Water is one of our planet’s most precious resources, and Great Lakes is doing its part to ensure that it is used wisely and safely. Great Lakes produces products that are used widely in industrial water treatment applications that contribute to our daily lives such as cooling water for office buildings and manufacturing facilities, processing, wastewater treatment, paper making, oil recovery, and water purification. The inorganic scale and corrosion inhibitors and microbiological control products produced by Great Lakes allow water to be used more efficiently and reduces waste. Our products are also used in arid regions of the world to turn salt water into fresh drinking water.
As a major producer of organic, polymer-based antiscalants and corrosion inhibitors and bromine-based biocides, Great Lakes is making water work even better.
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Types of Treatment
Flocculation refers to water treatment processes that combine or coagulate small particles into larger particles, which settle out of the water as sediment. Alum and iron salts or synthetic organic polymers (used alone or in combination with metal salts) are generally used to promote coagulation. Settling or sedimentation occurs naturally as flocculated particles settle out of the water.
Many water treatment facilities use filtration to remove all particles from the water. Those particles include clays and silts, natural organic matter, precipitates from other treatment processes in the facility, iron and manganese, and microorganisms. Filtration clarifies water and enhances the effectiveness of disinfection.
Ion exchange processes are used to remove inorganic contaminants if they cannot be removed adequately by filtration or sedimentation. Ion exchange can be used to treat hard water. It can also be used to remove arsenic, chromium, excess fluoride, nitrates, radium, and uranium.
Organic contaminants, unwanted coloring, and taste-and-odor-causing compounds can stick to the surface of granular or powder activated carbon and are thus removed from the drinking water.
Water is often disinfected before it enters the distribution system to ensure that potentially dangerous microbes are killed. Chlorine, chloramines, or chlorine dioxide are most often used because they are very effective disinfectants, not only at the treatment plant but also in the pipes that distribute water to our homes and businesses. Ozone is a powerful disinfectant, and ultraviolet radiation is an effective disinfectant and treatment for relatively clean source waters, but neither of these are effective in controlling biological contaminants in the distribution pipes. Industrial water treatment
Monitoring Water Quality
Water systems monitor for a wide variety of contaminants to verify that the water they provide to the public meets all federal and state standards. Currently, the nation’s community water systems (CWSs) and nontransient non-community water systems (NTNCWSs) must monitor for more than 83 contaminants. The major classes of contaminants include volatile organic compounds (VOCs), synthetic organic compounds (SOCs), inorganic compounds (IOCs), radionuclides, and microbial organisms (including bacteria). Testing for these contaminants takes place on varying schedules and at different locations throughout the water system. Industrial water treatment
Transient non-community water systems may monitor less frequently and for fewer contaminants than CWSs. Because these types of systems serve an ever-changing population, it is most important for them to monitor for contaminants such as microbiologicals and nitrate that can cause an immediate, acute public health effect.
Water systems also monitor for a number of contaminants that are currently not regulated. This monitoring data provides the basis for identifying contaminants to be regulated in the future.
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Humans are over 70% water and it is impossible to survive more than 5 days without water. With toxins in water pollution, including acid rain, illegal dumping, etc. it is becoming more and more necessary to utilize water treatment. Especially in the home, a water treatment system is important in keeping one’s family healthy. Water treatment systems can deliver clean, delicious water to an entire house and helps reduce the problems associated with hard water, which is caused by limescale in pipes.
Foul taste, color or smell of your household water are reasons to implement a water treatment system. Before attempting to remedy the situation, it is wise to get your water tested at your local hardware store. Many simple carbon filters, water softeners, reverse osmosis units, neutralizing filters or mechanical filters can be bought cost effectively and easily installed to help treat one’s water supply. Water is used so heavily in daily living that water treatment is a great idea for a home improvement project.
Why do we treat wastewater?
The most basic answer is to make dirty water clean. Treatment facilities simply compress the organic decomposition processes which take place in nature. This is performed by a combination of physical, biological, and chemical treatment stages. Nature (receiving waters) can only accept small amounts of sewage before becoming polluted, that is, natural bacteria feed on the sewage organics and create an abnormal amount of dissolved oxygen uptake. Dissolved oxygen which exists in minute amounts (10 parts per million @ 20ºC), is required by all marine life for survival. One of the principle objectives of wastewater treatment is to prevent as much of this “oxygen-demanding” organic material as possible from entering the receiving water.
What is hard water?
Hard water is the most common problem found in the average home. Hard water is water that contains dissolved hardness minerals above 1 GPG.
What are hardness minerals?
Calcium, manganese and magnesium are the most common.
How do you Measure Hardness?
Parts per million or grains per gallon are the most common. One part per million (PPM) is just what it says: out of one million units, one unit. Grains, or grains per gallon (GPG) is a weight measurement taken from the Egyptians; one dry grain of wheat, or about 1/7000 of a pound. It takes 17.1 PPM to equal 1 GPG.
Why Should Hard Water Concern Me?
For many uses, it would not matter. For instance, to put out fires, water your lawn, wash the mud off the streets or float your boat, water would have to be pretty hard to cause a problem. But for bathing, washing dishes and clothes, shaving, washing your car and many other uses of water, hard water is not as efficient or convenient as “soft water.” For instance:
you use only 1/2 as much soap cleaning with soft water.
because hard water and soap combine to form “soap scum” that can’t be rinsed off, forming a ‘bathtub ring’ on all surfaces and drys leaving unsightly spots on your dishes.
when hard water is heated, the hardness minerals are re-crystallized to form hardness scale. This scale can plug your pipes and hot water heater, causing premature failure, and costly replacement. the soap scum remains on your skin even after rinsing, clogging the pores of your skin and coating every hair on your body. This crud can serve as a home for bacteria, causing diaper rash, minor skin irritation and skin that continually itches.
for many industrial uses, the hardness minerals interfere with the process, causing inferior product.
Who Will Test My Water for Hardness?
If you are connected to a municipal supply, call the water Superintendent, or City Hall. They can either provide the answer, or direct you to the proper individual. Remember the conversion factor: it takes 17.1 PPM to equal 1 GPG. In other words, if your water has 171 PPM calcium in it, divide 171 by 17.1 to get the answer in grains. This example would be 10 grains, or GPG.
If you are on a private supply, you could contact your county extension agent: collect a sample in an approved container and send to the city or state health department for testing: find a testing lab (try the yellow pages): call a water conditioning company. By the way, if you are on a private well, YOU, AND YOU ALONE are responsible for the safety of the water you and your family drink. You should test your supply for bacteria at least once per year and other contaminants at least every three years — more under certain conditions.
My Water is Hard; Now What?
If your water tests over 3 GPG hard, you should mechanically soften it. Softening water that is less than 3 GPG, while it makes your shaving and bathing more comfortable, is considered a luxury due to the fact that the cost is more than your savings. Over 3 GPG, you will save enough to pay for the cost and maintenance of a water conditioner.
As of this writing, the most economical way for you to soften your household water is with an ion exchange water softener. This unit uses sodium chloride (salt) to recharge man made plastic like beads that exchange hardness minerals for sodium. As the hard water passes through and around the plastic like beads, the hardness minerals (ions) attach themselves to the bead, dislodging the sodium ions. This process is called “ion exchange”. When the plastic bead, called Resin, has no sodium ions left, it is exhausted, and can soften no more water. The resin is recharged by flushing with salt water. The sodium ions force the hardness ions off the resin beads; then the excess sodium is rinsed away, and the resin is ready to start the process all over again. This cycle can be repeated many, many time before the resin loses it’s ability to react to these forces. Industrial water treatment
Which Water Conditioning Company should I call?
As in any purchase, talk to your friends and neighbors — who do they use? Are they happy with them? Check with the Better Business Bureau for complaints. The BBB can’t prevent shady business, but they can and do keep a file of complaints filed by people who have had dealings with them. Remember, just because the unit or Company carries a brand name is not any indication that the unit is any better………but it may mean it is more costly for you!
