Category: Quality test

How to Choose the Right Arsenic Water Test Kit

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Arsenic is a poisonous element that is found in water and soil. It can cause serious health problems, so it’s important to test your water for arsenic levels. In this blog post, we will discuss how to choose the right arsenic water test kit for your needs. We’ll also provide some tips on how to use the test kit correctly. So if you’re concerned about the safety of your drinking water, read on!

Arsenic Water Test Kit
Industrial Test Systems Quick 481396-5 Arsenic Water Test Kit

What is arsenic and why do we need to test for it in our water supply?

Arsenic is a chemical element that can be found in water, air, and soil. It’s odorless and colorless, so you can’t see or smell it. Arsenic is poisonous and exposure to high levels can cause serious health problems. That’s why it’s important to test your water for arsenic levels.

There are two types of arsenic: inorganic and organic. Inorganic arsenic is the more dangerous type, but both types can be harmful to your health. The EPA has set a maximum contaminant level (MCL) for arsenic in drinking water at 0.010 mg/L. This means that water with an arsenic concentration above this level is not safe to drink.

If you’re on a private well, it’s your responsibility to test your water for arsenic and other contaminants. You should test your water at least once a year. If you live in an area where the water is known to be contaminated with arsenic, you may need to test more often.

How does an arsenic water test kit work and what do the results mean for your health and safety?

An arsenic water test kit usually comes with a vial of liquid reagent and a color chart. To use the kit, you’ll need to collect a sample of your water in a clean container. Then, you’ll add a few drops of the reagent to the water and compare the color of the water to the chart.

The color chart will tell you the arsenic concentration in your water. If the arsenic level is above the EPA’s MCL, your water is not safe to drink and you’ll need to take steps to remove the arsenic from your water supply.

What are some of the best arsenic water test kits on the market today, and how much do they cost?

There are many different types of arsenic water test kits available on the market. Some are designed for home use, while others are meant for commercial or industrial applications. The type of kit you need will depend on the amount of water you want to test, as well as your budget. For example, if you only need to test a small amount of water, a home kit may be sufficient. However, if you’re testing large quantities of water, you’ll need a more sophisticated and expensive commercial-grade kit.

Here are a few of the best arsenic water test kits on the market:

– Industrial Test Systems Quick 481396-5 Arsenic water Test Kit is one of the most popular options and it’s very affordable, costing a bit more expensive. This kit can measure levels as low as 0.005 mg/L, which is below the EPA’s MCL.

– The Hach Arsenic Test Kit is another popular choice and it’s a bit more expensive, costing around $30. This kit can measure levels as low as 0.001 mg/L, which is well below the EPA’s MCL.

– The LaMotte Arsenic Test Kit is a more expensive option, costing around $60. This kit can measure levels as low as 0.0001 mg/L, which is incredibly sensitive and can give you a very accurate picture of your water’s arsenic levels.

Choosing arsenic water test kit

When choosing an arsenic water test kit, it’s important to make sure that it can measure levels below the EPA’s MCL. It’s also important to read the instructions carefully. This will ensure that you’re using the kit correctly and getting accurate results. Pay attention to the recommended sampling methods and follow them closely. If you’re unsure about anything, don’t hesitate to contact the manufacturer for clarification. Remember, you can’t see or smell arsenic, so the only way to know if it’s in your water is to test for it.

Make sure you understand all of the steps involved in the testing process. If possible, practice using the kit on a small quantity of water before testing your drinking supply. This will help you get a feel for how the kit works and ensure that you’re using it correctly.

How often should you test your water for arsenic, and what should you do if levels are high or unsafe?”

You should test your water for arsenic at least once a year. If you live in an area where the water is known to be contaminated with arsenic, you may need to test more often.

If your water has high levels of arsenic, you’ll need to take steps to remove it from your water supply to protect your health. Arsenic exposure can cause a variety of health problems, including cancer. So, don’t delay in taking steps to remove it from your water supply. There are a few different ways to remove arsenic from water. One option is to install an arsenic removal system. These systems are usually expensive, but they’re very effective at removing arsenic from water.

Another option is to use bottled water for drinking and cooking. This is a more affordable option, but it’s not always convenient.

Conclusion

Now that you know more about arsenic water test kits, you can make an informed decision about which one is right for you. Remember, it’s important to test your water regularly for arsenic and take action if levels are high. By taking these simple steps, you can protect your health and ensure that your family has safe, clean water to drink.

The Best Water Hardness Test Kits: How to Choose the Right One for You

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Are you looking for the best water hardness test kit? If so, you’re in luck! In this article, we will discuss some of the best options on the market and how to choose the right one for you. Water hardness is a major issue for many homeowners, and it’s important to test your water regularly to make sure that it’s within safe levels. A quality water hardness test kit can help you do just that!

Factors for choosing a water hardness test kit

There are a few different factors that you’ll want to consider when choosing a water hardness test kit. The first is the type of kit that you need. There are two main types of kits: those that test for total hardness and those that test for specific minerals. Total hardness kits are generally more expensive, but they’re also more accurate. If you’re concerned about your water hardness, we recommend going with a total hardness kit.

The next factor to consider is the range of the kit. You’ll want to make sure that the kit you choose can test for the levels of hardness that are present in your water. Some kits only test for low levels of hardness, while others can test for high levels. If you’re not sure what range you need, we recommend choosing a kit that can test for a wide range of hardness levels.

Finally, you’ll want to consider the price of the kit. Water hardness test kits can vary widely in price, so it’s important to find one that fits your budget. We’ve included a few options below that are all reasonably priced and offer a variety of features.

The best way to choose a water hardness test kit is to read reviews from other homeowners who have used the product. Once you’ve narrowed down your options, make sure to test your water regularly to ensure that it’s within safe levels. With a quality water hardness test kit, you can rest assured that your family is drinking safe water.

