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Increasing pressure results in an increase in dissolved oxygen levels at a given temperature.
Increasing pressure results in an increase in dissolved oxygen levels at a given temperature.
True (A)
Dissolved Oxygen (DO) levels increase with an increase in temperature.
Dissolved Oxygen (DO) levels increase with an increase in temperature.
False (B)
Biochemical Oxygen Demand (BOD) measures the amount of oxygen needed for the biological oxidation of organic matter over a five-day period.
Biochemical Oxygen Demand (BOD) measures the amount of oxygen needed for the biological oxidation of organic matter over a five-day period.
True (A)
The Winkler method determines the concentration of carbon dioxide in water.
The Winkler method determines the concentration of carbon dioxide in water.
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Higher BOD values indicate a higher level of decomposable organic matter in sewage.
Higher BOD values indicate a higher level of decomposable organic matter in sewage.
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Sewage consists of approximately 50% organic and inorganic matters.
Sewage consists of approximately 50% organic and inorganic matters.
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Manganese hydroxide is used as an oxygen carrier in the Winkler's method for determining DO.
Manganese hydroxide is used as an oxygen carrier in the Winkler's method for determining DO.
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Dissolved oxygen is not essential for aerobic bacteria in wastewater treatment.
Dissolved oxygen is not essential for aerobic bacteria in wastewater treatment.
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A pH level of 8.5 is considered safe for aquatic life.
A pH level of 8.5 is considered safe for aquatic life.
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The measurement of BOD is performed over a period of 5 days.
The measurement of BOD is performed over a period of 5 days.
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The BOD values of effluents from paper and pulp industries are generally high due to excess biodegradable material.
The BOD values of effluents from paper and pulp industries are generally high due to excess biodegradable material.
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Total Dissolved Solids (TDS) must be less than 500 ppm for water to be considered potable.
Total Dissolved Solids (TDS) must be less than 500 ppm for water to be considered potable.
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COD values are typically lower than BOD values for a given sample.
COD values are typically lower than BOD values for a given sample.
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The formula for calculating TDS is TDS = (W/100) x 10^6 mg/L.
The formula for calculating TDS is TDS = (W/100) x 10^6 mg/L.
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Oxygen production through photosynthesis can affect the measurement of DO.
Oxygen production through photosynthesis can affect the measurement of DO.
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Higher TDS levels always indicate higher biological oxygen demand (BOD).
Higher TDS levels always indicate higher biological oxygen demand (BOD).
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The COD test can differentiate between biodegradable and non-biodegradable materials.
The COD test can differentiate between biodegradable and non-biodegradable materials.
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Conductivity measurements provide an indirect indication of Total Dissolved Solids (TDS).
Conductivity measurements provide an indirect indication of Total Dissolved Solids (TDS).
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A potassium dichromate solution is used during the COD measurement process.
A potassium dichromate solution is used during the COD measurement process.
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A TDS meter displays the concentration of suspended solids in a solution.
A TDS meter displays the concentration of suspended solids in a solution.
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The pH of a water sample is unrelated to the concentration of free hydrogen ions present.
The pH of a water sample is unrelated to the concentration of free hydrogen ions present.
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Gravimetry is one of the methods used to determine Total Dissolved Solids (TDS).
Gravimetry is one of the methods used to determine Total Dissolved Solids (TDS).
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COD determination is quicker than BOD determination.
COD determination is quicker than BOD determination.
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Acidic water has a pH greater than 7.
Acidic water has a pH greater than 7.
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Study Notes
Water and its Technology
- Water exists over a wide temperature range (0-100°C)
- Water has a high specific heat, meaning it takes a significant amount of energy to change its temperature
- Water has a high latent heat of vaporization, which leads to cooling effects during evaporation
- Water is an excellent solvent, carrying nutrients and pathogens
- Water has high surface tension, allowing it to rise through heights
- Water exhibits anomalous expansion; it expands when freezing, causing ice to float
- Common sources of water are rain, rivers, seas, glaciers, springs, and lakes.
- Rainwater is considered the purest form of water.
- Water contains various physical, chemical, and biological impurities that can cause issues in domestic and industrial settings.
