(b) Why is this zone not to be considered as a treatment entity of a body of water? (2)
(c) Which one of the sections A, Band C from the above figure represents the
actual mixing zone?
(1)
3.2 (a) Wastewater treatments are grouped into three main categories namely,
primary treatment, secondary treatment and tertiary treatment. What are the
respective purposes of these categories of treatment?
(3)
(b) Name the main types of secondary wastewater treatment.
(4)
(c) Which one of the types of treatment in (b) is the most efficient? Briefly explain
its principle and write the generic chemical reactions involved.
(8)
Question 4
4.1 Compare the following characteristics of saline soils and sodic (alkaline) soils:
(a) Location
(b) Clay type
(c) Properties
(d) Texture and effects
4.2 (a) What is the other name given to the "conventional techniques" for the
reclamation of Salt-Affected Soils?
(b) Name the main conventional techniques used for the reclamation of salt-
affected soils?
(c) What are the problems associated with the use of the techniques in (b)?
[20]
(2)
(2)
(4)
(2)
(2)
(4)
(4)
Question 5
[20]
5.1 It is recognized that legislation and regulations implemented to tackle
environmental pollution problems are largely a command and control approach
and they have a heavy reliance on "end-of-pipe" measures. Explain the underlined
concepts.
(4)
5.2 (a) Complete the following definition of Green Chemistry.
"Green Chemistry is the __ practice of chemical science and technology
within the framework of the practice of __ in a manner that is safe and
3