Is it a design flaw or is it the inoculum? - Do the so-called "anaerobic bacteria inoculum" for septic tanks work?

1046 views

  • vramesh
  • vramesh's Avatar
    Topic Author
  • I'm a master's student (Infrastructure and Environmental Engineering) at Chalmers University of Technology, Sweden. I'm interested in working with affordable decentralized wastewater treatment solutions.
  • Posts: 12
  • Karma: 1
  • Likes received: 5

Is it a design flaw or is it the inoculum? - Do the so-called "anaerobic bacteria inoculum" for septic tanks work?

One thing, we can observe throughout e-commerce stores across the world is the so-called "anaerobic bacteria inoculum" for your septic tanks. The popular claims are that don't desuldge your septic tank ever, just top it up with our inoculum, every 4-6 months... goes the advertisement.

But it's so hard to find any concrete evidence for the claims and I feel it remains understudied.
I don't find any peer-reviewed journal article evaluating these inoculums and their claims (kindly let me know if you find one I would be thankful).

On the other hand, if we observe any typical anaerobic bio-digester design, the mixing mechanism is a critical component.
It can be a simple mechanical mixer or it can be that the influent feed is fed through the bottom (as in UASB) to allow gaseous mixing of the substrate and the biomass.

So this raises the question, even if the inoculum is effective (as claimed by their manufacturers), just by dropping the inoculum into a conventional septic tank can we make it work? Will the mixing be good enough? (note: the inoculum is being advertised for septic tanks that aren't desludged for years) Don't we need any mixing mechanism?

Best regards,
Vasanth.
The following user(s) like this post: Taber
You need to login to reply
  • pkjha
  • pkjha's Avatar
  • Working for over 30 years in the fields of sanitation, biogas from human wastes, septage management, waste water treatment in rural as well as urban areas in India and other developing countries.
  • Posts: 166
  • Karma: 11
  • Likes received: 59

Re: Is it a design flaw or is it the inoculum? - Do the so-called "anaerobic bacteria inoculum" for septic tanks work?

Dear Vasanth
  Efficiency of  anaerobic cultures in markets was discussed in this Forum earlier also. 
Since human waste contains high population density of active hydrolytic bacteria, therefore, there is least or no effects of external bacteria on biodegradation of such wastes in septic tank.  There are companies who claim to have developed inoculums of bacteria to degrade wastes   effectively. Such inoculums may be suitable for kitchen wastes/ solid wastes - not for septic tank. I got tested some cultures of well known company with the control of human wastes and cold not find more effective than the control. 
As you mentioned,  inoculums needs to put at the top of the septic tank before it is filled. If it is so effective, then one should put inoculum   in septic tank on the day it is put in use. In such case, the tank will never be filled and therefore, its size can be reduced considerably.  Such advertisement is mostly commercial gimmick. 
It is common point that biodegradation continues till the substrate is stabilised. There is always residual matters. Empty of septic tank is always required. It may be longer in case of effective cultures of micro-organisms . 
Best regards

Pawan 
Pawan Jha
Chairman
Foundation for Environment and Sanitation
Mahavir Enclave
New Delhi 110045, India
Web: www.foundation4es.org
Linked: linkedin.com/in/drpkjha
You need to login to reply
  • Elisabeth
  • Elisabeth's Avatar
  • I'm passionate about SuSanA's role in the WASH sector since about 2005. I'm a freelance consultant since 2012 (former roles: program manager, lecturer, process engineer for wastewater treatment plants)
  • Posts: 3286
  • Karma: 54
  • Likes received: 892

Re: Is it a design flaw or is it the inoculum? - Do the so-called "anaerobic bacteria inoculum" for septic tanks work?

Dear Vasanth,
You're right to be skeptical, and I agree with Pawan's statement of "Such advertisement is mostly commercial gimmick.".

As these ads are so pervasive, we put together the relevant information a while ago and put it into this Wikipedia article about pit additives (could be in need of updating):
en.wikipedia.org/wiki/Pit_additive

You can find several discussion threads on this topic by searching for "pit additives" here on the forum. For example this one:
forum.susana.org/280-faecal-sludge-treat...l-sludge-includes-em

There is also this sub-category on odour issues:  forum.susana.org/233-odour-issues

Feel free to continue any of those older threads (or this one) if you feel that new questions have arisen.

And yes, mixing is more important than additives.

Regards,
Elisabeth
Head moderator of this Discussion Forum
(with financial support by GIZ)

Dr. Elisabeth von Muench
Independent consultant located in Brisbane, Australia
This email address is being protected from spambots. You need JavaScript enabled to view it.
Twitter: @EvMuench
Founder of WikiProject Sanitation: en.wikipedia.org/wiki/Wikipedia:WikiProject_Sanitation
My Wikipedia user profile: en.wikipedia.org/wiki/User:EMsmile
You need to login to reply
  • Rich
  • Posts: 1
  • Likes received: 1

Re: Is it a design flaw or is it the inoculum? - Do the so-called "anaerobic bacteria inoculum" for septic tanks work?

It is a never ending question, even wastewater utilities in USA are approached to buy these inoculums to treat say FOG in Pump Stations and as others have suggested my response to them is if biological why would I ever need to buy more than once.  I think most of us know how sophisticated digestion is, whether aerobic or anaerobic or septic. I have operated both aerobic and anaerobic digesters and the reality is most know a careful balance of time, mixing, temperature is required for successful operation.

I suspect septic tanks many missing elements in digestion make it at best a poor substitute with no control over mixing or temperature. The hope is sufficient digestion occurs and few compounds introduced that might thwart biological activity. I am a skeptic. I think generally speaking septic tanks and drainage fields were a cheap attempt at wastewater treatment in an era before conventional activated sludge put into practice and where collection system expense was too expensive or difficult. So what is answer, I doubt it is effective.

My suspicion from years of observation of somewhat static tanks is a layer of FOG almost as a rule forms at surface, this I would think would make any additive less likely to get through to liquid and digestion below in settled biomass. In fact it is my suspicion that FOG is typically why many septic tank systems fail and require regular pumping out.. 
The following user(s) like this post: Elisabeth
You need to login to reply
  • vramesh
  • vramesh's Avatar
    Topic Author
  • I'm a master's student (Infrastructure and Environmental Engineering) at Chalmers University of Technology, Sweden. I'm interested in working with affordable decentralized wastewater treatment solutions.
  • Posts: 12
  • Karma: 1
  • Likes received: 5

Re: Is it a design flaw or is it the inoculum? - Do the so-called "anaerobic bacteria inoculum" for septic tanks work?

I feel the insights from Rich makes much sense. Elisabeth thanks for sharing the thread "pit additives". It's extremely relevant and I even felt that I have just reframed an old question.

If at all we like to improve the septic tank's biological degradation performance, practically in any possible way, 
I think we must acknowledge and should focus on the design inadequacies in septic tanks as Rich mentioned "I have operated both aerobic and anaerobic digesters and the reality is most know a careful balance of time, mixing, temperature is required for successful operation.
I suspect septic tanks many missing elements indigestion make it at best a poor substitute with no control over mixing or temperature".
The following user(s) like this post: Elisabeth
You need to login to reply
Share this thread:
Recently active users. Who else has been active?
Time to create page: 0.645 seconds