5 best water hardness test kit

Now that you know what to look for in a water hardness test kit, let’s take a look at some of the best options on the market:

Hach Hardness Test Kit

– The Hach Hardness Test Kit is one of the most popular options on the market. It’s a total hardness kit that can test for both low and high levels of hardness.

Hach 145300 Total Hardness Test Kit is one of the best on the market. It’s a great choice for those who are looking for an accurate and reliable way to test their water hardness. This model is easy to use and comes with everything you need to get started.

Hach 145300 Total Hardness Test Kit
Hach 145300 Total Hardness Test Kit

LaMotte Water Hardness Test Kit

– The LaMotte Water Hardness Test Kit is another popular option. It’s a total hardness kit that offers a wide range of testing options.

LaMotte 4482-LI-02 Total Hardness Test Kit is one of the best options on the market. It is a Bottle type product with a capacity of 60ml. This product is made of Polypropylene and is designed for Adult use. The LaMotte company is known for its quality products.

LaMotte 4482-LI-02
LaMotte 4482-LI-02

AquaChek Total Hardness Test Kit

– The AquaChek Total Hardness Test Kit is a great choice for those on a budget. It’s a total hardness kit that offers accurate results at an affordable price.

AquaChek SPA 6-in-1 Test Strips is one of the best options on the market for testing water hardness. These strips offer accurate results in just 15 seconds, and they are very easy to use. Simply dip the strip in the water and remove it to find out the results. The strips also come with directions for water chemistry, so you can be sure that your spa is safe and clean.

AquaChek SPA 6-in-1 Test Strips
AquaChek SPA 6-in-1 Test Strips (552244)

Industrial Test Systems WaterWorks 481108 Total Hardness Test Strip

Industrial Test Systems WaterWorks 481108 Total Hardness Test Strip is a great option for those looking to test the hardness of their water. With a three-second test time and accuracy down to 0-1000ppm, this product is perfect for anyone needing to know the levels of calcium in their water.

Industrial Test Systems WaterWorks 481108 Total Hardness Test Strip
Industrial Test Systems WaterWorks 481108 Total Hardness Test Strip

U.S. Pool Supply 7-Way Swimming Pool & Spa Water Test Kit Strips

U.S. Pool Supply 7-Way Swimming Pool & Spa Water Test Kit Strips is our top pick for the best water hardness test kit. This product is easy to use, accurate and comes in a large bottle with 50 strips. These strips test for total hardness, total chlorine, free chlorine, total bromine, pH, total alkalinity, and cyanuric acid. Simply dip a strip into the water for a few seconds, shake off the excess water, and then compare the strip’s markings to the graduated measuring scale on the side of the bottle. This product is a great value and will help you keep your pool or spa properly balanced and safe for use.

U.S. Pool Supply 7-Way Swimming Pool & Spa Water Test Kit Strips
U.S. Pool Supply 7-Way Swimming Pool & Spa Water Test Kit Strips

Some kits use chemical strips that change color to indicate the level of hardness, while others use electronic testers that give a more precise reading. Second, you’ll want to think about how often you need to test your water. If you have hard water, you may need to test it more frequently than if you have soft water.

We hope this article has helped you choose the best water hardness test kit for your needs. If you have any questions or would like to share your own experiences with testing water hardness, please leave a comment below! Thanks for reading!

Digital TDS Meter – Measuring Total Dissolved Solids

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A Digital TDS meter is a hand-held instrument that used to indicate the Total Dissolved Solids in a water solution. It works based on the electrical conductivity of the water. When the dissolved ions increase then the conductivity of a solution increases. Normally, the TDS value represents as ppm. A TDS meter does not measure all kinds of contaminants such as heavy metals, pesticides, pharmaceuticals, or hexavalent chromium. Because these compounds are not ionic compounds.

lamotte digital tds meter

What is TDS

TDS stands for Total Dissolved Solids and represents the total amount of the soluble substances that are dissolved in the water. It can be organic or inorganic matter. Ingredients usually dissolved in water are calcium, manganese, sodium, potassium, copper, iron, other trace metals, chlorides, sulfates, dissolved dust, fertilizers, and all chemical treatment. These materials are entered into the water in different ways. These can be human activities or natural sources. The groundwater is normally hard water. On the other hand, although the rainwater is soft water, it travels through the soil and rocks, so it dissolves small amounts of minerals like calcium and magnesium salts and retains the solution. Moreover, we use fertilizer on the land, different chemicals in many industries. These chemicals also mix with the water in different ways. The lower TDS level indicates the water is soft whereas the higher TDS level indicates hard water.

Why should you measure total dissolved solids?

TDS is a parameter of water quality. A high concentration of TDS can produce hard water and it may cause some problems. Usually, a high TDS level is not a health hazard, but it is an indicator that the water may have present harmful contaminants, such as lead, copper, manganese, arsenic, etc. Although A specific amount of magnesium and calcium, are beneficial to our health. Moreover, it may improve the taste of water. The pure water is absent of taste, odor, and color, but high TDS water could be bitter, salty, bad odor, and colored. According to EPA water standards Canadian guidelines, the maximum acceptable level of TDS for drinking water is 500 ppm. But the TDS level over 1000 ppm probably unfit for human consumption. Increased level of dissolved solids can also have some technical problems such as boiler maintenance, filter maintenance, Plumbing and appliances, pool maintenance, cooking, cleaning, stain household fixtures, etc.

Digital TDS meters have been made depending on the electrical conductivity of the sample water. The electrical conductivity of pure water is zero. The electrical conductivity increases with the increase of the amount of Dissolved ions. There are many TDS meters available in the market. Therefore, some factors such as the price of TDS meter, used technology, battery saving features need to be carefully considered when purchasing a TDS meter. Following are some good quality Digital TDS meters.

