desalination plants and oil spills.

Hello everyone, I am water professional and studying some new technologies in water treatment. I been reading about desalination these days, I want to know are desalination plants vulnerable to oil spills?

And what is the cost of these plants in middle Easts?

5 Answers

1. If the source water contains over 0.05 mg/L of oil and grease or total hydrocarbons the RO membranes will get damaged permanently and cannot be easily cleaned. If the plant is operated at source water total hydrocarbon concentration of 1 mg/L the RO membranes will be permanently destroyed within 2 to 3 hours. For costs of seawater desalination see the following publication: http://www.multi-statesalinitycoalition.com/storage/summit/2012/presVoutchkov.pptx Overall, the cost of desalinated seawater could vary between 0.5 and 3 US$/m3. The cost of desalinated brackish water could vary between 0.1 and 1.0 US$/m3

2. Yes, Hydrocarbon in feed water is definitely a problem for RO plants. Major intake of oil will cause near permanent fouling of the RO membrane. If the plant has membrane pre-treatment, it will damage this also. The effect is to block the permeate 'pores' of the membrane and require much much higher operating pressures to produce permeate (often beyond the capability of the plant, resulting in reduced product water output). Oils are not easily removed, requiring frequent CIP (at pH extremes that result in reduced membrane life). For this exact reason, we design in Hydrocarbon sensors on our feed (to trip operation at lowest possible detection). Trace amounts of Hydrocarbons also casue significant problems. The natural breakdown of the hydrocarbons in the environment (by UV or other mechanisms), result in smaller and smaller chain lengths that are easily assimilable by micro-organisms. When these in trace amounts are feed to the RO plant it provides food/energy for bacteria grow (termed biofouling). Biofouling is already generally the most significant issue in plant operation, the 'fall-out' from a oil spill would make an already existing problem that much more difficult. Hope this helps, Anthony

   1 Comment

   1. In regard to the costs of such events, it is difficult to quantify (entirely depends on the specific process used, the location, and the extent of the problem). Based on nothing more than gut feeling, I would guestimate the opex costs could increase by as much as 25% as a result of such events (including increased chemical dosing, chemical cleaning, downtime, labour etc). Cheers, Anthony

3. I'm not studied on desalinization so these are reactions, but this problem seems to need a pre-treatment to avoid having pollutants get to the process, and from a focus on algae, bacteria and phytoplankton relating to wastewater purification can I suggest that by finding what species of them survives, then observing those which can digest or alter them such that they are removed or can be by another process.
   
   Another reaction, that is if the pollution is rather constant in composition of pollutants to arrange a specific pre-process for their removal. In wastewater floccation chemicals normally are used to remove dissolved solids and perhaps some of them can be useful in saltwater for this, haven't researched that.
   
   hth, tom

4. Oil in seawater can foul the piping, reduce exchange surfaces performance and even pollute fresh water if part of it distils with seawater.

5. Desalination plants are vulnerable to oil spills, and R.O plants more vulnerable than MSF plants. the costs of plant vary based on its capacity, technology used, materials, etc. For example the largest desalination plant which been built in Saudi Arabia (MSF technology) with a capacity of 1000,000 m3 per day and 1500MW is more than 5 billion US$.