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Gustavo Duarte

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MBBR Sludge Sedimentation
Feb 02^nd, 2012, 12:40pm

Hi everybody!

I am participating in a discussion about what would be the best technology for biological treatment of a petrochemical sewage stream. Among the various factors discussed, it was commented that the use of carriers in a conventional activated sludge could cause problems to the clarifier downstream of the aerated reactor because the consistency of the sludge generated by the detachment of the biofilm of the carriers is different from the sludge generated by substrate in suspension. The first one would have greater difficulty of settling.

Has anyone gone through this experience? Any measure had to be taken?

Our effluent is coming from a petrochemical and go through API separator, DAF, equalization and pH adjustment before treatment in the MBBR/IFAS.

Thanks in advance.

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Gustavo Duarte

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The sludge judge

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Re: MBBR Sludge Sedimentation
Reply #1 - Feb 2^nd, 2012, 1:55pm

It comes down more to the conditions in the plant that determine the settling. Both processes can have good and poor settling depending on how they're operated and the conditions they're under. The bacteria in both processes doing the majority of the "work" are the same.

As long as you have proper DO, temperature, amount of food: bugs, amount of retention time, proper pH, nutrients, lack of toxicity etc you should be ok.

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The sludge judge God Member Offline Posts: 649 Wisconsin Gender: Company or Organization: private	Re: MBBR Sludge Sedimentation Reply #2 - Feb 2^nd, 2012, 1:56pm Most likely (and this is the job for an engineer) it'll come down to cost, as well as the amount of time and attention the plant would need to recieve/ staffing etc.
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DoctorBug

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Re: MBBR Sludge Sedimentation
Reply #3 - Feb 2^nd, 2012, 2:36pm

Gustavo Duarte:

The sludge settling characteristics from a conventional and MBBR system are the same and both are subject to the quality of the biomass formed, independent of whether a carrier is used or not. However, in my exprience, addition of carriers (MBBR) to a petrochemical activated sludge system has been very beneficial in helping the system to survive and recover from toxic spills. Use of a MBBR process in a petrochemical system is recommended.

Hope that this helps.

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Gustavo Duarte

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Re: MBBR Sludge Sedimentation
Reply #4 - Feb 3^rd, 2012, 5:35am

Guys,

Thank you for the responses. I'm already feeling more confident to use this technology!

Another quick question concerning sludge: using carriers in a conventional activated sludge reactor will decrease sludge production? I think we'll have difficulties of disposal of the discharged sludge, so if it's true, would be a really big advantage for us.

Thank you again!

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Gustavo Duarte

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DoctorBug

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Re: MBBR Sludge Sedimentation
Reply #5 - Feb 3^rd, 2012, 10:00pm

Gustavo Duarte:

The sludge production rate, which determines the amount of waste sludge you generate, is a function of the sludge age and F/M, not of the form of sludge growth. Both these systems produce the same amount of waste sludge if the growth parameters are the same. One advantage of the MBBR system is that a higher sludge concentration can be maintained, lowering the F/M and forming less waste sludge due to this. So, if the MBBR system is operated at a higher sludge concentration than a concentional system, the sludge production rate will be less.

Hope that this helps.

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Gustavo Duarte

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Re: MBBR Sludge Sedimentation
Reply #6 - Feb 6^th, 2012, 12:02pm

Doctor Bug,

You say that if we have a higher concentration of sludge in the reactor, the waste sludge production will be smaller, and I agree with that.

But I believe that it will always happen in a MBBR plant because, beyond of the sludge in suspension, we'll also have the sludge in the carriers, so the need of rejecting sludge would be smaller, am I right? This would be a advantage of MBBR in comparison with an activated sludge system.

Thank you for the support!!

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Gustavo Duarte

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DoctorBug

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Re: MBBR Sludge Sedimentation
Reply #7 - Feb 6^th, 2012, 12:18pm

Gustavo Duarte:

A MBBR reactor will have less sludge production during the first few weeks of operation due to populating the disks. Once the system is at steady-state, an MBBR sludge system generates the same amount of waste sludge as the conventional system at the same F/M. The amount of biomass on a MBBR disk is not controlled, and it will fill up to capacity, then sluff additional growth. Sludge formation in suspension plus the sluff in a MBBR system equals the total sludge production in a conventional system. No magic !

