WATER TREATMENT PLANT

Sedimentation tank

Filtration tank

pump settings

Coagulation tank

Aeration

Plant Layout  

DIFFERENT MATERIALS USED FOR WATER PURIFICATION 

PH Conditioners

 Municipal water is often pH-adjusted, in order to prevent corrosion from pipes and to prevent dissolution of lead into water supplies. During water treatment pH adjustments may also be required. The pH is brought up or down through addition of basics or acids. An example of lowering the pH is the addition of hydrogen chloride, in case of a basic liquid. An example of bringing up the pH is the addition of natrium hydroxide, in case of an acidic liquid. The pH will be converted to approximately seven to seven and a half, after addition of certain concentrations of acids or basics. The concentration of the substance and the kind of substance that is added, depend upon the necessary decrease or increase of the pH. 

 Chlorine dioxide disinfection 

 ClO2 is used principally as a primary disinfectant for surface waters with odor and taste problems. It is an effective biocide at concentrations as low as 0.1 ppm and over a wide pH range. ClO2 penetrates the bacterial cell wall and reacts with vital amino acids in the cytoplasm of the cell to kill the organisms. The by-product of this reaction is chlorite. Chlorine dioxide disinfects according to the same principle as chlorine, however, as opposed to chlorine, chlorine dioxide has no harmful effects on human health. 

Hydrogen peroxide 

Hydrogen peroxide is widely used thanks to its properties; it is a safe, effective, powerful and versatile oxidant. The main applications of H2O2 are oxidation to aid odour control and corrosion control, organic oxidation, metal oxidation and toxicity oxidation. The most difficult pollutants to oxidize may require H2O2 to be activated with catalysts such as iron, copper, manganese or other transition metal compounds. 

Alum

An alum is the of chemical compound , usually a hydrated double sulfate salt of aluminium with the general formula XAI(SO4)2.12H2O, where X is a monovalent cation such as potassium or ammonium. By itself, “alum” often refers to potassium alum. Alum added to raw water react with the bicarbonate alkalinities present in water and forms a gelatinous precipitate. This flock attracts other fine particles and suspended materials in raw water, and settles down at the bottom of container. 

Lime

The raw material is processed into quick lime and hydrated lime. Since it is alkaline, its often used to adjust the pH of water and soils containing acidic components. Its used to treat both drinking water and waste water.

WATER PURITY TESTS

1. PH Testing 

2. Nitrate Testing

3. Dissolved Oxygen Testing

4. Chloride Testing

5. Fluoride Testing

1. PH TESTING

              

1. Rinse each test tube with sample water. Use gloves if drawing the sample by hand.

2. Fill the tube to the 5ml line with sample water.

3. While holding a dropper bottle vertically, add 10 drops of wide range indicator solution.

4. Cap and invert several times to mix

5. Insert the tube into the Wide Range pH Comparator. Hold the comparator up to a light source. Match the sample colour to a colour standard.

6. Record the pH value.

7.  Wash your hands

2. NITRATE TESTING PROCEDURE

1. Fill the sample bottle with sample water. Use gloves if drawing the sample by hand.

2. Rinse and fill one test tube to the 2.5 ml line with water from the sample bottle.

3. Dilute to the 5 ml line with the Mixed Acid Reagent. Cap and mix. Wait 2 minutes.

4. Use the 0.1 g spoon to add one level measure (avoid any 50-60 times in one minute). Wait 10 minutes.

5. Insert the test tube into the Nitrate Nitrogen Comparator. Match the sample colour to a colour standard. Record the result as mg/l (ppm) Nitrate Nitrogen (NO3-N). To convert to mg/Nitrate (NO3) multiply by 4.4.

6. Place the reacted sample in a clearly marked container. Arrangements should be made with toxic material handlers for safe disposal. Please wash your hands after this water test is completed.

3. DISSOLVED OXYGEN TESTING PROCEDURE

1. If you have a barometer, record the atmospheric pressure. Remove the cap and immerse the DO bottle beneath the river’s surface. Use gloves to avoid contact with the river.

2. Allow the water to overflow for two to three minutes (This will ensure the elimination of bubbles).

3. Make sure no air bubbles are present when you take the bottle from the river.

4. Add 8 drops of Manganese Sulfate Solution and 8 drops of Alkaline Potassium Iodide Azide.

5. Cap the bottle, making sure no air is trapped inside it, and invert repeatedly to fully mix. Be very careful not to splash the chemical-laden water. Wash your hands if you contact this water. If oxygen is present in the sample, a brownish-orange precipitate will form (floc). The first two reagents "fix" the available oxygen.

