Search results for "Sparging"
showing 6 items of 16 documents
Advanced control system for optimal filtration in submerged anaerobic MBRs (SAnMBRs)
2013
The main aim of this study was to develop an advanced controller to optimise filtration in submerged anaerobic MBRs (SAnMBRs). The proposed controller was developed, calibrated and validated in a SAnMBR demonstration plant fitted with industrial-scale hollow-fibre membranes with variable influent flow and load. This 2-layer control system is designed for membranes operating sub-critically and features a lower layer (on/off and PID controllers) and an upper layer (knowledge-based controller). The upper layer consists of a MIMO (multiple-input-multiple-output) control structure that regulates the gas sparging for membrane scouring and the frequency of physical cleaning (ventilation and back f…
Sub-critical long-term operation of industrial scale hollow-fibre membranes in a submerged anaerobic MBR (HF-SAnMBR) system
2012
The aim of this study was to evaluate the long-term performance of hollow-fibre (HF) membranes used to treat urban wastewater in a submerged anaerobic MBR when operating sub-critically. To this end, a demonstration plant with two industrial scale HF ultrafiltration membrane modules was operated under different conditions. The main factor affecting membrane performance was the concentration of mixed liquor total solids (MLTS). The reversible fouling rate remained low even when MLTS levels (about 25 g L−1) in the membrane tank were high. No chemical cleaning was conducted whilst operating the plant for more than one year because no irreversible fouling problems were detected. The almost compl…
Biofouling management in anaerobic membrane bioreactors
2020
Abstract This chapter is aimed at providing an insight on the main issues around the membrane fouling in anaerobic membrane bioreactors (AnMBRs). The analysis presented here shows that membrane fouling in AnMBRs is attributed to three major factors: membrane features, operating conditions, and wastewater characteristics. Several ad-hoc strategies have been implemented in literature to mitigate membrane fouling in AnMBRs, such as gas sparging, media addition, chemical cleaning, and membrane rotation/vibration. Among them, gas sparging is considered the most expensive strategy due to the high power requirement of the gas blower (up to 1.345 kWh m− 3). An accurate experimental and modeling ana…
Particle Suspension in Vortexing Unbaffled Stirred Tanks
2016
Three-phase processes in which particle suspension has to be achieved in conjunction with gas dispersion are traditionally carried out in sparged, baffled stirred tanks. The operation of such tanks can suffer, however, from particles tending to block the sparger holes. A viable alternative might be provided by uncovered unbaffled stirred tanks (UUSTs), where gas self-injection can occur when the free-surface vortex reaches the impeller blades and gas bubbles begin to be ingested by the liquid. In this work, the particle suspension and liquid aeration performances in three-phase UUSTs were experimentally investigated and compared with relevant literature correlations concerning baffled syste…
Influence of total solids concentration on membrane permeability in a submerged hollow-fibre anaerobic membrane bioreactor.
2012
The main aim of this work was to study the influence of the mixed liquor total solids (MLTS) concentration on membrane permeability (K 20) in a submerged anaerobic membrane bioreactor (SAnMBR) pilot plant, which is equipped with industrial hollow-fibre membranes and treats urban wastewater. This pilot plant was operated at 33°C and 70 days of SRT. Two different transmembrane fluxes (13.3 and 10 LMH) were tested with a gas sparging intensity of 0.23 Nm 3 m -2 h -1 (measured as Specific Gas Demand referred to membrane area). A linear dependence of K 20 on MLTS concentration was observed within a range of MLTS concentration from 13 to 32 g L -1 and J 20 of 10 LMH. K 20 was maintained at sustai…
Anaerobic dynamic membrane bioreactors for high strength wastewater treatment
2013
A laboratory scale external anaerobic dynamic membrane bioreactor (AnDMBR) treating high strength wastewater was operated to assess the effect of gas sparging velocity and organic loading rate on removal efficiency and dynamic membrane (DM) filtration characteristics. An increase in gas sparging velocity (GSV) results in a decrease in DM filtration resistance. DM or cake formation was identified as the main contribution to the total filtration resistance. Over 99% COD removal was obtained in the study regardless of the GSV. The results showed that the DM formation process proceeded until a stable cake layer thickness was reached. An effective pollutant removal and high permeate quality was …