Presentation on theme: "Water Purification and Treatment"— Presentation transcript:
1 Water Purification and Treatment Unit 1 – Section DWater Purification and Treatment
2 HW – 1Read and take notes on Unit 1 sections D.1 & D.2. The section starts on pg 86 D.3 write out and answer questions.
3 D.1 Natural Water Purification (aka Purifying through the hydrological cycle) Evaporation, followed by condensation removes nearly all dissolved substancesBacterial actions convert organic contaminants into a few simple compoundsFiltration through sand & gravel remove suspended materials
4 D.1 Natural Water Purification (continued) Pure rainwater is the best natural supply of clean water
5 D.2 Municipal Water Purification ScreeningCoagulent added (alum)Flocculation removing suspended particlesSettlingSand filtrationChlorinationOptional depending on water quality:AerationpH adjustmentFluoridation
6 D.3 Water Purification Natural Water Cycle Municipal Treatment SimilaritiesSand filtrationDifferencesBacterial actionChlorination
7 D.3 Water Purification (continued) Remember the natural cycle can be overwhelmed by over demand
9 D.4 Chlorination of Water Chlorination greatly helps reduce the risk of many diseases and illnesses.
10 D.4 Chlorination of Water (continued) How do we chlorinate water?Cl2 is bubbled through H2OA water solution of NaOCl - sodium hypochlorite, (household bleach) is added to waterCa(OCl)2 - Calcium hypochlorite is dissolved in water (commonly used in swimming pools)
11 D.4 Chlorination of Water (continued) Some chlorine is good, too much presents new chemical risks.Cl reacts with organics to produce THMc(trihalomenthanes)A common THM is chloroformCHCl3
12 D.5 Chlorination and THMs How to deal with THMs? 1) Pass treatment-water plant through charcoal filter. Disadvantages: expensive to install and operate
13 D.5 Chlorination and THMs (continued) 2 ) Eliminate chlorine and use ozone (O3) or ultraviolet light to disinfect. Disadvantages: does not protect water once it leaves treatment plant
14 D.5 Chlorination and THMs (continued) 3 ) Eliminate prechlorination add only once after filtering. Disadvantages: still promotes THMs (lesser extent) and decreased chlorination can allow bacterial growth
15 HW – 3Pre-read D.6 Bottled Water vs. Tap Water we will be doing this in class.Working with a partner answer the questions on pg. 92
16 D.6 Bottled Water vs. Tap Water Bottled water isTap water is•More consistent in taste •More convenient•stringently regulated •Readily available •costs less
17 In classWorking with a partner answer the questions on pg. 9217
18 HW – 4Pre-read and take notes on D.7 AND just like it looks on pg 94, create a data table as shown. This should be done in a word document.
19 D.7 Water SofteningWater hardness is not addressed at municipal treatment plants. Water containing an excess of dissolved calcium (Ca2+), magnesium (Mg2+) or iron (III) (Fe3+) ions is known as hard water.
20 D.7 Water Softening (continued) River water usually contains low levels of calcium (Ca2+), magnesium (Mg2+) or iron (III) (Fe3+) ions , however as it flows over limestone, chalk and other minerals that contain them it gains higher concentrations.
21 D.7 Water Softening (continued) One method of water softening is ion exchange , passing the water through tiny insoluble, porous beads capable of attracting and building cations.
22 HW – 5Read and take notes on D.8 Water & Water Softening
23 D.8 Water & Water Softening Hard water causes common household problems:Interferes with actions of soapScale may form as a result of heating
24 D.8 Water & Water Softening (continued) Most cleaning products today contain detergent rather than soap.
25 D.8 Water & Water Softening (continued) If you live in a hard-water region, your home plumbing may include a water-softener on you home plumbing.Hardness MagnitudeGrains Per Gallon (GPG)Soft WatergpgModerately Hard WatergpgHard WatergpgVery Hard WatergpgExtremely Hard Water> 10.5 gpg
26 Connecting the Concepts Due by end of classQ.s 20, 22 & 23* on pg. 103* Reference pg. 628 assume adult, age 50-70