Ask at least two to come to your home to look at your plumbing and then give you a quote on their equipment. Have them explain all the features of the unit, as well as the warranty.
What Should I look for in a Water Conditioner?
Make sure the unit has enough resin to treat all the water you and your family will use. As of this writing, the average usage per day, per person (including children), for inside the house is 87 gallons. You should also be shown two or three ways to initiate recharging the unit.
The oldest way is by a time clock, i.e., your water usage is calculated and the frequency of recharging programmed into the timer. On the appointed day, at the appointed hour, the unit recharges. If all went as calculated, ok. If you were gone — too bad — you just wasted salt and water. If you had extra company — too bad — you ran out of soft water. You must pick a unit that will treat one days supply of water and still have about 40% of the resin in the recharged state. This will provide you with the most efficiency for salt and regeneration water.
A second way to initiate recharge is by electronic sensing. By electronically checking the resin, these units can determine when the resin needs to be recharged — this is a great help when your water hardness changes, when you have extra company or when you are gone for a few days. These ‘sensor’ units can save you up to 42% of your salt and recharge water as well as keep you in soft water when you have extra guests.
A third way to initiate recharge is by using a meter. These units have a meter installed in the water line and simply measure how many gallons of water you actually used. The unit is set according to your water hardness, and will recharge when the gallons used approach exhaustion of the resin bed, saving you a high percentage of your recharge salt and water. Residential water treatment
Many variations of these methods are on the market. Some use computers to calculate in advance, when to recharge the unit; some have two resin beds (tanks), and switch back and forth between the two, keeping you in soft water all the time, at the highest efficiency. These systems are most effective in high hardness waters, i.e., over 10-12 GPG, and over 4 people in the family. Low hardness water and smaller families do not require the extra expense of these options.
I Have a Water Conditioner, Now my Water Feels “Slimy”
When the hardness minerals are removed, soap no longer forms a soap curd, or “bathtub ring” on your skin, plugging your pores, clinging to every strand of hair. You are now truly clean. That slick, slimy feeling you feel is your natural body oils — without the soap scum. The old saying that you get “squeaky clean” is a myth; that feeling was caused by the soap scum on your skin. By the way, that soap scum provided an excellent place for bacteria to hide and grow, causing numerous minor skin ailments.
My Water Stinks! What can I Do?
First, you must learn a little about your nose: Once you smell some things, your sense of smell is dulled for a short while, and you can’t make accurate judgments of smell. For instance, if I blindfold you, let you smell gasoline, hand you a piece of onion to eat and tell you it is an apple, you can’t tell it’s not because your nose isn’t working properly!! (Your sense of taste isn’t working either — smell and taste are closely related and affect each other!)
So, to correctly analyze your problem, you need to become a detective. The best time to locate the smell is after you have been away from home for a few hours — this allows your nose to become sensitive to “that smell” again. With your ‘sensitized’ nose, go to an outside spigot — one that the raw, untreated water flows from. Turn it on, let it run a few minutes, then smell it. If it smells — we found it. If not, we must look further. (Many, many smells are not in the raw water at all, they are introduced into the water inside the house.) Go to a cold, treated water spigot inside the house, turn it on and let it run a minute; then smell. If this water smells, and the outside, untreated water didn’t — you must have a device (cartridge filter, water softener, etc.) in the water line that needs to be cleaned and sanitized.
If it is a cartridge, or ‘string’ filter, replace the element and sanitize the housing. If you have a water conditioner call the Company where you bought the unit for advise on how to sanitize the unit. If you rent the unit, just call! You can sanitize the unit by pouring Hydrogen Peroxide or Chlorine Bleach in the brine well of the salt tank, and placing the unit into regeneration. Check with the seller, or, if they are no longer in business, any Professional Water Conditioning Dealer for how much to put in your particular unit.
If the cold, treated water inside didn’t smell, turn on the hot water and let it run a few minutes — does it smell? If it does, chances are you have a sacrificial anode inside your hot water heater that is “coming apart at the seams” and throwing off a “rotten egg” odor. This obnoxious smell will drive you right out of your shower! The only solution is to remove the anode from the heater, voiding your warranty, or replace it with a new one made with aluminum alloy. This anode is placed in a (glass lined) hot water heater to seal up any cracks in the glass lining and prevent corrosion of the heater tank. You will find the anode on the top of the heater; remove the tin cover and insulation — look for what looks like a pipe plug — about 3/4 inch in size with a 1 1/16″fitting. Turn off the heat source and the water; have someone hold the tank to prevent it from turning, and unscrew the “plug”. You will find that the ‘plug’ has a 30 – 40″ long pipe (or what’s left of one) attached to it. Hopefully, most of the rod is still attached — just corroded. Replace that plug with a pipe plug and throw the anode away. If part of the rod has corroded off, and fallen into the heater, you may have to try to fish it out. (Good Luck!!) Either way, before you plug the hole, pour about 2 pints of chlorine bleach into the tank. This will kill the smell left in the heater. If, after a week or so, the smell returns, you must fish out the rod that is in the bottom of the tank. The bad news is that by removing the anode, your water heater warranty may be voided. Good Luck!
OK, It’s my Raw Water That Smells — Now What?
First, you must determine what is causing the smell, and how strong it is.
Minor, musty smell:
If it is a minor, or low-level smell, you MIGHT be able to solve it with a small, point-of-use carbon filter. You can place these types of filters on the water line going to the cold water where you draw you drinking water. Or, you might solve it with a whole-house filter on your incoming water line to filter all of the water inside your home. Residential water treatment
Because carbon removes smells by ADsorbtion, i.e., the smell “sticks” or “adheres” to the carbon particles, you must be careful not to exceed the manufactures recommended flow — some filters even have a flow restriction built in them. If you run water through them too fast, you will not remove the smells. Whenever you place a carbon filter in your water line, you must be sure to replace the element and sanitize the housing on a regular basis. Carbon filters remove organics from water, and the bacteria found in water like to eat organics — the carbon filter is a nice, dark place, just full of food for them to grow and reproduce in. Regular and routine replacement will help prevent any buildup of bacteria in the cartridge.
Strong, rotten-egg smell:
Strong, rotten-egg odors in the raw water is usually the result of the decomposition of decaying underground organic deposits. As water is drawn to the surface, hydrogen sulfide gas can be released to the atmosphere. In strong concentrations, this gas is flammable and poisonous. It rapidly tarnishes silver, turning it black. It is toxic to aquarium fish in sufficient quantities. As little as 0.5 ppm hydrogen sulfide can be tasted in your drinking water.
Strong, musty smell:
If you are unlucky enough to have this problem, you should look for a company that has local experience in dealing with this problem. There are three basic ways to solve this problem for homeowners.
Installation of a whole house filter loaded with a media that is specific for hydrogen sulfide removal is successful many times. These types of filters must be recharged with chlorine or potassium permanganate. The removal capacities of these types of filters are usually fairly low, and must be sized to contain enough media to prevent premature exhaustion, and subsequent passage of the smell to service. It is also typical that the amount of hydrogen sulfide can fluctuate rapidly, causing great difficulty in sizing the unit. In addition, potassium permanganate is extremely “messy”, and will leave stains that are very difficult to remove.
Feeder systems consist of a small pump that injects small amounts of chlorine (usually) into the incoming water. The water must then be held for a short period of time to allow the hydrogen sulfide to precipitate out of the water. This tank should be designed in such a manner that the water that enters it will mix thoroughly with the water in the tank, to assure complete reaction. The water then should pass through a filter to remove both the precipitated matter and the chlorine remaining in the water. You should be aware, however, that whenever you mix chlorine with organic materials (remember where hydrogen sulfide come from!), the chances are very high that trihalomethanes (possible cancer causing cragginess) will be formed. Also, feeder maintenance is high, you should be prepared to “play” with the unit frequently.
