Aster Bio, my employer, has been working on reformulating plumbing and collection system grease degrading products. Why reformulate?
Well screening of industrial wastewater cultures has found some very interesting candidates that produce copious quantities of unique biosurfactants and cultures that tend to be attracted to the grease solid deposit.
In testing collection system products, we look at the ability of the organisms to shorten the fatty acid chains in grease creating a more soluble fatty acid. In shortening the fatty acids, the organisms are "growing" on the grease in a process called beta oxidation. With the consumption of long chain (insoluble) fatty acids, the organisms also produce extracellular enzymes and biosurfactants that emulsify the grease creating more surface area for the bacteria to attack the grease. The ideal degradation tests include increased water incorporation into the hard grease layer (emulsification) and reduction in weight of the insoluble portion.
To simulate the process in pipes, we used grease rendered from beef with associated proteins to best match what builds up in the collection system and grease traps. The grease was solidified in flasks. Two test microbe formulations for testing were introduced without any outside surfactants. The test include agitation for 30 seconds per day without aeration/mixing for the remaining time. Temperature was kept at 23 Deg C. (Lab Temp).
The original collection system and grease trap formulations containing only Bacillus sp. performed as expected in lowering the amount of solid grease. Most formulations on the market contain only Bacillus sp. as they have long shelf-life and are easy to grow/preserve. The new Aster Bio modifications included Pseudomonas oleovorans and Rhodococcus erythropolis strains. The addition of these vegetative strains was made via a dry product with 90%+ solubility.
As a picture is worth a 1,000 words, here is a photo of the flasks after 48 hours (below). The flask on the left is the Bacillus sp based product that represents the market standard. The grease has the standard "fluffy" appearance indicating enzyme, biosurfactant, and metabolism. The flask on the right contains the new formulation of P. oleovorans and R. erythropolis. Notices the grease is much "fluffier" and volume as been reduced over 30% more than the Bacillus product.
The results are clear, for systems where bacillus only products have not proven suitable for completely removing grease buildup or where greater efficiency is desired - the use of the new strains could prove quite effective in preventing grease blockages and associated sanitary sewer overflows (SSO).
Many systems require chemical additions to provide alkalinity needed for ammonia removal. Often I get questions on what is the "best" source of alkalinity. And, how much is needed to stabilize the system. In response to question frequency, I decided to post the following bullet points.
Municipal wastewater treatment generates tons of dried and composted sludge that are often applied to yards and pastures for their nutrient value. Current testing includes ensures the absence of enteric microbes and metals in the biosolids so the product is considered safe for most applications. However, recent research into xenobiotic or resistant chemicals that remain after biological treatment is causing some concern.
The USGS recently released a study of nine different commercially sold biosolids and tested for 87 different organic chemicals. Every sample had at least 25 of the chemicals present with one having 45 chemicals detected. Total summed concentrations ranged from 64 to 1,811 mg/kg (parts per million)
Amoebae are single cellular protozoa that move via pseudopodia, engulfing organics and bacteria cells. They are common in "young sludge" conditions, but testate (shelled) amoeba are also common in older sludges. The big issue I have with using amoeba as indicator organisms is that many operators only look for the typical amoeba view (below)
However, this is not the only way amoeba appear under the microscope. They also frequently look like this:
For the past month, I have been going through old R&D, training documents and marketing materials as we redesign the Aster Bio website. While the new site is not yet up, the diversity in application of microbial based solutions has once again impressed me. You may wonder how can a core technology work in applications as diverse as animal health (probiotic), aquaculture waste digestion, petroleum spill cleanup, high strength industrial wastewater, and sewer odor control.
Well the one unifying factor is the natural ability of microbes to convert complex compounds into harmless, building blocks used by higher life forms. Everywhere you look there is a diverse group of microbial forms including bacteria, fungi and protozoa that exist in a constantly changing micro-environment.
While microbiology and biotechnology usually are concerned with the individual organism or internal biochemical pathways, outside the lab it is the microbial ecologist that looks at the interaction and changes among environmental microbes. While it is obviously important for waste treatment, microbial ecosystems exist in animal guts, feed lot manure pits, plant roots & surrounding soils, aquaculture ponds, and even on human skin. While Aster Bio will leave the human skin microbial application to others, I enjoy seeing how a microbe that transforms manure also has application in sewage treatment and soil health. So as you look around, realize that billions and billions of microbes are working the the environment that surrounds you and research into their makeup, population changes, and managing their diversity is a key part of keeping your environment suitable for you!
I have been bench testing another unique industrial wastewater. This water contains multiple resistant compounds and long chain polymers that are difficult to degrade. When this influent is added to MLSS from mixed industrial and municipal systems, the biomass deflocculates and becomes very viscous with a 24 hours of feeding 100% the influent. Seeing this as a challenge, I started screening several blends of chemical wastewater microbial isolates to see if any of the strains could work with this water. What I looked for in lab testing:
The microbe tested was a interesting Rhodococcus strain that was originally isolated for chlorinated hydrocarbon and herbicide degradation. What is interesting is that within 24 hours of growing on the influent, the Rhodococcus cultures entered log phase growth. What is interesting is that in response to the waste, the Rhodococcus formed a hydrophobic mass that floated and was very stable. With continued feeding of the influent, we added other Pseudomonas cultures that had previously not done well on the waste. Interestingly, with the addition of the Pseudomonas strains the floc started to form without the hydrophobic or viscous biopolymers seen earlier. This is an very noticeable case of how finding the right cultures can create the needed biomass. It is rare to see a true hydrophobic growth phase, and every less common to see how the hydrophobic phase ends with the addition of a secondary culture. I'm including a photo of the test flask. I am continuing the test to see what increasing F/M ratio does to floc formation.
The Moving Bed Biological Reactor (MBBR) is a fixed film system for waste treatment. It relies on microbial biofilms in a similar manner to trickling filters and RBCs but has been designed to address short-comings of the older systems.
The MBBR is simply a tank with high surface area plastic media that moves freely in the tank. Screens keep the media in the tank where it provides a surface for biofilm development. Compared to activated sludge units, the MBBR has the following advantages:
· Smaller foot print
· Lower cell yield (fewer solids to dewater)
· Useful for high rate industrial pretreatment
· A simple once through MBBR is easier to maintain & operate compared to most other systems
So we have a potential system that has low maintenance and operational costs like an older lagoon or pond system yet has the higher activity rates and smaller footprint of advanced treatment systems.
So what is the big advance in technology that makes MBBR possible? Well it was improved production of durable, high surface area plastic media – contrary to marketing documents most of the media has similar performance when you have equivalent surface area to volume. Everything else already existed for MBBR systems built from the ground up as an MBBR or a retrofit to an existing activated sludge tank.
For the past two weeks, I have been evaluating the MBBR technology for industrial pretreatment of a high BOD5 waste stream that is discharged to a POTW. The goal is to reduce BOD5 from 4,700 mg/L to 500 mg/L in an effort to lower surcharges. The reason for MBBR selection is the need for concentrating a biomass for high BOD5 removal rates while also recognizing the facility does not want a complex wastewater system on-site. In lab testing, we are getting good results at loading rates of 5 – 7 kg BOD5 per cubic meter of media. In effect, we are building a “roughing” filter that is more resistant to fouling than older tricking filter systems. Below is the simple laboratory scale MBBR that I constructed for testing purposes.
Erik Rumbaugh has been involved in biological waste treatment for over 20 years. He has worked with industrial and municipal wastewater facilities to ensure optimal performance of their treatment systems. He is a founder of Aster Bio (www.asterbio.com) specializing in biological waste treatment.
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