1. HM Digital TDS-3 Handheld Digital TDS Meter With Carrying Case

The HM Digital TDS-3 Handheld TDS Meter is Ideal for commercial use. It comes with a Carrying Case with Belt Clip and a user’s guide. It uses Advanced Microprocessor Technology, so you will get Highly Efficient and Accurate result. It can Saves Measurements for Convenient Reading and Recording. It has a Built-in Digital Thermometer that can Measure 0/80 Degrees Celsius. It contains two LR44 batteries and LCD Screen. The LR44 batteries are available in the local market and amazon, so you can buy them if necessary. The meter is Factory Calibrated with a 342 ppm NaCl solution. which is not included. You can buy this from HM Digital. The Measuring Range of this TDS is 0-9990. It is Better than HM Digital TDS-4.

hm digital tds meter

Pros

  • Includes a Carrying Case
  • Easy to use
  • It has a Built-in Digital Thermometer
  • uses Advanced Microprocessor Technology
  • It comes with a warranty.
  • Quick results

Cons

  • not included Calibrated solution
  • Average quality

2. Water Quality Tester, Accurate and Reliable, HoneForest TDS Meter, EC Meter & Temperature Meter 3 in 1

The HoneForest TDS Meter is accurate and reliable and easy to use. It measures TDS, EC, and Temperature 3 in 1. It is ideal for drinking water, aquarium, hydroponics(test nutrients), Aquaculture, pool and spa, water treatment, and more. They offer 3 years warranty. It uses Advanced Microprocessor Technology. It has an auto-lock function to conserve battery. It comes with A colorful TDS chart on the back to explain ppm readings, a protective carrying case with belt clip, and a HoneForest Instruction. The Measuring Range of this Digital TDS meter; TDS: 0 – 9990 ppm, Conductivity: 0 – 9990 µs/cm, Degrees Celsius: 0.1 – 50.0°C. The meter is Factory Calibrated and they also said that no need for further calibration.

digital tds meter

Pros

  • Includes a Carrying Case
  • Easy to use
  • It has a Built-in Digital Thermometer to measure 0.1 – 50.0°C
  • Low price

Cons

  • not included Calibrated solution
  • Average quality

3. HM Digital AP-1 AquaPro Water Quality Total Dissolved Solids Tester

HM Digital AP-1 is great for checking the drinking water quality, water filtration and purification, hydroponics, colloidal silver, aquariums, RO/DI systems, pools and spas, and more. It has an Automatic Temperature Compensation that can Measure 0/80 Degrees Celsius and an easy-to-read LCD screen. It contains one CR2032 3v battery. The meter is Factory Calibrated with a 342 ppm NaCl solution. The Measuring Range of this TDS is 0-5000 ppm. It is durable, consistent, and worthy of purchase. You must store the meter in the fridge after use it.

hm tds meter

Pros

  • Easy to use
  • It has an Automatic Temperature Compensation (ATC)
  • Water-resistant housing
  • Auto-off function
  • Data-hold function

Cons

  • not included Calibrated solution
  • slightly costly compared to the other products

4. KETOTEK Water Quality Test Meter, PH Meter TDS Meter 2 in 1 Kit

KETOTEK Digital TDS meter and has to function of Auto-off, it will automatically shut off with inactivity to save the battery’s life. It is easy to use, just need to press “ON/OFF” to open and use it, and just need to press “ON/OFF” to close it. It has an Automatic Temperature Compensation that can Measure 0/80 Degrees Celsius. It has a measurement range of 0-9990ppm and ±2% accuracy.

ketotek tds meter

Conclusion

The Digital TDS meter cannot indicate the types of or the total amount of contamination. It will not tell us if the water is healthy or not. It can indicate to us the water may be suitable for drinking or it may be contaminated with harmful chemicals. Thus we can take our next steps.

Iron Related Bacteria Test – Hach Test

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BART (Biological Activity Reaction Test) is one of the most common iron related bacteria test. This Hach Company kit includes 9 tests. When IRB present in the sample, then a series of reaction occurs with IRB and nutrients ingredients in the inner tube. The change to red color of the water indicates a presence of bacteria within that sample. The IRB-BARTs can detect both iron oxidizing and iron reducing bacteria.

What are Iron Related Bacteria

Iron related bacteria are microorganisms that can use iron in their metabolism. Generally they are found in surface water and soil but they can also found in well water. The Common iron related bacteria are iron oxidizing bacteria, iron reducing bacteria gallionella, sheathed iron bacteria, pseudomonads and enteric bacteria. Among them the iron oxidizing and iron reducing bacteria are most important. These bacteria are usually found in waters having relatively high concentrations of iron and manganese in the water.

Iron related bacteria
Image: wikipedia

What are the effects of iron bacteria?

Iron related bacteria usually change the color of the water to red, brown or orange or stain on fixtures.  The IRB are responsible for slim production, creating corrosion, clogging, fouling, and hygiene risk. Besides they can also create unpleasant tastes and odor which are more noticeable in the water that is not used for long time.  Normally Iron bacteria are not hazard to health but some cases they cause problems. During drilling and handling the well and groundwater may contaminant with IRB so we have to carefully handle it. It don’t create hydrogen sulfide, the “rotten egg” smell.

Method of Iron Related Bacteria Test

1. Sample collection: This IRB BART contains two tube – inner tube and outer tube. To collect the sample water, firstly open the outer tube cap and remove the inner tube from the outer tube. Then collect at least 20 ml of sample water by using the outer tube. During sample collection do not touch the inside of the tube. Moreover, the outer side of the sample source should be cleaned so that bacteria cannot enter the sample from outside.

IRB Test

2. Now open the inner tube cap and keep on a clean surface so that the cap does not contaminant. It should be remember that IRB primarily grows on the pipes. Fill the inner tube with the collected sample water up to mark which is 15 ml. The inner tube contains nutrients ball to grow IRB.

Iron Related bacteria test

3. Then close the inner tube cap tightly. Discard the unused sample in the outer tube and return the inner tube into the empty outer tube. Then screw the outer tube cap tightly. Allow the ball to float to the top with no help. After placing the sample do not shake or swirl the tube.

