Abstract: A method for treating at least one liquid fluid comprising a high water content, and including a volatile fraction and a heavy fraction, in order to separate said two fractions. Said method consists in burning at least one gas fluid, recuperating the heat released by said combustion for subsequently heating the liquid fluid. The heated liquid fluid is pressurised and then expanded so as to separate the volatile fraction from the heavy fraction. The volatile fraction is then burnt with the gas fluid. The heavy fraction is extracted from the process to be subsequently treated. The invention also concerns an installation for implementing the treatment method.