Module, reactor, system and method for treating water

A method for treating water, the method comprises:

• introducing water into a bioreactor comprising at least one gas permeable, water impermeable membrane module, defining at least one gas enclosure and one or more water treatment spaces;
• introducing a water-treatment gas into the at least one gas enclosure;
• introducing gas into a gas diffuser arrangement positioned underneath the gas permeable, water impermeable membrane module, to thereby cause the discharge of a stream of gas into the one or more water treatment;
• and
• collecting treated water;
• wherein the gas is intermittently introduced through the diffuser arrangement into the one or more water treatment spaces and wherein any one of duration and frequency of the gas being introduced is determined by at least one parameter indicative of quality of water within the bioreactor,
• wherein the introducing of gas and discharge of a stream of gas causes mixing of the water, and
• wherein the at least one parameter is concentration of ammonium-containing compounds within the water, and
• wherein any one of said frequency and duration are increased in response to an increase of said concentration of ammonium-containing compounds.