Technology & Process Selection
Membrane filtration product offerings are normally provided with two main polymeric materials, ie PVDF and PES. Nearly all polymeric membranes are provided in a hollow fibre format with an inside diameter of about 0.5 to 1 mm, as illustrated in the figure below.
The flow configuration of the hollow fibre products may be on the inside of the fibre or the outside. Furthermore, the fibres may be encapsulated in a housing, referred to as pressure driven, or immersed in a tank, known as the submerged format. There are a few products based on ceramics using tubular or flat plate formats. Spirals have been used in some of the original UF products and these may still be provided for specialized application niches.
The chart below shows the evolution of technology over the past 35 years of market development, with the market leading materials PVDF and PES shown in bold.
The chart illustrates the use of materials in the two possible configurations, ie whether using an inside feed or outside feed format, and whether using a UF or MF pore size rating.
MCA helps users and specifiers to understand how the technology options would address potential applications needs.
MCA provides assistance to owners, user’s engineers, engineering firms, and system suppliers in reviewing designs,
considering technology options, and selecting appropriate design parameters.
The review may comprise inputs ranging from producing an initial outline design to an audit of a detailed design.
MCA can comment on the suitability of the proposed design and make recommendations regarding to options and design parameters.
MCA conducts plant reviews based on site visits or remotely by an examination of performance data such as permeability trends.
This chart shows UF permeability trends for a three month operation on a SWRO pre-treatment plant in the Middle East.
In a general troubleshooting programme, the review of data enables a report to be written which can establish:
- whether the problem has been caused by an inherent defect in the membranes or modules
- or whether the problem has been caused by aggressive design conditions or operational circumstances.
A report may cover issues such as:
- Review of plant data, including source water and performance observations
- Design and operational Issues/problems encountered
- Failure modes, both for membrane and module
- Potential remedies and design and operational improvements
- Conclusions & Recommendations
- Is the plant working within its design envelope?
- Is the failure due to product weakness or operations or a feed issue?
- What has caused the integrity issue?
MCA is experienced at conducting troubleshooting assignments on different feedwater types, particularly desalination from a surface intake, drinking water from a surface source, and wastewater reuse. The assignments have identified failure modes commonly encountered as a function of application and membrane format and this often enables MCA to make recommendations which can significantly improve future outcomes.