Sunday, January 20, 2013

MBR, SBR, Activated Sludge, ATU, Suspended Growth

MBR:  Membrane Bio Reactor
SBR:  Sequencing Batch Reactor
Activated Sludge
ATU:  Aerobic Treatment Unit

Question: What do these three types of system all have in common?

Answer: They are all Suspended Growth systems.

MBR's, SBR's and activated sludge and ATU systems all work in the same manner: they blow air into wastewater.  That's it.  Within the pool of frothy wastewater are free swimming microorganisms that utilize the wastewater as a food source. The wastewater is supposed to be treated as the microorganisms act on it. 

This design, generally best suited for municipal scale systems that have access to a supply of full time(24 hr/day) operation and maintenance personnel,  has been adapted for smaller scale and residential systems as well.  You can find them under a variety of brands but they all look about the same and they all operate in nearly exactly the same manner.  A blower blows air into a pool of wastewater 24 hours a day, seven days a week.

However, and this is common knowledge to almost everyone in this industry even if they don't like to admit it, suspended growth systems are notoriously unreliable.  In fact, I attended a conference where the president of one of the really big manufacturers of a suspended growth systems was arguing that his company's individual systems should not be assessed based upon the results they were producing but rather, all the systems should have their results averaged.  I would like to be able to extend this logic, however tortured, to traffic laws.  "Well officer, I was only speeding for 10 minutes but I have been driving for 3 hours, so on average, I have not been violating the speed limit!"

Eliminite is an advanced onsite wastewater treatment system that differs significantly from the suspended growth systems.  The microorganisms providing the treatment are not free swimming in a pool of liquid.  Instead they are attached and immobilized on the surfce of our patented MetaRocks.  Why is attached superior to suspended?

"It is obvious that attached microorganisms stay in the system longer than non-attached microorganisms. Retention of slow-growing microorganisms such as nitrifiers and methanogens is facilitated by attachment, this leads to a higher inventory of the microorganisms in the system and thus reduces the hydraulic retention time required for treatment."

One reason is that the biofilm in which the microorganisms are embedded provides significant protection from toxic substances.  You can think about this as the difference to being outside versus being indoors.  The free swimmers are relatively unprotected and exposed to the elements where the attached growth has the protection of the biofilm.

I recently read a study that helped explain why so many suspended growth systems have such poor results.  In my experience, the ATU systems seem to perform well if they are in a study that is carefully choreographed and executed.  Once they are in the real world, everyone is left scratching their heads trying to figure out 1) why the ATU is not working and 2) how to fix it.  I have written on this blog a few times about Maryland's Best Available Technology (BAT) and how the state was required to allow loads of additional nitrogen into the aquifer and Chesapeake Bay because the BAT-ATU could not duplicate the same level of treatment it displayed in one of those play-act studies. 

Here is what I learned:

Bacteria within biofilms are much more resistant to toxins than are free-floating bacteria.  One study found that a bacteria attached to glass slides displayed a 150-fold increased resistance to chlorine disinfectant compared to free-floaters.  In another study, antiseptic concentrations had to be incresed by 40 times to kill attached bacteria versus the free-floating counterpart.   

It was previously thought that attached growth systems resistance to shock loads was due to the huge numbers of bacteria present.  I will write about this in a few days because it is true and worth examining.

If you look at manufacturers recommendations for ATU systems you will find that they are very concerned about what you put down your drain.  They don't want you to use bleach, water softeners, anti-bacterial soap or pine based cleaners.  A distributor of ATU's told me, trying to make excuses for his systems poor performance, that one person in the home was taking chemotherapy drugs and this was why the residents, in addition to dealing with cancer, had to deal with a non-compliant septic system as well.

