V a h a k D. Sarkis Fulton-Montgomery Community College Johnstown, New York 12095
I
A Study of Water Pollution An undergraduate chemistry laboratory experience
In an attempt to make the teaching of chemistry more relevant to our times, a study of water pollution of lakes, rivers, wells, and city waters of the area, i.e. Fulton and Montgomery Counties of Upstate New York, was incorporated in the freshman laboratory experience. In addition to its environmental relevance, a water pollution study of the inorganic constituents in water as outlined below, provides the student with certain important principles of chemistry namely, colorimetric and titrimetric procedures. Equipment and Procedure
Althoueh anv standard colorimetric or wet analytical procedurl,l or other methods as presented in any quantitative chemical analvsis textbook, could be used to determine quantitatively the inorganic constituents in water, the was chosen for its "Hach (Direct Reading) Col~rimeter"~ versatility and simplicity of operation. The equipment (see figure) consists of a colorimeter unit and for volumetric tests a buret and titration stand fitted with a precision screw plunger, which accurately disperses titration solution. The procedures for the colorimeter are based on American Public Health Association Standard Methods. These 1 "Standard Methods for the Examination of Water and Wastewater," 12th Ed., American Public Health Association, Inc., New York, 1966. zThe "Haeh (Direct Reading) Calorimeter," purchased from Hach Chemical Company, Ames, Iowa. The manufacturers also supply a manual with full instructions for the different methods of analyses listed in Table 1.
Table 1. List of Major Chemical Constituents Analyzed in This Studv and Their Method of Analysis Chemical Constituent Akalinity as bicarbonates and carbonetea Chloride Chlorine, residual Chromium(hexavalentl or chromate Color, apparent and true copper Fluoride Hardness, total (am CaCOd Hardness (as ealoium and maenesiuml Manganese Nitrogen, nitrate Nitrogen, nitrite oxygen. dismlvd p H valve Phosphate, oztho and meta Silica Sulfate Turbidity
The "Hach (direct reading) colorimeter." Included in the unit are: the dry powdered reagents, premeasurad and individually packed in "powder pillows"; a set of precalibrated meter scales specific for a given test; a set of color filters: a buret and titration stand with a precision screw plunger, which accurately dispenses titration solution: all necessary standard titration solutions: and, a methods manual. (Photograph by courtesy of Hach Chemical Company, Ames Iowa1
Table 2. Results of Analysis of Major Chemical Constituents in Waters of Fulton and Montgomery Counties of Upstate New Yorka
Method of Anslyais Titratian- for phenolphthalein and total alkalinity Titration- Mercurio Nitrate method Colorimetric Ortholidine method Colorimetric- 1.5-Diphsnylearhohydrazide method ColorimetrirAmerican Public Health Assoeistio" method- PlatinumCobalt standard Colorimetric-Cuprethol method Colorimetrie--SPADNS method T i t r a m e t r i c EDTA method T i t r a m e t r i c EDTA method Co1orimet.i~- 1.10-Phenanthmline method C o l o r i m e t r i c Cold Periodate Oxidation method c o l o r i m e t r i c ~ a d m i u n ;Reduction method. Modified Diazotization (l-naphthylaminesulfanilie acid) method cotnrimetricniezoti~atiii .... ~ . . ~method ~ ~ (~.~~~hthylarnineaulfanilii acid1 Titmmtric-Modified Azide-Winkle method with D ~ o pCount Titration lusine PA01 Colorimetric- S t e m o w Reduction method c o l o r i m e t r i c Heteropoly Blue method C o l o r i m e t r i c Turbidimetric method Colorimetric Absorption method 1" Jackaan Turbidity Units-Formsrin
Chemiesl Constituent
FMC College Well water
300 Alkalinity ss hiesrbonates and carbonates Chloride chlorine, reeidusl Chromium (hexavalent) Color, in unita Copper Fluoride Hardndn, total Hardness, ealoium Hardness. magnesium Iron ~
-
~
Johnstown City Water
M"-.~ hawk Sacsn- River Optimum Limits dsga (Am(set by U.S. R-7sterPvhlic Heaith "air dam1 Service)
60
30
68
250.0 upto0.75 0.05
below 15 1.00
0.60-1.70 100-250 15-200 50-150
0.30
~
Manganese Nitrogen as ~ nitrate ~ ~ Nitroeen as nitrite O x y ~ e ndieaolved , pH Phosphate, ortho Phosphate, meta, Silica Sulfate Turbidity, in Jackson units
none
11.0 ~ 0.006 5.3
7.2 0.05 0.18 I1
32.0 0
0-150
none 5.0
0.007 7.9 1.5 0.03 0.25 61 6.5 0
none 7.5
none 8.5
0.05 45.0
0.010
0.60 0.100
6.8 6.7
7.8
0.30 0.08 32 7.0 21
7.0 0.44
seater than
6.5-8.0 preferably 0 0.16 preferably 0 28 0-30
14.5 6
250.0
below 5
a ~ e a e u l e m e n t in s ppm or mg/L unless otherwise stated.
