Environmental Engineering

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Declaration of Authorship2
Contents page4
Question 15
Question 27
Question 310

Environmental Engineering IV
Assignment 1: Block 4
Question 1
Use a block diagram and brief notes to provide a step-by-step description of a conventional potable water treatment plant. (3 pages maximum)(20 marks)

Question 2
The new Goreangab Reclamation Plant (Namibia) incorporates the following established and new treatment processes: Briefly describe each process and include reaction equations where necessary. (3 pages maximum)(30 marks)

Powdered activated carbon (PAC), acid, polymers (used as and when required) •Pre-Ozonation
Dissolved air flotation (DAF)
Rapid sand/Anthracite filtration
Biological activated carbon (BAC) filtration/adsorption •Granular activated carbon (GAC) filtration/adsorption
Membrane ultra-filtration

Powdered activated carbon (PAC) is used in the water treatment process to absorb organic matter. It may also occasionally cause bad smells or tastes in the drinking water. Pre-ozonation is when the gas released from the main ozonation step of the water treatment process in the plant is captured and introduced in into the influent of raw water. Releasing this ozone directly into the raw water assists in breaking down long-strained organic matter as it is a strong oxidizing agent and this makes removal in later processes easier. Coagulation occurs when the water is destabilised by adding coagulants (chemicals) to the water, the small particles of pollutants then flock or cling together (flocculation) to form larger particles which make it easier to remove the pollutants. Dissolved air flotation (DAF) is when...
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