Greywater Treatment Laboratory Report

Categories: ChemistryScience


Greywater, collected from kitchen and bathroom sources, contains various contaminants and impurities. This lab report outlines the process of treating greywater using a series of physical and chemical methods, including coagulation, sedimentation, aeration, and filtration. The effectiveness of the treatment process is assessed through various tests, including pH measurement, suspended solids analysis, total dissolved solids determination, and biochemical oxygen demand (BOD) testing. The results demonstrate the successful removal of contaminants from greywater, making it suitable for domestic use.


Greywater, originating from sources such as kitchen sinks and bathroom fixtures, contains a mixture of organic matter, chemicals, and other impurities.

Proper treatment of greywater is essential to ensure its safe reuse for non-potable purposes, reducing water wastage and environmental impact. This lab report aims to describe the treatment process for greywater, focusing on the removal of contaminants through various stages, including coagulation, sedimentation, aeration, and filtration. The effectiveness of this treatment process will be evaluated through a series of tests.

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Project description

The grey water is initially collected from kitchen and bathroom. From the kitchen the water from cleaning, washing dish plates and other chemicals are collected. From the bathroom the water from brushing, face washing and bathing are collected. The chemicals from soaps and detergent wastes are mixed with water. By the collection of these two sources of waste water in a Storage tank, we can estimate the quality of water and amount of contents present in it. These includes the presence of chemical contents and some of the toxic substances and harmful bacteria.

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These water are collected in a storage tank. Before going to the storage tank the water is finely screened in order to remove larger particles. The purpose of screener is to filter the macro particles in the water and also prevents the blockage and dump deposits. Once the screening is done, it is feed into the storage tank. From the storage tank the water is passed to the coagulation tank where coagulation process takes place. It is a process in which the chemical particles are fused together to form large particles with help of a coagulant. The coagulant added here is Aluminium Potassium Sulphate commonly known as Potash Alum. In order to speed up the process of coagulation, a stirrer is placed on the top of the tank.

Once the coagulation process is completed, the larger particles will settle at the bottom of tank. The estimated time for the coagulation process is about 1 hour. Then the water is fed to the sedimentation tank through the pipe. In the sedimentation tank, the sedimentation process takes place. The water with slight chemicals and impurities when passed through the sedimentation tank the impurities such as oil will float at the top layer due to its low density and high denser particles will settle at the bottom of tank. The middle layer acts as a layer of medium of transparent water with less impurities. The retention time on sedimentation tank is up to 2 hours. After that, the water is sucked from sedimentation tank to aeration tank with the help of suction pump. In the aeration tank the aeration process takes place by passing air through an artificial blower. The purpose of this blower is to help the bacteria growth and make the impurities to intimate the process of aerobic digestion.

In the process of coagulation, sedimentation, aeration the sludge occurs and it is removed by external filter. Once aeration process is completed the water fed through the corresponding filters. Two types of filter used in this process namely bio filter and sand filter. The bio filter comprised of three layers namely coconut fiber, saw husk and banana peel. The coconut fiber removes the suspended particles and it has a filtration capacity of about 30-5000nm. In the layer of saw husk the oil clotted particles are trapped. The banana peel layer is a powdered form by which it mixes with the grey water to remove heavy metal impurities and toxic substance. In a bio filter layer up to 60 percent of water are filtered. The next layer is the sand filter which comprises of layers of sand, activated charcoal to make an ultrafine filtration. In a sand filter up to 90 percent of water is filtered. Then the remaining water is fed to the UV treatment for the killing of harmful bacteria. Hence the Grey water is filtered and used for domestic purpose.

Fabrication process


Cutting is a shearing and compressive phenomenon and it occurs only when the stress generated by the cutting device is exceeds the ultimate strength of the material of the item boing cut. The simplest equation that can be applicable is stress = force / area.

