Environmental Engineering Reference
In-Depth Information
9.2.8.1 Chlorine Demand
Chlorine demand is the amount of chlorine in milligrams per liter
that must be added to the wastewater to complete all of the chemical
reactions that must occur prior to producing a residual:
Chlorine Demand = Chlorine Dose (mg/L) - Chlorine Residual (mg/L) (9.1)
Example 9.1
Problem:
The plant effluent currently requires a chlorine dose of 7.1
mg/L to produce the required 1.0 mg/L chlorine residual in the chlorine
contact tank. What is the chlorine demand in milligrams per liter?
Solution:
Chlorine Demand = 7.1 mg/L - 1.0 mg/L = 6.1 mg/L
9.2.8.2 Chlorine Feed Rate
The chlorine feed rate is the amount of chlorine added to the wastewater
in pounds per day:
Chlorine Feed Rate = Dose (mg/L) × Flow (MGD) × 8.34 lb/MG/mg/L (9.2)
Example 9.2
Problem:
The current chlorine dose is 5.55 mg/L. What is the feed rate
in pounds per day if the flow is 22.89 MGD?
Solution:
Feed = 5.55 mg/L × 22.89 MGD × 8.34 lb/MG/mg/L = 1060 lb/day
9.2.8.3 Chlorine Dose
Chlorine dose is the concentration of chlorine being added to the
wastewater. It is expressed in milligrams per liter:
Chlorine Feed Rate (lb/day)
Flow
Dose (mg/L)
=
(9.3)
(MGD)
×
8.34 lb/MG/mg/L
Example 9.3
Problem:
Each day, 320 lb of chlorine are added to a wastewater flow of
5.60 MGD. What is the chlorine does in milligrams per liter?
Solution:
320 lb/day
5.60 MGD8.34lb/MG/mg/L
Dose
=
= mg/L
6.9
×