Aeration consists of breaking the incoming water into small droplets (spray) into the air, drawing fresh air through that spray, collecting the water into a storage tank, repressurize the water, passing it through a particulate filter to catch any particles that might be carried out of the storage tank. The air drawn though the spray must be vented outside the house — remember, it is toxic and explosive. Although this system necessitates another pump to repressurize your supply, you are not adding any chemicals to your water, which makes it attractive. This system is low maintenance and no chemicals to purchase. Initial cost may be higher, however, and space requirements may be greater.
I have Red Stains in my Sinks and Other Fixtures — Help!
Red stains are normally caused by iron in the water. You must test to determine the amount and the type of iron you have. Some types are: oxidized, soluble, colloidal, bacteria or organic-bound. All are a problem! It only takes 0.3 ppm to stain clothes, fixtures, etc.
This type of iron is usually found in a surface water supply. This is water that contains red particles when first drawn from the tap. The easiest way to remove this type of iron is by a fine mechanical filter. A cartridge type filter is usually not a good solution, due to the rapid plugging of the element. Another method or removal is by feeding a chemical into the water to cause the little particles of iron to clump together, and then fall to the bottom of a holding tank, where they can be flushed away.
Industrial Water Treatment
Soluble iron is called “clear water” iron. After being drawn form the well and contacting the air, the iron oxidizes, or “rusts”, forming reddish brown particles in the water. Depending on the amount of iron in the water, you may solve this problem with a water conditioner, or a combination of softener and filter. You may use an iron filter that recharges with chlorine or potassium permanganate, or feed chemicals to oxidize the iron and then filter it with a mechanical filter. You can sometimes hide the effects of soluble iron by adding chemicals that, in effect, coat the iron in the water and prevent it from reaching oxygen and oxidizing.
Colloidal iron is very small particles of oxidized iron suspended in the water. They are usually bound together with other substances. They resist agglomeration, i.e., the combining together of like substances forming larger, heavier, more filterable ones, due to the static electrical charge they carry. This iron looks more like a color than particles when held up in a clear glass, as they are so small. Treatment is usually one of two: Feed chlorine to oxidize the organic away from the iron, thus allowing agglomeration to occur, or, feeding polymers that attract the static charge on the particles, forming larger clumps of matter that is filterable.
Iron bacteria are living organisms that feed on the iron found in the water, pipes, fittings, etc. They build slime all along the water flow path. Occasionally, the slimy growths break free, causing extremely discolored water. If a large slug breaks loose, it can pass through to the point of use, plugging fixtures. These types of bacteria are becoming more common throughout the United States. If you suspect bacteria iron, look for a reddish or green slime buildup in your toilet flush tank. To confirm your suspicions, gather a sample of this slime and take it to your local health department, or water department for observation under the microscope. This type of iron problem is very hard to eliminate. You must kill the bacteria, usually by chlorination. You must use high amounts of chlorine throughout your plumbing system to kill all organisms. You may find it necessary to feed chlorine continuously to prevent re-growth. A filter alone will not solve this problem.
When iron combines with tannins and other organics, complexes are formed that cannot be removed by ion exchange or oxidizing filters. This iron may be mistaken for colloidal iron. Test for tannins; if they are present, it is most likely combined with the iron. Low level amounts of this pest can be removed by use of a carbon filter, which absorbs the complex. You must replace the carbon bed when it becomes saturated. Higher amounts require feeding chlorine to oxidize the organics to break apart from the iron and cause both to precipitate into a filterable particle.
I Have Blue or Green Stains on my Fixtures — Help!
You either have copper in your water supply, or you have copper pipes and corrosive water. Test for copper in your water. Test the pH, total dissolved solids content and the oxygen content of your water.
Copper can be removed by ion exchange, i.e., a water softener. The removal rate is about the same as it is for iron.
Copper pipes and corrosive water
If your pH is from 5 to 7, you may raise it by passing the water through a sacrificial media. By sacrificing calcium carbonate into the water, the corrosively will be reduced. If the pH is below 5, you will need to feed chemicals into the water.
Industrial Water Treatment
If the corrosively is caused by excess oxygen, the hot water will be much more corrosive than the cold. Treatment is by feeding polyphosphate or silicates to coat and protect the plumbing, or to aerate the water to release the excess oxygen.
The goal of water treatment is to reduce or remove all contaminants that are present in the water. No water, irrespective of the original source, should be assumed to be completely free of contaminants. The most common process used for treatment of surface water and ground water consists of sedimentation, coagulation, filtration, disinfection, conditioning, softening, fluoridation, removal of tastes and odors, corrosion control, algae control, and aeration.
Sedimentation allows any coarse particles to settle out. Coagulation consists of forming flocculent particles in a liquid by adding a chemical such as alum; these particles then settle to the bottom. Filtration, as the name implies, is the passing of the water through a porous media; the amount of removal is a function of the filtering media. Disinfection kills most harmful organisms and pathogenic bacteria—chlorine is the most commonly used disinfecting agent. Softening means removal of materials that cause “hardness,” such as calcium and magnesium. Corrosion is an electrochemical reaction in which metal deteriorates when it comes in contact with air, water, or soil.
In a typical municipal water treatment process, water flows through pumps to a rapid mix basin, then to a flocculation basin, to a settling basin, through filters to a clear well, then after disinfection, to storage tanks, and finally to the end users.
In areas that derive their water from rivers, pumps must be used since rivers are usually in low areas. Water enters the treatment plant at what is called the rapid-mix basin, where aluminum sulfate, polyelectrolytes, polymers, or lime and furic chloride are added as coagulants. The water flows next to the flocculation basins, where the coagulant mixes with the suspended solids. The coagulant is used to form suspended solids into clumps, or floc, which then settle out of the water. Floc forms when the particles from small solids gather to form larger particles. The water then slowly flows through settling basins where the floc settles from the water. Activated carbon is then added to the water to remove color, radioactivity, taste, and odor. Filtration then removes bacteria and turbidity from the water as it removes any remaining suspended solids and the activated carbon. Residential water treatment
The Highs and Lows of Industrial Water Treatment
In Industrial water treatment, heating and cooling play an important role in industry. After agriculture, industrial water treatment is the largest consumer of water. Besides other applications in process, washing, drinking and firefighting, the main application of water in industrial water treatment is for heat transfer in boilers and cooling towers. Several factors make water ideal for heat transfer.
- It is normally plentiful, readily available and inexpensive.
- It is easily handled.
- It can carry large amount of heat per unit volume.
- It doesn’t expand or compress significantly within normally encountered
- It doesn’t decompose.
In industrial water treatment, at one end, water is heated to a very high temperature and converted to steam in boilers by the combustion of various fuels. Water transfers the heat to the point of use that could be power generation or some other purposes. Hot water could also be needed for various applications in industry.
At the other end, about 70% of the water in industrial water treatment that industry uses is for cooling purposes. Although power-generating stations are among the largest users of this cooling water, almost all industry incorporates processes, which require the dissipation of heat. In addition to these process cooling requirements, comfort air conditioning systems also consume large quantities of cooling water. Power cannot be generated, gasoline cannot be produced, chemical processes cannot operate, and your boss cannot be kept cool without the assured availability of cooling water. Cooling water is the most common substance used as a heat transfer medium and the most common method of use is by indirect heat exchange.
In both boilers and cooling towers, the quality of water is absolutely critical. While several water treatment equipments like demineralizers and deaerators are installed to treat the raw water, various water treatment chemicals are also regularly needed for proper control and smooth operations. These include scale inhibitors, corrosion inhibitors, microbiocides, descaling chemicals, pH boosters, oxygen scavengers and passivators. Various instruments like water testing kits, pH meters and conductivity meters are also needed for regular monitoring and correction.
Water Treatment Steps
Have water tested for contaminants.
Remove fine sand, silt, clay and other particles, using a mechanical filter or sedimentation.
Treat bacterial contamination, using chlorination or other forms of disinfection.
Remove hydrogen sulfide gas and other odor-causing substances, using chlorination, an oxidizing filter, or activated carbon.
