The taking in or soaking up of one substance into the body of another by molecular or chemical action.

Tree roots absorb nutrients in the soil.

A representative portion of a sample.

Often an equally divided portion of a sample.

Sodium Fluorosilicate - (Na₂SiF₆)

Chemical used in the Fluorodation of drinking water.

98.5% purity

60.7% ion F present

2.7 gm/cm³ Density

2.7 * 8.34 = 22.52 #/gal.

Salt of fluorosilicic acid

Generated as by-product of fertilizer

White, odorless crystalline powder

Solubility varies with temperature

Principle hazard is dust

Most expensive

Sodium Fluoride - NaF

Fist compound used for fluoridation

98% purity

45.29% ion present

2.56 Density

2.56*8.34 = 21.35 #/gal.

White, odorless crystals or powder

Solubility constant at 4 grams per 100 mL

Solutions have pH near neutral

Principle hazard is dust

Fluorosilicic Acid - H₂SiF₆

18%-23%- purity

79.2%- ion present

1.22 gm/cm³ @ 23%

1.22 * 8.34 = 10.2 #/gal.

Once referred to as “silly acid”

Also known as hydrofluosilicic acid

Clear, colorless to slightly yellow liquid

Pungent odor, fuming, will etch glass

Corrosive, pH 1.0 – 1.5

Can cause burns, respiratory irritation

More costly, easier to handle than dry chemicals

Sodium Hypochlorite- NaClO

Reffered to as bleach, or liquid bleach.

Used to disinfect water for drinking.

10% - 15% strength or purity

1.11 gm/cm³ - density

1.11 * 8.34 = 9.5 #/gal.

MG = Million Gallons, used to designate tank volumes in million gallons

MGD = Million Gallons per Day, used to designate flow in million gallon increments per day.

CL₂ = CHLORINE

CHLORINE COMES AS A GAS, GRANULAR OR SOILD TABLET, AND A LIQUID.

CHLORINE GAS IS A YELLOW GREEN HIGHLY TOXIC GAS THAT IS 100% CHLORINE.

GRANULAR IS A WHITE POWDRE OR TABLET THAT IS 65% CHLORINE AND WILL FOR A TOXIC GAS WHEN EXPOSED TO MOISTURE.

LIQUID CHLORINE IS 10 TO 15 % CHLORINE AND IS YELLOW IN COLOR. THERE IS SOME VAPOR ASSOCIATED WITH LIQUID AND SHOULD NOT BE BREATHED FOR LONG PERIODS.

P Alkalinity or P Alk. is Phenolphthalein Alkalinity.

If the pH is above 8.3 P Alk. is present, if the pH is below 8.3 no P Alk. is present.

No CO₂ is present when the pH is above 8.3 so if P Alk. is present there is no CO₂.

When the pH is below 8.3 there is no Carbonate or Hydroxied present.

T Alk. or Total Alkalinity is  a measure of the capacity of a water's ability to neutralize acids.

Total Alkalinity is all the alkalinity present. It includes the P Akl. if present.

1.      The Hydrologic Cycle is the Natural Cycle that moves water from oceans to rivers, lakes and streams, and to aquifer recharge zones.

   Terms to remember from the Hydrologic Cycle

a.      Evaporation- solar radiation heats the water and water vapor is released.

b.      Condensation- water vapor collects and condenses to form clouds.

c.       Precipitation- when the clouds cool the water vapor condenses into droplets and may fall in the form of rain, snow, and hail.

d.      Percolation- the act of water seeping into the ground to form and recharge aquifers.

    Surface water- water in lakes, rivers, streams, and manmade reservoirs.

 Ground water- water contained in underground formations (aquifers) of porous water bearing

1.      The reason for runoff is that some surfaces are Impermeable – they don’t allow water to percolate.

     The four agents that alter water quality as it goes through the hydrologic cycle are:

a.      Physical- characteristics related to sensory qualities of water.       

                                                              i.      Color

                                                            ii.      Turbidity

                                                          iii.      Taste

                                                           iv.      Odor

                                                             v.      Temperature

b.      Chemical- Characteristics relating to mineral content, hardness, fluoride, sulfides, and the acidity of the water.

c.       Biological- The presence of viruses, bacteria, and algae. Also the presence of mosquito larvae.  The biological processes of these constituents can modify the physical and chemical characteristics of the water.

d.      Radiological- natural and manmade radioactive elements can affect the characteristics of the water.

  There are three types of water rights ( ownership of a water source):

a.      Riparian- rights that acquired with the title to the land bordering a source of Surface Water.

b.      Appropriative- rights that are acquired for the beneficial use of water, through following a specific legal procedures.

c.       Prescriptive-  rights that are acquired by diverting a source of water, to which others may or may not have prior claims, and putting it to use for a period of time, as specified by statute.

The four points of   The Safe Drinking Water Act of 1974:

a.      Went into effect on December 16, 1974

b.      Set national Standards regarding the levels of Contaminants in drinking water.

c.       Required Public Water Systems to monitor and report their levels of identified contaminants in drinking water.

d.      Established uniform guidelines specifying the acceptable treatment methods (technologies) for cleansing (removing) unsafe levels of pollutants (contaminants) from Drinking Water.

a.      any public or private system that has:

                                                              i.      At least 15 service connections or

                                                            ii.      Regularly serves an average of 25 individuals daily at least 60 days out of the year.

    Community Water Systems-

                                 i.      A system that serves at 15 service connection used by all year round residents or

                                ii.      Regularly serves 25 all year residents

a.      any system that is not a Community Water System.

