Activated Sludge SBR

Published on by in Technology

How can I RE-SEED my ​SBR that has ​potentially ​dead biomass ?

I would like to implement this in a location without other fully functioning waste water treatment plants.

The system has been running at a pH of 4.5-5.5 for approximately 3-4 years. 

Taxonomy

19 Answers

  2. There's no consensus on whether dry seeding scores over wet ones

  3. SVI might b a problem due t filamentous bacterial macrobiotic growth.

    Bioaugmentation technology is well developed.

    Wet seeding with culture from similar process situation and feed types need t b considered.

    Or problems from wrong biomass would b acute.

    Other than SVI,SOURand of course pH corrections and calculations or remedying r crucial.

    Sludge age is also an important parameter t b considered.

    1 Comment

  4. 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

    2 Comments

    1. 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 

    2. 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 

      4 Comment replies

      1. 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

      3. 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  

      4. 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

  6. hi Randall, if the pH is 4.5, we can help.  we have alkalizing acidophiles.  that can bring the pH back to 7.    40 years is a long time in microbiology. many things have happened and many microbiologists have made wonderful discoveries.    cheers

     REPLY (0)   LIKE (0)  

  7. Chris,

    I am reminded of a saying by my microbiology professor at Berkeley 40 years ago, "You can find every organism in Bergey's Manual at the front door of your local wastewater treatment plant. All you need to do to get organisms to grow in treatment is to provide the right conditions." This doesn't necessarily hold if we are talking about a purely industrial waste, but it is a good rule to remember.  If you have a pH of 4.5 in your system, re-seeding will not help you. You need to look into why you have such a low pH. Acids in the influent? In which case, alkaline pH adjustment could be needed.

    Best wishes,

    Randal

    1 Comment

    1. Thanks Randall. I have inherited this system a few months ago. No testing equipment, not pH probe, no chemicals, nothing. Recently I had a grease trap overflow into the system which has added to the problem. For the past few weeks I have been manually dosing lime mainly for alkalinity and also NaOH. Today I saw a pH of 7.09 in my main aeration tank and 6.97 in the decant aeration take where my stages happen. Today I installed a dosing pump to dose NaOH into the main aeration tank to no longer manually dose and to also have a good regular dose maintained. I am waiting on test gear to test for nutrients and alkalinity . It really has been a dogs breakfast , I hope I am making inroads . My first goal was to reach a good pH of about 7.2. The only problem now is that I work on a roster which is 3weeks on 3weeks off, the other workers have no understanding so I am worried I will be back to square 1 when I come back. Hopefully the lime addition will go some way in preserving my pH . I appreciate your advice. Thank you 

  8. Normally suggest you feed the bacterial with a readily biodegradable substrate such as Molasses or even Sugar. I have seen cases where plants have used animal feed to provide nutrient balance. Aerate to supply oxygen and mixing. I would suggest you limit your normal feed as much as possible to allow the recovery to take shape. Check the activity level by switching off the air for a short period and measuring the rate of dissolved oxygen decline before settlement starts to impact the DO level. If your plant has gone Anaerobic you may find the Ammonia levels are currently high and as the plant recovers you may start to lose akalinity due to Nitrification (although unlikley to be a problem if the pH remains between 4 and 5). You will therefore need to have Alkaline materials such as lime or caustic soda available to add. Agree with previous suggestion that you should have some anti-foam and be prepared to go to on / off aeration if foam generation is too high. Then you will need to careful as you re-introduce normal feed materials. If the pH drops back to 4-5 quickly you may shock the bacteria. Slowly increase the amount of normal feed and reduce the readily biodegradable substrate. 

    1 Comment

    1. Thanks Michael . I am guessing pinfloc or deflocculation is happening due to firstly my pH's and for how long it has been operating in these conditions for (3-4years) and from the settling characteristics I see in my 30min sludge test. It will settle from 1000ml to 900ml after 30 and have the consistency of thick soup. The start point for me is to get my pH's correct. Finally, today I saw a pH of 7.02 & 6.97, and I have installed a dosing pump for NaOH to removed  manual dosing and ensure a consistent steady dose rate. Lime is being added for alkalinity.