Remove insoluble iron and manganese particles using:
a mechanical filter
a water softener, for small amounts of dissolved iron and manganese
an oxidizing filter for higher amounts of dissolved iron and manganese
a chlorinator followed by a mechanical filter or an activated carbon filter for very high amounts of dissolved iron and manganese.
Treat for hardness using a water softener.
Neutralize acidity using a neutralizing filter.
Remove volatile organic chemicals, trihalomethanes, certain pesticides and radon, using an activated carbon filter.
Remove heavy metals, such as lead, mercury, arsenic, or cadmium, with reverse osmosis units or a distiller.
Glossary of Water & Wastewater Terms
Drinking Water Treatment for Homes and Industries. Residential water treatment
Absorb – To soak up or take in.
Acidic – Containing an excess of acids, or hydrogen ions (H+) Having a pH less than 7. The opposite of basic. A lemon is acidic.
Activated Sludge – Sludge floc produced in raw or settled sewage by the growth of bacteria and other organisms in the presence of dissolved oxygen.
Activated Sludge Process – A biological sewage treatment process in which a mixture of sewage and activated sludge is agitated and aerated. Activated sludge separates from the treated sewage by settling and is disposed of or returned to the process as needed. The treated wastewater overflows to the next treatment stage.
Aeration – Contact between air and a liquid by diffusion or mechanical mixing.
Aerobic Bacteria – Bacteria which require oxygen for their growth.
Agar – A gel-like substance containing nutrients used for growing bacteria for study.
Alkaline – Also referred to as basic. Having a pH greater than 7. The opposite of acid. i.e. Dishwashing detergent
Ammonia – A chemical which combines with chlorine in the water treatment process to form chloramine, a long-lasting disinfectant.
Anaerobic Bacteria – Bacteria which grow in the absence of oxygen and get oxygen from breaking down complex substances.
Aquifer – Any formation of rock that contains water. Usually underground and formed by layers of soil and rock. May supply water to a well or a spring.
Atmosphere – The layer of gases surrounding the earth. Residential water treatment
Bacteria – Single-cell microorganisms occurring naturally almost everywhere. They range from beneficial, to harmless, to deadly. Too small to be seen with the naked eye.
Basic – Also referred to as alkaline. Having a pH greater than 7. The opposite of acid. i.e. Dishwashing detergent
Biochemical Oxygen Demand – (BOD) The quantity of oxygen utilized in the metabolism of organic matter in a specified time and at a specified temperature. It is determined by the availability of a material as a biological food and by the amount of oxygen utilized by the microorganisms during oxidation.
Buffer – A substance that alters the pH of a solution by neutralizing acids and bases. This process is called ‘buffering.’ Residential water treatment
Carbon Activated – Carbon powder is added to the water treatment process to absorb taste and odor, most often in the spring.
Chloramine – A long-lasting disinfectant formed by ammonia and chlorine, A small amount of the disinfectant remains in the drinking water to kill any bacteria in the pipes running between the water treatment plant and your home.
Chlorine – A liquid or gas chemical used to disinfect water. Chlorine can destroy harmful microorganisms and reduce some tastes and odors in water.
Cholera – A dangerous disease caused by a type of bacteria that causes intestinal disorders. This bacterium is often found in untreated water.
Clarifier – Drinking water is treated in clarifiers which look like huge swimming pools. Clarifiers are used to settle out dirt and alum sludge.
Colonies – A group of the same kind living or growing together. i.e. Bacteria colony
Conservation – Keeping, protecting or preserving a resource. Using natural resources wisely.
Contaminant – Anything added to a substance that makes the substance unfit for use. i.e. motor oil is a contaminant in drinking water but not for a car engine.
Cross Connection – A connecting pipe in plumbing, through which drinking water could be contaminated, polluted, or infected.
Cyst – A microorganism with a tough protective covering.
Drinking Water Treatment for Homes and commercial use. Residential water treatment
Decomposition of Sewage – The break down of the organic matter in sewage through aerobic and anaerobic bacterial processes.
Denitrification – The reduction of nitrates in a solution by biochemical action.
Detention Time – The theoretical length of time for water to pass through a basin or tank, if all the water moves with the same speed.
Digester – A tank in which the solids from sewage sedimentation are stored to allow total aerobic or anaerobic decomposition to occur.
Dilute – To water down and make less concentrated.
Disinfectant – A substance used to purify water by removing or killing contaminants.
Dissolved Oxygen – (DO) The amount of oxygen dissolved in sewage, water, or any other liquid. Usually expressed in mg/L or percent of saturation.
Distillation – A process used to purify water by evaporation; boiling it and then collecting the steam as it condenses. Most pollutants remain in the unevaporated water.
Dysentery – A disease caused by a type of bacteria, characterized by severe diarrhea and loss of body fluids.
Drinking Water Treatment for Homes and Industries . Residential water treatment
Ecosystem – All the living and non-living things that interact together in a given area.
Effluent – Liquid waste discharged into the environment. i.e. sewage, liquid industrial waste or smoke.
Eutrophication – The process by which a pond or lake becomes rich in dissolved nutrients. This encourages growth of oxygen-depleting plant life, resulting in harm to other organisms. Pollutants such as sewage and fertilizers speed up the process.
Evaporation – The process by which water becomes vapor in the atmosphere.
Facultative – Bacteria organisms having the capacity to live under multiple environmental conditions (aerobic vs. anaerobic).
Filter – A screening device or porous substance used to remove solid material from liquids. Filters, made out of a layer a coal and a layer of sand, trap dirt or bacteria in the water treatment process.
Floc – The chemical alum attracts dirt and silt particles to form larger particles called floc. Floc looks like big snowflakes floating in water which settle in the clarifiers and are later removed as sludge.
Flotation – A method of raising suspended matter to the surface of the liquid in a tank as scum – by aeration, the evolution of gas, chemicals, electrolysis, heat, or bacterial decomposition – and the subsequent removal of the scum by skimming.
Fluoride – A chemical compound added to drinking water to help prevent cavities.
Food Chain – The transfer of energy from its primary source (plants) to larger animals.
Food Web – An interlocking pattern of food chains.
Fungus/Fungi – Plants lacking chlorophyll (green pigment) which include yeasts, molds, smuts and mushrooms. Residential water treatment
Giardia – A parasitic microorganism carried by animals in the form of a cyst. It is spread in animal feces and causes a disease commonly known as Beaver Fever.
Grit – The heavy mineral matter in water or sewage, such as gravel. Residential water treatment
Incubator – A small oven-like appliance that is used to heat and grow bacteria samples.
Intake – The point where water enters a channel or pipe into a treatment plant.
Irrigate – To water agriculture crops. Residential water treatment
Microorganism – Small living creatures that you need a microscope to see, i.e. bacteria, protozoa and algae.
Mixed Liquor – A mixture of activated sludge and sewage in the aeration tank undergoing activated sludge treatment.
Molecule – The smallest physical unit of an element or compound, consisting of one or more atoms.
Nitrification – The oxidation of ammonia nitrogen into nitrate through biochemical action.
Non-Point Source – Pollution which enters the environment from a non-specific site. This is the most common form of water pollution and the most difficult to control. It includes runoff from farms, logging operations, construction sites, golf courses, landfills, gardens, streets and parking lots.
Drinking Water Treatment for Homes and commercial use.
Oligotrophic – Lakes that are abundant in oxygen and contain few plant nutrients. Water is usually clear with little weed or algae growth. Mountain lakes are often oligotrophic.
Organic – Pertaining to, or derived from living organisms.
Ozone – Three molecules of oxygen bound together – 03. The oxygen we normally breathe has 2 molecules of oxygen bound together – 02. Ozone is used as a disinfectant in some water treatment plants.
Pathogenic – Something which can cause disease.
pH “power of Hydrogen” – On the pH scale, a reading of 7 is neutral. Below 7 is acidic with lower numbers indicating greater acidity. Above 7 is basic, with higher ratings showing higher alkalinity. Lemons, for example, are acidic and many detergents are basic.
