The range of HyDAF dissolved air production systems are designed to provide various flows of dissolved air. Each HyDAF system is matched with a specific dissolved air system to ensure that the air to solids ratio and DAF surface loading is optimised in each case.
Micro-bubble precipitation is achieved through the following steps:
- First a recycle stream of treated effluent is taken from the discharge end of the HyDAF and is pressurised to a pressure of 400-600kPa.
- This pressurised flow is injected into specially designed process pipework called a Saturator. Air is added to the Saturator to maintain a “headspace” which acts to provide contact between the air and the treated effluent and it is here that air is dissolved into the recycle stream.
- To precipitate the dissolved air back as micro air bubbles, the pressure is relieved through a Pressure Regulating Valve (PRV). The PRV creates back pressure against the Recycle Pump and establishes the pressure in the system, and in the Saturator. This valve also provides for a high level of shear which aids in the precipitation of the air from the pressurised solution.