Eliminite systems seem to take whatever is thrown at them, deal with it and produce stellar results.  A recent set of samples taken from one of our heavily used, high strength waste systems produced the following results:

Eliminite Results
Ammonia: 99% removal
TKN: 99% removal
TSS:99% removal
BOD: 99% removal
TN: 90% Removal

This data was collected in Montana in late December from a system that has had nothing done to it and no operator. It has been receiving high strength waste:  BOD>1200 mg/L, Total nitrogen>400 mg/L.  I will gladly provide the actual lab data if you ask.

Saturday, January 12, 2013

Isn't there something useful they could be doing?

"Wrightstown officials have filed citations in district court against 77 township property owners who haven't pumped out their septic systems in more than three years."

"He said residents who have been cited can still pump out their systems and avoid a court hearing, but must still reimburse the township for the cost of filing the citation. Penalties for continued failure to comply include fines of up to $500 a day, said Pantano."

Someone needs to spend a few minutes with Chester and teach him how a septic tank functions:

"The big picture is public health and making sure it is maintained properly," said township supervisor Chairman Chester Pogonowski. "While there is no imminent health threat, these residents need to get their systems pumped out so they don't overflow."

Septic tanks don't overflow?  Where does the liquid go?

"Wrightstown has an ordinance requiring the systems to be pumped out every three years to avoid problems such as sewage leaking out of septic tanks and into ground water or wells."

Wow, they must have some enormous holding tanks.

Thursday, January 10, 2013

The gift that keeps on giving

I was reading a short newspaper article the other day about a company that installs and repairs septic systems. Specifically, they focus on aeration septic systems. Another term used to refer to these types of systems are aerobic treatment units (ATU).  In general, while there are many different brands,ATU's all do exactly the same thing: a pump of some sort runs 24 hours a day, 7 days a week, 365 days a year forcing air into the sewage. 

My interest in the article focused on the service interval they were saying is necessary to keep these types of systems operation because, according to the service provider:
"If these systems are not properly maintained, they could release raw sewage, which is known to spread disease."

Apparently it is necessary for the service provider to visit the system several times per year to keep it from releasing its load of raw sewage.   The article goes on to say:

"Getting people to understand the importance of maintaining their septic system. Aeration systems need consistent maintenance. On average, homeowners need to service their systems two times a year. Serving the motor in your septic system is just as important as servicing your car. The motor will last longer without expensive repairs."

To be clear, I am not faulting the service provider. They obviously an provide an important service to the people that have these systems.  I was, however, amused by their candor regarding the necessity of the service requirements because the potential for surfacing raw sewage sure doesn't sound like a very powerful selling point making me want to run out and spend $12,000 for one of these things.
As I read the article I compared Eliminite system service requirements to the service requirements being discussed for the aerobic systems. 

First, an Eliminite system rarely needs "service."  State regulations generally require advanced onsite systems receive periodic maintenance visits based on a model developed by NSF, at minimum, two visits per year for the first two years and annual visits thereafter.

In Montana, ATU's are required by the State DEQ to recieve twice the number of O&M visits required for Eliminite technology.  If an ATU is installed in Montana, the State DEQ requires four visits per year for the first two years and 2 visits per year thereafter. 
Eliminite systems receive an inspection and inspections are quite a bit different from service.  If the effluent pump, for example, has reached the end of its long life, it is simply replaced with a new effluent pump.  Inspections generally involve looking the system over, reading the dose counters in the control panel, taking a wastewater sample for lab analysis and cleaning the effluent filter.  The whole operation takes about 30 minutes and is a "clean" operation (No tyvek suits).

The idea that if the ATU septic system will release raw sewage if it is not serviced regularly should send owners and regulators running from these things.  Aerobic Treatment Units usually are built in a single tank.  The building sewer dumps its entire load into this tank and the air blower forces air into the sewage.  If the air blower fails or if the volume of air is insufficient to stabilize the sewage or if  someone in the house uses some anti-bacterial soap, or does an additional load of laundry, or if the weather is cold or if the owners horoscope said it was going to be a bad day,  the ATU stops working.  When this happens, whatever comes in goes straight out.  And it is not uncommon to see ATU's permitted with a surface water(river, stream, creek) discharge.

