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WorksheetsDAY 32 WORKSHEET LSGD (Water Treatment ,WATER QUALITY)
Total questions: 15
Worksheet time: 8mins
When raw water contains both colloidal impurities and objectionable odour, the correct sequential treatment is —
Screening → Filtration → Disinfection
Screening → Coagulation → Sedimentation
Aeration → Coagulation → Sedimentation → Filtration
Softening → Disinfection → Filtration
The principal reason why coagulation precedes rapid sand filtration is —
Removal of microorganisms
Reduction of head loss
Increase grain size of suspended particles
Reduction of total solids
In an Imhoff tank, mixing of fresh sewage with digesting sludge is prevented due to —
Longer retention time
Separate lower digestion chamber
Floating cover
External recirculation
In chlorination, the dominating species above pH 10 is —
HOCl
Cl2
OCl –
NaOCl
For septic tank design, if number of users is 60 and daily sewage flow is 60 L/capita, detention period = 24 hr and sludge accumulation = 30 L/capita/year for 2 years — approximate minimum sludge storage requirement =
(a)
At pH below 5, free elemental chlorine exists and is ineffective for disinfection.
True
False
Simplex joint in AC pipes not only allows angular deflection but can also be laid under water without leakage.
True
False
Assertion (A): Pressure filters require neither prior flocculation nor sedimentation. Reason (R): Because flocculation takes place inside the pressure vessel itself.
A True, R True and R explains A
A True, R True but R not explanation
A True, R False
A False, R True
The effective thickness of sand in a slow sand filter is usually ________ to ________ cm.
(a)
In rapid sand filters, backwashing consumes about (a) % of filtered water.
The optimum pH range for free chlorine (HOCl) dominance is ________ to ________.
(a)
For mesophilic digestion, the optimum temperature is about (a) °C.
The scum + sludge combination removed from a septic tank is technically referred to as (a) .
MATCH THE FOLLOWING
Disinfection Type vs Major Constraint
A. UV treatment→4. Generates chloramines
B. Ozone→3. Requires crystal clear water
C. Chlorination→1. Very high capital & O&M
D. KMnO₄→2. Least effective in coloured water
A–1, B–3, C–4, D–2
A–3, B–1, C–4, D–2
A–3, B–4, C–1, D–2
A–3, B–1, C–2, D–4
MATCH THE FOLLOWING
On-site Units vs Governing Parameter
A. Septic tank→4. 60–65% solids removal
B. Imhoff tank→3. Percolation disposal
C. Soak pit→1. 24 hrs detention in settling zone
D. Sludge digester→2. 30–40% BOD removal
A–4, B–1, C–3, D–2
A–4, B–3, C–1, D–2
A–1, B–4, C–3, D–2
A–1, B–4, C–2, D–3