Voiume51, Number 11. November 1974 / 745
Table 3. Major Chemical Constituents in Water-Their Sources, Optimum Limits on Concentration, and Effect on Usability of Water
~. ,:.";*-
ootimum as set by
U.S. constituent or Prope*ty
Major source or cause Action of carbon di-
and earbonstes)
Chloride
Chlorine (residual)
Chromium ihera-
~~~
Public Health Service 0-150 ppm
~
limestone and dolomile
Dissolved from roeks and soils. Present in sewage and industrial wates.
Usually added to municipal wrtex
mar 250 ppm
UP to 0.75 ppm
Fluoride
From sewage or induatrial waste. Copper is also added to ponds and reservoirs to control aquatic weeds
1 ppm
I n amau eoneentrations fluoride is dissobed from mila and rocks. I t is also added to drinkkg waters by fluoridation a t water purification plants
.06-1.7
Most hardness due to calcium and magnesium and may result from soils and geologic formations or from industrial and o m mezcial wastes
100-250 ppm
75-200
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Alkaline water, containing carbonates and biesrbonstes, when heated in the presence of calcium and magnesium forms crustlike scales in pipes restricting the flow of fluids in pipes and releasing corrosive carbon dioxide w s . Chloride in exeew of 100 ppm has salty taste and in exof 150 ppm may cause physiological damage. Also, in large quantities increases the corrosiveness of wster. Its primary function is as bactericide in puhlic water ayatems and swimming pogls. Depending on the presence of other substances in water, chlorine can imorove taate and d o r
From industrial waate. 0.05 ppm Used to prevent corrosion in cooling towere Fmm industrial wastes 15 units
substance copper
signifiesnee or effect upon usability of water
Journal of Chemical Education
optimum limits aa set by US. Public S i w e a n c s or effect Conatitvent Health or h 0 ~ ~ t htsjor y source or Cauae Service upon usability of water 2. Hazdness (mame-
See abovehardness (total)
50-150 mm
Iron
From natural sources as rocks and soils, and in industrial waste. and as result of corrosion from iron pipes and other equipment
0.3 ppm
Menganeae Nitrogen ("itrate)
Nitrogen (nitrite)
p~oeessing, laundries, dairies, and man" manufaeturinp, processes. Color is s good indicator of water pollution. Although capper is essential to the human body wltb an adult daily req1,irement of 2.0 mg, in large doses i t esn cause liver damage. I n m n centrations above 1 ppm copper imparts a bitter taste to drinkinp water. Fluoride concentration between 0.6-1.7 ppm in drinking wster is beneficial to children's teeth structure in resisting tooth decay. concentrations of fluoride in excess of 8 . 0 ppm will cause mottlmg and disfiguretion of teeth. Calcium snd magnesinm combine with bicarbonate.. earbonates, sulfate, and silica to form ~ c s l e which s d. po8it in pipes and boilers. Calcium and megnesium d m precipitste soap thus requiring excessive amount of soap and detergents for laundering. See above-hardn(totel).
oxygen (dismlved)
Mostly from rocks. soils and sediments From atmowhere. decaying vegetation, nitrates end fert2i.e.s from amirieu1ture. animal excrement and
Seeabove--hard(total). Also, high eonmtrstion of magnesium he8 a laxative eseet, especially on new users of the watns. Above 0 . 1 ppm iron precipitates upon exMBv.e to air. this staining laundry. plumbing
teste t o food and drinks. 0.05 ppm same objeetionsble qualities as iron. A concentration of 45 PPm more than 100 ppm imnsrts s bitter
Nitritee r-It fmm 0 . 1 ppm biological dacompzeitian of organic nitroeen from smmvnia and from conversion of nitrates. In industry nitrites added to inhibit c0,rosion Should Dissolved from the be atmoephere higher than
pH
F m m innumerable sour- of natural and man-made origin
6.5-8.5 pH
phosphate (total)
0 (PrefComposed of two erably) types: ortho end mete (or poly). From three main sources: Fertilizers used in sgrieulture; waete waters of domestie origin such as human, animal, and d s n t residues.
more than 45 ppm of nitrate can cause methemaglobinemia (blue babies) in infants. Nitrates esuse the overgrowth of algae and other orgsniams and foul the water ayatems. presence of large concentrations indieate waste water pollution.
