Wastewater Technology Fact Sheet - Denitrification Filters
Information about denitrification filters, including downflow denitrification filters, which operate in a conventional filtration mode and consist of media and support gravel supported by an underdrain....
https://www.epa.gov/sites/default/files/2019-08/documents/de...

Biological filters - biofilters - Degremont® - SUEZ water handbook
https://www.suezwaterhandbook.com/processes-and-technologies...

Comparison of Filters for Concentrating Microbial Indicators and Pathogens in Lake Water Samples
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3568591/

Chapter 8: Laboratory Ventilation for Biosafety
https://www.unr.edu/ehs/policies-manuals/biosafety-manual/ch...

Further references:
https://iopscience.iop.org/article/10.1088/1757-899X/928/2/0...
https://iopscience.iop.org/article/10.1088/1755-1315/419/1/0...

Metode de separare
various filtration methods, including the concept of downward flow in filters. It explains the resistance of the filter cake and the filtration coefficient, which are crucial in understanding how downward flow filters operate in terms of resistance and efficiency in fluid passage through the filter...
https://sim.utcluj.ro/stm/download/Procedee_separare/Cap_5.p...

Seria CleanZone - Office Barista
reorientation of the CleanZone 5000 filter to a downward flow.....
https://www.officebarista.ro/aer/seria-cleanzone/

Manual operare valva s10 model basic, dedurizare sof 4 - Aqualine.ro
settings of a valve, including positions for downward and upward flow, which relates to how the direction of flow can be adjusted in filtration systems...
https://www.aqualine.ro/utility/file/download?file=download_...