Hi Chris, Just reading some ...

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Hi Chris,

Just reading some of your replies this morning and you've mentioned that the biomass has the consistency of "thick soup" and you expressed doubts over the effectiveness of your sludge outlet pipe. This sounds like you may have a very high MLSS concentration and I guess you don't have the equipment to measure the MLSS? I'm not sure how much experience you have of operating activated sludge plants and whether you know what is "normal". Forgive me if I'm telling you something you already know, but SBRs normally operate with a MLSS concentration of around 2.5-3 grams/litre. It should look similar to (or slightly stronger than) what you see in this video https://www.youtube.com/watch?v=Sav1pzO_iN8 (please note I have no connection to this company - I just searched for a video which shows activated sludge in a clear vessel!)

If your MLSS is too high, it can have an adverse effect on performance. The additional bugs create an additional demand for oxygen plus the viscosity of the liquid increases meaning that oxygen transfer is less efficient. It also impedes settlement.

Tanker drivers love hauling away clear liquid / thin sludge - it means more business for them because they'll have to come back more often, it pumps quicker so they don't have to wait around, and it is easier for the receiving works to treat than thick sludge. Make sure the sludge tankered away is as thick as possible.

If you are concerned that your desludge pipe is blocked, and the tanker is a vacuum tanker, you may be able to get the driver to blow air back down the desludge pipe which might clear blockages and perhaps allow you to see where the end of the pipe is (from the pattern of bubbles). 

 

Jeremy

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Also further to my last, I had a grease trap issue that was political. The island government refused to take it, management let it overflow. So I had ingress of grease trap fluid into my system. Prior to this, I had at least some settling characteristics. Since this happened, the current situation is what I have been dealing with. A positive is however, I am managing to get the pH under control which is a start. Until I get further lab equipment, these simple tests are all I have at my disposal 

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Thanks Jeremy. You are 100% correct in regards to test gear. It is on order, I hope to see it soon. But I cannot measure MLSS , SVI and I don't have any reagents for various nutrient levels. Currently , I only have 2x imhoff cones to conduct SSV 30min test and a new HACH multi parameter hq40d pH meter. My other problem is I have a relief crew that are plumbers only, and don't really care about what I am doing or trying to achieve. 2 steps forward one step back. In regards to the pipe situation, I am not worried about blockage, I am worried about " rat holing". 3x loads of sludge trucked away has seen no drop in SSV levels. I examine the sludge when it is transferred into another tank and it seems thickish. I conduct an SSV test on both the continuous aeration tank (CAT) and the decant aeration tank (DAT). Floc formation in the CAT if well developed, gravity settling is easily seen and the supernatant is clear. Finished level I should 20%.  The DAT characteristics are pretty much the complete opposite. Thank you very much mate for the indication on MLSS levels ideal for SBR's, that is information that I require . My last plant was an activated sludge extended aeration . I am relatively new to this industry, plumber by trade and also spent the last 3-4 years as operator. This is my second SBR. I have received a DO probe for the HACH 40d, I will endeavor to grab some readings for your heads up in both tanks. I appreciate the information . Cheers 

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Chris,

Sounds like things are heading in the right direction. Well done. Enjoy your R&R and feel free to keep in touch. It may be easier to revert to email if you don't mind (jeremy.biddle@bluewaterbio.com) as notifications from Water Network don't take you to the comment - just to the discussion - and sometimes it is difficult to find the latest reply!

Cheers, Jeremy

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Hi Jeremy. No RAS mate. There is only balance pipe work approx 60-70% the way up of the tanks. The DAT has a floating weir that decants into a contact tank. Today I finally reached 7.18ph in the CAT and 7.04 in the DAT. Settling was down to 70% with some floc formation. I am seeing results, but won't get too carried away yet. Another tanker load tomorrow and will see on tomorrow afternoon what the result is , before I fly out for R&R for 3 weeks , where it isn't at the mercy of other untrained plumbers !!!!! Thanks for your help mate and if I may , I would like to keep in touch. Thank you again  

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Hi Chris, a couple of other things you could try tomorrow...

I'm not familiar with your exact SBR but often there's a recycle from the DAT to the CAT to provide enough biomass in the CAT. Your comments about different sludges suggest there isn't a recycle on your plant but perhaps it is worth checking in case there is but its not working.

In the absence of MLSS measurement, you could try pouring a small amount of mixed liquor from the DAT onto a sheet of paper and sending a photo or short video to me at jeremy.biddle@bluewaterbio.com. I'll try to estimate the MLSS concentration, but it will be rough! You may be able to attach files to forum posts alternatively.

From your description of the poor settlement in the DAT, it seems unlikely that it is rat-holing because there's no clear liquid. It may just be that the MLSS is so high and the settlement so poor that a tanker load (or three) has little impact.

Hats off to you for having the diligence and persistence to get this sorted. I hope we can get there in the end but it will take some time...

Jeremy

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