IRB Test

4. Label the outer IRB test tube with the date and sample name.

IRB Test

5. Place the IRB test tube away from direct sunlight and allow incubating at room temperature for eight days (if necessary). Check the BART visually for reaction daily.

Iron Related bacteria test

6. Foam or a brown slime ring around the ball and on the bottom of the sample tube will indicate the sample contains iron related bacteria. Whereas the absence of foam or brown slime will indicates the sample has no iron related bacteria.

Iron Related bacteria test

7. Estimate bacteria population: When the iron related bacteria test result is positive then come in the question, how many the bacteria in the water sample? By observing how many days brown slime is formed we can make an estimate of the bacterial population. When the bacteria population is high, then a faster reaction is occurred. We can determine the amount of bacteria by the following table. If the IRB is higher, then you can consider a fecal coliform test.

Days to reaction Approximate IRB population (cfu/ml) Aggressivity
1 540,000 Very high
2 140,000 High
3 35,000 High
4 9,000 Moderate
5 2,300 Moderate
6 500 Moderate
7 150 Moderate
8 25 Low

8. Dominant bacteria:

IRB BART

If the iron related bacteria test result is positive then we have to examine the type of dominant bacteria. With the color comparison of the IRB test tube we can determine the dominant bacteria type in the sample water. If the sample tube water is red color and cloudy then the dominant bacteria is enteric while it is black then the dominant bacteria type is pseudomonad’s and enteric.

Total coliform bacteria test – LaMotte 4-3616 Coliform Test Kit

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Total coliform bacteria test is an easy method with The LaMotte 4-3616 Coliform Test Kit. It Contains 5 disposable tubes and a water sample bag. Each of the tube contains a nutrients tablet that supports the growth of coliform bacteria, a gelling substance, and a pH indicator. If the coliform bacteria are present in the water sample then the bacteria metabolizing the nutrients in the tablet and generated gas. This gas will get stuck in the gelling substance and the gel will rise in the tube. The pH indicator will change the color of the water from red to yellow as further evidence of coliform bacterial activity. The higher the number of positive results in the supply tube, the greater the risk of serious bacterial infection. The test required a 44-48 hours to get the result.

Total coliform bacteria test

Total coliform bacteria are a collection of different types of bacteria in water, soil, human or animal waste. Most of them are harmless. Detection of these bacteria in drinking water or water sources is very important because the presence of total coliform bacteria is an indicator of possible contamination. Consequently we can easily move forward to solve the problem. If only the total coliform bacteria are present in the water and fecal coliform bacteria are absent; This indicates that the source is probably environmental (portable water).

Method of Total coliform bacteria test by LaMotte 4-3616 Coliform Test Kit

  • Sample collection: First you have to collect water sample in the supplied water sampling bag with the LaMotte 4-3616 Coliform Test Kit. Note that the bag contains a tablet rich in dechlorinating agent (2-2197), which is provided to neutralize any chlorine present in the water. Chlorine helps to suppress the growth of coliform bacteria. The outlet at the source of the sample should be cleaned and erased during sample collection and the sample collection bag should not be touched on the inside so that bacteria cannot enter the sample from outside.
LaMotte 4-3616
  • Allow the tap (cold water) to run for 2 to 3 minutes or until the line is flush. Reduce the flow of tap water at such a rate that water can be collected in the sampling bag without spraying water. Now tear off the top of the bag in the scored line and pull the tabs outwards to open the bag. Do not touch the inner surface when opening the bag.
  • Fill the bag up to 4 oz field line. Pull the wire ends to close and whirl the bag for three complete revolutions. Shake the bag to dissolve the tablet.
coliform mpn test
  • Remove all 5 tubes from the display package and open the caps. Unwhirl the bag and pull the tabs outward to open the bag. Fold the inside of a tape wire to form the spout. Carefully fill all 5 tubes up to the 10 ml line with the water sample. Replace the caps tightly. Do not mix or shake the tubes.
total coliform test

LaMotte 4-3616 Coliform Test Kit

  • Stand the carton straight and carefully place all 5 tubes in the display package. Make sure all the tubes are standing vertically. The tablet should lie flat on the bottom of each tube.
total coliform in well water
  • Store the tubes at room temperature for 44-48 hours without direct sunlight. The air temperature should be fairly constant and between 70°-85°F (21°-29°C). While the tubes can be incubated at room temperature, incubation at 44.5° C (112° F) will accelerate growth and result in a more rapid test result. Do not disturb or shake the tubes during the scheduled incubation period. If these storage conditions are not followed properly, then the total coliform bacteria test results may not be appropriate.
  • A positive result in any one of the five tubes should be considered as a potential coliform bacterial contamination. Both yellow color and gas bubbles must be present for positive test results. You should remember that yellow color without gas bubble does not indicate the presence of bacteria. If any positive results are found in two or more tubes, there is a possibility of a serious bacterial infection problem. Further steps should be taken to validate these results by a certified ad bacteriological laboratory.
LaMotte 4-3616 Coliform Test Kit

DISPOSAL
After recording the results of total coliform bacteria test dispose the inoculated tubes by treating with chlorine bleach. Dispose of the LaMotte 4-3616 Coliform Test Kit tubes and package as required by local jurisdiction. Do not reuse the tubes for the test of total coliform bacteria.

Questions & answers

Q. Is the product for a single test or 5 different tests?

Answer: The 5 vials of the kit are for a single test. You should know that a positive result can be found in any one of the five tubes. One positive result considered as a possible coliform bacterial contamination whereas two or more positive results considered as a possibility of a serious coliform bacterial contamination.

Q. Can I use the kit to test for fecal coliform?

Answer: No, It only tests if coliform is present or absence in the water sample.

Q. Can it count how many total coliform are present ?

Answer: No, it does not count how many total coliform are present in the water sample. We can just idea if the sample water has serious or low coliform bacterial contamination. The higher the number of positive results in the supply tube, the greater the risk of serious bacterial infection.

