ADDS (At Depth DeSalinization)
Placing the salt water reverse osmosis (swro) collector on the sea floor, at depths of 1,500 to 2,000’ seems to have some distinct advantages over onshore installations.
-energy efficient since only processed water is pumped, reducing energy consumption. Gravity provides the water pressure necessary to run the reverse osmosis process.
-throughput is maximized since as many standard units as needed can be economically installed.
-intake currents are not created so no sea life is harmed.
-no prefilter is required.
-biofouling is minimized since the environment is not conducive to bacteria or plant growth.
-the units are offshore so prime real estate is not impacted.
-no brine exhaust is produced so no remediation is required.
-the units are standardized and cheap to produce.
-other than the pumps and sensors, only inert materials are used in the construction of the modules.
-maintenance is reduced since an onboard rotating brush removes accumulated debris and salt.
-all components are off the shelf and readily available. No new tech is required.
The disadvantages include
-flat sea floor terrain with the required depths, water temperature of 40 C or less, and as close to shore as possible.
-long outlet runs with repeater pump stations and check valves.
-the use of an ROV or similar device to retrieve nonfunctioning/damaged units from the sea bed.
-the use of a support/maintenance ship with positional stability for deployment and/or retrieval.
The outside pressure of about 70 atmospheres forces seawater through the reverse osmosis filter medium into the concrete container vessel whose internal pressure is at ambient, or at 1 atmosphere. Filtered water enters the hollow vessel, and a switch is triggered, which turns on a high-pressure pump, which forces the filtered water into a collapsed output pipe (like a firehose). This pressurized water, at 100 – 150 psi above the ambient water pressure, inflates the output pipe and moves the filtered water shoreward. As many repeater pump stations as are required will force the flow onshore, where the water, at about 98% salt free, may be mixed with other onshore supplies or further processed. Power and data lines for the at depth desalinization unit will be incorporated into the output pipe. Onshore and in vessel sensors will maintain quality control of the effluent and automatically shut the offending unit down and notify support personnel if it exceeds certain parameters. All the other units in that field will continue to operate as normal.
A hydraulically controlled brush, powered by the onboard high-pressure pump, automatically sweeps the outside of the filter on a daily basis, to remove accumulated debris and salt. Unlike, onshore desalinization plants, which require a monthly or bimonthly shutdown to clear the filters, this one keeps operating.
While this method solves or mitigates the issues associated with onshore desalinization, it has, like real life, its own issues. Only experienced experts in the field can determine the viability of this proposal.