Membrane bioreactors as pre-treatment systems

Leader

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Challenge

The pre-treatment systems currently used in desalination plants are not 100% efficient in controlling biofouling and events continue to occur downstream in the cartridge filters and on the surface of the reverse osmosis (RO) membranes.

Membrane bioreactors (MBR) are becoming increasingly attractive as a water pre-treatment option due to the system’s low energy requirements and high quality of the effluent produced. These reactors use microorganisms to remove the organics and nutrients from feedwaters and could be applied successfully in a modified form as a pre-treatment process for RO desalination. Although MBR are not capable of organic pollutant removal in traditional systems, a submerged membrane absorption hybrid system could be capable of removing these compounds through the addition of an absorbent. There have only been a few studies to date examining the effectiveness of MBR to treat saline water and many have used synthetic water spiked with salt or wastewater with high salinity.

Investigation

Design, construct and test a submerged MBR system for the pre-treatment of seawater and determine any correlation between the modified fouling index and organics removal. Compare the biofouling reduction and organics removal effectiveness between the submerged MBR system to standard MBR and other pre-treatment systems currently in use. Develop a novel rapid bioluminescence-based assay for the detection of assimilable organic carbon in seawater.

Outcomes

A sustainable submerged MBR system was successfully developed that effectively reduces the biofouling occurrence downstream on RO membranes and is environmentally friendly. The system incorporates microfiltration and requires the addition of an absorbent, namely powder activated carbon (PAC). Significant amounts of organic matter in seawater were removed by the system resulting in a higher flux through the RO membranes. Long-term operation found minimal backwashing was required and the removal of organics, particularly low molecular weight compounds, was consistent.

A novel bioluminescence assay was developed for the early detection of biofouling in seawater by determining the levels of a low molecular weight compound. Compared to other methods, this assay is rapid (results within one hour) and highly sensitive.

Future Direction

There are plans to further develop a portable assay device and establish a reliable biofouling index to assess biofouling potential in situ.

Partners

Filtration partners


 

Total Value: $485,000 (cash and in-kind contributions)

Principal Investigator: Professor Saravanamuth Vigneswaran

Title: Membrane adsorption bioreactor hybrid system as a pretreatment to reverse osmosis desalination

Length: 33 months

Personnel: 12 collaborators contributing 1.1 FTE

Related Project: The optimisation and improvement of direct filtration pre-treatment to reduce both organic and bio-fouling of reverse osmosis membranes

Further Information

FR3 UTS Vigneswaran (Membrane) Summary Poster

Project Summary Poster – MBR

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