A transportable modular system for emergency treatment of water polluted by liquid hydrocarbon spillage comprises: at least a first containerized treatment module, comprising a container in the form of a standard size intermodal container which houses a coalescence separator device, configured to operate an oil/water separation; a suction pipe having a first end connected to the coalescence separator device and a second end provided with an inlet connected to at least one floating skimmer; a pump positioned on the suction pipe; a water drain pipe and an oil drain pipe, connected to a water outlet and an oil outlet, respectively, of the coalescence separator device.