Laboratory Procedures

pH

pH is an expression of the intensity of the basic or acidic condition of a liquid. Mathematically, pH is the logarithm (base 10) of the reciprocal of the hydrogen ion activity. pH = Log 1 divided by H+ The pH may range from 0 to 14, where 0 is most acidic, 14 most basic, and 7 neutral. Natural waters usually have a pH between 6.5 and 8.5.

Volatile

1 A volatile substance is one that is capable of being evaporated or changed to a vapor at relatively low temperatures. Volatile substances also can be partially removed by air stripping. 2 In terms of solids analysis, volatile refers to material lost, including most organic matter, upon ignition in a muffle furnace for 60 minutes at 550 degree celcius. Natural voltile materials are chemical substances usually of animal or plant origin. Manufactured or synthetic volatile materials such as ether, acetone and carbon tetrachloride are highly volatile and not of plant or animal origin.

Chemicals in water treatment that are alkalinity changers

1 Alum 2 Chlorine 3 Lime

Chlorine variation causes?

1 Amount chlorine 2 Contact time length 3 pH 4 Temperature 5 Organics 6 Reducing agents

Precipitate

1 An insoluble, finely divided substance which is a product of a chemical reaction within a liquid 2 The seperation from solution of an insoluble substance.

Grab sample water quality indicators usually measured

1 Dissolved gases 2 Coliform bacteria 3 Residual chlorine 4 Temperature 5 pH

Two general sample types collected by water treatment

1 Grab 2 Composite

Six laboratory hazards

1 Hazardous materials 2 Explosions 3 Cuts and bruises 4 Electric shock 5 Fire 6 Burns from heat and or chemical

Greatest source of error in lab tests are these 3

1 Improper sampling 2 Poor sample preservation 3 Lack of enough mixing during testing

Four sources or causes of poor quality of analytical data are

1 Sloppy laboratory technique 2 Deteriorated reagents and standards 3 Poorly operating instruments 4 Calculation mistakes

Grab sample preferred over a composite sample when?

1 The water to be sampled does not flow continuously 2 The water's characteristics are relatively constant 3 The water is to be analyzed for water quality indicators that may change with time, such as dissolved gases, coliform bacteria, residual chlorine, temperature, and pH.

Prefix milli ?

1/1000 or 0.001 of the unit following

Steam autoclave kills how?

15 psi and 121 Celcius and 15-minute time period at sea level

Compound

A pure substance composed of two or more elements whose composition is constant. For example, table salt (sodium chloride, NaCl) is a compound.

Blank

A bottle containing only dilution water or distilled water; the sample being tested is not added. Tests are frequently run on a Sample and a Blank and the differences are compared. The procedure helps to eliminate or reduce test result errors that could be caused when the dilution water or distilled water used is contaminated.

Desiccator

A closed container into which heated weighing or drying dishes are placed to cool in a dry environment in preparation for weighing. The dishes may be empty or they may contain a sample. Desiccators contain a substance, such as anydrous calcium chloride, which absorbs moisture and keeps the relative humidity near zero so that the dish or sample will not gain weight from absorbed moisture.

Composite

A composite sample is a collection of individual samples obtained at regular intervals, usually every one or two hours during a twenty four hour time span. Each individual sample is combined with the others in proportion to the rate of flow when the sample was collected. The resulting mixture (composite sample) forms a representative sample and is analyzed to determine the average conditions during the sampling period.

Solution

A liquid mixture of dissolved substances. In a solution it is impossible to see all the separate parts.

Amperometric Titration

A means of measuring concentrations of certain substances in water such as strong oxidizers based on the electric current that flows during a chemical reaction.

Nephelometric

A means of measuring turbidity in a sample by using an instrument called a nephelometer. A nephelometer passes light through a sample and the amount of light deflected (usually at a 90-degree angle) is then measured.

Colorimetric Measurement

A means of measuring unknown chemical concentrations in water by measuring a sample's color intensity. The specific color of the sample, developed by addition of chemical reagents, is measured with a photoelectric colorimeter or is compared with "color standards" using, or corresponding with, known concentrations of the chemical.

Gravimetric

A means of measuring unknown concentrations of water quality indicators in a sample by Weighing a precipitate or residue of the sample.

Buffer Capacity

A measure of the capacity of a solution or liquid to neutralize acids or bases. This is a measure of the capacity of water for offering a resistance to changes in pH.

