A desalination brine dispersal system for a submerged seawater desalination apparatus, the seawater desalination apparatus having submerged components comprising distillation equipment, evaporation equipment or separation membranes; one or more pumps; and a brine removal conduit. The brine removal conduit receives brine from the desalination apparatus, and has an upwardly-directed length and at least one fluid outlet that is at a lesser depth than the desalination apparatus components. They system disperses brine into seawater without causing pooling of brine on the seafloor, can avoid the formation of concentrated, high shear brine plumes, and can disperse brine into seawater over a wide area well away from the brine removal conduit.

The present disclosure provides a complete set of equipment for supplying drinking water in field. The complete set of equipment for supplying drinking water in field consists of several units carried by single person, making the water purification equipment easy to use and transport. The complete set of equipment includes a multi-stage filtration unit, a reverse osmosis unit, and a power control unit connected by a plug-in pipeline.

A reverse osmosis system includes a first conductivity sensor for measuring electrical conductivity of water supplied to the reverse osmosis system, and a second conductivity sensor for measuring electrical conductivity of a permeate produced by the reverse osmosis system. The system also includes an AI unit designed to use a statistical model for calculating and accordingly setting a proportion of a concentrate produced by the reverse osmosis system that is to be recirculated according to the measured electrical conductivity of the water supplied to the reverse osmosis system, and according to the measured electrical conductivity of the permeate produced by the reverse osmosis system. The statistical model can be trained with training data.

A method of operating a dual reverse osmosis/pressure retarded osmosis plant, including when electricity costs less than a first predetermined price, moderate salinity water is pumped into the first portion of a pressure vessel having first and second portions separated by a water permeable/salt impermeable osmotic membrane to yield desalinated permeate in the second portion and brine in the first portion. Further, when electricity costs greater than the first predetermined price, low salinity water is pumped into the second portion and brine is pumped into the first portion to yield pressurized moderate salinity water in the second portion which is run through an energy recovery device to generate electricity. The salinity of the low salinity water is lower than the salinity of the moderate salinity water, and the salinity of the moderate salinity water is lower than the salinity of the brine.