Test: Environmental Engineering- 1 - Civil Engineering (CE) MCQ

TCU represent the true colour unit. It is a unit to represent colour impurities in water. 1 TCU is equivalent to the colour produced by 1 mg/L of platinum in form of chloroplatinate ion.

As per IS10500:2012, the total concentration of manganese (as Mn) and iron (as Fe) for drinking water purpose shall not exceed 0.3 mg/L.

1) Measurement suspended solid is done by a gravimetric test involving the mass of residual measurement.

2) Measurement of Turbidity: -

A) Based on absorption principles

i) Turbidity Rod

ii) Jackson’s Turbidity meter

iii) Baylis Turbidimeter

B) Based on the scattering principle

i) Modern Nephelometer

3) Through Nessler’s tubes on Burgess scale, true colour is measured.

Concept:-

pH = -log₁₀ [H⁺]

-log₁₀ [H⁺] = pH

[H⁺] = 10 ^-pH

Calculation

[H⁺]_I = 10^-6.2

[H⁺]_II = 10^-6.8

Hence, first sample is 4 times acidic than second sample.

Free Ammonia – indicate recent pollution

Nitrate – indicate old pollution (fully oxidized)

Nitrite – indicate partly decomposed condition

Organic – indicate quantity of nitrogen before decomposition started.

Concept:

Carbonate hardness = minimum of {Alkalinity, Total Hardness}

Total hardness = Carbonate Hardness + Non-carbonate Hardness.

Calculation:

Carbonate Hardness= minimum of {200 mg/L , 250 mg/L}

Carbonate Hardness = 200 mg/L as CaCO3

Non-Carbonate Hardness = Total Hardness – Carbonate Hardness

= 250 – 200

= 50 mg/L ​as CaCO₃

Hardness (expressed as Ca CO 3 equivalent) is 75-115 ppm or mg/lit

- The pollution potential of sewage is often measured using the concept of "population equivalent."
- Population equivalent reflects the organic pollution load that domestic sewage would impose if it were discharged untreated.
- It provides a comparative scale by equating the pollution load of industrial sewage to a certain number of people.
- This makes it easier to compare different sewage types, as it standardizes the pollution potential and facilitates planning and treatment processes.
- Hence, the correct answer is B: population equivalent.