      Is there a formula for dosing of CaOH hydrated lime that you know of ?

      thanks for your help  

      1 Comment reply

      1. Hi Chris. With regards to alkalinity dosing depends on what you are trying to achieve. If you are removing ammonia you need 7.2mg of Alkalinity per 1 mg of Nitrogen removed. SBR's will normally have an anoxic section which can recover alkalinity in the system if some dissolved BOD is left leaving a nett requirement of approx 4mg/l. However your influent may be having a big impact if it is acidic. Best way to control alkalinity is standard pH control loop dosing in the NaOH and then checking actual alkalinity on a daily basis. If Nitrifying suggest a target alkalinity around 500mg/l. 

        The settlement rate you have shown above is really poor and you are probably correct that your low pH level is causing the floc binders to split apart - however if it is a thick soup its likely to also be build up of significant trash and possibly non-organic solvents or even bacterial slime. It would be worth doing an MLSS test followed by vMLSS to see how much of your sludge is organic. If you can't empty and restart the SBR you are looking at a long slow road to recovery but it is feasible. You have made a great start with getting the pH working. If possible speed up the process by putting one basin into manual and continously aerating with the Nutrient make up I previously recommended. This basin can then act as the seed basin for your other SBR's. 

  9. Hi Chris,

    If you want, you can contact me directly at kurt.rasmussen@saskwater.com or at 1-306-630-5648.  There are just too many questions that I have and I do not want to respond to you back and forth forever on a forum and waste your time when a simple phone call do the trick.  I will leave it up to you on how you wish to proceed.

    All the best,

    Kurt Rasmussen, P.Eng.

    Saskatchewan Water Corporation, Government of Saskatchewan

    1 Comment

  11. SBR's are quite interesting and I'm afraid they are far from my favourite.  The normal pH for aerobic operation is 6.8-7.8.  When the plant goes into settlement stage, then frequently anaerobic bacteria grow with the resultant drop in pH and this in turn stresses the aerobic bacteria.  Frequently this results in foam and may result in poor settlement due to zoogleal growth.  How can you change things?  You can try the use of lime in short term to correct the pH, because there will be some live aerobic bacteria present.  There are freeze dried bacteria which you can add.  However, they want aerobic conditions and the correct pH to become established, so if you just add freeze-dried to your plant they will be wasted unless you have already corrected your plant.  So before I started, I would heavily de-sludge then run the aeration stage for longer than normal to kick start the plant.  After saying this, I am trying to advise you remotely.  I would normally want to look at the plant and examine it microscopically.  There are questions you need to ask such as How good is the aeration system?  If it is producing coarse air and reaching the surface without transferring oxygen to the water then you will return to the same conditions, which you have at present.  This can be overcome by supplementing the air by installing fine bubble aeration, which can be retro-fitted.  My e mail is don@lansonmicrobe.co.uk.  If you are interested then I can put you in touch with suppliers of Freeze-dried bacteria and fine bubble aerators.

    2 Comments

    2. Thanks very much Don. You have given me some good information there. There was no form of pH control at this plant. The last 2 weeks I have been manually dosing hydrated lime for mainly alkalinity but also for pH , as well as NaOH. The SBR is set up like this : sewer enters a continuous aeration tank, from there it decant into the DAT ( decant aeration tank ). The DAT is where my stages happen. The manufacturer has set up the timings : aeration for 2 hrs, non aeration for 70min. There are 2 decant per day. My settled sludge volume 30min test shows 90%. We remove sludge from this plant via a truck, which connects to a single outlet 80 mm camlock fitting. Approx 10,000 is drawn from tank. Internal tank pipe work is unknown , potentially outlet is just that and no network of pipe at tank bottom to when withdrawing which will mean a small area of sludge is withdrawn  and mainly just fluid, this would make sense as I have withdrawn 20,000 Ltrs of "sludge" but have seen no shift in SSV. Settling characteristics of the sludge test = very poor flow formation, similar to soup consistency. The 10% supernatant from SSV is clear. The CAT tank SSV has very good settling characteristics/floc formation. Today's pH was - CAT=7.09 DAT=6.97. Not too sure if this brief description will give you a head start up but hope it does. 

      Thanks again 

  13. Hi Chris，

    To start up a new activated WWTP, you don't have to seeding the SBR. However, it would take a relative long time (the difference of them might be 1 or 2 weeks) to get a stable operation. If you maintain a suitable operational condition, the growth speed of activated sludge is more than your expectation.