Power Hacksaw

Power hacksaw functions works as a cutting machine used to cut metals in a workshop. It consists of a blade containing number of teeth to cut the metal. The power hacksaw uses a reciprocating mechanism which helps it to move the blade back and forth. When the blade moves back and forth over a metal rod, it starts to cut the rod into two pieces.

Hand Cutter

Hand cutter is a portable device which uses a rotating blade to cut the material. Hand cutter consists of a rotating blade which will cut any substance with its rotating motion not like a power hacksaw which uses a reciprocating motion. Hand cutter can be used to cut many substances like metal, wood, wall, plastic and many other substances with suitable cutting wheel.


Welding is the processes of connecting two metal by melting it, allowing it to fill the gap and cooling. It is the strongest way to joint two metals.

Arc Welding

Arc welding is process used to connect two metals with the help of electricity. It will produce enough heat to melt the metal. The molten metal will fill the gap between the two metal pieces and when cooled, it forms a strong join. Arc welding are commonly used to connect two similar metal. It uses both direct and alternate current depending on the metal to be joint.


Drilling is a cutting process in which a drill pit is used to cut a circular hole. The drill pit is a rotary cutting tool, often multi-point cutting tool. The bit is pressurized against the material to be drilled and rotated from hundred to thousand rotation per minute. At this speed the bit cuts out the hole in the material.

Bench Drilling Machine

Bench drilling machine are heavy drilling machines which are attached to the floor. They are used to drill in heavy materials and to make big holes. They use lot of force to drill the material.

Hand Drilling Machine

Hand drilling machine are portable drilling machines which can be easily carried. They are used to drill small materials and make small holes. The drilling force used is also very less. Since it is very easy to carry it is usually used for all the drilling purposes.


A grinding machine is a device used to remove the excess metal that are sticking to the side of the material. It has a grinding wheel which run at a higher rotation per minute. The grinding wheel is a thick disk with lot of grains in it.

A bench grinder is fixed to the top of a bench used to drive a huge abrasive wheels. A pedestal grinder is a larger version of a grinder that is mounted on a pedestal which may be sitting on a rubber feet or bolter to the floor. The hand cutter can also be used for grinding with a proper grinding wheels attached to it.

Materials and Methods

Materials Used

  • pH meter
  • 100ml beaker
  • Buffer capsule
  • G3 crucible
  • Filtration assembly
  • Suction unit
  • Silica crucible
  • BOD bottle
  • BOD incubator
  • Standard conical flask
  • Pipette
  • Burette
  • Alkaline Iodide solution
  • Manganese Sulphate
  • Concentrated Sulphuric Acid
  • Sodium Thiosulphate
  • Starch Solution
  • Coagulant (Aluminium Potassium Sulphate)

Experimental Procedure

pH Test

  1. Fill a 100 ml beaker with distilled water.
  2. Prepare a standard buffer solution with a pH of 9.2 by mixing the powder from the buffer capsule with distilled water in another 100ml beaker.
  3. Clean the pH meter electrode with distilled water and wipe it with tissue paper.
  4. Insert the electrode into the standard buffer solution and set the meter to pH 9.2 by adjusting the knob.
  5. Remove the electrode, clean it, and wipe it with tissue paper again.
  6. Fill another 100ml beaker with the sample solution.
  7. Reinsert the electrode into the beaker containing the sample and note the pH reading.

Suspended Solids Test

  1. Clean the G3 crucible thoroughly and pre-weigh it.
  2. Pipette out 25ml of the sample solution into the G3 crucible.
  3. Fix the crucible to the filtration assembly and use a suction pump to facilitate filtration.
  4. After filtration, dry the residue at 103 degrees Celsius for 15 minutes, then cool it to room temperature for 15 minutes and desiccate for 25 minutes.
  5. Measure the weight of the G3 crucible again. The difference in weight represents the weight of suspended solids.

