Foaming Due to Nocardia Bacteria

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How can I prevent the formation of foam in a civil wastewater treatment plant?

In my case, foaming occurs specifically due to the Nocardia bacteria. 

How can I reduce the bacteria levels in order to reduce the foaming? Also, how can I treat the foaming in case the bacteria cannot be eliminated? 

Taxonomy

18 Answers

  1. Nocardioforms nearly always have some form of fat or oil as a source for their growth. They produce their own surfactant, which then allows them to grow on the surface of the water producing the orange foam.  This foam will be a mixture of bacteria held together by the Nocardia and the surfactant as well as some protozoa.  In the past, I have combined the use of antifoam with chlorine and as others have said being careful with the dosing of chlorine not to kill or upset the plant.  One way to reduce this is to install a form of oil/fat removal prior to the aeration process.  This will reduce the cause of the foam and foam will start reducing.

  2. Bacterial treatments with off-the-shelf biological consortium products are the answer. I have written on this topic, defending the use of biological products (bioaugmentation products) in WWTPs, as a standard practice, in order to achieve and maintain optimum performance of operations.

    This may not be easy to do, since in many countries, including Brazil, there is strong resistance to using a biological product treatment regimen, often mistakenly viewed as a costly practice. Even sanitary authorities have reservations about the use of bioaugmentation products, and, naturally, chemical suppliers leverage this fact in order to plug their products, which are often less effective, have many undesirable side effects, and may be even more expensive.

    Furthermore, many companies offering such solutions tend to be very unprofessional in their claims and explanations, as some responses herein demonstrate, with untenable claims. This notwithstanding, the more professional suppliers will be able to offer products that are more effective, and, in some cases, quite specific for certain WWTP applications.

    It would be unfortunate if the poor practices of some less scrupulous suppliers resulted in discrediting effective solutions. In most cases, any WWTP will be able to improve efficiency or other parameters, including cost of operations, with a biological product that is well matched to the operating conditions. Such a constant treatment regimen will go a long ways in preventing upsets and Nocardia breakouts, and will allow occasional problems to be solved through temporary adjustments in dosage and operations (increased doses and changes in some operating parameters, for short periods).

    The selection of a biological product should consider whether the supplier can offer adequate, prompt and effective technical support and problem solving.

    Good luck!

    Prof. Cleveland M. Jones, DSc.

    Researcher – INOG (Instituto Nacional de Óleo e Gás/CNPq)

    UERJ – State University of Rio de Janeiro

    Rio de Janeiro, BRAZIL

    1 Comment

    1. Bonjour 

      Sur le fond vous avez totalement raison, mais dans la pratique même en adoptant votre raisonnement c'est impossible.

      Il faut toujours garder à l'esprit ce qu'est la caractéristique -Biologique- de l'effluent.

      Au tout départ de la production de l'effluent d'eaux usées dans l'habitat, entre le robinet et le siphon de l'évacuation la caractéristique est -biologique- en partant du principe que les utilisateurs.consommateurs de l'eau n'utilisent pas de produits léssiviels contenant des molécules chimiques.

      Si cet effluent rejoint un effluent contaminé par le chimique, il perd sa caractéristique -biologique-

      Dans un réseau d'assainissement collectif des milliards de litres de produits chimiques sont déversés dans le collecteur: eau de Javel, Destop, Déboucheur chimique, acide chlorydrique, désinfectant et aseptisant de toutes sortes provenant du Médical et du paramédical ainsique les solvants de peinture, platre et autre ciment.

      On ne peut donc faire de l'épuration -biologique- qu'au niveau de la production d'eaux usées. C'est aussi responsabiliser les consommateurs sur l'idée du pollueur/payeur.

      L'infastructure d'épuration individuelle est 1000 fois moins chère que le réseau collectif, totalement efficace à plus de 98% avec un procédé d'épuration -biologique-

      Même si les utilisateurs de l'eau dans l'habitat sont respectueux de son usage, le dispositif de collecte et la STEP détruisent la caractéristique -biologique- des effluents

      Dans le procédé "Fosse Biologique"lyseconcept sont activés entre 14/16 paramètres biologiques

      English

      Hello on the bottom you're totally right, but in practice even by your reasoning it is impossible.