Milligrams Per Liter, mg/L

A measure of the concentration by weight of a substance per unit volume. For practical purposes, one mg/L of a substance in fresh waer is equal to one part per million parts (ppm). Thus a liter of water with a specific gravity of 1.0 weighs one million milligrams. If water contains 10 milligrams of calcium, the concentration is 10 milligrams per million milligrams, or 10 milligrams per liter (10 mg/L), or 10 parts of calcium per million parts of water, or 10 parts per million (10 ppm).

Volumetric

A measurement based on the volume of some factor. Volumetric titration is a means of measuring unknown concentrations of water quality indicators in a sample BY DETERMINING THE VOLUME of titrant or liquid reagent needed to complete particular reactions.

Amperometric

A method of measurement that records electric current flowing or generated, rather than recording voltage. Amperometric titration is a means of measuring concentrations of certain substances in water.

DPD

A method of measuring the chlorine residual in water. The residual may be determined by either titrating or comparing a developed color with color standards. DPD stands for N, N-diethyl-p-phenylene-diamine.

M or Molar

A molar solution consists of one gram molecular weight of a compound dissolved in enough water to make one liter of solution. A gram molecular weight is the molecular weight of a compound in grams. For example, the molecular weight of sulfuric acid H2SO4 is 98. A one M solution of sulfuric acid would consist of 98 grams of H2SO4 dissolved in enough distilled water to make one liter of solution.

N or Normal

A normal solution contains one gram equivalent weight of reactant (compound) per liter of solution. The equivalent weight of an acid is that weight which contains one gram atom of ionizable hydrogen or its chemical equivalent. For example, the equivalent weight of sulfuric acid H2SO4 is 49 98 divided by 2 because there are two replaceable hydrogen ions. A one N solution of sulfuric acid would consist of 49 grams of H2SO4 dissolved in enough water to make one liter of solution.

Reagent

A pure chemical substance that is used to make new products or is used in chemical tests to measure, detect, or examine other substances.

Representative Sample

A sample portion of material or water that is as nearly identical in content and consistency as possible to that in the larger body or material or water being sampled.

Grab Sample

A single sample of water collected at a particular time and place which represents the composition of the water only at that time and place.

Standard Solution

A solution in which the exact concentration of a chemical or compoud is known.

Buffer

A solution or liquid whose chemical makeup neutralizes acids or bases without a great change in pH.

Indicator

A substance that gives a visible change, usually of color, at a desired point in a chemical reaction, generally at a specified end point.

Element

A substance which cannot be separated into its constituent parts and still retain its chemical identity. For example, sodium (NA) is an element.

Surfactant

Abbreviation for surface-active agent. The active agent in detergents that possesses a high cleaning ability.

pH Discussion

Acidic or basic strength indicator. Important for processes such as disinfection, coagulation, softening and corrosion control. Also indicates changes in raw and finished water quality.

Calcium Carbonate Equivalent

An expression of the concentration of specified constituents in water in terms of their equivalent value to calcium carbonate. For example, the hardness in water which is caused by calcium, magnesium and other ions is usually described as calcium carbonate equivalent. Alkalinity test results are usually reported as mg/L CaCO3 equivalents. To convert chloride to CaCO3 equivalents, multiply the concentratoin of chloride ions in mg/L by 1.41 and for sulfate, multiply by 1.04.

Organism

Any form of animal or plant life.

Alkali

Any of certain soluble salts, principally of sodium, potassium, magnesium. and calcium, that have the property of combining with acids to form neutral salts and may be used in chemical water treatment processes.

Carcinogen

Any substance which tends to produce cancer in an organism.

Bacteria

Bacteria are living organisms, microscopic in size, which usually consist of a single cell. Most bacteria use organic matter for their food and produce waste products as a result of their life processes.

CaCO3?

Calcium Carbonate

Principle hardness-causing ions?

Calcium and magnesium

Chlorine Demand Discussion

Calculate demand in various samples to determine best dosage for desired residual. Difference between amount applied and amount of free, combined, or total residual chlorine remaining after contact time, times vary. Other variances are time length (contact time), amount applied, pH, temperature, organics, reducing agents.

Hardness Discussion

Caused mainly by calcium and magnesium. Also caused by iron, manganese, aluminum, strontium and zinc. 2 types are Carbonate hardness, caused by calcium/magnesium bicarbonate or carbonate. Noncarbanate hardness, caused by calcium/magnesium sulfate, chloride, or nitrate. Can cause scale incrustations when water evaporates or when heated. Also combines with soap to form insoluble precipitates. Remedied by softening.