Photosynthesis – The process plants use to get energy from the sun. Plants use the sun’s energy and the chlorophyll (green stuff) found in their leaves to produce the food they need to live.
Point Source – Pollution entering the environment at a specific site, i.e. a factory discharging effluent into a river or a person dumping used motor oil down a storm sewer.
Pollutant – Anything added to a substance that makes the substance impure. i.e. motor oil in drinking water.
Precipitation – Water from rain, hail, sleet, or snow.
Pump – Mechanical device allowing water to be lifted or raised. Residential water treatment
Reservoir – A storage tank holding one to two days’ supply of drinking water.
Resource – A valuable supply of natural materials, i.e. oil, water, coal and trees.
Riparian – Land bordering a river, lake or stream.
Runoff – Rain or melted snow which is not absorbed into the soil, but flows across land into streams, lakes and rivers.
Drinking Water Treatment for Homes and Industries
Screen – A device for removing large suspended or floating debris from wastewater.
Sector – Part of a society or a nation’s economy, i.e. the housing sector, the education sector.
Sediment – Matter which settles to the bottom of a tank, pond, river or ocean.
Sedimentation – The process by which particles suspended in water are allowed to settle to the bottom of a lake, river or container. Dirt, solid minerals and some bacteria are removed from drinking water through the sedimentation process.
Sewage – Solid and liquid waste including human feces and urine.
Sewage Treatment, Tertiary – Additional treatment of biologically treated sewage to reduce nutrients or other constituents.
Sewer – A pipe carrying wastewater or drainage water.
Sludge – Floc (alum + dirt) or calcium carbonate settled on the bottom of a water treatment clarifier it is called sludge. It is also the accumulated settled solids deposited from sewage in tanks or basins, and containing water to form a semi liquid mass. The sludge is removed and disposed of.
Sludge Volume Index – (SVI) The volume in milliliters occupied by one gram of dry solids after the aerated mixed liquor settles 30 minutes.
Stakeholder – Person or group with an investment or interest in something such as a business or industry.
Surface Water – Water on the surface of land, such as rivers, lakes, and ponds.
Sustainable – Extracting natural resources without destroying the ecological balance of an area, i.e. sustainable development.
Transpiration – The process by which green plants give off water through pores in their leaves. Water is a by-product of the photosynthesis process.
Turbidity – The amount of solid material floating in water. It may be organic (from plants and animals) or inorganic (silt and clay).
Typhoid – A potentially fatal intestinal disease. Bacteria usually enter a human’s body in food or drink. In Canada and the United States, typhoid from water sources has been brought under control by filtration and chlorinating.
Ultraviolet – (UV) Exposing drinking water or wastewater to ultraviolet light to deactivate harmful microorganisms ability to reporoduce, rendering them harmless.
Drinking Water Treatment for Homes and Industries
Waste Stabilization Pond – (or Lagoon) Any pond, natural or artificial, receiving raw or partially treated sewage or waste, in which stabilization occurs through sunlight, air and microorganisms.
Wastewater – Water from homes and businesses that flows down the drain or toilet.
Water Meter – An instrument for measuring the quantity of water flowing into a building.
Water Treatment – A method of cleaning water for a specific purpose, such as drinking.
Water Vapour – The gaseous state of water.
Watershed – The entire region draining into a river, river system or body of water.
Well – A pit, hole, or shaft dug into the earth to tap an underground supply of water
Residential water treatment
In industrial processing, an abrasive is commonly referred to as a substance that is used for polishing or smoothing other products, by rubbing it against the other and causing friction. Abrasives are also used in blast processing. Abrasives also have a wide array of usage in day-to-day life. Abrasives are used extensively in polishing wooden furniture and metals and for removing surface materials such as metal, ceramics, glass, plastics, and paint. They are also used in operations such as optical lens polishing as well as in the grinding of metal and glass, wet and dry grinding, sanding, cleaning, polishing, lapping, and surface preparation in various of industrial settings, including metalworking, woodworking, ceramics, and semiconductors. They are also ideal to sharpen tools, cut optical components, and finish concrete.
Abrasive materials are naturally available as in the case with minerals as well as being man-made. Some examples of natural abrasives are emery, sand and flint. Manufactured abrasives are obtained by chemically treating certain substances to attain abrasive qualities such as borazon and carborandum. Other examples of abrasives include: aluminum oxide, zirconia alumina, ceramic, garnet, tungsten carbine, silicon carbide, diamond dust, grinding wheels, powdered glass, pumice dust, and sandpaper.
An aerator is generally used in wastewater treatment and helps to clean the water in the final stages of this involved process. For instance, the Singulair aerator will sit in a concrete water treatment compartment and will continuously add oxygen to the water being treated. The Singulair aerator is an amazing piece of technology, with all its electrical segments safely away from the water and an electrical connecting piece that retards water. It also has a foam guard to keep the aerator from being damaged by water that may reach a higher than expected level.
Valves are used in a wide array of industrial, medical and commercial applications. They are primarily used to regulate the flow of fluids, gases and semi-solid materials by operating certain hatches or passages. These valves are designed to provide tight shut-off and characterizable control. They possess a high range ability because of the design of the regulating element, without the complications any of side loads that are typical of butterfly or globe valves.
Ball valves are extremely efficient in regulating the flow of liquids. A ball valve in principle is a handle connected to a ball which is placed inside a valve. The ball has an aperture through which liquids can flow when the ball is in proper alignment with the valve. The ball has a hole or port through the middle of it so when the port is in line with both ends of the valve the flow of liquid will be allowed. When the ball valve is closed, the hole is then perpendicular to the ends of the valve and the flow of liquid is blocked. The handle position on the valve will allow you the valve’s position. Three-way ball valves are also available which have a T-shaped hole through the middle of them. The flow of liquid can be directed to either one or the other or both sides or be closed off completely with this type of valve. Industrial water Treatment.
Disinfection reduces pathogenic microorganisms in water to levels designated safe by public health standards. This prevents the transmission of disease.
An effective disinfection system kills or neutralizes all pathogens in the water. It is automatic, simply maintained, safe, and inexpensive. An ideal system treats all the water and provides residual (long term) disinfection. Chemicals should be easily stored and not make the water unpalatable.
State and federal governments require public water supplies to be biologically safe. The U.S. Environmental Protection Agency (EPA) recently proposed expanded regulations to increase the protection provided by public water systems. Water supply operators will be directed to disinfect and, if necessary, filter the water to prevent contamination from Giardia lamblia, coliform bacteria, viruses, heterotrophic bacteria, turbidity, and Legionella.
Private systems, while not federally regulated, also are vulnerable to biological contamination from sewage, improper well construction, and poor-quality water sources. Since more than 30 million people in the United States rely on private wells for drinking water, maintaining biologically safe water is a major concern.
Testing water for biological quality
The biological quality of drinking water is determined by tests for coliform group bacteria. These organisms are found in the intestinal tract of warm-blooded animals and in soil. Their presence in water indicates pathogenic contamination, but they are not considered to be pathogens. The standard for coliform bacteria in drinking water is “less than 1 coliform colony per 100 milliliters of sample” (< 1/ 100ml).
Public water systems are required to test regularly for coliform bacteria. Private system testing is done at the owner’s discretion. Drinking water from a private system should be tested for biological quality at least once each year, usually in the spring. Testing is also recommended following repair or improvements in the well.
Coliform presence in a water sample does not necessarily mean that the water is hazardous to drink. The test is a screening technique, and a positive result (more than 1 colony per 100 ml water sample) means the water should be retested. The retested sample should be analyzed for fecal coliform organisms. A high positive test result, however, indicates substantial contamination requiring prompt action. Such water should not be consumed until the source of contamination is determined and the water purified.
