Hollow fiber membrane is a device that can serve to transfer gases and hydrophobic vapors, for example volatile and semi volatile organic compounds between two fluids, usually a gas and a liquid. It is a compact de-gasification module designed for separation of volatile gases from water by using a bundle of hydrophobic hollow fiber membranes as a contacting device. The configuration of the fiber bundle is designed to maximize the contact interface between water and gas phases. The contaminated water is passed through the inner part of the membrane and a counter current airflow is pulled by vacuum applied to the outer part of the membrane. The dissolved contaminants are transferred to the gas phase, induced by a concentration gradient and a vacuum. A concentration gradient is established between the contaminants in the ground water and clean air, leading to transfer of the volatile constituents through the membrane. The selective physiochemical properties of the membrane allow only the organic compounds to transfer across the membrane to the air phase.