back pulse vs backwash

‘6.1 Minimization of Flux Decline with Backpulse or Backwash

An essential difference between a back pulse and a backwash is the speed and force utilized to dislodge accumulated matter on the membrane surface. In back pulsing, periodic counter pressure is applied, typically in a fraction of a second (0.1�0.5 seconds), while generating high permeate backpressure (up to 10 bar). Backwash on the other hand is relatively gentle where permeate backpressure values may increase up to 3 bar over a few seconds duration. Backwash is commonly used with polymer MF/UF filters due to their lower pressure limitations [4,17] compared with inorganic MF/UF filters where back pulsing is used [3]. The maximum benefit of back pulse or backwash is obtained when the retentate pressure during instantaneous reverse filtration is lowest and the applied permeate backpressure is highest.’

(Fermentation and Biochemical Engineering Handbook - Principles, Process Design, and Equipment; Third Edition)