A testing laboratory provides specific sampling instructions and containers. The sampling protocol includes the following:
use sterile sample container and handle only the outside of container and cap;
run cold water for a few minutes (15 minutes) to clear the lines;
upon collecting sample, immediately cap bottle and place in chilled container if delivery to lab exceeds 1 hour (never exceed 30 hours). Many laboratories do not accept samples on Friday due to time limits.
Chlorine readily combines with chemicals dissolved in water, microorganisms, small animals, plant material, tastes, odors, and colors. These components “use up” chlorine and comprise the chlorine demand of the treatment system. It is important to add sufficient chlorine to the water to meet the chlorine demand and provide residual disinfection.
The chlorine that does not combine with other components in the water is free (residual) chlorine, and the breakpoint is the point at which free chlorine is available for continuous disinfection. An ideal system supplies free chlorine at a concentration of 0.3-0.5 mg/l. Simple test kits, most commonly the DPD colorimetric test kit (so called because diethyl phenylene diamine produces the color reaction), are available for testing breakpoint and chlorine residual in private systems. The kit must test free chlorine, not total chlorine. Industrial water treatment
Contact time with microorganisms
The contact (retention) time (Table 1) in chlorination is that period between introduction of the disinfectant and when the water is used. A long interaction between chlorine and the microorganisms results in an effective disinfection process. Contact time varies with chlorine concentration, the type of pathogens present, pH, and temperature of the water. The calculation procedure is given below.
Contact time must increase under conditions of low water temperature or high pH (alkalinity). Complete mixing of chlorine and water is necessary, and often a holding tank is needed to achieve appropriate contact time. In a private well system, the minimum-size holding tank is determined by multiplying the capacity of the pump by 10. For example, a 5-gallons-per-minute (gpm) pump requires a 50-gallon holding tank. Pressure tanks are not recommended for this purpose since they usually have a combined inlet/outlet and all the water does not pass through the tank.
An alternative to the holding tank is a long length of coiled pipe to increase contact between water and chlorine. Scaling and sediment build-up inside the pipe make this method inferior to the holding tank. Industrial water treatment
If your home water comes from a public water supply, it has been tested and meets EPA standards for drinking water. If you use a private well, however, you are responsible for assuring that the water is safe to drink. This means that you should periodically have your water tested, make sure your well is in proper condition without faulty well caps or seals, and identify and remove potential sources of contamination to your well such as leaking septic systems or surface contamination. With a private well, you are also responsible for any treatment your water may need if it contains harmful pollutants or contaminants that affect the taste, odor, corrosiveness or hardness of the water. Industrial water treatment .This fact sheet discusses different types of water treatment systems available to homeowners. Addressing the source of the problem is often less costly in the long run than installing and maintaining a water system. For more information on identifying pollutant sources, problems with your well, or help in testing your well water, see the references at the end of this fact sheet.
There are many types of water treatment systems available. No one type of treatment can address every water
quality problem, so make sure you purchase the type of equipment that can effectively treat your particular water quality issue. The table below can help direct you to the right solution for your problem. Industrial water treatment
Sources of Bacteria in Drinking Water
Human and animal wastes are a primary source of bacteria in water. These sources of bacterial contamination include runoff from feedlots, pastures, dog runs, and other land areas where animal wastes are deposited. Additional sources include seepage or discharge from septic tanks, sewage treatment facilities, and natural soil/plant bacteria. Bacteria from these sources can enter wells that are either open at the land surface, or do not have water-tight casings or caps.
Insects, rodents or animals entering the well are other sources of contamination. Old wells were dug by hand and lined (cased) with rocks or bricks. These wells usually have large openings and casings that often are not well-sealed. This makes it easy for insects, rodents, or animals to enter the well.
Another way bacteria can enter a water supply is through inundation or infiltration by flood waters or by surface runoff. Flood waters commonly contain high levels of bacteria. Small depressions filled with flood water provide an excellent breeding ground for bacteria. Whenever a well is inundated by flood waters or surface runoff, bacterial contamination is likely. Shallow wells and wells that do not have water-tight casings can be contaminated by bacteria infiltrating with the water through the soil near the well, especially in coarse-textured soils.
Older water systems, especially, dug wells, spring-fed systems and cistern-type systems are most vulnerable to bacterial contamination. Any system with casings or caps that are not water-tight are vulnerable. This is particularly true if the well is located so surface runoff might be able to enter the well. During the last five to 10 years, well and water distribution system construction has improved to the point where bacterial contamination is rare in newer wells.
Indications of Bacteria
Bacterial contamination cannot be detected by sight, smell or taste. The only way to know if a water supply contains bacteria is to have it tested. The Environmental Protection Agency (EPA) requires that all public water suppliers regularly test for coliform bacteria and deliver water that meets the EPA standards. There is no requirement to have private water wells, springs or other sources tested, it is up to the individual homeowner. For Public water supplies, frequency of testing depends on the size of the population served. Bacteria test results are available from the supplier and there must be a public notification if the water supply does not meet the standard. For Homeowners, I would suggest that your source be tested at least four times per year (quarterly) and then at least annually.
Owners of private water supplies are responsible for having their water supply tested to ensure it is safe from bacterial contamination. Generally, private water supplies should be tested for bacterial safety as follows:
- at least once a year;
- when a new well is constructed;
- when an existing well is returned to service;
- any time a component of the water system is opened for repair — the water system includes the well, pump, pressure tank, piping, and any other components the water will contact;
- whenever the well is inundated by flood waters or surface runoff;
- whenever bacterial contamination is suspected, as might be indicated by continuing illness;
- when a laboratory test indicates high nitrate and human or livestock waste is suspected.
Often, lending agencies require private water supplies be tested before home loans will be approved, including refinancing a loan.
Potential Health Effects
Coliform bacteria may not cause disease, but can be indicators of pathogenic organisms that cause diseases. The latter could cause intestinal infections, dysentery, hepatitis, typhoid fever, cholera and other illnesses. However, these illnesses are not limited to disease-causing organisms in drinking water. Other factors not associated with drinking water may be the cause.
Intestinal infections and dysentery are generally considered minor health problems. They can, however, prove fatal to infants, the elderly, and those who are ill. Today typhoid, hepatitis and cholera are rarely encountered in the United States. Other bacteria also may be present in water. No specific sanitary significance or health standards have been indicated for non-pathogenic non-coliform bacteria.
Drinking Water Testing
Testing for all individual pathogens is impractical and expensive. Instead, the EPA has designated total coliform bacteria as a standard to determine bacterial safety of water. Coliform bacteria originate in the intestinal tract of warm-blooded animals and can be found in their wastes. Coliform bacteria can also be found in soil and on vegetation. Coliform bacteria are relatively simple to identify and are present in much larger numbers than more dangerous pathogens. Coliform bacteria react to the natural environment and treatment processes in a manner and degree similar to pathogens. By monitoring coliform bacteria, the increase or decrease of many pathogenic bacteria can be estimated. Industrial water treatment.
Due to this association, bacterial safety of drinking water is monitored by testing for coliform bacteria. Bacterial testing is provided, for a fee, by the Center for Environmental Quality, some city/county health department laboratories, and most commercial water testing laboratories. After selecting a laboratory, contact them to obtain a drinking water bacterial purity test kit. The kit will contain a sterilized sampling bottle, an information form, sampling instructions, and a return mailing box. Use of the bacterial test kit is necessary to help ensure the test is accurate. The bottle in the kit is completely sterilized. This assures the sample is not contaminated by bacteria in the bottle. The use of any other container is discouraged. The kit contains detailed instructions on how to collect the water sample. Follow the instructions carefully to avoid outside contamination and to obtain a good representative sample. Residential water treatment
To avoid unnecessary delays and possibly a need for resampling, mail or carry the sample to the laboratory immediately. The sample must be received at the laboratory within 48 hours after collection or it will not be tested. Avoid mailing samples when they may be delayed over a weekend or a holiday. In most cases, samples need to arrive at the laboratory on Monday, Tuesday, or Wednesday. Be sure the form accompanying the sample is accurate and complete. If there is no date or time of collection on the form, it will be assumed the sample is over 48 hours old. If there is no return address, test results cannot be sent to you. Industrial wastewater treatment
When a laboratory receives a water sample, it gives the sample a number and the time of arrival is stamped on the accompanying form. One hundred milliliters (ml) (about 3.4 fl. oz.) of the sample is then drawn through a membrane filter. This filter is placed on a nutrient broth culture plate and placed in an incubator for 24 hours at 35°C (95°F) for culturing. The plates then are removed from the incubator and the number of coliform bacteria colonies are counted. Residential water treatment.
