Waste Water MCQ Quiz in मल्याळम - Objective Question with Answer for Waste Water - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

Explanation:

Dissolved Oxygen:

• The Winkler Method is a technique used to measure dissolved oxygen in freshwater systems.
• Dissolved oxygen (DO) is a measure of how much oxygen is dissolved in the water. The amount of dissolved oxygen in a stream or lake can tell us a lot about its water quality. 
• For the survival of fish in a river stream, the minimum dissolved oxygen is prescribed 4 mg/l.
• The main compounds for conducting this test are Azide Iodide, Starch solution, and Sodium thiosulphate.

Important PointsNatural factor affecting Dissolved Oxygen:

• Aquatic life: Animals living in water use up dissolved oxygen. Bacteria take up oxygen as they decompose materials. Dissolved oxygen levels drop in a water body that contains a lot of dead, decomposing material.
• Elevation: Since streams get much of their oxygen from the atmosphere, streams at higher elevations will generally have less oxygen.
• Salinity (saltiness): Salty water holds less oxygen than freshwater.
• Temperature: The Solubility of oxygen decreases as temperature increases. Cold water holds more dissolved oxygen than warm water.
• Turbulence: More turbulence creates more opportunities for oxygen to enter streams.
• Aquatic Vegetation: Aquatic vegetation and algae directly release oxygen into the water during photosynthesis (during the day). At night, plants actually use oxygen for their metabolism.

Thus, the dissolved oxygen concentration decreases with the increase in the temperature of the water.

Stabilization ponds may be classified as aerobic, facultative, or anaerobic depending on the mechanism of purification.

In an aerobic pond the stabilization of waste is done by the aerobic bacteria, which act and grow in the presence of oxygen.

In an anaerobic pond, the stabilization of waste is generally done by anaerobic conversion of organic waste to different end product by anaerobic bacteria in the absence of oxygen.

Concept:

The total microbial mass in the aeration system (M) is computed by multiplying the average concentration of solids in the mixed liquor of the aeration tank, called Mixed Liquor Suspended Solids with the volume of the tank (V).

∴ M = MLSS × V

Calculation:

The concentration of mixed liquor suspended solids,

MLSS = 1000 mg/l ⇒ \(\frac{{1000 \times {{10}^{ - 6}}}}{{{{10}^{ - 3}}}}\;kg/{m^3} = \;1\;kg/{m^3}\)

For a volume of 400 m³,

M = 1 × 400 = 400 kg

The biological treatment that causes stabilization of organic impurities in sewage by symbiotic action due to algae and bacteria in an artificially excavated earthen basin is called an oxidation pond. Algae in the pond provide oxygen for degradation through photosynthesis and bacteria releases carbon dioxide, ammonia, sulfates, and phosphates after the reaction.

Oxidation pond is also known as stabilization pond.

Waste stabilization pond can be aerobic, anaerobic, facultative, or combination of any two or all three of them.

It is economical treatment requiring 20 – 50 days for complete waste stabilization

The correct answer is Both biogas and sludge.

Key Points

• Biogas and sludge are the products of wastewater treatment.
• The biogas forms due to the microbial degradation of the waste and sludge are the end by-product of the wastewater treatment.
• The main by-product from wastewater treatment plants is sewage sludge which is usually treated in the same or another wastewater treatment plant.
• Biogas can be another by-product if anaerobic treatment processes are used.

Important Points

• Anaerobic respiration - Anaerobic respiration is respiration using electron acceptors other than molecular oxygen. 
• Aerobic respiration - It is the process of cellular respiration that takes place in the presence of oxygen gas to produce energy from food. 

Discrete settling, the phenomenon can be analysed by the classic sedimentation laws of Newton and Stokes.

Types of Settling:

Type I: Discrete particle settling - Particles settle individually without interaction with neighboring particles.

Type II: Flocculent Particles – Flocculation causes the particles to increase in mass and settle at a faster rate.

Type III: Hindered or Zone settling –The mass of particles tends to settle as a unit with individual particles remaining in fixed positions with respect to each other.

Type IV: Compression – The concentration of particles is so high that sedimentation can only occur through compaction of the structure

Explanation:

Natural Organic Matter (NOM):

• Natural organic matter (NOM) is an extremely complex mixture of organic compounds that vary greatly in terms of their physical and chemical characteristics.
• NOM occurs naturally in the environment and may also be the result of human activities.
• NOM is found in particulate, colloidal, and dissolved forms in all ground and surface waters, as well as in rainwater.
• NOM will have significant impacts on drinking water treatment processes aimed at protecting public health. 

Chemical Effervescence:

• Effervescence is the formation of bubbles of gas in a liquid due to a chemical reaction.

Biochemical Matter:

• The biochemical matter is defined as matter (or material) that is produced by living things due to chemical reactions.

Biological Load:

• Biological load defined as the total biodegradable organic matter (material) present in a water sample is called the biological load.

Cast iron pipe is most appropriate sewer material to resist high internal and external pressure.

These pipes are stronger and capable to withstand greater tensile, compressive, as well as bending stresses. However, these are costly. Cast iron pipes are used for outfall sewers, rising mains of pumping stations, and inverted siphons, where pipes are running under pressure.

These are also suitable for sewers under heavy traffic loads, such as sewers below railways and highways.

Concept:

• The inorganic compound calcium hypochlorite has the formula Ca(OCl)2.
• It is the main active ingredient in industrial bleaching powder and chlorine powder products that are used for water treatment and bleaching.
• This compound is more stable than sodium hypochlorite and has more available chlorine (liquid bleach). In the late 18th century, Charles Tennant and Charles Macintosh invented an industrial method for producing chloride of lime.
• To sanitize public swimming pools and disinfect drinking water, calcium hypochlorite is widely used.
• Commercial substances are typically marketed with a purity of 65 to 73 percent, with other chemicals like calcium chloride and calcium carbonate present as a result of the manufacturing process.

Additional Information

• Calcium hypochlorite is a general oxidizing agent that has applications in organic chemistry.
• In the industry, calcium hypochlorite is made by treating lime (Ca(OH)2) with chlorine gas. Slaked lime that is slightly moist is used to make bleaching powder.

https://pubchem.ncbi.nlm.nih.gov/compound/Calcium-hypochlorite 

Concept:

Threshold Odour Number:

The threshold odour Number is the dilution factor at which the odour is just detectable.
The Dilution factor is given by,

DF = \(\left ( \frac{V_{f}}{V_{i}} \right )\)

Where,

V_f = Final Volume 

V_i = Initial Volume 

Calculation:

Given,

Vf = 100 mL

V_i = 20 mL

DF = \(\left ( \frac{V_{f}}{V_{i}} \right )\)

DF = \(\frac{100}{20}\) = 5

TON = 5