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Charecteristics of wastewater

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Venuri Lakshani

Wastewater has physical, chemical, and biological characteristics. Physically, it contains solids like total suspended solids and total dissolved solids that affect turbidity. Chemically, wastewater has parameters like pH, alkalinity, nitrogen, and phosphorus. Common methods to measure organic content include biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total organic carbon (TOC). Biologically, wastewater contains organisms like bacteria, algae, protozoa, and viruses, some of which can be pathogenic.

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CHARECTERISTICS OF WASTEWATER
Physical characteristics 1. Solids Composed of floating matter, settleable matter, colloidal matter and matter in solution. Total Suspended Solids (TSS) Total suspended solids (TSS) include all particles suspended in water which will not pass through a filter. As levels of TSS increase, a water body begins to lose its ability to support a diversity of aquatic life. Suspended solids absorb heat from sunlight, which increases water temperature and subsequently decreases levels of dissolved oxygen
Total Dissolved Solids (TDS) TDS are passed through the filter. TDS comprised of colloidal and dissolved solids. Colloids are typically in the size range from 0.001 to 1亮m. Volatile Suspended Solids (VSS) Those solids that can be volatilized and burned off when the TSS are ignited. Volatile suspended solids data is critical in determining the operational behavior and biological concentration throughout the system. 2. Turbidity Measure of the light-transmitting properties of water, is another test used to indicate the quality of waste discharges and natural waters with respect to colloidal and residual suspended matter. Units NTU (Nephelometric Turbidity Units) Equipment using to measure - electronic turbidity meter or a turbidity tube
3. Colour Age of the waste water is determined qualitatively by its colour and odour. Fresh wastewater is usually a light brownish- gray colour. Travel time of the collection system increases anaerobic conditions develop and colour of the waste water changes sequentially for gray to dark gray, and ultimately to black. This black colour is due to the metallic sulfides which formed under the anaerobic conditions. 4. Absorption / Transmittance This is measure of the amount of light, of a specified wave length, that is absorbed by the constituents in a solution. Absorbance measure using the spectrophotometer. 5. Temperature The temperature of waste water is commonly higher due to the addition of warm water from households and industrial activities. Temp. is effects on chemical reactions and reaction rates, aquatic life and the suitability of the water.
6. Electrical Conductivity It is measure of the ability of a solution to conduct an electric current. EC is one of the important parameter used to determine the suitability of the water for irrigation. SI units millisiemens per meter (mS/m) or micromhos per centimeter (亮mhoms/cm) Equipment use to measure Electrical conductivity meters.
Chemical characteristics 1. pH This represent the hydrogen ion concentration. Waste water with an extreme concentration of hydrogen ion is difficult to treat by biological means. For treated effluent discharged to the environment the allowable ph range usually varies from 6.5 to 8.5. 1. Chlorides Human excreta, contain 6g of chlorides per person par day. Infiltration of salty water into sewers is also a potential source of high chlorides 3. Alkalinity Alkalinity in waste water results from the presence of the hydroxides (OH-), carbonates (CO3 2-), and bicarbonates (HCO3 -) of elements such as Calcium, Magnesium, etc. Waste water is normally alkaline, receiving its alkalinity from material added during domestic use. The alkalinity in waste water helps to resist changes in pH caused by the addition of acids.