Interpreting Test Results
The EPA establishes standards for drinking water which fall into two categories — Primary Standards and Secondary Standards. Primary Standards are based on health considerations, and are designed to protect people from three classes of toxic pollutants: pathogens, radioactive elements and toxic chemicals.
Bacterial contamination falls under the category of pathogens. The EPA Maximum Contaminant Level (MCL) for coliform bacteria in drinking water is zero (or no) total coliform per 100 ml of water. The number of coliform colonies found in the incubated water sample, if any, is reported and the form is checked to indicate whether or not the water meets the EPA bacteriological standard of zero. At times, excessive numbers of other bacteria in a sample can interfere with the counting of coliform types. These samples may be classified as “too numerous to count” or “confluent growth.” Residential water treatment.
If the laboratory report indicates the presence of coliforms, or states “too numerous to count,” or “confluent growth,” the State Department of Health recommends another sample be analyzed to help evaluate the contamination. If you suspect bacterial contamination in your water supply, use an alternative water supply or disinfect your water supply while waiting for test results.
If laboratory tests confirm the presence of coliform bacteria in your water supply, use an alternative water supply or disinfect your water supply until the problem can be corrected. For short term disinfection of small amounts of water, two options exist. Water can be boiled at a rolling boil for at least five to ten minutes to kill disease-causing bacteria. Alternately, water can be treated with chlorine to kill bacteria. Industrial water treatment.
Use household chlorine bleach that does not have scents or other additives. It might be advisable to shock disinfect your water supply system. The next step is to attempt to identify and eliminate the source of contamination. As you attempt to find the source of contamination, evaluate both well location and well construction. Check the entire water distribution system for potential problem areas. To evaluate well location, ask the following questions. You should be able to answer “yes” to all of the following.
- Is the well located at least 50 feet from a septic tank or any non-watertight sewer line?
- Is the well located at least 100 feet from any seepage pit, cesspool, tile field, privy or other subsurface disposal system?
- Is the well located at least 100 feet away from any feedlot, manure pit, manure or sewage lagoon or livestock lot?
To evaluate well construction ask the following questions. You should be able to answer “yes” to all of the following.
- Does the well have a watertight casing, preferably of heavy-gauge metal or National Sanitation Foundation approved plastic?
- Are all joints in the well casing screwed, double welded or otherwise properly sealed?
- Does the well casing extend at least 12 inches above the grade of the land surface?
- Is a sanitary well cap used on the casing?
- Is pitless installation used; or, if pit installation of pumping and storage equipment is used, is the pit at least 10 feet away from the well?
Driven and sandpoint wells are not acceptable. If possible, correct any problems identified in regard to well location or construction. Industrial water treatment.
After addressing the contamination source, the entire water system should be disinfected using shock chlorination. Shock chlorination involves placing a strong chlorine solution in the well and the complete distribution system to kill nuisance and disease-causing organisms.
Shock chlorination is recommended:
- upon completion of a new well or when an existing well is returned to service;
- when any portion of the distribution system is opened for repairs or maintenance;
- following contamination by flood water or surface runoff;
- or when lab results indicate a presence of bacteria.
For directions on how to shock chlorinate a water supply, see Help Guide on Shock Chlorination After shock chlorination, submit another water sample for testing. The water should test negative before use.
More than one shock chlorination treatment may be needed to effectively treat the entire water supply. If the source of bacterial contamination cannot be identified or eliminated, continuous disinfection of the water supply may be necessary. Options include: continuous chlorination, ultraviolet radiation, distillation, and ozone treatment. Chlorination is the most common disinfection method. Industrial water treatment.
Table 5-1 lists a number of common inorganic coagulants. Typical iron and aluminum coagulants are acid salts that lower the pH of the treated water by hydrolysis. Depending on initial raw water alkalinity and pH, an alkali such as lime or caustic must be added to counteract the pH depression of the primary coagulant. Iron and aluminum hydrolysis products play a significant role in the coagulation process, especially in cases where low-turbidity influent waters benefit from the presence of additional collision surface areas. Residential drinking water treatment.
Table 5-1. Common inorganic coagulants
|Name||Typical Formula||Typical Strength||Typical Forms Used in Water Treatment||Density||Typical Uses|
|Aluminum sulfate||Al2(SO4)3 ·
14 to 18 H2O
|17% Al2O3||lump, granular, or powder||60-70 lb/ft3||primary coagulant|
|Alum||8.25% Al2O3||liquid||11.1 lb/gal|
|Aluminum chloride||AlCl3 · 6H2O||35% AlCl3||liquid||12.5 lb/gal||primary coagulant|
|Ferric sulfate||Fe2(SO4)3 ·9H2O||68% Fe2(SO4)3||granular||70-72 lb/ft3||primary coagulant|
|Ferric-floc||Fe2(SO4)3 ·9H2O||41% Fe2(SO4)3||solution||12.3 lb/gal||primary coagulant|
|Ferric chloride||FeCl3||60% FeCl3,
|crystal, solution||60-64 lb/ft3
|Sodium aluminate||Na2Al2O4||38-46% Na2Al2O4||liquid||12.3-12.9 lb/gal||primary coagulant; cold/hot precipitation softening|
Variation in pH affects particle surface charge and floc precipitation during coagulation. Iron and aluminum hydroxide flocs are best precipitated at pH levels that minimize the coagulant solubility. However, the best clarification performance may not always coincide with the optimum pH for hydroxide floc formation. Also, the iron and aluminum hydroxide flocs increase volume requirements for the disposal of settled sludge. Industrial water treatment and residential water treatment.
|aluminum sulfate||sodium bicarbonate||aluminum hydroxide||sodium sulfate||carbon dioxide|
|ferric sulfate||sodium bicarbonate||ferric hydroxide||sodium sulfate||carbon dioxide|
|sodium aluminate||water||aluminum hydroxide||sodium hydroxide|
Water Sources, Impurities and Chemistry
Abundant supplies of fresh water are essential to the development of industry. Enormous quantities are required for the cooling of products and equipment, for process needs, for boiler feed, and for sanitary and potable water supply.
THE PLANETARY WATER CYCLE
Industry is a small participant in the global water cycle .The finite amount of water on the planet participates in a very complicated recycling scheme that provides for its reuse.
Evaporation under the influence of sunlight takes water from a liquid to a gaseous phase. The water may condense in clouds as the temperature drops in the upper atmosphere. Wind transports the water over great distances before releasing it in some form of precipitation. As the water condenses and falls to the ground, it absorbs gases from the environment. This is the principal cause of acid rain and acid snow. Industrial water treatment
WATER AS A SOLVENT
Pure water (H20) is colorless, tasteless, and odorless. It is composed of hydrogen and oxygen. Because water becomes contaminated by the substances with which it comes into contact, it is not available for use in its pure state. To some degree, water can dissolve every naturally occurring substance on the earth. Because of this property, water has been termed a “universal solvent.” Although beneficial to mankind, the solvency power of water can pose a major threat to industrial equipment. Corrosion reactions cause the slow dissolution of metals by water. Deposition reactions, which produce scale on heat transfer surfaces, represent a change in the solvency power of water as its temperature is varied. The control of corrosion and scale is a major focus of water treatment technology.