      Always keep in mind what is the feature--biological effluent.

      At the very start of production of the effluent of sewage into habitat between the faucet and the siphon of the evacuation of the characteristic is - biological - on the premise that the utilisateurs.consommateurs water do not use product lessiviels containing chemical molecules.

      If this effluent joined an effluent contaminated with the chemical, it loses its feature - biological-

      In a collective sanitation of billions of liters of chemicals are dumped into the collector: bleach, Destop, chemical Unblocker, acid piece, disinfecting and sanitizing of all kinds from the Medical and the paramedical as well as the solvents in paint, plaster and other cement.

      So can - biological - treatment at the level of the production of sewage. It is also empowering consumers on the idea of the polluter pays.

      The infrastructure of individual purification is 1000 times cheaper than completely effective, collective network to more than 98% with a process of biological - treatment-

      Even if the users of water in the habitat are respectful of its use, collection and the STEP destroy - biological - characteristic of the effluent

      In the process "Fosse Biologique"lyseconcept are activated between 14/16 biological parameters

       

  3. Guilty, Thomas.  

     

    You can easily Jar test this.   :)

    Jar test this with nocardia

     

    and jar test this with sludge

     

    in our system, there is no need for sludge wasting.  

     

     

     

     

     

  4. The  links Eros provides do  not  seem to  mention  Nocardia...I  am very suspicious of  any company  that  claims "..t he microbes digest all the waste including all the sludge. No more sludge treatment needed. ..." as  the  link says.

    Eros apparently  works for the  company selling  this  "sure  fire solution"

     

  5. Paolo, you do not need a lecture on what Nocardia is and what harm it does.  what you need is a sure fire solution that is affordable and quick.  And that will make sure the Nocardia does not ever return.  and that there will be no risk..sure fire.

    Please do not even try chlorination. 

    use biocleaner.

    https://www.youtube.com/watch?v=NO3xdno7nIc

     

    this Pepsi factory wwtp got hit by Nocardia many years ago.  It has not returned.   in a day, odors disappeared.  in 4 days, it was out defeated

     

    https://www.youtube.com/watch?v=NO3xdno7nIc

     

     

     

     

     

     

  6. I would suggest looking at the sludge storage on site as in my experience, Nocardia is often caused by problem of sludge backlog i.e. sludge storage tanks in high level, leading to ssludge solids introduced to the treatment process via liquor return.  This situation needs to be checked and rectified first.  Controlling SRT and DO levels as described by others here is worth trying but if you have floating sludge or foam on your final tanks, this may need to be physically removed, possibly by suction to prevent the Nocardia entrained in the foam/floating sludge being re-introduced to the aeration process via the scum removal system.

  7. Unfortunately there does not seem to be a definitive solution to Nocardia problems. As with any adverse condition, the ultimate goal is to pinpoint the cause of the issue. Lowering the MCRT seems to have the greatest results but they may not be immediate. We had little success with chlorination and antifoam agents. Since Nocardia are hydrophobic, they tend to attach themselves to air bubbles, preventing their collapse (this contributes to foam formation). For this reason, lowering the luxury D.O. levels may be helpful for long-term prevention of Nocardia. Longer MCRT and higher D.O. levels both may be required for nitrification, however, so adjustments should be made with caution. We ran a series of tests and determined that high levels of FOG were causing our Nocardia. It is important to run composite tests for FOG in the influent, as it may be coming into the plant in plug flows, therefore may not be detected with a grab sample. In our case we discovered a broken grease trap at a local restaurant had been sending large amounts of grease to our plant at a specific time in the morning. After fixing the grease trap, our FOG levels went down and Nocardia foam never returned. Be warned, however, that a massive die off of Nocardia may affect effluent quality for a period of time. Although the Nocardia was more unsightly than destructive while alive, once it had died off it deteriorated our effluent quality for almost two weeks, increased total suspended solids, backing up our filters and making disinfection more difficult. If possible, have some contingency plan prepared for when the Nocardia makes its way through the system. 

