In one aspect there is provided a fluid treatment system for treating a contaminated fluid having a gaseous contaminant mixed or dissolved in the liquid portion thereof. The system comprises a generally enclosed and substantially airtight container defining an interior volume. The container comprises an inlet to receive the contaminated fluid, a gas outlet to discharge any gaseous contaminant and a liquid outlet to discharge any liquid that may be separated from said contaminated fluid. During operations, the container is sealed to maintain a seal between the interior volume and any outside environment, so as to prevent the escape of any liquids and gasses out of the interior volume, except as may be provided for via the inlet, the gas outlet or the liquid outlet. Also during operations, a continuous headspace is maintained between the at least one inlet and the at least one gas outlet.