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Mademuasel [1]
3 years ago
11

You are managing a city that needs to upgrade its disinfection basin at your 40 MGD surface water drinking water treatment plant

. You would like to use chlorine (Cl2) as your disinfectant and you need to achieve a 4-log removal of E. coli. You are deciding between a traditional 750,000 gallon PFR contact basin (serpentine flow) and a newer system which contains three 150,000 gallon CSTRs in series, each receiving an equal injection of Cl2. Your final decision is going to be based on which system requires the least amount of Cl2 to achieve a 4-log removal of E. coli.
Required:
What is the amount of Cl2 required to operate each system (please answer in units of kg Cl/day)?
Chemistry
1 answer:
nignag [31]3 years ago
3 0

Solution :

According to Chick's law

$\frac{N_t}{N_0}=e^{-k'C^n t}$

where, t = contact time

            c = concentration of disinfectant

            k' = lethality coefficient = 4.71

            n = dilution coefficient = 1

            4 log removal = % removal = 99.99

$\frac{N_t}{N_0}=\frac{\text{bacteria remaining}}{\text{bacteria initailly present}}$

      = 1 - R

      = 1 - 0.9999

Now for plug flow reactor contact time,

$\tau =\frac{V}{Q} =\frac{75000}{40 \times 10^6}$

          = 0.01875 days

          = 27 minutes

For CSTR, $\tau =\frac{V}{Q} =\frac{150000}{40 \times 10^6}$

                             $=3.75 \times 10^{-3}$ days

                            = 5.4 minute

There are 3 reactors, hence total contact time = 3 x 5.4

                                                                            = 16.2 minute

Or $\frac{N_t}{N_0}=e^{-k'C^n t}$

or $(1-0.9999)=e^{-4.71 \times C \times t}$

∴ C x t = 1.955

For PFR, $t_1 = 27 $ min

∴ C $=\frac{1.955}{27}$ = 0.072 mg/L

For CSIR, $t_2=16.2$ min

$C=\frac{1.955}{16.2} = 0.1206$ mg/L

∴ Chlorine required for PFR in kg/day

$=\frac{0.072 \times 40 \times 10^6 \times 3.785}{10^6}$      (1 gallon = 3.785 L)

= 18.25 kg/day

Therefore we should go for PFR system.

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You may suppose you have a 0.1 M solution of NH3, from:

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3 0
3 years ago
Chloroform has a density of 1.483g/ml. A sample of chloroform has a volume of 1.93 liters. How many kilograms does it weight? ​
ollegr [7]

Weight of Chloroform : = 2.862 kg

<h3>Further explanation</h3>

Given

Density 1.483 g/ml

Volume = 1.93 L

Required

Weight of Chloroform

Solution

Density is a quantity derived from the mass and volume  

Density is the ratio of mass per unit volume  

Density formula:  

\large {\boxed {\bold {\rho ~ = ~ \frac {m} {V}}}}

ρ = density  

m = mass  

v = volume  

Convert density to kg/L :

=1.483g/ml = 1.483 kg/L

So the weight(mass) :

= ρ x V

= 1.483 kg/L x 1.93 L

= 2.862 kg

8 0
2 years ago
In the Hall-Heroult process, a large electric current is passed through a solution of aluminum oxide Al2O3 dissolved in molten c
Darya [45]

Answer:

0.382g

Explanation:

Step 1: Write the reduction half-reaction

Al³⁺(aq) + 3 e⁻ ⇒ Al(s)

Step 2: Calculate the mass of Al produced when a current of 100. A passes through the cell for 41.0 s

We will use the following relationships.

  • 1 A = 1 C/s
  • 1 mole of electrons has a charge of 96486 C (Faraday's constant)
  • 1 mole of Al is produced when 3 moles of electrons pass through the cell.
  • The molar mass of Al is 26.98 g/mol.

The mass of Al produced is:

41.0s \times \frac{100C}{s} \times \frac{1mole^{-} }{96486C} \times \frac{1molAl}{3mole^{-} } \times \frac{26.98gAl}{1molAl} = 0.382gAl

7 0
3 years ago
An ionic bond is an _________ attraction between ions.
BabaBlast [244]

Answer:

An ionic bond is an attraction between ions of opposite charge in an ionic compound.

8 0
2 years ago
A liquid has a density of 1.17 g/cm3, how many liters of the liquid have a mass of 3.75 kg
Luda [366]
<span>There are 1000 cm3 in 1 liters. Hence 1 liter of the liquid would weigh: 1000 cm3 x (1.17 g/cm3) = 1170 gm and there are 1000 gm in 1 kg, so we want enough liters to have a mass of 3.75 kg x 1000 gm/kg = 3750 gm Hence, # of liters = desired mass / # of gm per liter = 3750 gm / 1170 gm/liter = 3.2051282 liters</span>
5 0
2 years ago
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