Q.
Explain any three (3) of the following:
i) Separate system in underground sewerage system
ii) The function of manhole in sewerage system
iii) Back Siphonage in water supply system
iv) Recycling in waste management
(25 marks, 2017 Q7)
A.
i) Separate system in underground sewerage system
Similar question was asked in
ii) The function of manhole in sewerage system
Manhole, Diversion Manhole - what is it?
Functions are:
To provide access for humans to carry out operation and maintenance (surveys and inspections) of the pipe (main pipe).
Manhole is provided when
- There is change in grade of sewer
- There is change in alignment
- There is change in size of sewer
- At junction of two or more sewers
iii) Back Siphonage in water supply system
Similar question was asked in
2011 Q5b
What is back-siphonage?
2016 Q5a & b
iv) Recycling in waste management
Similar question was asked in
Recycling is the process of converting waste materials into new materials and objects. It is an alternative to "conventional" waste disposal that can save material and help lower greenhouse gas emissions (compared to plastic production,[1][2] for example). Recycling can prevent the waste of potentially useful materials and reduce the consumption of fresh raw materials, thereby reducing: energy usage, air pollution (from incineration), and water pollution (from landfilling).
Recycling is a key component of modern waste reduction and is the third component of the "Reduce, Reuse, and Recycle" waste hierarchy.
There are some ISO standards related to recycling such as ISO 15270:2008 for plastics waste and ISO 14001:2004 for environmental management control of recycling practice.
Recyclable materials include many kinds of glass, paper, and cardboard, metal, plastic, tires, textiles, and electronics. The composting or other reuse of biodegradable waste—such as food or garden waste—is also considered recycling.[2]Materials to be recycled are either brought to a collection centre or picked up from the curbside, then sorted, cleaned, and reprocessed into new materials destined for manufacturing.
In the strictest sense, recycling of a material would produce a fresh supply of the same material—for example, used office paper would be converted into new office paper or used polystyrene foam into new polystyrene. However, this is often difficult or too expensive (compared with producing the same product from raw materials or other sources), so "recycling" of many products or materials involves their reuse in producing different materials (for example, paperboard) instead. Another form of recycling is the salvage of certain materials from complex products, either due to their intrinsic value (such as lead from car batteries, or gold from circuit boards), or due to their hazardous nature (e.g., removal and reuse of mercury from thermometers and thermostats).
Further reading in here.
Ref:
https://en.wikipedia.org/wiki/Recycling