite bed in a domestic water softener?
Water softeners are manufactured in both down-flow and up-flow models.
- What factors determine the size of a domestic water softener?
The size of water softening equipment depends on the amount of water to be treated and the degree of hardness.
- What materials are commonly used for softening hard water?
Zeolite, lime or lime-soda, and synthetic ion exchange resins.
- Zeolite water softeners must be chemically reactivated at periodic intervals. What is the name of the chemical that is used to reactivate the zeolite?
Sodium chloride (common salt).
- What type of filters or treatment equipment, other than water softeners, are used for the treatment of water for domestic use?
Sand filters to reduce turbidity, iron removal filters to remove iron and iron taste, equipment containing activated carbon to remove odors and bad taste including the taste due to chlorination, and equipment containing a neutralizer to reduce or neutralize acidity.
- Give the name of a chemical that is usually used to disinfect water before it is delivered to the city water mains.
Chlorine.
- Roof tank disinfection?
- The underside of the top, bottom and walls shall be washed with a hypochlorite solution containing 100 or more parts per million of available chlorine.
- The tank shall be filled with water to which hypochlorite solution is added during the filling in sufficient quantity so that the treated water in the tank will contain at least 10 parts per million of available chlorine.
- The chlorinated water shall be allowed to remain in the tank for two hours.
- Finally, the tank shall be drained completely before refilling.
- Disinfection of potable water system?
General.
New or repaired water system shall be purged of deleterious matter and disinfected prior to utilization.The method to be followed shall be that prescribed method, the procedure described in either AWWA C651 or AWWA C652, or as described in this section. This requirement shall apply to “one-site” or “in-plant” fabrication of a system or to a modular of a system.
1. The pipe system shall be flushed with clean, potable water until dirty water does not appear at the point of outlet.
2. The system or part thereof shall be filled with a water/chlorine solution containing at least 50 parts per million of chlorine, and the system or part thereof shallbe valved off and allowed to stand for 24 hours: or the system or part thereof shall be filled with a water/chlorine solution containing at least 200 parts per million of chlorine and allowed to stand for 3 hours.
3. Following the required standing time, the system shall be flushed with clean potable water until the chlorine is purged from the system.
4. The procedure shall be repeated where shown by a bacteriological examination that contamination remains present in the system.