- Total water on Earth is distributed as follows: Oceans (97.5%), Freshwater (2.5%)
- Freshwater is further divided into: Glaciers (68.7%), Groundwater (30.1%), Freshwater Lakes (67.4%), Atmosphere (9.5%), Other Wetlands (8.5%), Soil Moisture (12.2%), Rivers (1.6%), Plants and Animals (0.8%), Permafrost (0.8%)
- Impurities in water include: Physical (insoluble), Inorganic (clay, sand), Organic (oil globules, organic matter), Colloidal (Fe(OH)3, complex proteins) Chemical (soluble), Anions (Cl-, SO42-, CO32-, HCO3-, NO3-), Cations (Ca2+, Mg2+, Na+, K+, Fe3+, Al3+), Dissolved gases (O2, N2, CO2, H2S, NH3). Biological (microorganisms like algae, fungi, bacteria).
- Water hardness is caused by dissolved salts primarily calcium and magnesium, and other heavy metals.
- Hardness is classified into two types: Temporary and Permanent
- Temporary hardness is due to bicarbonates of calcium and magnesium, and carbonates of iron and other heavy metals that can be removed by boiling.
- Permanent hardness is caused by dissolved chlorides and sulfates of calcium and magnesium that can be removed via zeolite, Lime-soda, ion-exchange processes.
- Water hardness impacts both domestic and industrial processes.
- Domestic issues include soap wastage, fuel wastage, urinary infections, kidney stones, skin dryness, etc.
- Industrial concerns often include boiler scale, sludge, caustic embrittlement, priming, foaming, and problems in industries like textile, sugar, paper, laundry, and pharma.
- The units of hardness are typically measured as parts per million (ppm) or as calcium carbonate equivalents.
- 1 ppm is equal to 1 mg/L, 1 part of CaCO3 equivalent in 106 of parts of water, in Clark's degree 1 part of CaCO3 equivalent in 70,000 parts of water and in French degree 1 part of CaCO3 equivalent in 105 parts of water.
- Methods used to measure hardness include complexometric titration using EDTA and Eriochrome Black T (EBT). Other methods include flame photometry.
Dissolved Oxygen (DO)
- Dissolved oxygen is the amount of oxygen dissolved in water.
- The amount of DO in water depends on physical, chemical, and biological activities like temp. and pressure.
- Higher pressure leads to more dissolved oxygen at a given temperature. The amount is also lower when the water temperature increases.
- The measurement of dissolved oxygen often employs Winkler's method.
- DO is important for living organisms' biological activities.
- It influences precipitation and dissolution of inorganic and organic substances.
- DO is crucial for pollutant degradation.
- DO level affects boiler corrosion.
Biochemical Oxygen Demand (BOD)
- BOD measures the amount of oxygen needed for the biological oxidation of organic matter in water over five days at 20°C.
- Higher BOD indicates a greater amount of decomposable organic matter.
- BOD is used as a parameter in designing effluent treatment, particularly for industries like domestic sewage, cow shed sewage, paper mills, and tanneries.
- Various factors like pollutants and temperature affect BOD.
Chemical Oxygen Demand (COD)
- COD measures the oxygen equivalent of any oxidizable impurity in water using strong chemical oxidants.
- COD is typically higher than BOD for a sample of water.
- COD is a useful parameter for designing treatment plants for effluents like cellulose and other non-degradable organic matter, as it doesn't get affected by toxins and microorganisms.
- COD measurement takes hours, while BOD requires several days.
pH
- pH measures the concentration of hydrogen ions in a water sample.
- A lower pH indicates higher acidity.
- A higher pH indicates higher alkalinity.
- Water with pH values below 6.5 or above 8.5 is considered harmful.
- pH is measured using instruments like a pH meter.
Total Dissolved Solids (TDS)
- TDS refers to the total amount of dissolved minerals and solids in water.
- TDS can be determined by evaporating a known amount of water to dryness.
- Higher TDS indicates a higher possibility of higher hardness.
- Desired TDS levels in potable water are below 500 ppm, which is crucial for human consumption.
- TDS is measured using gravimetry, chemical analysis, and conductivity methods.
Alkalinity
- Alkalinity in water is due to dissolved anions like HCO3-, CO32-, and OH-
- Alkalinity is quantified by titrating water against standardized acid solution, such as HCl or H2SO4.
- OH- and HCO3- ions can't coexist as they react creating CO32- and water.
- Alkalinity is calculated typically with indicators like phenolphthalein (pH 10 - 8.3, indicating caustic alkalinity) and methyl orange (pH 3.1 - 4.4, illustrating temporary hardness).
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Description
This quiz covers the fundamental properties of water, including its temperature range, high specific heat, and exceptional solvent capabilities. Explore concepts such as latent heat of vaporization, surface tension, and the distribution of water on Earth. Test your knowledge on this vital resource!
