Direct Reuse

Direct membrane reuse is one of the most favourable end-of-life options across all categories, and is recommended for all situations where it is possible[1]. Direct membrane reuse involves taking membranes that have been deemed unsuitable for their primary application from one plant and transporting them to a secondary plant, potentially for use in harsh conditions were high replacement rates makes low cost second hand modules economically attractive. Although direct reuse of used membranes without any additional treatment is obviously preferred, appropriate assessment of their current performances, further validation and potential chemical cleaning will most likely be required. Information on the used membrane performance from the plant of origin, as well as a number of additional monitoring and characterisation methods, can enable a tailored cleaning system to be developed[2]. Based on the type of feed water used and location of the RO membranes within the filtration train, standard chemical cleaning protocols could be established in order to efficiently remove most of the fouling/scaling that may have occurred during the filtration. A critical step in this reuse process is the validation of the cleaned membranes, as integrity, permeability and rejection must be demonstrated before the membranes can be successfully reused.

To date, one US-based company, WaterSurplus, has recognised the potential directly reusing membranes. The company offers a wide range of surplus new, as well as used, cleaned and repackaged, RO, UF and NF Membranes and associated equipment. While a third party company managing the reuse process is helpful, it is not necessary for its success. The long term goal of this MemEOL tool is to develop a database of used membranes, which will help directly connect primary and secondary users. If you currently have membranes that you would like to provide for direct reuse, or are looking for low cost used membranes, please contact Pierre Le-Clech (p.le-clech@unsw.edu.au) for further information.

Based on the inputs provided, the used membranes have been categorised in the table below. Please refer to this table for information about potential applications, quality ranking and expected reuse lifespan.

Compatible with plastic components	Yes
Compatible with fibreglass components	Yes
Available in Australia	Yes
Available globally	Yes
Manual disassembly required	No

NaCl rejection range (%)	Permeability range (L.m⁻².h⁻¹.bar⁻¹)	Designation	Action	Estimated reuse lifespan (yrs)
99.9 - 99.6	> 0.45	High quality SWRO	Direct reuse as SWRO possible in normal applications	2 –5
99.7 - 99.2	> 1.6	High quality BWRO	Direct reuse as BWRO possible in normal applications	2 – 3
99.2 – 98	> 1.6	Medium quality BWRO	Direct reuse as BWRO in standard applications possible	1 – 2
98 – 96	> 1	Low quality BWRO	Direct reuse as BWRO in harsh applications where regular replacement is required	1
96 – 80	> 5	Medium quality NF	Direct reuse as NF membrane possible	-
< 96	< 5	Unsuitable for RO or NF	Membrane suitable for UF conversion.	-

Direct Reuse

References