Water Kwal-E.T. Flashcards
Disinfectants
For chemical disinfection of water the following disinfectants can be used:
- Chlorine (Cl2)
- Chlorine dioxide (ClO2)
- Hypo chlorite (OCl-)
- Ozone (O3)
- Halogens: bromine (Br2), iodene (I)
- Bromine chloride (BrCl)
- Metals: copper (Cu2+), silver (Ag+)
- Kaliumpermanganate (KMnO4)
- Fenols
- Alcohols
- Soaps and detergents
- Kwartair ammonium salts
- Hydrogen peroxide
- Several acids and bases
For physical disinfection of water the following disinfectants can be used:
- Ultraviolet light (UV)
- Electronic radiation
- Gamma rays
- Sounds
- Hea
Read more: http://www.lenntech.com/processes/disinfection/what-is-water-disinfection.htm#ixzz3b3w9enTn
Palatable water
Considers the presence of chemicals that are not a threat to human health, affected by chloride, colour, corrosivity, iron, manganese, taste and odour, dissolved solids, tubidity
Potable water
considers the presence of harmful chemicals, affected by microbials, organic chemicals (disinfection by-products), inorganic chemicals (cadmium, copper, lead, mercury), radionuclides.
sources of drinking water
groundwater: shallow wells, deep wells
surface water: rivers, lakes, reservoirs
Groundwater Characteristics
High in hardness, mineral content and metals
Low in variability, suspended sediments, turbidity, colour, dissolved oxygen, and cracking taste.
Surface Water Characteristics
Low in hardness and mineral content.
High in all other parameters of concern.
Sources of pollution
Point sources - discharges from industries and spills into surface water or groundwater.
Diffuse sources - runoff at multiple sources, varies substantially with use of the land
- agricultural, urban, commercial, special (golf courses)
There is minimal regulation
Oxygen Demanding material
Organic materials convert oxygen to co2
High oxygen levels necessary for healthy ecology
- trout requires 5-8 mg/L D.O.
- aesthetic problem at less than 1mg/L
Nutrients
Problems: aesthetic, taste and odour, toxicity (especially to farm animals), fouling, diurnal D.O cycles.
Phosphurus is typically the limiting nutrient in surface waters.
Sources - fertilisers, detergents, can exist in a variety of chemical forms so total P is normally measured.
Nitrogen
Nitrogen is often the limiting nutrient in estuarine and ocean waters
It can exist in numerous forms, but nitrate (NO3-), nitrite (NO2-), ammonia (NH3) are most commonly measured
Sources include fertilisers and acid deposition.
Eutrophication remedial actions
Reduce nutrient input, focus is on Phosphurus due to the 1:10 ratio of P:N required for algal growth.
Dissolved Solids / Salts
May be present as any number of ions
- cations, Na +, K +, Mg 2+, Ca 2+
- anions, Cl-, SO4 2-, HCO3 -
Classifications
- Freshwater less than 1500 mg/L TDS
- Brackish water 1500 - 5000 mg/L TDS
- Saline more than 5000 mg/L
- Sea water 30-34 g/L TDS
Salty Sources
minerals, deicing, evaporative losses, irrigation, industrial discharges, sea water intrusion.
Effects: limits use for drinking, crop damage and soil poisoning
Suspended Solids
- organic or inorganic particles in water, measured by filtering and weighing.
- distinguished from colloids which are particles that do not settle readily
Problems: sedimentation, oxygen demand, transport mechanism for (metals, organics + pathogens), aesthetics
Sources: storm water and wastes, erosion,
Pathogenic Organisms
human and animal diseases live outside the body for a period of time,
carriers excrete organisms in large quantities, water contaminated by excretia,
organisms transmitted by contact with the water.
