Study of 3D-Printed Pressure Release Nozzle for Microbubble Formation in Full-Scale Dissolved Air Flotation (DAF)

• Published in: Chemical engineering and processing 2020-09, Vol.155, p.108070, Article 108070
• Main Authors: Kouhestani, Alireza, Amani Tehrani, Ali, Parsaeian, Hesam, Nikfar, Mohamad Hosein, Bazargan, Alireza, Masoumi Isfahani, Hamidreza
• Format: Article
• Language: English
• Subjects: advanced manufacturing; flotation filtration; pilot test; seawater DAF; silt density index
• ISSN: 0255-2701; 1873-3204
• DOI: 10.1016/j.cep.2020.108070

[Display omitted] •New pressure release nozzles for DAF have been 3D printed.•The saturator pressure and nozzle flow rate have been studied.•The system has been tested in a full-scale SWRO desalination plant.•Employing filtration within the DAF tank results in excellent water quality.•SDI and NTU measurements of treated water are as per required RO standards. Pressure-release equipment for the formation of microbubbles is an important part of any DAF system. In this study, 3D printing was employed to produce new nozzles, followed by testing to find the optimum pressure and flowrate. The flowrate through the nozzle affected both the empty bed residence time (EBRT) of the saturator and also the nucleation of bubbles. With the increase of flow rate, the total number of bubbles was seen to increase. This is a significant observation meaning that the enhanced precipitation of bubbles outweighs the reduced EBRT. This fact can improve equipment sizing and reduce CAPEX. Meanwhile, DAF is a technology that can help extend membrane life and reduce operational issues in seawater reverse osmosis (SWRO). So for further validation, a full-scale DAF was built and tested for SWRO pretreatment on the coast of the Persian Gulf. The system was tested with/without coagulation as well as with/without filtration media embedded inside the DAF tank. The results showed that the use of coagulation alongside DAF reduced the turbidity by more than 60% while using a DAF with embedded filtration could reduce the turbidity to less than 1 NTU. In comparison to common media filters, the proposed setup showed better performance.