Chlorine demand formula

Chlorine added, mg/L minus Free Residual chlorine mg/L equals Demand

Chlorine Residual Discussion

Chlorine reacts with iron, manganese, protein substances, sulfide, taste and odor producing compounds, microorganisms that interfere with coagulation and flocculation, lime growths and undesirable color, bleaches it out. 2 types, free residual chlorine and combined residual chlorine. Could cause carcinogenic chlororaganic compounds like chloroform and other THMs. Know the 2 residuals.

Alkalinity determined for?

Dosages, softening, calculate corrosivity, estimate carbonate hardness

Facultative

Facultative bacteria can use either dissolved molecular oxygen or oxygen obtained from food materials such as sulfate or nitrate ions. In other words, facultative bacteria can live under aerobic or anaerobic conditions.

Volatile Acids

Fatty acids produced during digestion which are soluble in water and can be steam-distilled at atmospheric pressure. Also called organic acids. Voltile acids are commonly reported as equivalent to acetic acid.

Aseptic

Free from the living germs of disease, fermentation, or putrefaction. Sterile.

Coliform Bacteria Discussion

Indicator organisms the coliform group of bacteria, tested for instead of for specific pathogens such as giardiasis. Coliforms presence indicates other bad stuff could also be there. Coliform group includes aerobic and Facultative anaerobic gram-negative, nonspore-forming rod-shaped bacteria. Fecal grows at higher temps than non-fecal. The Maximun Contaminant Level Goal MCLG for coliform is zero. A positive sample requires furthur testing.

Temperature Discussion

Influences chemical reaction rates, biological growth, dissolved gas concentrations, and water stability with respect to calcium carbonate and for consumer satisfaction.

Supernatant

Liquid removed from settled sludge. Supernatant commonly refers to the liquid betweeen the sludge on the bottom and the scum on the water surface of a basin or container.

Volatile Liquids

Liquids which easily vaporize or evaporate at room temperature.

Inorganic

Material such as sand, salt, iron, calcium salts and other mineral materials. Inorganic substances are of mineral origin, whereas organic substances are usually of animal or plant origin.

Nonvolatile Matter

Material such as sand, salt, iron, calcium, and other mineral materials which are only slightly affected by the actions of organisms and are not lost on ignition of the dry solids at 550 degrees celcius. Volatile materials are chemical substances usually of animal or plant origin.

Volatile Matter

Matter in water, wastewater, or other liquids that is lost on ignition of the dry solids at 550 degree celcius.

Why is total coliform test inadequate for measuring extent of human waste in water?

Measures both fecal coliforms, E. coli, and soil coliforms. Additional tests are needed to count fecal coliforms specifically.

Flame Polished

Melted by a flame to smooth out irregularities. Sharp or broken edges of glass (such as the end of a glass tube) are rotated in a flame until the edge melts slightly and becomes smooth.

Chlororganic

Organic compounds combined with chlorine. These compounds generally originate from, or are associated with, life processes such as those of algae in water.

Pathogenic Organisms

Organisms, including bacteria, viruses or cysts, capable of causing diseases such as giardiasis, cryptosporidiosis, typhoid, chlolera, dysentery, in a host such as a person. There are many types of organisms which do NOT cause disease. These organisms ar called non-pathogenic.

Oxidation

Oxidation is the addition of oxygen, removal of hydrogen, or the removal of electrons from an element or compound. In the environment, organic matter is oxidized to more stable substances.

Parts Per Million

Parts per million parts, a measurement of concentration on a weight or volume basis. This term is equivalent to milligrams per liter mg/L which is the preferred term.

Pathogens

Pathogenic or disease-causing organisms.

Turbidity Discussion

Physical cloudiness of water caused by silt, finely divided organic and inorganic matter and microscopic organisms such as algae. Measured by nephelometric method. Greater intensity of scattered light means higher turbidity. Maximum contaminant level MCL is 1 TU with 5 TU allowed under certain circumstances. Strive for 0.1 or less.

Laboratory quality control tests important why?

Provide the info to monitor the treatment processes and guarantee a safe and pleasant tasting drinking water

Standard Methods

Publication outlines the accepted laboratory procdures used to analyze the impuities in water and wastewater.

Reduction

Reduction is the addition of Hydrogen, removal of Oxygen, or the addition of electrons to an element or compound. Under anaerobic conditions, sulfur compounds are reduced to odor-producing hydrogen sulfide H2S and other compounds.

Aliquot

Representative portion of a sample. Often an equally divided portion of a sample.

Alkalinity discussion

Result of bicarbonates, carbonates, and hydroxides of metals of calcium, magnesium, and sodium. 5 alkalinity conditions 1 bicarbonate alone 2 bicarbonate and carbonate 3 carbonate alone 4 carbonate and hydroxide 5 hydroxide alone. Alum, chlorine, lime cause changes in alkalinity. Coagulation, water softening, corrosivity and carbonate hardness estimate rely on alkalinity determination.

