A support coil comprises a sheet wound up in a spiral, and a side wall arranged along a longitudinal edge of the sheet, so the side wall remains arranged between successive turns of the coil, and an inner spiral space is defined between the turns and is partly limited by the side wall, wherein the side wall comprises a continuous strip and a discontinuous strip. Also provided are reactors which use such a support coil arranged inside a container such as to be rotatable and cause a flow of liquid along the wound up sheet, from the outside towards the inside of the spiral, as well as methods for producing and operating such reactors for a variety of purposes.