Monday, May 24, 2010

Trickling Filter, Packed Bed Reactor, RTF, Fixed Film Bio-Reactor

I will be presenting several technical references related to the treatment mechanism utilized in the Eliminite system.  The first is from WEF Manual of Practice 8.  The section I am posting should answer questions related to the ability of trickling filters to equal or exceed suspended growth processes.  If you click on the image it will be easier to read.
The key to achieving high treatment levels is a thorough understanding of how these types of systems function.  I talk to quite a few people, usually "experts" that tell me RTF systems cannot match the performance of suspended growth systems.  The fact is, our systems can meet suspended growth performance and usually exceed them because the process is inherently more stable and resistant to upsets.  The result is more reliable treatment performance, lower energy consumption, lower O&M costs and lower capital cost.  The next technical post will discuss media size and its relationship to fouling. This should help with decisions related to media selection employed by specific systems.  ie. MetaRocks vs. gravel vs. fish tank filter floss(textile) vs. peat moss vs. foam cubes. 

Sunday, May 16, 2010

Treated wastewater from a cluster system

This is a sample of treated effluent from an Eliminite MBR (MetaRocks Bio Reactor) .  It was tested and found to have less than 1 mg/l ammonia and obviously no TSS.  I spoke with the operator and this system has been producing treated effluent to this degree since it was installed almost four years ago.  He has never had to change, clean, fluff or hose off the fixed film media.  The photo below was taken through the access hatch and lets you see the condition of the MetaRocks.  They are clean and full of large pathways for air movement. A thin bio-film has developed on their polar surface but the main paths or oxygen transfer are available and open.  This means the microorganisms providing the treatment have easy access to fresh air and the MBR will remain aerobic.  Eliminite systems remain aerobic while using much less power than SBR, membrane reactors or other suspended growth systems. This means they cost less to operate and need a lot less babysitting.   

I get frustrated when the "experts" of this industry pound their desks and proclaim with conviction that onsite systems need constant maintenance to function properly.  Maybe the mainstream onsite systems, (Peat, textile, foam cube, aerated septic tanks etc) need constant operation and maintenance hand holding, but Eliminite systems absolutely do not.  I know this concept shatters the perceptions of those in government and academia and it is clear that those people are reluctant to even entertain the possibility that maybe there is a system that is far more robust and stable that the mainstream gadgets.  Apparently they think it better to cling tightly to their opinions and close their eyes to possibilities than to simply admit that they have modified their position based upon this new evidence.  (It reminds me of the controversy that erupted when Copernicus published his theory contradicting current thinking  and stated the the Earth was not the center of the universe).  

 An Eliminite distributor suggested an analogy between Eliminite and some of the other, more well known, systems.  He said Eliminite is like a 20 year old man that eats anything and everything with no concerns for calories, sodium, fat or carbs and still stays thin.  Who stays out late and gets up the next morning ready to go.  Who plays extreme sports, takes a bruising, shakes it off and keeps on playing.  Who has never been sick a day in his life.  The other systems (textile, peat, foam cube,aerated septic tanks) are like a 90 year old man.  He has to watch everything he eats carefully or he will get develop stomach problems.  Who takes a rainbow of different medications every day just to keep going.  Who, if he falls down will have to have his hip pinned.  Who has a history of illness and constantly has one foot in the grave and he other on a banana peel, ready at any second and for the slightest perturbation in his schedule, to give up the ghost.   I think that is an accurate analogy.

The picture on the bottom shows Eliminite effluent compared to bottled drinking water.  It is time, if you are truly looking for a system providing high treatment levels and ease of operation that you investigate Eliminite.   Oh...we cost a lot less and occupy a much smaller area than peat, textile or foam cube systems.  Or I guess maybe it it is heresy to suggest that the earth is NOT at the center of the universe.

Saturday, May 8, 2010

Tuesday, May 4, 2010

A short comparison of advanced wastewater treatment systems

Three main concerns clients express when exploring options for onsite wastewater treatment systems:
  • What is the initial cost?
  • Is the system reliable?
  • What are the O&M Costs?
In reality O&M costs and system reliability are opposite sides of the same coin.   First consider the two main classes of onsite systems: 
  • Fixed film
  • Suspended growth
Fixed film systems include Eliminite, textile filters, peat bogs, sand filters, upholstery foam and others.   Suspended growth systems do not have nearly the wide variety of bright ideas as the fixed film systems and are really just aerated septic tanks.  

