Physical cleaning initiation controlled by transmembrane pressure set-point in a submerged membrane bioreactor

Analysis of backwashing efficiency in dead-end hollow-fibre ultrafiltration of anaerobic suspensions

“…As previously stated (Villarroel et al 2013), during the operation with pressure-controlled backwashing initiation, the residual resistance varied with the number of cycles. Most of this residual fouling was detected in the first few cycles and progressively increased to a lesser extent in subsequent cycles.…”

“…By operating under TMP set-point control mode, once an upper limit of TMP is reached (i.e. TMP set-point, TMP sp ), the permeate flux is immediately reversed, initiating the backwashing cycle (Villarroel et al 2013;Vera et al 2014). In several trials, nitrogen was supplied during backwashing through an extended aeration tube located inside the membrane module at a flow rate of 4.2 Nm 3 /h m 2 , managed by a mass flow controller (Bronkhorst®-EL-FLOW, The Netherlands).…”

“…Smith et al (2006) have successfully validated a control system for backwashing initiation by monitoring TMP and automatically adjusting the backwashing frequency as a function of membrane fouling. This control system was developed in a previous lab-scale study (Villarroel et al 2013), which showed that membrane fouling can be significantly affected by the value of the transmembrane pressure set-point (TMPsp) selected for backwashing initiation. In addition, higher water productivity has been achieved in this controlled operation mode than in the conventional temporised filtration/backwashing mode on a pilot scale (Vera et al 2014).…”

Optimal control of physical backwash strategy - towards the enhancement of membrane filtration process performance

“…However, infrequent backwashing increases the build-up rate of the internal fouling. The key factors for the optimization of the backwash operation are its flow rate, pressure, duration and frequency, along with the ratio between these two last parameters [7,8]. In practice, due to the complexity of the membrane filtration system these parameters are fixed according to the recommendations of the membrane manufactures or chosen according to the operator's experience [3].…”

“…Similarly, the automatic control system presented in the work of Villarroel et al [8] monitored the TMP to adjust the duration of relaxation and backwash. The results showed that the automatic control of membrane cleaning permitted an increase in filtration time and, thus, overall system productivity.…”