Q. Is the LaMotte 4-3616 suitable for testing pool water?

Answer: Yes, you can use The LaMotte 4-3616 Coliform Test Kit for testing pool water. It can only show the presence or absence of coliform but does not shows how many total coliform are present in the supplied water.

Determination of chemical oxygen demand of water

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Chemical Oxygen Demand indicates the amount of oxygen required to oxidize all soluble and particulate organic substances in water under specific conditions. All organic compounds may convert into carbon dioxide, water and ammonia. It is a significant parameter to determinate water characteristic. The COD value depends on oxidizing agent, pH, temperature, and period of time. It is expressed as ppm or milligrams per liter (mg/l) of oxygen. There are several methods for determination of Chemical Oxygen Demand but the wet chemical method (dichromate method) is the most common Method.

Principle of chemical oxygen demand

In dichromate method the organic matter in water oxidize with the strong oxidizing agent potassium dichromate under acidic conditions. Normally sulfuric acid is used to achieve the acidity in this COD test method. An additional amount of potassium dichromate are taken, to sure completely oxidation of all organic matter. After complete the oxidation, measure the excess amount of potassium dichromate by titrating with ferrous ammonium sulfate. During the titration the ferroin is used as indicator. At the end point the color of the ferroin changes from blue-green to a reddish brown. The consumption of the dichromate is proportional to the amount of organic matters that are present in the water.
3[CH2O] + 16H+ + 2Cr2O72- → 4Cr3+ + 3CO2 + 11H2O

It is a fast applicable parameter for industrial wastewater, water controlling plant, sewage, rivers, lakes or aquifers but not applicable for drinking water as the lower content of oxidizable organic matter. Frequently, a silver compound like Silver sulfate is used as a catalyst to promote oxidation of certain organic compounds such as linear aliphatic compounds, aromatic compounds and pyridine. Some inorganic materials like chloride, nitrite may interfere with the result of COD. Chloride interference can eliminate by adding Mercuric sulfate whereas nitrite interference can eliminate by adding sulfamic acid.

COD testing equipment and reagents

  1. Water sample
  2. Distilled water
  3. Standard Potassium dichromate solution (0.25N)
  4. Sulfuric acid reagent
  5. Standard ferrous ammonium sulfate (0.25 N)
  6. Ferroin indicator
  7. Mercuric sulfate
  8. Silver sulfate
  9. Water bath
  10. Titration apparatus
  11. 500ml conical flask (Erlenmeyer Flask)
  12. Burette
  13. Pipettes
  14. Pipette bulb
  15. Wash bottle

COD test procedure

  1. Collect the sample water from a source.
  2. Take 500 ml conical flask/ reflux flask and filled with 50ml of sample water.
  3. Place several boiling stones in the reflux flask.
  4. Determinate the chloride ion. If it contains a significant amount then, add 1 g of HgSO4 and 5.0 ml conc. H2SO4; then swirl the mixture until the mercuric sulfate dissolves.
  5. After that place the reflux flask in an ice bath and slowly add 25ml of potassium dichromate solution (K2Cr2O7) with swirling.
  6. Now add 75 ml of a mixture of sulfuric acid-silver sulfate solution to the cooled reflux flask with swirling.
  7. Apply heat to the mixture under reflux in water bath at 150°C temperature for two hours.
  8. Then allow the flask to cool about room temperature and wash the condenser with distilled water. Transfer the mixture into 500 ml Erlenmeyer flask.
  9. Then titrate the excess dichromate with 0.25 N ferrous ammonium sulfate, Fe(NH4)2SO4 solution by using 2 to 4 drops of ferroin indicator. At the end point the color turns from blue-green to reddish brown and take the burette reading. Let the reading is ‘B’ ml.
  10. Run a blank titration similarly. Let the reading is ‘A’ ml.

Chemical oxygen demand calculation

COD in mg/L= 8000 (A-B) N / V

Where,
A is the volume of FAS used in the blank sample, in milliliters.
B is the volume of FAS in the original sample, in milliliters.
N is the normality of FAS solution.
V = milliliters of sample used for the test.

Relation between BOD and COD

Now a days, water is contaminant by various type of organic substances. Chemical Oxygen Demand is an important water quality parameter as like BOD. But we cannot get a clear picture of all type of organic substances from the BOD values alone whereas COD values gives a better result. Because, biodegradable and non-biodegradable substances are includes in COD values. Consequently, COD values are larger than BOD. Moreover, the measurement of COD requires a shorter time about 2-3 hours. On the other hand bod requires longer time period 5 days. The higher the chemical oxygen demand, the higher the amount of pollution in the water.

Brand New COD-572 Chemical Oxygen Demand Meter Analyzer

Biochemical Oxygen Demand – BOD determination

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There is a close relationship between dissolved oxygen and biochemical oxygen demand. BOD is the amount of dissolved oxygen required to break down the organic material of the sample water by aerobic biological organisms at certain temperature over a specific time period. Generally this parameter is determined with the consumption of oxygen by the micro organism during 5 days of incubation at 20⁰C. It is expressed as milligrams/liter or ppm. It is also known as biological oxygen demand. You should remember that BOD is an indicator and not a pollutant.
biochemical oxygen demand

Importance of BOD

BOD is the best and reliable method to determine the level of pollution by the organic waste. Although it has some natural limitation but it is a significant method. It is important method to analysis the sewerage, industrial, effluent and extensive pollutant water. If one liter of sample water consumes 100mg of oxygen to biodegrade of organic matter, then the BOD is 100 ppm. The BOD value of drinking water should have less than 1 ppm. On the other hand the BOD value of raw sewerage runs from 200 ppm to several hundred ppm.

BOD indicates the amount of pollution of water bodies. Lower BOD indicates the water is good quality for aquatic life or little aerobic activity whereas higher BOD indicates the water is highly polluted. When the BOD is higher, then DO becomes lower. All the aquatic animals rely on this dissolved oxygen to live. So the reduction of DO in the water can bring a negative effect on the fish and other aquatic life. When it is drops below a certain level, the aquatic life are unable to continue at a normal rate. Aquatic organisms become stressed, asphyxiate, and may die.

