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14 October 2016

We solved the 2 biggest MBR issues

Thembrsite.com conducted a survey in which they asked “what is the main issue with MBRs?”.  The top two issues with MBR sludge quality were identified as membrane fouling and clogging...

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Thembrsite.com conducted a survey in which they asked “what is the main issue with MBRs?”.  The top two issues with MBR sludge quality were identified as membrane fouling and clogging (see Figure 1). Fouling was well ahead of clogging as the primary challenge perceived by most of the correspondents. 

Figure 1: Responses to our question: In your experience, what is the biggest challenge posed by MBR sludge?

Irreversible membrane surface fouling and membrane channel clogging lead to the same symptoms of stubbornly low permeabilities with a largely ineffective chemical clean. It’s only by removing the membrane that it’s possible to distinguish between the two, with the clogged solids visible between the flat sheets or hollow fibers of the immersed membrane modules. Clogging is a lot less of an issue for sidestream modules in pumped systems, if proper strainers are installed upfront the membrane system.

The Helix technology to prevent fouling

The solution to prevent fouling is our patented Helix flux enhancement technology. It  addresses the bottleneck in high-solids ultrafiltration (UF) by preventing the buildup of foulants. Our innovative Helix technology design features a helical shape on the inside of a tubular membrane, creating continuous turbulence to prevent rapid fouling. By introducing turbulence right at the membrane wall, the Helix technology provides continuous mixing and efficient removal of the cake layer that would otherwise reduce the membrane's hydraulic permeability. The resulting higher permeate flow contributes to higher productivity and lower energy costs.

Pentair’s Feed Flow Reversal to prevent clogging

Clogging (i.e. filling the channels of the membrane, or blocking the channels inlets with rags) can be prevented with the Feed Flow Reversal of Pentair. This is an unique way to prevent membranes from clogging due to hairs and fibers which are blocking the inlet, this technology reduces the strainer capacity required and can handle a very high amount of fibers, hairs and debris. The graph in Figure 2 shows the DP  (pressure loss over the membranes), after a Feed Flow Reversal, the pressure drop has been reduced to the initial value. This technology is unique and will keep the membrane skid running under the most extreme conditions. This data was gathered from a plant that has a high amount of debris and hairs in the MBR sludge despite of proper straining upfront the MBR reactor.  

Figure 2: DP  (pressure loss over the membranes) after a Feed Flow Reversal

Source: thembrsite.com