  10. Dear paolo,

    Nocardia  is a genus of weakly staining Gram-positive, catalase-positive, rod-shaped  bacteria . It forms partially acid-fast beaded branching filaments (acting as fungi, but being truly bacteria ). It contains a total of 85 species. Some species are nonpathogenic, while others are responsible for  nocardiosis . Severe Nocardial foams cause a number of operational problems. These include aesthetics, odors, and safety hazards if they overflow basins to cover walkways and handrails. In cold weather these foams can freeze, necessitating "pick and shovel" removal.

    Higher aeration basin temperature provides favorable conditions for the growth of Nocardia while M. parvicella grows at lower temperatures. Due to the physical interlocking of the filaments in the foam provides stability to the foam and this type of foam is difficult to remove by antifoam chemicals. Nocardia and M.parvicella bacteria are tolerant to chlorine and are found within the flocs so, high chlorine dosages required for this type of foam control.

    Foaming and bulking problems in ASPs are associated with the presence of a variety of filamentous bacteria along with that parameters have been identified as the causative agents of filamentous bulking and foaming. In situ, filamentous bacteria, Sphaerotilus spp. and Leptothrix spp. Microthrix parvicella, Corynebacterium, Dietzia, Gordonia, Skermania, Mycobacterium, Nocardia, Rhodococcus, and Tsukamurella are the key organic degraders and offer the skeletal matrix for the formation of compact flocs.

    Conditions that Contribute to Nocardia Growth / Foam

    • Low F:M (0.08-0.35 lbs BOD) and long MCRT (10-40 days)
    • High levels of surfactants and fat, oil, and grease (F.O.G.)
    • Internal recycling of floating material
    • Warm temperatures generally above 60°F (15.55°C)
    • Very low effluent BOD (observation)

     

    How to control

    To overcome the Nocardia problem high dose of chlorine is required which may destroy the activated sludge floc and negatively effect the settling characterstics of the sludge .It was observed to exert a total destruction of the filamentous texture between the flocs, leaving only a lot of loose and chopped filament fragments with resulting turbidity in the bulk solution. All of these filaments grow on grease and oil, and these can become a problem when grease and oil are high in amount in the influent wastewater. Systems that lack primary clarification (the main grease and oil removal mechanism) appear to suffer more foaming problems. Communities with enforced grease and fat ordinances appear to suffer less from foaming problems. Also, disposal of septage, which contains substantial grease and oil content, to small activated sludge systems has been associated with foaming problems. Note that Nocardia here is used as a group name rather than a specific species. Recent work has shown that a number of actinomycetes can cause foaming and include Nocardia amarae, N. pinensis, N. rhodochrus and other Nocardia-like species. These are often collectively referred to as the Nocardioforms, or the foam-causing actinomycetes. Nocardia and M. parvicella also occur at a longer sludge age. The sludge age at which these filaments can be controlled is a function of the wastewater temperature, being lower at higher temperature. Nocardia appears to be favored at higher aeration basin temperatures and M. parvicella at lower aeration basin temperatures. Nocardia can usually be controlled by a sludge age below 6-8 days and M. parvicella at a sludge age below 8-10 days at moderate wastewater temperatures. However, many plants have had to reduce the sludge age to less than 2 days for Nocardia control, and this may be inconsistent with other process goals, such as nitrification or sludge handling capability. A third factor in the growth of Nocardia and M. parvicella is septicity or low oxygen conditions.

    https://www.google.co.in/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&ved=0ahUKEwj6qbHs0ozTAhUDrY8KHee1AHAQjhwIBQ&url=https%3A%2F%2Fteamaquafix.com%2Fnocardia-in-wastewater%2F&psig=AFQjCNFrirdFkQvp6YaxcGZh0zrkGULaTQ&ust=1491458634001413

  11. In my previous job, I had come across to similar plant issues. A control action can be, if it is a sever problem and the foam is overflowing from the unit and spread around, and if at all cover other adjacent equipment (pumps/blowers/sensors),  I can suggest to use a suitable antifoam agent. Carry out jar tests prior to its application to examine effectiveness and dosages of antifoam agents.  A preventive major can be worked out only after knowing wastewater characteristics, treatment process and system configuration, etc. If you can share these details, we can discuss it further. 