Sources of organic materials

Common sources of organic materials are plant decay, leaves, grass clippings, woody debris; animal wastes; wastewater from residential areas, food processing plants, dairy plants, pulp and paper mills, canneries; septic systems leakage; fertilizer runoff and urban storm-water runoff. These organic materials run into water bodies and increases oxygen demand. Dead algae or other organisms are also part of the decomposition cycle. They are responsible for water pollution because they stimulate the growth of micro organisms that can increase the biochemical oxygen demand. All most all natural water contain small amount of organic materials.

Determination of BOD

The most common and popular method for determination of Biochemical Oxygen Demand is Standard Method which is recognized by U.S. EPA and leveled as 5210B. It is not a accurate quantitative test, although it is widely used as an indication of water pollution.

BOD test procedure

  1. At first analyzed and conditioned the water sample to ensure favorable growth conditions for bacteria, which may include adjustment for pH (6.5-7.5), neutralization of residual chlorine, or reduction of DO in supersaturated samples. If there is no or less oxygen in any sample then oxygen is provided to the sample water. To provide oxygen entered air into the water sample with fusion tube up to 5 minutes or the DO level up to 7 ppm.
  2. If BOD is higher than DO, then dilute the sample water with BOD free water (distilled water) to lower the BOD level.
  3. Then added the appropriate amount of seed bacteria. The selection of micro organisms (seed bacteria) is very important and the results are obviously not reproducible.
  4. Determination the initial DO (D1) of one portion of the sample.
  5. Then rest of the dilute sample filled into a 250-300ml incubation bottle. The sample incubates for 5 days in the dark room at 20 °C to prevent DO production via photosynthesis. You can cover the sample bottle completely with aluminum foil.
  6. After the 5 days, the sample is removed from the incubator and the bottles uncork, then take the final dissolved oxygen (D2) reading.
  7. The difference between the first and the last of the samples is called the BOD.

BOD calculation

Calculate the BOD from the DO depletion and volume of sample used following the formula below:
BOD calculation
Where:
D1 is the DO of the sample after dilution (ppm).
D2 is the DO of the diluted sample after 5 day incubation (ppm).
B1 is the DO of diluted seed sample after preparation (ppm).
B2 is the DO of diluted seed sample after 5 day incubation (ppm).
f is the ratio of seed volume in dilution solution to seed volume in BOD test on seed.
P is the decimal dilution factor. [For example, if a sample of 100 ml dilute into 500 ml, then P = 100/500 = 0.20].

BOD of some collected sample from different sources:

Sample BOD Remarks
Normal water 0-3 Acceptable
River water 5-20 Polluted
Sewerage water 50-100 Very bad water
Industrial water 150-1000 Worst water

Dissolved oxygen in water

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Dissolved oxygen (DO) means the amount of oxygen that is dissolved in the water. Oxygen is the essential element to all animals. No animals can survive without it. Dissolved oxygen in water makes aquatic life possible. Human being takes oxygen from the air with the lungs. On the other hand, Fishes take dissolved oxygen through their gills. Gills work better if the water contains more oxygen. Hence to growth and reproduction of aquatic life must have sufficient levels of dissolved oxygen (DO) in the water. Otherwise, it becomes harder for animals to get the oxygen. It is not visible to us. Moreover it is not the oxygen component of the water molecule H2O. It is express as milligrams per liter (mg/L) or ppm.

Higher DO level can increases the taste of drinking water. So many water companies try to keep higher dissolved oxygen in water. In the case industries dissolved oxygen is not good sign, it may corrosion the water pipes. It is also corrosive to boiler.

Sources of dissolved oxygen

Oxygen enters into the water by following ways (1) direct absorption from the atmosphere, (2) rapid movement, or (3) release of oxygen from aquatic plants during photosynthesis.

Photosynthesis: in presence of light and chlorophyll green plants and some bacteria produce Oxygen and glucose by using carbon-di-oxide and water. It is recognized as Photosynthesis process.

CO2 + H2O → O2 + C6H12O6

Moving water such as mountain stream or river is greatly contact with atmospheric air. Therefore they are able to mix with air that tends to dissolve more oxygen. On the other hand stagnant water contains less dissolved oxygen.

Dissolved oxygen levels in water

The solubility range of oxygen is about 5-14 ppm. Sufficient amount of dissolved oxygen is important to all forms of aquatic life. If the levels drop below 5.0 ppm then it would stress to aquatic life. Lower concentrations cause greater stress. If the oxygen levels go to below 1-2 ppm then large amount of fish may die. On the other hand 8-9 ppm is generally good fishing waters to support a large diverse fish population. Most aquatic animals cannot live in the areas where the dissolved oxygen level is less than 0.2 ppm. This is anoxic. Moreover, it will increase the solubility of many toxic elements such as lead, zinc, copper, hydrogen sulfide, ammonia, cyanide. In addition it can also alter the structure and diversity of aquatic communities. Although too much dissolved oxygen concentrations is a very rare but it may creates gas bubble disease of fish.

Dissolved oxygen test procedure

You can measure Dissolved Oxygen in different ways. Electronic meter is one of the important methods. It does not measure oxygen directly, it measure the partial pressure of oxygen in the water. Then it would convert to oxygen mass weight concentration. The BOD is another significant method. It determines the oxygen requirements during a specified period of organic matter degradation. The other methods are drop bottle (iodometric), a microburet, or a digital titrator. The amount of oxygen dissolved in water is often expressed as ppm or mg/l.
Dissolved oxygen in water
Extech 407510 Dissolved Oxygen Meter

Factors affecting dissolved oxygen in water

Several natural and man-made factors affecting dissolved oxygen in water such as temperature, nutrient pollution, altitude, salinity, organic waste.

