Mobile modular installation 'Aqua-Express' is a liquid low level and intermediate level radioactive waste (LL&ILRW) treatment facility, intended for not large research centers and other organizations, which activity causes the formation of a few quantity (up to 500 m3/year) of low and intermediate level radioactive waste water. Mobile modular installation 'Aqua-Express' has the following features: (1) filtration, sorption and ultra-filtration units are used for LL&ILRW purification; (2) installation 'Aqua-Express' consists of a cascade of three autonomous aqueous liquid waste-purifying installations; (3) installation 'Aqua-Express' is a mobile installation; the installation can be transported by car, train, ship, or plane, as well as placed in a standard transport (sea or railway) container; (4) installation 'Aqua-Express' does not includes any technological equipment for conditioning the secondary radioactive waste. Productivity of the installation 'Aqua-Express' by purified water depends on composition of the initial liquid waste and makes up to 300 l/h. In present report is described the design of installation 'Aqua-Express', theory of LRW purification in the installation 'Aqua-Express' and some results of its use at cleaning real radioactive waters at State unitary enterprise - MosNPO 'Radon'.