A municipal wastewater treatment station in Niuniuba Town, Meigu County, Sichuan Province, China, provides an engineering example of replacing polymeric MBR membranes with alumina ceramic flat sheet membranes.
The facility has a treatment capacity of 3,000 m³/day and uses an A²/O biological treatment process combined with a submerged membrane bioreactor (MBR) system.
According to the collected project information, the retrofit was designed to address membrane fouling, material aging, unstable effluent quality, and frequent maintenance requirements.
This case analysis examines the membrane replacement approach and its key design considerations, particularly under low-temperature operating conditions.
1. Challenges with the Existing Polymeric MBR SystemThe original wastewater treatment system was equipped with polymeric MBR membrane modules.
Several operational challenges were identified:
-
Membrane fouling and declining filtration performance
-
Oxidative aging of polymeric membrane materials
-
Fluctuations in treated effluent quality
-
Frequent membrane replacement and increased maintenance workload
These issues created a need to evaluate an alternative membrane solution for the existing treatment facility.
2. Retrofit Solution: Alumina Ceramic Flat Sheet MembranesThe retrofit scheme involved removing the original polymeric membrane modules and replacing them with submerged alumina ceramic flat sheet membrane modules.
The treatment process was configured as:
A²/O Biological Treatment → Submerged Ceramic Flat Sheet MBR → Treated Effluent
Alumina ceramic membranes offer mechanical rigidity, chemical resistance under compatible cleaning conditions, and potential suitability for repeated cleaning.
However, replacing polymeric membranes with ceramic membranes requires more than changing the membrane material.
Engineers must also evaluate module dimensions, aeration requirements, permeate connections, cleaning procedures, and compatibility with the existing MBR tank.
3. Key Design ParametersThe collected project information specifies the following technical parameters:
| Parameter | Design Specification |
|---|---|
| Treatment Capacity | 3,000 m³/day |
| Wastewater Type | Municipal Domestic Wastewater |
| Treatment Process | A²/O + Submerged Ceramic MBR |
| Original Membrane | Polymeric MBR Membranes |
| Replacement Membrane | Alumina Ceramic Flat Sheet Membranes |
| MLSS Concentration | 7–10 g/L |
| Net Design Flux at 15°C | 24 LMH |
| Net Design Flux at 10°C | 21 LMH |
These values represent project design specifications rather than independently verified long-term operating results.
4. Why Low-Temperature Design MattersOne important feature of this project is the difference in membrane design flux between 15°C and 10°C.
The specified net design flux decreases from 24 LMH at 15°C to 21 LMH at 10°C, a reduction of approximately 12.5%.
As wastewater temperature decreases, water viscosity increases, potentially affecting membrane permeability and filtration resistance. Lower temperatures may also influence sludge characteristics and biological treatment performance.
Therefore, membrane sizing should account for seasonal temperature variations rather than relying only on nominal flux values.
Engineers should also distinguish between gross filtration flux and net design flux when comparing membrane solutions. Net flux reflects the applicable operating-cycle assumptions and is particularly important for practical MBR system design.
5. Engineering Insights for MBR Retrofit ProjectsThis project highlights several considerations for wastewater treatment operators and system designers.
Membrane compatibility: Replacement modules must match the existing tank layout, hydraulic connections, and operating requirements.
Temperature-dependent flux: Winter operating conditions should be considered when determining membrane area and filtration capacity.
Fouling control: Membrane material alone cannot eliminate fouling. Aeration, sludge characteristics, filtration cycles, and cleaning strategies remain essential.
Performance verification: Long-term operating data, including TMP trends, permeate quality, and cleaning frequency, are needed to evaluate actual retrofit performance.
ConclusionThe 3,000 m³/day municipal wastewater treatment retrofit in Sichuan illustrates the engineering considerations involved in replacing polymeric MBR membranes with alumina ceramic flat sheet membranes.
Its design parameters—particularly the MLSS range of 7–10 g/L and net design flux of 21 LMH at 10°C—highlight the importance of realistic operating assumptions in ceramic MBR system design.
For similar municipal wastewater treatment projects, membrane selection should consider wastewater characteristics, seasonal temperatures, module compatibility, and long-term operating requirements.
Explore Ceramic Membrane SolutionsShaanxi Kegu New Material Technology Co., Ltd. (KEGU) supplies ceramic membrane products and supports technical coordination for wastewater treatment applications.
Learn more about our Ceramic Membrane Products or visit KEGU's official website.
Disclaimer: This article is based on externally collected engineering project information and is provided for technical reference only. The project is not presented as a KEGU supply or installation reference. Design parameters should not be interpreted as verified operating performance.
