The MBR Blog

Misc Simon Judd 2

Simon Judd

Professor Simon Judd has over 20 years’ experience in teaching the fundamentals of water and wastewater technologies and is author of The MBR Book, watermaths (2nd ed), and Industrial MBRs.

Contact Simon at

STOP PRESS: The third edition of watermaths is now available, published by IWA. Get 20% off the standard price (GBP £55) by using code MBRIWAP20 at checkout.

The origins of ragging in MBRs − a story of cotton wool

Ragging in MBRs is almost certainly caused by cotton wool or similar cellulosic textile fibres. Only very short lengths of tiny filaments must break through the 1–3 mm fine screens, which suggests that they are originally dispersed. But they soon get together again to form those long rags.

view blog

Footprint − the factors governing size in an MBR

It's their compactness that is one of the beauties of MBRs and often leads to their selection as the preferred technology. Crucially, MBRs permit a higher MLSS concentration than a conventional CAS process, and this means proportionately smaller biological process tanks. 

view blog

MBR hybrids − ain't broke, don't fix it?

For MBR hybrid technologies to be viable they need to offer a material advantage over the two separate technologies. And, of course, there has to be some sort of application for them in the first place.

view blog

Degritting in MBRs − true grit costs

There’s plenty of tales of the impact of poor screening on downstream unit operations in MBRs. While there is little actual proper research into the performance of screens published in the peer-reviewed literature, there are some useful guidelines produced by practitioners.

view blog

MBR sludge − fouling or clogging?

We’ve spent a few months now here at Qatar University looking at clogging in membrane channels, with our single-channel bench-scale plant. We're taking a few litres of sludge from a nearby MBR and running tests at relatively high flux and slightly diminished air scour rates.

view blog