the concentration ia 1e99 than 4 VDm the" fresh water i&ms are unsuitable for game fish. oxygen also needed to oxidize bacteria and organic mat* oresent in water: therefore, low eoncentrations or absence of oxygen is a g a d indication of wllvted waters. he ;H is a measure of the activity of acid of alkaline (basicity) materials in water. A p H of 7 . 0 ia neutral, a p H of less than 7 . 0 ia acid, and a p H of more than 1 . 0 is alkaline. A very low 8s well ae s very high p H value makes water emrosive to metal pipea and equipment. Phosphate when added to city and farm water systems controls hardness. However, phosphate as part of laundry detergents results in ovewroarth of algae, a water plant. This overahvndanee
Table 3. Continued
Constituant or Property
optimum 1imi'S 88 set by US. Publio Health Significance or effeot Major source or Cause Service upon usability of water cleaning age"%: and waste waters of industrial origin
1. phosphate See above-Phm(ortho) phste(total) 2. Phosphate SeeabovePhosohate(totsl) (met* or PIY) Silica in the form of Silica ai1iC.a dioxide such as sand and silicates constitutes the earth% second most abundant element, next to oxygen. Thus it is diawlved in w a t e from practically all rocks and soils nisrnlved from rocks Sulfate and mils which& tain sulfides and gypsum. Also from industrial w a s h , in liquid or in gaseous form
causes algae t o die a t s fast rate and undergo d e e o m p i tion. Deeomoosition as a process occurs in the presence of Oxygen, which when depleted results in fish kill and eutrophication of the water system, thue changing it into s swamp. 0 (Praf- See above--Phosphate erably) (total). 0 iPref- See sbove-Phosohste
the following simple steps: (1) placing the appropriate color filter and the sample blank (demineralized water) in the path of light source; (2) placing a precalibrated meter scale specific for the test into the meter case and adjusting the light control for a meter reading of zero; (3) removing the sample blank and inserting in its place the sample to he tested (with premeasured individually packed reagent(s) added to it; and (4) finally, reading the quantitative measure directly in ppm or other specified units, without the use of calibration graphs or calculations. There are two models of the Hach Calorimeter: the DREL with ac power source for laboratory use, and the DREL portable battery operated model which is ideal for testing water in the field. Testing the water a t the source is a necessity for certain tests such as, iron and manganese which nlate on the inside of the samole bottle and for analyses of gases such as, hydrogen sulfide, carbon dioxide, and chlorine which have the tendency t o dissipate readily. Results and Discussion
0 9 0 ppm In the preaeneaene of esleium and magneaium silica forms 'tales in p i p , boilers. and turbines thus h;mp,ing their opezation. Silica when added to soft water diminishes the "3.meion of iron pipe. 250 ppm When sulfate is present with calcium, scale results in nines and steam b o i i e r e some calcium su1fate is said to be beneficial in brewine omeess. Sulfate concentrations of about 500 ppm tastes bitter. Sulfate concentrations of 1,000 ppm may be cathartic. Turbidity is objectionable far aesthetic r e a m s . I" indust.isl bidity proeessea the degree units and tvoe of turbidity hamper operations. Turbidity ia removed up.,,, eettling, coaeu1stion and
The major chemical constituents analyzed in this study are listed with their method of analysis in Tahle 1. The results of student analysis, Tahle 2, give the major chemical constituents in water, the sources, and the optimum limits on concentration as set by the United States Public Health Service.3 The optimum limits are given as a single value (an average) or as a range indicating the lower and the upper limits. The units unless otherwise stated are in ppm or mgh. In Tahle 3, the major chemical constituents in water are listed along with major source or cause, optimum limits as set by the US. Public Health Service, and the significance or effect (ohvsioloeical. .. - . industrial, and other) upon usability of these waters.' Based on the limited data used for this study, .. we could conclude that, generally, the chemical quality of the waters of Fulton and Montgomery Counties of Upstate New York is good to excellent. This means that the waters in these areas are suitable for most purposes and that only little or no treatment is required. However, for drinking purposes, even the cleanest water should be subjected to proper purification treatments and chlorination to prevent the danger of bacterial pollution, and sewage treatment processes are essential to reuse our limited supply of water.
methods (supplied with the instrument) have heen simplified with the use of dry powdered reagents which are Premeasured and individually packed in "powder pillows." The instrument has the capability of analyzing up to 56 different chemical constituents in water, from aluminum to zinc. Each procedure takes but only few minutes and consists of
"Public Health Service Drinking Water Standards-Revised No. 956, U,S. Govern. 1962,MPublic Health Service merit printingOffice, Washington,D.C., 1962, p. 7-8, p. 21, p. 3536, dTodd, David K. (Editor),"The Water Encyclopedia," Water Information Center, Port Washington, New York, 1970, p. 307308.
Turbidity
Caused h y the presence of suspended and colloidal matter resulting from clay, silt, organic matter. microorganisms and ,"dustrial wastes
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