If you ask people familiar with the industry you will find that suspended growth onsite systems are notoriously unreliable.  I am not arbitrarily slamming these systems, it is just a fact that when you use an undersized septic tank, dump into it all the liquid, solids and grease and bubble air into the resulting "soup" you are going to have problems.  The only positive aspect of these aerated septic tanks is that they are cheap!   But, once an owner has one of these installed, there is a reasonable probability that the permit limits will never be met.  The unreliability of suspended growth onsite systems has caused many manufacturers to turn towards fixed film systems.

The first Eliminite was installed in early 1994.  At that time most of the advanced onsite systems were suspended growth systems.  There were no textile filters...the main purveyor of these systems was busy selling sand filters.  Foam upholstery cubes were unheard of and most of the peat was still in the bog.  I am being facetious to a degree but you get my point, the industry was dominated by suspended growth systems.  Maybe this is one reason why there was such a huge push in the 1970's and 1980's to sewer everything; it was a well accepted concept that onsite systems simply did not work.

Fixed film systems changed that.  But, what is the most important thing that has to be provided to a fixed film system for it to function?  Well wastewater of course...second most important thing then?....AIR.  If air cannot get to the biofilm, the system is going to have problems, period.  Now think.....Imagine laying on you back and having someone shovel two feet of saturated peat on your face.  Can you breathe?   Probably not, and you have the benefit of a diaphragm muscle expanding your chest cavity to allow air to be forced into your lungs in response to atmospheric pressure.   Microorganisms growing on the surface of the wet peat do not have diaphragm muscles.  How about textiles?  At about 1/2 inch thick these fabric sheets also become saturated with liquid effectively blocking the free diffusion of air to the biofilm.  Eliminite uses our proprietary MetaRocks as the medium to which microorganisms attach.  When dosed with wastewater,  MetaRocks allow the development of a thin liquid film across their surface.  A film sufficiently thin to allow efficient oxygen diffusion into the biofilm.  But that is not all....the size and shape of the MetaRocks allows air to move freely and if we go back to the example of trying to breathe through wet MetaRocks you will see that the large pores allow free air movement.  In fact, even as the biofilm develops on the surface, the pores remain open and available to unhindered passage of air.  This is not the case with the other fixed film media.  Think about it.  Their tiny pore spaces quickly become closed off due to inevitable biofouling.  The only thing to do then is to pull the filter media out and clean it.   MetaRocks do not require cleaning.  So back to the point,O&M.

Do you suppose that maintenance costs will increase if the saturated, dirty media has to be removed and cleaned regularly?  Will the maintenance costs be lower for a system that has already considered the potential for biological fouling?  Why do some systems have such large lids/covers?  These big covers are expensive and a manufacturer would not add them (and their additional cost) unless they were absolutely necessary.  But they are not necessary to get the media IN, they are necessary to get the media OUT for cleaning or replacement.   Eliminite MetaRocks were designed to address and overcome the issue of biological fouling.

Look at the photo of the MetaRocks in the tank (click on it to enlarge the photo) and notice the huge interstitial openings.  These wide open passages allow air to move freely.  They also accommodate a wide range of hydraulic loading meaning the system can handle varying waste strength and flow.  We measured the hydraulic capacity of the media at over 200 gallons per ft^2 per minute.  At that rate flushing (even though I have never seen a situation where it has been necessary) is as easy as opening a valve.

Another really useful feature of MetaRocks is that they are lightweight and free-flowing.  This means that you can build larger systems by using larger tanks.  Think about that for a minute and compare an Eliminite system treating 5000 or 10000 gallons to a peat system or textile filter.   The Eliminite system can be built in one tank, two tanks, you choose.  The peat and textile configurations are only available as a daisy-chain of little toy pods strung together.  Which option sounds easier and less expensive to build and maintain:  a single central treatment plant or a spread out maze of little parts and pieces?