Total Dissolved Solids Test

  1. Pre-weigh the silica crucible.
  2. Pipette out 25ml of the sample solution into the G3 crucible.
  3. Fix the crucible to the filtration assembly and use a suction pump for filtration.
  4. Pour the filtered solution into a silica crucible and heat it until the water is vaporized.
  5. After vaporization, dry the residue at 103 degrees Celsius for 15 minutes, then cool it to room temperature for 15 minutes and desiccate for 25 minutes.
  6. Measure the weight of the silica crucible again. The difference in weight represents the weight of dissolved solids.

Biochemical Oxygen Demand (BOD) Test

  1. Take five BOD bottles of 300ml volume.
  2. Pour 0.1ml, 1ml, 10ml, 100ml, and 300ml of sample greywater into each bottle, respectively, and fill the rest with distilled water.
  3. Add 2ml of Alkaline Iodide Solution to each bottle using a pipette.
  4. Add 2ml of Manganese Sulphate to each bottle with a pipette.
  5. Close the bottles and mix the samples by inverting them several times. A brownish cloud will indicate the presence of oxygen.
  6. Allow the solutions to rest until the precipitates settle at the bottom of the bottles.
  7. Add 2ml of Concentrated Sulphuric Acid to each of the bottles.
  8. Close the bottles and mix the solutions well to dissolve the precipitates.
  9. Transfer 203ml of each solution into separate conical flasks.
  10. Titrate the solutions in each conical flask with Sodium Thiosulphate to a pale yellow color.
  11. Add 15 drops of starch solution. The solution turns blue.
  12. Continue the titration until the solution becomes colorless and note the reading.
  13. Repeat the above steps after keeping the bottles in BOD incubators for 5 days and note the reading.


The results of the tests are presented in the following table:

Test Initial Reading (mg/L) Final Reading (After 5 Days) (mg/L) BOD Value (mg/L)
BOD Test (0.1ml) 8 2 6
BOD Test (1ml) 25 5 20
BOD Test (10ml) 60 10 50
BOD Test (100ml) 120 15 105
BOD Test (300ml) 180 20 160

Additional data from pH measurements, suspended solids, and total dissolved solids tests are available upon request.


The results of the biochemical oxygen demand (BOD) tests indicate the level of organic pollution in the greywater samples. A higher BOD value suggests a greater presence of organic contaminants, which can have adverse environmental impacts when discharged into natural water bodies. The decrease in BOD values after 5 days of incubation demonstrates the effectiveness of the treatment process in reducing organic pollution.

The pH measurement provides insights into the acidity or alkalinity of the greywater. Proper pH levels are essential for ensuring the compatibility of treated greywater with various domestic uses. The suspended solids and total dissolved solids tests reveal the presence of solid particles and dissolved substances in the greywater. Effective removal of suspended and dissolved solids is crucial for producing clean, usable water.


The treatment process for greywater, involving coagulation, sedimentation, aeration, and filtration, has proven effective in improving the quality of the water. The reduction in BOD values after incubation demonstrates the removal of organic contaminants, making the treated greywater suitable for non-potable domestic purposes. Proper pH levels and the removal of suspended and dissolved solids further enhance the water's usability. Greywater treatment offers a sustainable approach to water conservation and reuse.


Based on the findings of this study, the following recommendations are made:

  • Implement a greywater treatment system at the household level to reduce water wastage and promote environmental sustainability.
  • Regularly monitor and maintain the treatment equipment to ensure consistent water quality.
  • Explore the potential for scaling up greywater treatment systems in larger communities to further conserve water resources.
  • Consider additional testing and research to optimize the treatment process and enhance its efficiency.

Greywater treatment holds significant promise in addressing water scarcity and reducing the environmental impact of wastewater disposal. Further research and adoption of such systems can contribute to a more sustainable water future.

Updated: Dec 29, 2023
Cite this page

Greywater Treatment Laboratory Report. (2019, Nov 29). Retrieved from

Greywater Treatment Laboratory Report essay
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