End Point

Samples of water or wastewater are titrated to the end point. This means that a chemical is added, drop by drop, to a sample until a certain color change (blue to clear, for example) occurs. This is called the End Point of the titration. In addition to a color change, an end point may be reached by the formation of a precipitate or the reaching of a specified pH. An end point may be detected by the use of an electronic device such as a pH meter. The completion of a desired chemical reaction.

Jar Test Discussion

Shows how chemicals are working. Small scale reproduction evaluates mainly coagulation with alum and polymers. Helps with dosage as raw water changes occur in turbidity, color, or other factors.

Organic

Substances that come from animal or plant sources. Organic substances always contain carbon. (Inorganic materials are chemical substances of mineral origin.)

Ambient

Temperature of the surrounding air or other medium. For example, temperature of the room where a gas chlorinator is installed.

OSHA

The Williams-Steiger Occupational Safety and Health Act of 1970 (OSHA) is a federal law designed to protect the health and safey of industrial workers and also the operators of water supply systems and treatment plants. The Act regulates the design, construction, operation and maintenance of water supply systems and water treatment plants. OSHA also refers to the federal and state agencies which administer the OSHA regulations.

Percent Saturation

The amount of a substance that is dissolved in a solution compared with the amount dissolved in the solution at saturation expressed as a percent. Percent Saturation = Amount of Substance That Is Dissolved x 100 percent divided by Amount Dissolved in Solution at Saturation.

Acidic

The condition of water or soil which contains a sufficient amount of acid substances to lower the pH below 7.0.

Alkaline

The condition of water or soil which contains a sufficient amount of alkali substances to raise the pH above 7.0.

Meniscus

The curved surface of a column of liquid (water, oil, mercury) in a small tube. When the liquid wets the sides of the container the curve forms a valley. When the confining sides are not wetted the curve forms a hill or upward bulge. When a meniscus forms in a measuring device, the top of the liquid level of the sample is determined by the bottom of the meniscus.

Oxidation-Reduction Potential

The electrical potential required to transfer electrons from one compound or element (the oxidant) to another compound or element (the reductant); used as a qualitative measure of the state of oxidation in water treatment systems. ORP is measured in millivolts, with negative values indicating a tendency to oxidize compounds or elements and positive values indicating a tendency to oxidize compounds or elements.

Molecular Weight

The molecular weight of a compound in grams is the sum of the atomic weights of the elements in the compound. The molecular weight of sulfuric acid H2SO4 in grams is 98.

Mole

The molecular weight of a substance, usually expressed in grams.

Disinfection

The process designed to kill or inactivate most microorganisms in water, including essentially all pathogenic (disease-causing) bacteria. There are several ways to disinfect, with chlorination being the most frequently used in water treatment.

Sterilization

The removal or destruction of all microorgancisms, including pathogenic and other bacteria, vegetative forms and spores.

Molecule

The smallest division of a compound that still retains or exhibits all of the properties of the substance.

Volatile Solids

Those solids in water or other liquids that are lost on ignition of the dry solids at 550 degree celcius.

Titrate

To Titrate a sample, a chemical solution of known strength is added drop by drop until a certain color change, precipitate, or pH change in the sample is observed (end point). Titration is the process of adding chemical reagent in small increments 0.1 to 1.0 milliliter until completion of the reaction, as signaled by the end point.

Standardize

To compare with a standard. 1 In wet chemistry, to find out the exact strength of a solution by comparing it with a standard of known strength. This information is used to adust the strength by adding more water or more of the substance dissolved. 2 To set up an instrument or device to read a standard. This allows you to adust the instrument so that it reads accurately, or enables you to apply a correction factor to the readings.

Turbidity Units (TU)

Turbidity units are a measure of the cloudiness of water. If measured by a nephelometric, meaning deflected light, instrumental procedure, turbidity units are expressed in nephelometric turbidity units NTU or simply TU. Those turbidity units obtained by visual methods are expressed in Jackson Turbidity Units JTU which are a measure of the cloudiness of water; they are used to indicate the clarity of water.

Inorganic Waste

Waste material such as sand, salt, iron, calcium and other mineral materials which are only slightly affected by the action of organisms. Inorganic wastes are chemical substances of mineral origin; wheras organic wastes ore chemical substances of an animal or plant origin.

Potable

Water that does not contain objectionable pollution, contamination, minerals, or infective agents and is considered satisfactory for drinking.