Desalinisation-The biggest facor in the process of desalinisation is I understand the amt of energy needed.?

Question

swege water is now recycled in many cities the cleand water is quite safe for human consumption.

Does this process take much less energy than removing salt from sea water?

Oil rich Countries r desalinising I know due to almost free energy.

Answer 1

I don't think treated sewage goes directly back into the reservoir or potable water supply anywhere.  It generally get dumped into a river so it is diluted before the next town down stream treats it for drinking water.

Sewage and drinkinge water treatment It is mostly a filtration process with some chemicals, most of the energy is used for pumping.  Desalination is distilling using heat to evaporate water.  It takes much more energy.

Answer 2

The major reasons for making Desalination expensive is Power, Maintenance, and a Hugh waste problem.

It take a lot of energy to either boil it in an evaporation process, or pump it in a Reverse Osmosis Plant. Both processes have high maintenance costs. The evap. process is very corrosive, and the RO system requires replacement of membranes used which are expensive. Both systems end up with a very strong brine as waste (About 80% of the water pumped into the system ends up as brine waste). Only 20% comes out as good water.

I have a good friend that has a 100% solar home. He can't have air conditioning and had to have his water trucked in. He installed a very small system just for showers, drinking, and cooking water. He must run the generator when he operates the RO unit because the pumps take to much power.