Photosynthesis

The photosynthesis process occurs in presence of light and chlorophyll. Therefore huge amount of oxygen produces during day time. On the other hand the photosynthesis process terminates during night time. But at this time the respiration process occurs and consumes oxygen. As a result DO level higher at day time and lower at night time. Turbidity (due to suspended solids) can restrain the sunlight to go into the water that limits the photosynthesis process.

Temperature

There is a significant relationship between water temperature and DO concentrations. Oxygen easily dissolves in cool water. Cold water can holds more dissolved oxygen than warmer water. Moreover the solubility of oxygen in water decreases with the increases of temperature.

Seasonal changes

Seasonal changes is the another factor that affecting dissolved oxygen concentrations in water. During summer season the water becomes warmer. Therefore at this time water contains less DO. Conversely the water becomes cooler at the time of winter season. So this time the water holds more oxygen. Rainy seasons also effects on oxygen concentrations. As the rain water interact with the atmospheric oxygen then it tends to higher the dissolved oxygen level.

Altitude

The atmospheric pressure decreases at higher altitude. When the atmospheric pressure decreases then the solubility of oxygen in water also decreases. So the amount of oxygen decreases at higher altitudes than at low altitudes.

Salinity

Waters with high amounts of salt holds less oxygen than fresh water. Reason, the solubility of oxygen decreases if the salinity of the water increases. Hence the freshwater like lakes, streams, and tap water generally contains higher concentrations of DO than the ocean. Higher suspended solids in the water also decrease the DO.

Moving water

The ocean, rivers and streams water are moving water. When this water is moving then they contact with air. Oxygen concentrations are much higher in air than in water, which are about 21% and 5-14 mg/l respectively. This huge difference of concentrations helps to dissolve the oxygen into the water. Moreover the volume and speed of moving water can also affect on dissolved oxygen levels.

Organic waste

The water may contain a lot of organic waste including leaves, grass, dead plants or animals, organic chemicals and sewage. Microorganisms like Bacteria decompose these materials by taking up oxygen. Therefore the levels of dissolved oxygen drop in the water body.

Fertilizer

Fertilizer runoff from farm fields and lawns may decrease The DO. As like land plants the aquatic plants also grow better with these nutrients. These large amounts of nutrients such as nitrate and phosphate help to produce great quantities of algae. When these aquatic plants die, then the bacteria decompose them by using large amounts of DO. This process is known as eutrophication. As a result Dissolved Oxygen levels can drop too low.

Determination of permanent hardness of water

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The available methods for determination of permanent hardness of water are O’Heners method, EDTA method and Soap titration method. Initially we have to know; what is hardness? –Hardness is due to presence of bicarbonate, sulphates, chlorides and nitrates of calcium and magnesium. It is expressed in ppm (part per million) as calcium carbonate. There are two types of hardness:

  1. Temporary hardness
  2. Permanent hardness

Bicarbonate of calcium and magnesium is responsible for temporary hardness whereas sulphates, chlorides and nitrates of calcium and magnesium are responsible for permanent hardness. The salt of Na, K and NH4- do not reacts with soap; hence the presence of these salt do not creates hardness of water.

Determination of permanent hardness of water by O’hehners method
Theory: At first, the water is boiled to remove temporary hardness. When the water is boiled then, the Bicarbonate of calcium and magnesium are change into non-dissolve carbonate.
Ca(HCO3)2 → CaCO3 + H2O + CO2
Mg(HCO3)2 → MgCO3 + H2O + CO2

After that, added Na2CO3 solution. This chemical reacts with dissolved calcium and magnesium salts and converts them into insoluble carbonate.
CaCl2 + Na2CO3 → CaCO3 + 2NaCl
MgCl2 + Na2CO3 → MgCO3 + 2NaCl
The residue Na2CO3 is then determined by titrating against a standard acid. The reduction in the amount of soda added is equivalent to permanent hardness.
Burette for determination of permanent hardness of water

BrandTech 4761161 Borosilicate Glass 50mL Titrette Bottletop Burette, with Titration and Recirculation Valve

Apparatus

  • Beaker
  • Weighing Balance
  • Burette with stand
  • Pipette
  • Conical flask
  • Hot plate

Chemicals

  • N/10 Sodium carbonate solution
  • N/10 HCl acid

Indicator

  • Methyl orange

Procedure:

  1. Take 50ml of water sample into a 500ml beaker and boil for 15 min.
  2. Add 50ml of N/10 Na2CO3 solution into it with stare.
  3. Separate the precipitate with filter paper and wash the precipitate 3-4 times with a little distilled water. Take the filtrate and cool the solution to room temperature. Then, take it into a 250ml volumetric flask and dilute it up to the mark with distilled water.
  4. Take 50ml in a conical flask from volumetric flask with a pipette and titrate it against N/10 HCl using Methyl orange indicator. At the end point the color of the solution turns into reddish yellow.
  5. Take the burette reading. Let, it is v ml.
  6. For blank titration, take 50ml of N/10 Na2CO3 solution into a 250ml volumetric flask and dilute it up to the mark with distilled water. Take 50ml in a conical flask from it with a pipette and titrate it as same process against N/10 HCl using Methyl orange indicator.
  7. Determine the consumed N/10 Na2CO3 solution from the difference of this two reading.

1ml 0.1N HCl ≡ 0.005005g CaCO3

Calculation:
Volume of N/50 Na2CO3 used for removing permanent hardness in 50ml of water sample
=50 -43.5 = 6.5 ml
Normality of water due to permanent hardness:
N1V1 = N2V2
N1 × 50 = N/50 × (6.5)
N1 = 6.5 /50 × 50 = 0.0026
Amount/Lit = N × Eq.wt
= 0.0026 × 50 = 0.13 gm/lit
Mg/lit = 0.13 gm/lit × 1000mg/1gm = 130 mg/lit
As,
1mg/lit = 1ppm
Permanent hardness = 130 ppm
Result: the given sample of water contains 130ppm permanent hardness.