4. Nitrogen and Phosphorous Elements Nitrogen and Phosphorous, essential to the growth of microorganisms, plants, and animals are known as nutrient or bio-stimulants. These are required to evaluate the treatability of of waste water by biological processes. Insufficient Nitrogen and phosphorous can necessitate the addition of nitrogen to make the waste treatable. But if control of algal growth in the receiving water is necessary, removal or reduction of nitrogen in waste water prior to discharge may be desirable. 5. Metallic constituents Trace quantities of many metals such as Cadmium (Cd), Chromium(Cr), Copper(Cu), Iron (Fe), lead (Pb), Manganese (Mn), Mercury (Hg), Nickel (Ni) and Zinc(Zn) are important constituents of most waters.
Measurement of Organic Content Methods used to measure the aggregate organic material can be divided into two groups. 1. Methods used to measure the gross concentration of organic matter greater than about 1.0mg/l. BOD, COD, Total Organic Carbon (TOC) 2. Methods used to measure trace concentration in the range of 10-12 to 100 mg/l - Determined using instrumental methods including gas chromotography and mass spectroscopy.
Biological Oxygen Demand (BOD) BOD5 - 5 day, 20oC BOD3 - 3 day, 27oC The most wildly used parameter of organic pollution applied to both waste water and surface water is the 5 day BOD (BOD5). BOD test results are used to; Determine the approximate quantity of oxygen that will be required to biologically oxidized (Stabilized) the organic matter. To determine the size of waste treatment facilities Measure the efficiency of some treatment processes. Determine the compliance with wastewater discharge permits.
Chemical Oxygen Demand (COD) COD test is used to measure the oxygen equivalent of the organic materials in waste water that can be oxidized chemically. Normally use the dichromate in an acid solution. The reasons for difference between the BOD and COD are as follows; 1. Many Organic substances which are difficult to oxidize biologically such as lignin can be oxidized chemically. 2. Certain organic substances that are toxic to microorganisms use in BOD test oxidize by chemicals. Total Organic Carbon (TOC) The TOC of a wastewater can be used as a measure of its pollution characteristics and in some cases it has been possible to relate to TOC to BOD and COD values. This test is done instrumentally by converting organic carbon into carbon dioxide which is measured with an infrared analyzer.
Units of measurement for physical and chemical parameters Measurements of chemical parameters are usually expressed in milligrams per liter (mg/L ) or grams per cubic meter (g/m3) Concentrations also can be expressed as part per million (ppm). ppm = mg/L Specific gravity of fluid
Biological Characteristics Organisms found in surface water and waste water include bacteria, fungi, algae, protozoa, plants and viruses. Above some types can only be observed microscopically. Pathogenic Organisms Pathogenic organisms found in waste water may be excreted by human beings and animals who are infected with disease or who carriers of a particular infection disease. These organisms can four broad categories bacteria, protozoa, helminthes (worms) and viruses.