                                                              i.      This is divided into 2 sub categories:

1.      Non-transient Non-community-

a.      Serves at least 25 of the same person for at least 6 months per year

                                                                                                                                      i.      This type of classification is for places that serve the same people but no one actually lives there such as:

1.      Schools

2.      Factories

2.      Transient Non-community-

a.      Does not serve 25 of the same people for 6 months of the year

                                                                                                                                      i.      This is used for places that do not meet the criteria for Community, Non-community, or Non-transient Non-community system.

                                                                                                                                    ii.      Typically the EPA regulates these systems for Nitrates and Coliform Bacteria(State standards may require additional testing)

                                                                                                                                  iii.      These systems include, but not limited to:

1.      Gas Stations

2.      Convenience Stores

3.      Campgrounds

  The Three Main Objectives  of a Water Treatment Plant :

a.      Produce a safe drinking water

b.      Produce an esthetically pleasing drinking water

c.       Produce drinking water a reasonable cost with respect to :

                                                              i.      Capital costs (infrastructure costs)

                                                            ii.      Operational costs ( operator salaries, daily costs)

                                                          iii.      Maintenance costs (cost of equipment and repairs)

     – a structure for holding water, either manmade (dams, and lakes) or naturally occurring (lakes).

a.      Reservoirs used for domestic supply range in size from 100 acre-feet to several million acre-feet.

b.      Reservoirs may be open for recreational use either year round or certain times during the year.

c.       Reservoirs may also prohibit recreational activity.

     Treatment of water contained in a reservoir can range from:

a.      Direct Filtration

b.  Complete Treatment

a.      Eutrophic- having high nutrient levels and an abundance of aquatic and plant life.

b.      Mesotrophic- having moderate levels of nutrients and moderate amounts of aquatic and plant life.

c.       Oligotrophic-having very low levels of nutrients and low levels on aquatic and plant life.

     In reservoirs with abundant life the life is concentrated in the Littoral Zone or shallow water.

     Problems associated with Algal Blooms include:

a.      Taste and Odor problems

b.      Shortened filter runs in complete treatment  plants

c.       Increases in  pH ( which interferes with chlorination efficiency)

d.      Dissolved oxygen depletion

e.      Organic loading

   Taste and Odor Causes

      A watershed is the area surrounding a reservoir or lake or stream that is used for a water source and is defined by its topography. Basically, the highest point above the supply from which surface runoff will occur and flow to the water supply.

      Thermal Stratification occurs when the surface water becomes warmer and lighter than the colder more dense water below. These layers stratify because they resist the mixing action of wind turbulence.

   The layers in stratification have different characteristics:

a.      The upper layer that continues mixing is called the Epilimnion.

b.      The middle layer is the zone of rapid temperature decrease with depth is called the Thermocline or Metalimnion.

c.       The lowest layer of colder, denser water is called the Hypolimnion.

1.      is similar to removal of turbidity by coagulation, flocculation, and sedimentation.  There are many variations, but the typical process involves adding lime to raise the pH of water until it is high enough for reactions to occur which prompt hardness compounds to settle out of the water.  The equipment used also resembles turbidity removal equipment - lime is added in the flash mixer, the water is flocculated, and then the hardness compounds precipitate out in the sedimentation basin. 

2.      As mentioned above, groundwater is more likely to need softening than surface water is.  Groundwater also may not need flocculation to remove turbidity, so the softening process can sometimes replace the turbidity removal process.  If both turbidity removal and softening are required, then the two processes can occur simultaneously, using the same equipment. 

3.      Chemical precipitation using lime will remove carbonate hardness.  If soda ash is added as well as lime, both Carbonate and Noncarbonate hardness may be removed.  In either case, chemical precipitation does not remove all hardness from water.  The hardness can be reduced as low as 30 to 40 mg/L using chemical precipitation, although the typical goal is 80 to 90 mg/L.  We will discuss the chemical reactions which occur in lime-soda ash softening in a later section.

4.      Chemical precipitation is an effective softening process, but it does have some disadvantages.  The process requires a lot of operator control to get an efficient result, which may make lime softening too operator-intensive for small treatment plants.  The high pH used in lime softening can set colors in water and make them difficult to remove.  Finally, lime softening produces large quantities of sludge which can create disposal problems. 

Hard water is usually defined as water which contains a high concentration of calcium and magnesium ions.  Measurements of hardness are given in terms of the calcium carbonate equivalent, which is an expression of the concentration of hardness ions in water in terms of their equivalent value of calcium carbonate.  Water is considered to be hard if it has a hardness of 100 mg/L or more as calcium carbonate. 

      also known as zeolite softening, passes water through a filter containing resin granules.  In the filter, known as a softener, calcium and magnesium in the water are exchanged for sodium from the resin granules.  The resulting water has a hardness of 0 mg/L and must be mixed with hard water to prevent softness problems in the distributed water. 

      involves water being forced through a semi-permeable membrane.  Calcium, magnesium, and dissolved solids are captured while the softened water is passed through the membrane

    involves passing water between two plates with opposite electrical charges.  The metals in the water are attracted to the plate with the negative charge while the non-metals are attracted to the plate with the positive charge.  Both types of ions can be removed from the plates and discarded.  Electrodialysis is used on very hard water, with a hardness of more than 500 mg/L as calcium carbonate.

     involves the evaporation of water.  The evaporated water leaves behind all hardness compounds, softening the water.

Chlorine demand is the the difference in the  amount of chlorine added to the water or wastewater and the amount of residual chlorine remaining in the water or wastewater after a given contact time.

To find the chlorine demand you use the following equation.

Chlorine Demand, mg/L =

Chlorine Dosage, mg/L -Chlorine Residual, mg/L

Chlorine dosage is the total amount of chlorine applied to the water or wastewater for disinfection.

To find the dosage we add the demand and the residual.

 Chlorine Dosage, mg/L =

Chlorine Demand, mg/L + Chlorine Residual, mg/L