The present invention provides an adjustable pulsed gas agitator including a gas accumulation chamber with a gas discharge pipe, a gas supply unit, and an adjustable gas discharge unit. The adjustable gas discharge unit has an elongatable gas pipe slidably disposed over the lower part of the gas discharge pipe, and a gas cap disposed underneath the elongatable gas pipe; so that when the adjustable gas discharge unit is moved upward or downward, the volume of the stirring gas accumulated within the gas accumulation chamber is decreased or increased; thereby the frequency and strength of the discharged pulsed gas flows is varied.

The present invention provides modular devices and systems for infusing gas into a liquid and methods of manufacture and use thereof. In accordance with an embodiment, a modular device for infusing gas into a liquid is provided. The modular device comprises a plurality of microporous hollow fibers, and a cap covering open ends of the microporous hollow fibers. The cap is configured to receive a gas into an opening and to deliver the gas into the open ends of the microporous hollow fibers. The cap is further configured to removably mount the modular device to a fixture. A system for infusing gas into a liquid may include one or more of the modular gas infusion devices configured to be removably mounted to a fixture such that the microporous hollow fibers are within a hollow cavity. The hollow cavity includes a first opening configured to receive a liquid and a second opening configured to discharge the liquid infused with a gas. Because the system is modular, it is economical to manufacture, scale to different application requirements and to maintain.