     

    But you need to prepare sufficient antifoam reagent during a WWTP starting up period, which is used to control the foam generation no matter you have seeded it or not.

     

     

    1 Comment

    1. Hi Laing. Thanks for your reply. The system is an existing system. As per the original question, it has been running for 3-4 years at a low pH of 4-5. I am a new employee to this remote site. An island 4000km from Australia. There is no other treatment plant that gives me the ability to reseed. The plant has  very poor settling characteristics. I am currently dosing NaOH to rectify pH. The PAC was getting watered down due to costs. I was asking for ideas on alternative reseeding 

  14. Hi Chris, sorry but with all due respect, your question was not very clear (nothing to do with bad mediation it seems); as indicated below, bacteria indeed is the solution, you can try with yogurts, I know it sounds too simple but have heard that it often does the job instead of buying expensive bacteria (not always available in remote locations). Good luck!

    2 Comments

    1. Yogurt is made using Lactobacillus species, which thrive in an anaerobic environment and derive energy through lactic acid fermentation. These are NOT the right species for an aerobic treatment plant.

      If yogurt does work, I suspect it would be due to the other nutrients in there such as sugars and fats which your aerobic bacteria can consume for energy.

      Animal carcasses contain lots of bacteria specialising in breaking down fats and proteins, which are present in wastewater too, so as long as those bacteria are primarily aerobic species it is going to help.

    2. Without getting into a too and fro match, they key word/phrase was re-seeding an SBR , not reusing dead biomass. This in itself changes the whole question does it not ? 

      Thanks for your reply, I have also heard of animal carcass , but that I said a bit extreme 

  15. Once again , this site and its mediator have misrepresented this question. Whoever it is may have to get a firm grasp on the English language. This is my second question on this site and it's the second time it has been mediated incorrectly.

    I do not want to REUSE DEAD BIOMASS!!! How bloody ridiculous is that. 

    My question is ...." how do I RE-SEED my SBR that has potentially dead biomass. I am in a remote location without any other healthy waste water treatment plants.

    As you can see, vastly different question 

    1 Comment

    1. Chris Riley so sorry about the moderation. Not sure how that happened. I will investigate. In the mean time your question has been corrected. Please let me know if now ok.

      1 Comment reply

  16. The biosolids can be used as fuel in a biomass gasification system to produce heat and even electricity.  The heat can be used to dry the fuel and to produce distilled water.

    Neal@newrangepower.com

    1 Comment

  17. there's a system called Cannibal by siemens water technologies, you can do a variation, basically you liquefy the wasted sludge and use it as food for the new ones. Send you a brochure. 

  18. Just to ensure I understand your question correctly, you have an old reactor with "potentially dead" biomass at pH 4.5 - 5.5 and you want to use it to seed a new reactor? If not, please ignore the following...

    Bacteria are incredibly resilient and will adapt to changes, provided they are made over a period of time. They generally just take a few hours to adapt to pH and osmotic pressure As long as the biomass you have is reasonably aerobic, it should make a reasonable seed sludge. As always with commissioning, you may have to feed it a bit slowly to start, but get it up to full load as soon as possible or the bugs may acclimatise to being underloaded.

    1 Comment

    1. Thanks Jeremy. This site and whoever is mediating the questions hasn't an understanding of English. "How do I reseed my SBR that has potentially dead biomass. It has been running acidic for approx 4 years. I arrive to site march 2017 and have only received a pH probe. No other working waste water treatment plants on this remote island, 4000km from Australia in the middle of the pacific 

      1 Comment reply

      1. Hi Chris, sounds like a lovely location. Perhaps I could visit and bring some seed sludge with me??

        Is the sludge brown and with a "healthy" earthy smell, or black and sulphurous? If the latter, I'd suggest emptying it out and starting again, but no need to clean the tank scrupulously. As others have said, you can start a SBR from scratch, growing your own sludge from whatever bugs you have in the tank or in the sewage. Keep it aerobic and don't be afraid to decant the supernatant liquid when you need to - you have to get rid of the non-floc forming bugs and select for the floc-formers. Your effluent quality will be poor for several weeks, but from the sound of it the works has been non-functional for a while already.

        I can't quite understand why the pH got so low in the first place. Did the tank turn completely anaerobic and begin acid fermentation? If not, and the acidic conditions occurred while the system was aerobic then you might need to investigate further. Could someone be dumping acid down the drain?