In an Eliminite this condition simply cannot exist.  If the recirculation pump experiences a malfunction, the control panel activates an alarm.  If the problem is not corrected, the system will not allow any further discharge of wastewater.  The system provides several days of storage giving the service provider time to get to the site and correct the problem.  Additionally, the wastewater enters the Eliminite after having been partially treated through a septic tank.  So in the worst case scenario, the system would function as a normal septic tank and drainfield. 

Most of the ATU manufacturers do not require that a septic tank precede the aeration tank.  This means that, in order to sell these things cheap, they omit the single most reliable component of any onsite system, the septic tank. 

Owners of onsite wastewater treatment systems generally do not enjoy paying for service visits.  If you look at the cost of ATU's in, for example, Maryland, where the prices for "Best Available Technology" are listed on the department of environment website, it's not difficult to understand why owners don't want to continue to keep pouring money into their septic sytstem.

We have had some systems where for whatever reason the service contract was not renewed. It was good to find that after almost five years of no visits, the system serving two homes was still functioning (It hadn't caused an Ebola outbreak) and the sample showed a total nitrogen concentration of under 10 mg/L.  ATU's  could not meet this standard if the president of the company built his house over the thing with it exposed in his living room and fed it a hormone-free vegan diet of alfalfa sprouts and tofu.

When we developed Eliminite in the 1990's there were no requirements for maintenance contracts in the state. (These came later on at the prompting of manufacturers of other systems because they knew that in order for their system to have a prayer of operating, there were going to have to be governmental regulations in place forcing owners into a service contract.  In fact I heard recently that one of the manufacturers that sells systems in Montana routinely turns homeowners into the state enforcement department if they don't renew their service contract.  How is that for service after the sale?!)  We decided to develop a reliable system who's operation did not depend on the services of a full time septic nanny.  We have data showing systems operating for years without service that once they were visited and checked were still were operating correctly and removing 75%+ of the total nitrogen load to the system.  This is what I mean by reliability.

I think the reason manufacturers and service providers advocate unreliable systems is because they reap the monetary benefit of a perpetual maintenance contract.  This idea is not unlike the concept of planned obsolescence. Think about it, the cell phone company will give you the phone if you sign the contract.  For the ATU's however, the owner gets to pay dearly for the contraption while the state holds the threat of hard time in a septic gulag over their heads if they don't agree to a perpetual maintenance contract.  What a business model.

I mentioned the Peoples Republic of Maryland earlier.  They are having quite a time with their onsite program right now.  Their governor has decreed that onsite system are the scourge of the planet and must be stamped out at all costs.  Maryland's department of the environment has identified, on pretty scant data, a set of systems designated as Best Available Technology (BAT).  They should seriously consider dropping the "Best"because these systems are merely, "Available Technology."  We participated in two studies (government run, third party, long term)  with a system Maryland claims is "Best" and in both studies, the manufacturer of that system pulled their "Best" system out because it was failing so miserably.  These systems were the recipient of special favors award in Maryland because the state gifted the manufacturer special consideration regarding the treatment results from the system.  After the system was approved, they figured out they weren't working.  I think the original approval required a total nitrogen limit of 20 mg/L but after it was apparent there was no way the systems could meet this standard, the regulators in Maryland rewrote the approval allowing that system to discharge 35mg/L.  Maryland apparently doesn't require compliance samples anymore and I would bet that most of those system are not meeting the 35 mg/L standard. What confuses me is, if the 20 mg/L standard was developed to protect the Chesapeake Bay, who or what is the the 35 mg?L standard intended to  protect?

Wednesday, January 2, 2013

Happy New Year

To our friends we have worked with this past year, Thank you.  You have helped make 2012 a great year for us and we hope we have helped streamline your projects and assist in your success.

