We have five MBBR reactors designed to handle peak flow. Under normal flow (which is below annual average) we can live by with two reactors in operation. To save energy costs needed for mixing, we can shut-off three reactors. However we are not sure for how long we can shut them down without significantly affecting the performance potential i.e. will the microbes starve to death or get detached from the media if we shut off the flow and methanol to the reactors for 24 hours?

The idea is to schedule a rotating cycle for five reactors so that two are always be in operation and three are in standby. The question is: what is the longest standby period? Few hours or few days?

If somebody has tried this before or has some knowledge please share.

Thank you.

Dilli Neupane

I wonder if anyone has seen this or has an iadea as to what is happening?

We are a nitrifying plant that recently (~1 year ago) added a CEPT pilot project.  For CEPT, we add alum and polymer at 50mg/L and 0.3 mg/L, respectively.  During our P removal season, we introduce additional alum in the secondary system with Mg(OH)2 added for alkalinity.  We began supplimentary alum addition along with Mg/(OH)2 this year in July.  We observed our effluent ammonia, which is typically baseline from full nitrification, steadily rise to about an average of 0.5 mg/L.  There was no associatetd rise in nitrites, as would be expected with incomplete nitrification.  We made certain our MCRT was more than sufficient and the system pH was at or slightly above historic levels.  We add alum (and Mg(OH)2) every year for P removal and have always acheived full nitrification with baseline ammonia, baseline nitrites, and the expected levels of nitrates.  Other than the CEPT project, nothing is different.  Any ideas why the ammonia of 0.5 mg/L?  Our consultant opines it's pH and once we eliminated secondary system alum for P removal (Nov 1), the pH and alkalinity did indeed increase and the ammonia currently appears to be returning to baseline.  But, for me, that does not explain the lack of nitrites at the same time having an ammonia "residual" in the effluent.  Any thoughts would be appreciated.

I'm wondering if anyone has expertise on algae wastewater treatment in conjunction with biofuels. I am in the process of preparing for a webinar we are hosting this Thursday, August 9th, on the market potential, current state of the art technologies and future directions of algae biofuels in wastewater treatment.

Less negative ORP's observed could be related to recycle flows (RAS and IMLR).  If recycle flow rates are not paced to wastewater flow, more highly oxidized mixed liquor (higher ORP value) will be a greater proportion of the flow through the anoxic zone.  Is this consistent with your operation?

Cheers, RS

Gunalan, I'm not sure where you're located.  Your regulatory authority likely has specified you to run BOD, and you'd have to get your permit modified to analyze and report CBOD. 

Since BOD measures DO depletion, it is a report of the amount of organic material consumed, along with nitrification.  For most monitoring, the amount of nitrification is negligible. 

The quickest way you can measure the impact of nitrification in your case, would be to run BODs and CBOD's using Hach's powder pillows.  To run CBOD, you just add an additional powder pilllow for the inhibitor. 

We used to operate a wastewater lagoon with a long HRT-~30 days.  With that long a hold up time, nitrification had a significant impact on the BOD, and we changed our permit to report CBOD. 

Key point for us, with the excessive HRT, our fecal coliforms died off naturally and we were able to meet our fecal coliform limit without disinfection.  Because we didn't disinfect the effluent, our BOD samples contained a high proportion of nitrifying bacteria which skewed our BOD results high.   

If you are disinfecting your effluent, and then seeding your samples with a raw sewage sample, I would not expect nitrification to be a significant factor in your results. 

Hi

I wish to find about about the nitrification effect on BOD analysis. iN the test method used in our department it is stated that the BOD value calculated is a total sum of carbonaceous dan nitrogenaceous.

My concern is is this value calculated true according to defination of BOD?

How mandatory in nitrification inhibator? If i use nitrification inhibitor does that mean i should use the term CBOD instead of BOD?

Please enlighten me on the matter

Hi

I wish to find about about the nitrification effect on BOD analysis. iN the test method used in our department it is stated that the BOD value calculated is a total sum of carbonaceous dan nitrogenaceous.

My concern is is this value calculated true according to defination of BOD?

How mandatory in nitrification inhibator? If i use nitrification inhibitor does that mean i should use the term CBOD instead of BOD?

Please enlighten me on the matter

I'm wondering if anyone is aware of any active Anaerobic Membrane Bioreactors currently in operation. 

I'm in the process of preparing for a webinar we are hosting next Wednesday on the subject of Anaerobic Membrane Bioreactors and I'm interested in finding out about any AnMBRs in operation.

In a fiber recycling plant, the ETP is being established. Since the plant is small and effluent is just 3000 lt per hour, they have set up a small lab. But don't have any equipment for BOD, COD measurement. Can any body help me out for BOD and COD calibration. 

Thanks for that Mike, very helpful little explanation. I think I saw a diagram for this a while a go from searching on Google but can't seem to find it. Thanks for refreshing my memory.

What were your TKN numbers before this increase. Those numbers are higher than I have ever seen in any facility. Have you tested your trunk lines for TKN or ammonia. If you are able to convert that much ammonia, the nitrate numbers before denitrification must be extremely high. You will be hard pressed to convert that much nitrate to N because the carbon necessary has detrimental affects, such as high oxygen demand. 

 Does anyone have experience or knowledge of the impact high influent sulfates (600+ ppm) can have on an activated sludge process? Our lagoon facility is upgrading to an activated sludge process for nitrification. However, we are also looking at expected upcoming nutrient limits (TN < 10 ppm, TP < 1 ppm) and considering incorporating BNR into the new facility now. New facility will be O-Ditch. Any comments on how the high influent sulfates may (or may not) impact the treatment? References to technical papers or other published material would be great.

Does anyone have any knowledge of how sodium could effect Biological Nutrient Removal, Enhanced Nutrient Removal, and Anaerobic Digestion?

I think you need membranes to get down to 30 ppb consistently. Sand filters will not do it. DAF is for sludge thickening, not polishing steps like this.

Would you give us more detail about wastewater? Do you need to supplement nutrient and/or control pH before MBR?

Most of the P when it leaves a wastewater treatment is made up of bacterial solids.  The bacteria will readily give up P and the result would be more otho P.  My practice is to use total P when dealing with effluent.