Hope that this helps.

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DS

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Re: MBBR Sludge Sedimentation
Reply #8 - Feb 6^th, 2012, 12:33pm

I agree with dr. Bug, especially on the non-controllability of the sludge Sad

Often, there is more sludge in suspension then one would like, and this fraction will take a more or less important fraction of the food, at the expenses of the biofilm... Sad

the effluent of MBBR sometimes/often is quite turbid => you need a daf... Sad

The quality of the biofilm on the carriers sometimes is horrible (e.g; infested with Type 021N ... Angry

I have my doubts about this technology... and the "plastic" is expensive too!!

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Gustavo Duarte

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Re: MBBR Sludge Sedimentation
Reply #9 - Feb 7^th, 2012, 5:43am

DS,

Thank you for your comments. We're thinking of a tertiary treatment to decrease turbidity, such as a sand filter or something like that. Do you believe this treatment can handle with this high turbidity?

I've visited a MBBR pilot-plant in a University here in Brazil and I was told that the carriers designed by MBBR suppliers (the expensive ones) show results not too different from manufactured carriers, made with PVC tubes by the students. I believe there is more "marketing" than techonology about these carriers, isn't there? I don't know how they would work in industrial process, but they did very well in lab scale.

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Gustavo Duarte

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DS

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Re: MBBR Sludge Sedimentation
Reply #10 - Feb 7^th, 2012, 6:03am

Hi Gustavo,

the problem with sand filters is that they tend to blind fairly easily (all depends on the type of sand filter and the media dimension(s)). The type of turbidity ex MBBR may vary heavily and suddenly both in size distribution and total amount SS. If you want to be able to cope with these variations, you'll need quite some extra units....

agree on the (sometimes) exuberant pricing of this plastic. Anyway, the price is what someone ("fool or not" Wink

) wants to pay for it. They call it "engineered platic", to make it sound better (make you swallow it), but I do not see the "engineering part" in that plastic... (It is rather boring plastic, isn't it?)

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Gustavo Duarte

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Re: MBBR Sludge Sedimentation
Reply #11 - Feb 24^th, 2012, 6:43am

Hi guys!

Still concerning MBBR, I'm readind an Anox Kaldness presentation and they (obviously) are telling the advantages of applying this technology on Activated Sludge plants. I would like to know your opinion about this information:

They say that, when you use nitrifying bacteria in the media and BOD removal on suspended bacteria, there is a dramatical risk decrease of filamentous problems. Why would it happen? Which are the conditions to avoid this situation?

Sorry about the many questions about MBBR... All the data I have here is from suppliers, so I'd like to get some info from people that already used the technology. Wink

Thanks in advance!

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Gustavo Duarte

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DS God Member Offline sapere aude Posts: 1582 Company or Organization: Indept. Freelance Consultant	Re: MBBR Sludge Sedimentation Reply #12 - Feb 24^th, 2012, 7:25am Hi gustavo, Can you send me that doc on my private mail? I would like to read it first. I left you a personal msg with my E-address. best regards, ds
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Gustavo Duarte YaBB Newbies Offline I love Water and Wastewater.com Posts: 30 Rio de Janeiro Gender: Company or Organization: Petrobras	Re: MBBR Sludge Sedimentation Reply #13 - Feb 24^th, 2012, 7:55am Hi DS! I sent the PDF file! Regards!
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mangesh_surve YaBB Newbies Offline Water and Wastewater.com is the best! Posts: 25 Gender: Company or Organization: ENVICARE	Re: MBBR Sludge Sedimentation Reply #14 - Feb 28^th, 2012, 9:26am Hi Gustavo, We too facing the same problem of bulking of sludge in MBBR process. Please share the some relevent data If you found. Thanks in Advance.
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