  13. Here is what we have done 20 years ago. We had a similar filamentus bloom situation and client wanted to get rid of the foam as soon as possible. we did some jar tests to determine practical chlorine dose to destroy bacterial cell wall. (white color indicates that), then estimated the chlorine volume by multiplying with aeration reactor. After that we stopped the aeration for 15 minutes making sure that good bacteria settles, then threw the chlorine to the surface destroying the foam at high concentration, by the time chlorine reaches to the bottom diluted and not to damage the "good" bacteria. waited for a while. then re-started the aeration system foam was gone. :) 

    We took the risk, but it worked that time. Don't try this without precisely estimating the dose with multiple jar tests. Otherwise you might destroy good  bacteria as well. 

  14. If you have access to the book "Troubleshooting the Sequencing Batch Reactor" by Michael Gerardi, there are suggestions as to solutions once the ratio of filamentous organisms to beneficial floc are calculated by lab analysis the conditions can be deciphered to develope an appropriate solution: Sources include: excess FOG materials, high MCRT, low dissolved oxygen levels, low F/M ratios, nutrient deficiency, readily-degradable substances such as short chain acids and alcohols, and septicity and sulfides, pH outside the optimal range +/- >1 .  Foam is from the secretion of hydrophobic compounds or the productions of lipids and biosurfactants that capture air and gas bubbles creating the light brown foam. Returning the floc to an appropriate density and cell ratio is the objective.

  15. I agree with Wiff that it’s best   not to overreact and not try to fix something that does not need fixing. However if you have anaerobic digesters, if   even a little   Nocardia foaming is visible on aeration tanks, you can have serious digester foaming problems…so if you have anaerobic digesters you probably should be more careful. Also these in days of  energy recovery, the  extra sludge produced  at  lower  SRTs can  mean less energy  consumption in the  activated sludge  system an more “fuel” for  energy production from  anaerobic  digesters.

  16. First ask yourself if it's really a problem.  An inch to 2 or even 3 inches of foam, especially if not fully covering the tank is not really a problem.  As Tom mentions surface wasting (skimming mixed liquor to WAS) essentially acting as a "mechanical selector" (to select out nocardia) is the best way to do it, if you can do so with the set up you have, or could reasonably have, with a few relatively minor modifications.  Lowering MCRT may help but lower MCRT's often lead to more WAS and may make nitrification difficult as noted by another comment, assuming you need to meet a nitrogen goal.  The last resort is chlorination applied either to the surface through foam sprays (add hypo to the lines feeding foam spray system) and or by adding hypo directly to the RAS.  The latter may impede nitrification and or harm other desirable microrganisms so you should start with low dosage (7-10 mg/L on RAS Q) and gradually increase til you either see problems or achieve nocardia reduction.  Some would say if it's not deep enough to pose a risk of overflowing the aeration tank then it's not a sufficient problem to be concerned about.  You definitely don't want to allow it to build up to that level and believe me some plants have experienced that big a nocardia problem.  So don't sweat the small stuff and do go through progressive steps to control these nuisance microorganisms, starting with a mechanical selector first if you can set your plant up for it.

  18. Lowering  SRT always  works...but  if  you have  to  nitrify this could  be tricky... in  warm  waters  (like Florida) we  had  to  to  drop it  to below 0.5  days...but  it   was  a  2 sludge  system and  25 dg. C

    Chlorinating RAS can work  but also  can  be tricky...I  do  not  remember dosage needed..check WEF  publications

    Surface wasting of   MLSS also works and  is   a  standard  design detail  of  many  major  design  firms  like  Brown  & Caldwell