Abstract: A method of treating and disposing of waste water containing salt, such as the brine that results from production of oil and/or gas wells, which includes introducing the waste water into a reverse osmosis unit to produce concentrated brine, and passing the concentrated brine through a combustion heat evaporator wherein said combustion heat is generated in a submerged combustion evaporator or exhaust gases from an internal combustion engine to power a waste heat evaporator to produce a further concentrated brine. The concentrated brine from the combustion heat evaporator can then be mixed with a liquid such as the waste water that is introduced into the reverse osmosis unit. The resulting product can then be injected into a subterranean formation for purposes of disposal. The method allows the volume of the waste water to be significantly reduced while also increasing the salt concentration of the waste water.