01. Membrane flux has many names, it's hard to tell them apart

Membrane flux is known by various names, often confusing for newcomers to membrane treatment. In summary, flux refers to the amount of component passing through a unit area of membrane per unit of time. For MBR processes, this component is typically the water produced. Therefore, depending on the actual time frame, flux can be referred to in several ways:

Average Membrane Flux: Refers to the water production per unit membrane area within the design period, typically denoted as the daily average flux (indicating the average water production per hour and per unit area over a 24-hour period); there are also monthly average flux and annual average flux references.

Operating Membrane Flux: Refers to the water output per unit time and per unit area during the actual operation of the membrane. Operating flux includes the total of water output and backwash water, etc.

Peak Membrane Flux: Refers to the water output per unit time and per unit area under peak water volume conditions.

Design Membrane Flux: Refers to the membrane system flux selected by considering both the service life and operating environment. Typically, the design flux specified by the design unit is equivalent to the operating flux of the membrane system.

Understanding the actual significance of various fluxes aids in the rationality and accuracy of system design. For system design, what we need to determine is the operating flux and average flux of the membrane system. Once the design parameters such as the system operation mode are established, a definite conversion relationship exists between the operating flux and the design flux. Therefore, for a real system, we only need to determine one flux and design accordingly.

The Importance of Rational Designing for Throughput

The selection of design throughput requires considerations not only of system stability and the rationality of cleaning cycles, but also factors such as project investment budget and subsequent film replacement costs. Typically, we need to weigh these aspects to achieve a balanced operating throughput that satisfies all conditions.