Filtration system

A method of operating a filtration system for separating particulate solid matter from a liquid and having a housing having a surface of revolution shaped cavity therein defined around an axis, the cavity housing a filter element including a filtration membrane and a support membrane mounted concentrically around the axis with the filtration membrane being rotatably mounted to the housing externally to the support membrane, the housing also having a filtrate outlet located inside the filter element, an inlet and at least one purge outlet, the inlet and the at least one purge outlet both being located outside the filter element;

• the method comprising:
• operating the filtration system in a regular filtration mode including simultaneously:
• feeding an inlet flow rate tangentially into the cavity through the inlet and extracting a purge flow rate across the at least one purge outlet, thereby entraining a rotary fluid flow around the filtration element, in a rotary fluid flow angular direction;
• rotating the filtration membrane about the axis, in the rotary fluid flow angular direction, at a rotation speed relative to the support membrane;
• extracting a filtrate flow rate sequentially across the rotating filtration membrane, the support membrane, and the filtrate outlet;
• and, subsequently
• temporarily operating the filtration system in a declogging mode including:
• extracting a greater purge flow rate through the at least one purge outlet than during the regular filtration mode.