Determination of permanent hardness of water by EDTA method:
The temporary hardness can be removed by boiling. The permanent hardness is determined first by precipitating the bicarbonates of Ca2+ and Mg2+ by heating and filtering off.

Procedure:

  1. Take 100ml of water sample into a beaker and boil gently for 15-20 minutes.
  2. Cool the solution then filter and wash the precipitate several times. Collect both the filtrate into a 250ml volumetric flask and level upto the mark with distilled water. Then, shake well.
  3. Take 50ml of solution from volumetric flask with pipette and place into a conical flask.
  4. Add 1-5ml NH4OH/NH4Cl buffer solution. It increases the pH level and should be 10. Check the pH with standardize pH meter.
  5. Add 2-3 drops 0.1M Mg-EDTA solution and 3-4 drops Eriochrome Black T indicator. Then, shake well and the color becomes wine red.
  6. Fill up the burette with standardized 0.01M EDTA solution. Record the initial burette reading and titrate the water sample with this standard solution.
  7. At the end point the color of the solution turns into blue from wine red. Titrate carefully near the end point.
  8. Take the final burette reading. Let, it is V1 ml.
  9. Repeat the titration process at least three times.
  10. You can run a blank titration for more accurate result. Let, it is V2 ml.

Water sample Vs EDTA

Serial No Volume of water sample (ml) Burette readings (ml) Volume of EDTA solution (ml)
Initial Final
1
2
3

Permanent hardness calculation:
In case of blank titration, the calculate volume of EDTA required by sample water, V = (V1-V2)ml
The permanent hardness can be calculated by using the following formula.
1ml 0.01M EDTA ≡ 1.00mg CaCO3
∴ Vml 0.01M EDTA = V ᵡ 1.00mg CaCO3

The 100ml sample water is dilute into a 250ml volumetric flask
Hence, 50ml dilute water = 100 ᵡ 50/250 ml = 20ml sample water

Now, 20ml of sample water ≡ V ᵡ 1.00mg CaCO3
∴ 1000ml of sample water ≡ V ᵡ 1.00mg ᵡ 1000/20 CaCO3
≡ V ᵡ 1.00 ᵡ 50 ppm CaCO3

Result
Amount of permanent hardness present in the given water sample = ppm

Determination of total hardness of water

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To determine the Total Hardness of Water, EDTA is the easiest method. Reason, EDTA reacts with all metal without alkali metal and the proportion is 1:1. The main cause of water hardness is dissolved salts of calcium and magnesium. Moreover the other ions like Strontium, Iron, Barium and Manganese also contribute of water hardness. Traditional it is measured by the amount of soap that is required to produce leather. The EDTA method is more accurate and more rapid.

Mn+ + Na2H2EDTA → [M-EDTA](4-n)- + 2Na+ + 2H+

There are two types of hardness: (1) temporary hardness and (2) permanent hardness.
The temporary hardness is due to the presence of Ca(HCO3) or Mg(HCO3) or both. On the other hand, permanent hardness is due to the presence of sulphates, chlorides and nitrates of calcium and magnesium (as like CaCl2, CaSO4, MgCl2 and MgSO4) in water.

To determine the Total Hardness of Water with EDTA method initially an inorganic acid is added to convert temporary hardness into permanent hardness.
Ca(HCO3)2 + 2HCl → CaCl2 + H2O + 2CO2

At pH 10, EDTA forms colorless, water soluble stable complexes with calcium and magnesium ions. When the indicator Erichrome black T dye is added into the hard water, then the indicator forms unstable complex with calcium and magnesium ions and the solution turn into wine red. If there is no hardness the color becomes blue which is original color of indicator. Now, when this solution is titrated against EDTA, then the calcium and magnesium ions started to form a stable metal-EDTA complex. After all the free calcium and magnesium ions are consumed, the EBT is replaced by EDTA from the unstable complex and liberates the free Eriochrome Black-T. Then the water color change from wine red to blue that indicates the end point.

Apparatus:

  • Conical Flask
  • Funnel
  • Burette
  • Sand
  • Beaker
  • Pipette
  • Graduated cylinder
  • Hot plate stirrer
  • Wash bottle
  • Spatula

Chemicals:

  • Buffer solution
  • Inhibitor
  • Eriochrome black T indicator (blue color)
  • NaOH
  • Standard EDTA Solution 0.01M
  • Magnesium sulphate

Procedure:

  1. Take 50ml of water sample into a conical flask.
  2. Then add 2-3ml 1:1 HCl and boil for 2 min.
  3. Cool the solution and neutralized with the dil NaOH.
  4. Add 1-5ml NH4OH/NH4Cl buffer solution. The pH should be 10. Check the pH with standardize pH meter. (you can also add an Inhibitor, after the buffer solution)
  5. Add 2-3 drops 0.1M Mg-EDTA solution and 3-4 drops Eriochrome Black T indicator. Then, shake well and the color becomes wine red.
  6. Fill the burette with standardized 0.01M EDTA solution. Record the initial burette reading and titrate the water sample with this standard solution.
  7. At the end point the color of the solution turns into blue from wine red. Titrate carefully near the endpoint.
  8. Take the final burette reading. Let, it is V1 ml.
  9. You can run a blank titration for more accurate result. Let, it is V2 ml.

Total hardness calculation:

Serial No Volume of water sample (ml) Burette readings (ml) Volume of EDTA solution (ml)
Initial Final
1
2
3

In case of blank titration, the calculate volume of EDTA required by sample water, V = (V1-V2)ml
The total hardness (temporary + permanent) can be calculated by using the following formula.

1ml 0.01M EDTA ≡ 0.001001g CaCO3
∴ Vml 0.01M EDTA = V ᵡ 0.001001g CaCO3

Now, 50ml of water sample ≡ V ᵡ 1.001mg CaCO3
∴ 1000ml of water sample ≡ V ᵡ 1.001mg ᵡ 1000/50 CaCO3
≡ V ᵡ 1.001 ᵡ 20 ppm CaCO3