6. Allow the sample to stand until the precipitate settles halfway. When the top half of the sample turns clear, shake again, and wait for the same changes.

7. Add 8 drops of Sulfuric Acid 1:1 Reagent. Cap and invert repeatedly until the reagent and the precipitate have dissolved. A clear yellow to brown-orange color will develop depending on the oxygen content of the sample.

8. Fill the titration tube to the 20 ml line with the "fixed": sample and cap.

9. Fill the Direct Reading Titrator with Sodium Thiosulfate 0.025 N Reagent. Insert the Titrator into the center hole of the titration tube cap. While gently swirling the tube, slowly press the plunger to titrate until the yellow-brown color is reduced to a very faint yellow. If the color of the fixed sample is already a faint yellow, skip to step 10.

10. Remove the cap and Tritrator. Be careful not to disturb the Titrator plunger, as the tiration begun in step 8 will continue in step 11. Add 8 drops of Starch Indicator Solution. The sample should turn blue.

11. Replace the cap and Titrator. Continue titrating until the sample changes from blue to a colorless solution. Read the test result where the plunger top meets the scale. Record as mg/L (ppm) dissolved oxygen.

4. CHLORIDE TESTING

1. Take 10ml of water in a beaker.

2. Add two drops of reagent-1 and mixed it with a glass rod.

3. The color changes to yellow.

4. Add 20 drops of reagent-2 and then again mixed it with glass rod.

5. Observe the color changes takes place in it.

6. When the water color changes to yellow to cherry red, the water is use full. The chloride level in this water is less than 1000mg/lit.

7. If the yellow color does not change the water is not use full. The chloride level is greater than 1000mg/lit.

8. The level of chloride is greater, the water is salty.

9. This type of water is harmful to health. The water supplying pipes and machines used to flow through this water is damaged by rusting.

5. FLURIDE TESTING

1. Take 50 drops of reagent-8 on nessler tube. Add water continuously when the level of water is 50ml.On other tests we add reagents to the water sample, but in this case we add water sample to the reagent.

2. Mixed thoroughly and take rest on 30 minutes. Then we can see that the color of liquid is changes to pink color dark yellow.

3. We can determine the fluride level by comparing the liquid color with the color chart. The fluride level in water is accordance with the numbers in color chart (mg/lit).

4. The fluride level is 1.5mg/l or below water is useful. If above 1.5mg/l water is useless.

5.   By the 1.5mg/l above the fluride level of water, cause cavity problems to the teeth.

PURIFICATION PROCESS

1. PUMPING

          Pumping stations are facilities including pumps and equipment for pumping fluids from one place to another. They are used for a variety of infrastructure systems, such as the supply of water to canals, the drainage of low-lying land, and the removal of sewage to processing sites.

2. SCREENING

          The raw water is passed through bar screens or mesh screens to remove coarse soils, gravel or silt.

3. SEDIMENTATION

           In this process, water is allowed to stand undisturbed in big tanks for 6-12 hours. During this most of the suspended particles settle down under force of gravity.

4. COAGULATION

            Finally divided suspended particles can be made to settle down by adding certain chemicals called coagulants. Common coagulants used are alum, ferrous sulphate, ferric chloride, sodium aluminate etc.

5. FILTRATION

            By filtration process, insoluble colloidal and bacterial impurities are removed from water by means of filters.

Rapid sand filtration

               This system consists of a layer of gravel with layers of sand of decreasing coarseness above the gravel. As solids build up on top, flow decreases until it stops. This is corrected by back-flushing the system to remove the solid build up on top, Figure.

 The main advantages are:

• Cost of filtration media is negligible.

• Operation is simple.

The main disadvantages are:

· A holding tank for filtered water is required to provide clear water back flushing.
· Pumping loads increase as sediments build up.

UP-FLOW FILTRATION

Filtration can be at atmospheric pressure or by using a pressurised system, Figures 5 and 6.

The main advantages are:

· High flow rates are easily attained.
· Water with turbidity up to 1500 ppm can be handled.
· Degree of filtration can be easily adjusted.
· The filter bed can be easily cleaned using the filtered water.

The main disadvantage is:

· Close supervision is necessary to ensure that the filter bed does not rupture.

1. STERILIZATION

           Water even after sedimentation, coagulation and filtration operations may contain a small percentage of pathogenic bacteria. The process of destroying the disease producing bacteria and micro-organisms from the water and making it safe for drinking is called sterilization or disinfection. Chemicals used for sterilization are called sterilizers or disinfectants.

2. CHLORINATION

        Chlorination is the most widely used process for sterilization throughout the world. Chlorine gas          or chlorine water can be used.