Water impurities include dissolved and suspended solids. Calcium bicarbonate is a soluble salt. A solution of calcium bicarbonate is clear, because the calcium and bicarbonate are present as atomic sized ions which are not large enough to reflect light. Some soluble minerals impart a color to the solution. Soluble iron salts produce pale yellow or green solutions; some copper salts form intensely blue solutions. Although colored, these solutions are clear. Suspended solids are substances that are not completely soluble in water and are present as particles. These particles usually impart a visible turbidity to the water. Dissolved and suspended solids are present in most surface waters. Seawater is very high in soluble sodium chloride; suspended sand and silt make it slightly cloudy. An extensive list of soluble and suspended impurities found in water is given in Table 1-1.
Table 1-1. Common impurities found in fresh water.
pH varies according to acidic or alkaline solids in water; most natural waters have a pH of 6.0-8.0pH can be increased by alkalies and decreased by acidsSulfateSO42-adds to solids content of water, but in itself is not usually significant, combines with calcium to form calcium sulfate scaledemineralization, reverse osmosis, electrodialysis, evaporationChlorideCl –adds to solids content and increases corrosive character of waterdemineralization, reverse osmosis, electrodialysis, evaporationNitrateNO3-adds to solids content, but is not usually significant industrially: high concentrations cause methemoglobinemia in infants; useful for control of boiler metal embrittlementdemineralization, reverse osmosis, electrodialysis, evaporationFluorideF-cause of mottled enamel in teeth; also used for control of dental decay: not usually significant industriallyadsorption with magnesium hydroxide, calcium phosphate, or bone black; alum coagulationSodiumNa+adds to solids content of water: when combined with OH-, causes corrosion in boilers under certain conditionsdemineralization, reverse osmosis, electrodialysis, evaporationSilicaSiO2scale in boilers and cooling water systems; insoluble turbine blade deposits due to silica vaporizationhot and warm process removal by magnesium salts; adsorption by highly basic anion exchange resins, in conjunction with demineralization, reverse osmosis, evaporationIronFe2+ (ferrous) Fe3+ (ferric)discolors water on precipitation; source of deposits in water lines, boilers. etc.; interferes with dyeing, tanning, papermaking, etc.aeration; coagulation and filtration; lime softening; cation exchange; contact filtration; surface active agents for iron retentionManganeseMn2+same as ironsame as ironAluminumAI3+usually present as a result of floc carryover from clarifier; can cause deposits in cooling systems and contribute to complex boiler scalesimproved clarifier and filter operationOxygenO2corrosion of water lines, heat exchange equipment, boilers, return lines, etc.deaeration; sodium sulfite; corrosion inhibitorsHydrogen SulfideH2Scause of “rotten egg” odor; corrosionaeration; chlorination; highly basic anion exchangeAmmoniaNH3corrosion of copper and zinc alloys by formation of complex soluble ioncation exchange with hydrogen zeolite; chlorination; deaerationDissolved Solidsnonerefers to total amount of dissolved matter, determined by evaporation; high concentrations are objectionable because of process interference and as a cause of foaming in boilerslime softening and cation exchange by hydrogen zeolite; demineralization, reverse osmosis, electrodialysis, evaporationSuspended Solidsnonerefers to the measure of undissolved matter, determined gravimetrically; deposits in heat exchange equipment, boilers, water lines, etc.subsidence; filtration, usually preceded by coagulation and settlingTotal Solidsnonerefers to the sum of dissolved and suspended solids, determined gravimetrically
|see “Dissolved Solids” and “Suspended Solids”|
All natural waters contain, in various concentrations, dissolved salts which dissociate in water to form charged ions. Positively charged ions are called cations; negatively charged ions are called anions. Ionic impurities can seriously affect the reliability and operating efficiency of a boiler or process system. Overheating caused by the buildup of scale or deposits formed by these impurities can lead to catastrophic tube failures, costly production losses, and unscheduled downtime. Hardness ions, such as calcium and magnesium, must be removed from the water supply before it can be used as boiler feedwater. For high-pressure boiler feedwater systems and many process systems, nearly complete removal of all ions, including carbon dioxide and silica, is required. Ion exchange systems are used for efficient removal of dissolved ions from water. industrial drinking water treatment and residential drinking water treatment.
Ion exchangers exchange one ion for another, hold it temporarily, and then release it to a regenerant solution. In an ion exchange system, undesirable ions in the water supply are replaced with more acceptable ions. For example, in a sodium zeolite softener, scale-forming calcium and magnesium ions are replaced with sodium ions.
The total coliform bacteria test is a primary indicator of “potability” , suitability for consumption, of drinking water. It measures the concentration of total coliform bacteria associated with the possible presence of disease causing organisms.
Coliform bacteria are a natural part of the microbiology of the intestinal tract of warm blooded mammals, including man. Coliform bacteria can also be found in soil, other animals, insects, etc. The total coliform group is relatively easy to culture in the lab, and therefore, has been selected as the primary indicator bacteria for the presence of disease causing organisms.
Coliform bacteria are not pathogenic (disease causing) organisms, and are only mildly infectious. For this reason these bacteria are relatively safe to work with in the laboratory. If large numbers of coliforms are found in water, there is a high probability that other pathogenic bacteria or organisms, such as Giardia and Cryptosporidium, may be present. The PADEP requires public drinking water supplies to demonstrate the absence of total coliform per 100 mls (about 4 oz) of drinking water. At this time, there are no regulations governing individual water wells. It is up to the private well owner to have his or her water tested. Used in residential drinking water treatment.
Approved tests for total coliform bacteria include the membrane filter, multiple tube fermentation, MPN and MMO-MUG (“Colilert”) methods. The membrane filter method uses a fine porosity filter which can retain bacteria. The filter is placed in a petri (culture) dish on a pad with growth enrichment media (mEndo) and is incubated for 24 hrs at 35 degrees C. Individual bacteria cells which collect on the filter grow into dome-shaped colonies. The coliform bacteria have a gold-green sheen, and are counted directly from the dish. Since some other bacteria may develop a similar color, a confirmation test using more specific media is required. The confirmation procedure requires an additional 24 to 48 hrs to complete the test for suspected positive total coliform tests.
The MPN (most probable number) method uses a test tube full of media with a smaller inverted test tube inside which captures carbon dioxide gas released from the growth of coliform bacteria. A series of dilutions and replicates are set up, and those producing gas in 24 hrs at 35 degrees C are counted. A statistical analysis is used to determine the most probable number of bacteria cells present. Industrial drinking water treatment.
One of the methodologies used by our research laboratory is the membrane filter technique. The sample should be collected in a specially prepared, sterile whirl pack bag for the test to be valid. The bags contain a small amount of sodium thiosulfate to remove any chlorine present, and have been sterilized. Sample collection should be done very carefully and directly into the bottle from the tap to avoid contamination of the bottle from hands or a transfer vessel such as a cup. The sample should be kept cool and delivered to the lab within 24 hrs for analysis. Total coliform bacteria testing is a relatively inexpensive when compared to the cost for the determination of the concentration or presence of viruses, Giardia, or Cryptosporidium.
Bacteria are removed by disinfection and/or filtration. Filtration alone may not be completely effective, but can improve the performance of disinfectants by removing sediment that can shelter the bacteria. Methods of adding chlorine to water include solution feeders for dry chlorine or liquid chlorine or by feeding gas chlorine directly from 100, 150, or 2000 lb. cylinders. Gas chlorination is recommended only for larger systems that can support the services of a trained water treatment plant operator. Chlorine is normally dosed to a concentration sufficient to maintain a free residual of at least 0.2 parts per million (PPM). Industrial wastewater treatment.
Other disinfectants include iodine, ozone, ultraviolet light, and physical methods such as boiling or steam sterilization. Chlorination is still the most common disinfection method in the United States, although recent concerns have been raised about the reaction of chlorine with organic matter in water. Such a reaction can result in the formation of trihalomethanes, which are suspect carcinogenic compounds. For most individual water supply systems, the most common form of treatment is ultraviolet disinfection. For information on water testing, please visit our Homeowner Outreach Webpage.