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Charecteristics of wastewater

  • 2. Physical characteristics 1. Solids Composed of floating matter, settleable matter, colloidal matter and matter in solution. Total Suspended Solids (TSS) Total suspended solids (TSS) include all particles suspended in water which will not pass through a filter. As levels of TSS increase, a water body begins to lose its ability to support a diversity of aquatic life. Suspended solids absorb heat from sunlight, which increases water temperature and subsequently decreases levels of dissolved oxygen
  • 3. Total Dissolved Solids (TDS) TDS are passed through the filter. TDS comprised of colloidal and dissolved solids. Colloids are typically in the size range from 0.001 to 1亮m. Volatile Suspended Solids (VSS) Those solids that can be volatilized and burned off when the TSS are ignited. Volatile suspended solids data is critical in determining the operational behavior and biological concentration throughout the system. 2. Turbidity Measure of the light-transmitting properties of water, is another test used to indicate the quality of waste discharges and natural waters with respect to colloidal and residual suspended matter. Units NTU (Nephelometric Turbidity Units) Equipment using to measure - electronic turbidity meter or a turbidity tube
  • 4. 3. Colour Age of the waste water is determined qualitatively by its colour and odour. Fresh wastewater is usually a light brownish- gray colour. Travel time of the collection system increases anaerobic conditions develop and colour of the waste water changes sequentially for gray to dark gray, and ultimately to black. This black colour is due to the metallic sulfides which formed under the anaerobic conditions. 4. Absorption / Transmittance This is measure of the amount of light, of a specified wave length, that is absorbed by the constituents in a solution. Absorbance measure using the spectrophotometer. 5. Temperature The temperature of waste water is commonly higher due to the addition of warm water from households and industrial activities. Temp. is effects on chemical reactions and reaction rates, aquatic life and the suitability of the water.
  • 5. 6. Electrical Conductivity It is measure of the ability of a solution to conduct an electric current. EC is one of the important parameter used to determine the suitability of the water for irrigation. SI units millisiemens per meter (mS/m) or micromhos per centimeter (亮mhoms/cm) Equipment use to measure Electrical conductivity meters.
  • 6. Chemical characteristics 1. pH This represent the hydrogen ion concentration. Waste water with an extreme concentration of hydrogen ion is difficult to treat by biological means. For treated effluent discharged to the environment the allowable ph range usually varies from 6.5 to 8.5. 1. Chlorides Human excreta, contain 6g of chlorides per person par day. Infiltration of salty water into sewers is also a potential source of high chlorides 3. Alkalinity Alkalinity in waste water results from the presence of the hydroxides (OH-), carbonates (CO3 2-), and bicarbonates (HCO3 -) of elements such as Calcium, Magnesium, etc. Waste water is normally alkaline, receiving its alkalinity from material added during domestic use. The alkalinity in waste water helps to resist changes in pH caused by the addition of acids.
  • 7. 4. Nitrogen and Phosphorous Elements Nitrogen and Phosphorous, essential to the growth of microorganisms, plants, and animals are known as nutrient or bio-stimulants. These are required to evaluate the treatability of of waste water by biological processes. Insufficient Nitrogen and phosphorous can necessitate the addition of nitrogen to make the waste treatable. But if control of algal growth in the receiving water is necessary, removal or reduction of nitrogen in waste water prior to discharge may be desirable. 5. Metallic constituents Trace quantities of many metals such as Cadmium (Cd), Chromium(Cr), Copper(Cu), Iron (Fe), lead (Pb), Manganese (Mn), Mercury (Hg), Nickel (Ni) and Zinc(Zn) are important constituents of most waters.
  • 8. Measurement of Organic Content Methods used to measure the aggregate organic material can be divided into two groups. 1. Methods used to measure the gross concentration of organic matter greater than about 1.0mg/l. BOD, COD, Total Organic Carbon (TOC) 2. Methods used to measure trace concentration in the range of 10-12 to 100 mg/l - Determined using instrumental methods including gas chromotography and mass spectroscopy.
  • 9. Biological Oxygen Demand (BOD) BOD5 - 5 day, 20oC BOD3 - 3 day, 27oC The most wildly used parameter of organic pollution applied to both waste water and surface water is the 5 day BOD (BOD5). BOD test results are used to; Determine the approximate quantity of oxygen that will be required to biologically oxidized (Stabilized) the organic matter. To determine the size of waste treatment facilities Measure the efficiency of some treatment processes. Determine the compliance with wastewater discharge permits.
  • 10. Chemical Oxygen Demand (COD) COD test is used to measure the oxygen equivalent of the organic materials in waste water that can be oxidized chemically. Normally use the dichromate in an acid solution. The reasons for difference between the BOD and COD are as follows; 1. Many Organic substances which are difficult to oxidize biologically such as lignin can be oxidized chemically. 2. Certain organic substances that are toxic to microorganisms use in BOD test oxidize by chemicals. Total Organic Carbon (TOC) The TOC of a wastewater can be used as a measure of its pollution characteristics and in some cases it has been possible to relate to TOC to BOD and COD values. This test is done instrumentally by converting organic carbon into carbon dioxide which is measured with an infrared analyzer.
  • 11. Units of measurement for physical and chemical parameters Measurements of chemical parameters are usually expressed in milligrams per liter (mg/L ) or grams per cubic meter (g/m3) Concentrations also can be expressed as part per million (ppm). ppm = mg/L Specific gravity of fluid
  • 12. Biological Characteristics Organisms found in surface water and waste water include bacteria, fungi, algae, protozoa, plants and viruses. Above some types can only be observed microscopically. Pathogenic Organisms Pathogenic organisms found in waste water may be excreted by human beings and animals who are infected with disease or who carriers of a particular infection disease. These organisms can four broad categories bacteria, protozoa, helminthes (worms) and viruses.