With Regard to the fact that bacteria which is harmful to humans can exist in drinking and washing water:
A)State the constraints placed on the installation and use of shipboard production of fresh water;
Answer:- Low pressure evaporators can be used only when the Main engine for propulsion is running at the rated power output or at full speed such that the outlet jacket water temperature is at sufficient temperature to boil the sea water.
The evaporators must not be used within 20 miles of coastline. This distance increases according to circumstances due to pollution present in inshore waters from sewage outfalls, disposal of chemical wastes from industry, drainage of fertilizers from the land.
Formation of scales decreases efficiency i.e. production after some interval, which requires complete cleaning of all plates/tubes at regular intervals.
Due to production of fresh water at very low operating temperature, it is not sufficient to sterilize the water. and hence a separate sterilizer to be installed.
The water produced is distilled which tastes flat. It is also slightly acidic due to ready absorption of carbon Dioxide. This condition makes it corrosive to pipe systems and less beneficial to human digestive tract. hence a separate minerilizer have to be installed.
