WEF Discussions — Now on LinkedIn!

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salinity in activated sludge
Greg Gress
Posted: Friday, August 26, 2011 9:30 PM
Joined: 6/23/2010
Posts: 5

How much salinity can an activated sludge process tolerate? in ppt please. We are seeing 1.3 ppt in OD and no sings of any problems. Potential exists for more. Not sure how much is too much.

Anyone have any ideas?



Jurek Patoczka
Posted: Friday, September 23, 2011 3:45 PM
Joined: 4/24/2010
Posts: 3


We have investigated this for couple of industrial facilities. Both literature and direct experience indicates that activated sludge will nitrify at TDS (salinity) of up to 20,000 mg/L (= 20 ppt), if properly acclimated and not stressed/overloaded otherwise. We recommend to operate activated sludge at less than 15 ppt (which is about half of the salinity of ocean water).  Such conditions are unlikely to occur at a municipal ww treatment plant, rather only in high TDS, industrial streams.

Hope this helps.

Greg Gress
Posted: Thursday, June 14, 2012 5:21 AM
Joined: 6/23/2010
Posts: 5

We operate a collection system and wwtp on a island and are concerned about the salt water intrusion. We would like to know, perforable with out actually experiencing it, at what level of salinity is too much and will affect our effluent water quality. We have a few properties on the beach that are suspect of saltwater intrusion at high tide. As beach erosion creeps inland, other properties become suspects as well. So at what ppt salinity do we set as the cut off?