2013, can you believe it?  I remember being a kid watching the movie '2001: A Space Odyssey', thinking that, by now, we would all be flying around with jet packs and taking weekend vacations to Mars.  I was certain that our energy was going to come from fusion reactors, and transporter beams were going to start looking like a real possibility.  When I watched Apollo 11 land on the moon, I was pretty sure space colonies were just around the corner.  Man, was I a few years off, because in 2013 most advanced onsite treatment manufacturers can't even build a reliable denitrifying septic system yet, but, to their credit, they sure have mastered the art of marketing in the 21st century to make you believe they can.

Eliminite has been busy with quite a few new and interesting projects.  We currently have three new highway rest areas in various stages of completion.  We completed a good deal of field work on a large highway rest area treatment system in November. The working conditions were pretty miserable, but we were able to get the internal components of the treatment system installed before the contractor had to shut down for winter. 

Justin and Tony at the highway rest area installation on one of the nicer days.
This is a custom system specifically designed for the application and site conditions.  For many reasons, most manufacturers only supply pre-fabricated pods.  Big pods, little pods, medium pods, but always just a bunch of pods, most of which feature parts manufactured overseas or, at minimum, outside the U.S.  That's one way to run a business, but it's not how we run our business at Eliminite. We balance many interests and needs on every single job; each client has different objectives, different budgets, different treatment demands. So, we select design configurations and materials best suited for the job, utilizing as many locally-sourced materials as possible.  Anything we don't make ourselves, we prefer to purchase from a business in or near the same location as the actual job. Sounds obvious, but it is less common than you'd think...a lot less common than it should be, in this industry. On this particular rest area, we used tanks from a local supplier, which is better for the local economy than shipping in pods from who-knows-where, and minimizes waste inherent to shipping long distances. Sometimes, cheaper isn't better, especially when the "cheaper" per-item cost fails to reflect the true cost of importing something thousands of miles, from a place with few environmental regulations.  The local supplier was able to manufacture tanks that fit the site conditions very well, which made the job easier on the contractor. 

Back in 2005 at this site, the first contractor installed fiberglass septic tanks which, from what I hear, was quite a failure.  The site has high ground water and the contractor had a heck of a time dewatering and setting the fiberglass.  It sounds as if the tanks were never installed properly and, if the engineering consultants had thought about it, they would have designed something different.  But, big fiberglass tanks are usually selected without any thought for site conditions or bedding haul distances, particularly on jobs where state, federal and grant funding are available.  The system we are constructing is housed in strong, durable precast concrete cells.  This means that backfill and bedding operations are not nearly as critical as they would be with fiberglass, and there was no need to import expensive sand and peagravel to be placed by hand.  Dewatering was not as critical because the concrete tanks do not float like fiberglass.  In miserable field conditions(snow, cold, rain, sleet, ice pellets and frozen fog) the last thing you want to be doing is monkeying around with a bunch of temperamental, fragile pods and installation-sensitive fiberglass tanks. Of course fiberglass tanks have their place and when they make sense they are a good product.  My point is, Eliminite provides options that the others cannot provide due to inherent limitations to their underlying technologies and processes.
Eliminite systems are less expensive, period, and that's by design.  We are working on a highway rest area job that was recently out for competitive bid. The Eliminite system was quite a bit less expensive than the pod system, and Eliminite was awarded the job.  This is a common occurrence:  once engineers, contractors and owners see and understand what we can do, we usually get the job.   We also have the experience and knowledge to provide meaningful design assistance to the design-build team and can usually help save them some additional time and money. 

The bottom line is, this all comes down to numbers, not feelings, catchy sales slogans, or who has a bigger team of full time lobbyists.
  • Equipment cost numbers
  • Installation cost numbers
  • Treated results numbers
  • Time between maintenance interval numbers 

I look forward to working with you all in the new year, and I can assure you that Eliminite is committed to you and your project.  Now is a good time, if you don't have experience with us already, to give me a call and discuss that important project and the numbers.  We have a nice long list of references that I would be happy to share with you.