I have just finished a quick summary course on bioaugmentation. Every day I see bioaugmentation, nutrients, and other additives offered as a panacea for all sorts of problems in waste treatment. The course below covers the basics of bioaugmenation including how products are designed and what to expect if you use bioaugmentation including its limitations.
Almost all organic compounds can be transformed by microbes into carbon dioxide, water, and new cellular material. Problems arise when the degradation rate occurs only under specific conditions not present at the site or the decay rate is so slow that changes are required for bioremediation to be a viable cleanup option.
A site's bioremediation potential is first evaluated by determining the types and extent of pollutants present. Following site characterization, a remediation plan is developed based on the pollutants present, site characteristics, environmental variables, and cleanup time frame.
The compounds present may include some organics that are slow to degrade or have a degree of toxicity/quasi-toxicity to many microbes. In these cases, the time for cleanup can be reduced by first adding the mixing/aeration and fertilizers as used in biostimulation; then on-site time can be further reduced by avoiding the adaptation and lag phase growth of indigenous microbes via the use of bioaugmentation.
Using data from the site characterization, microbiologists can develop a microbial blend containing organisms having specific metabolic pathways for degrading target organics. Another consideration is the ability of organisms to produce biosurfactants, that improve activity by enhancing hydrophobic compound solubility. The extent of the benefit depends upon the "fit" of the microbial inoculum used and the general state of indigenous microbes already at the site. Overall, usually the decrease in on-site remediation activities including labor, lab testing, and risks associated with an active remediation project can pay for the use bioaugmentation.
Lagoons treating waste water or storm water eventually build up organic solids that reduce hydraulic retention time, periodically washout solids in the effluent, and cause odors from H2S production. The primary quick way to remove solids is to mechanically dredge, dewater and landfill these solids. However, this is a big ticket event that many facilities do not have the budget to undertake. Over the years numerous additives and technologies have been proposed to enable microbes to break down organic sludge into carbon dioxide, water, and methane. None has proven particularly effective and dredging has remained the primary way to deal with sludge.
I have been monitoring new technologies for "biodredging" or biological sludge decomposition for years and evaluated numerous new technologies. To be successful, biological dredging requires the following:
For the past twenty years, I have worked in the field of biological waste treatment and have often used bioaugmentation as an operational tool. Similar to adding select yeasts in producing wine or bread, waste treatment professionals can add a "seed" culture to water or soils to supplement the indigenous microbes with beneficial microbes. These beneficial microbes are selected for a number of reasons including:
By adding select cultures to a working waste treatment system, operators can adjust the biomass to meet target treatment goals without the time delay or unexpected results often seen as the indigenous microbes adjust to the environment or changing waste stream.
The bioaugmentation seed culture is developed after laboratory testing and must meet criteria for stabilty, biosafety, and ability to adapt to changing conditions. After selecting the cultures, the individual microbes are grown and stabilized using techniques similar to those used to produce antibiotics and other pharmaceutical compounds. The pure microbes are then stabilized on various carriers for preservation until applied by operators.
Often waste professionals faced with difficult treatment criteria, cost concerns, or a new waste stream find themselves pressured to purchase strange additives. Today I will address one of the most common that I see being marketed to industrial and municipal wastewater professionals.
What I offer is like a "Bug Steroid" - natural extracts and vitamins that make bugs grow faster, degrade more compounds, reduce odors, and produce less sludge. Of course it sounds great, but I am of the curious/scientific type and always ask.... "well how does it actually work?" In this case the answer is almost a uniform... "We don't know the exact mechanisms, but it does what we say it does.... Can I have your purchase order."
I am not suggesting that vitamins and micronutrients cannot increase microbial growth rates and in some cases be necessary for proper function. The most common use of micronutrient additives is in operating anaerobic systems where methane production is often increased by adding rare elements such as Co, Ni, & Mo. Again; before adding micronutrients the system should be examined to see if the additives are needed based on influent characterization.
In addition to anaerobic systems, I have seen adding some micronutrient/vitamin formulations make slight improvements to floc formation and microbial activity in systems with some lacking micronutrients. The most cost effective way to get these micronutrients is not some expensive additive. In my lab tests on pulp mill wastewater, I have found that adding glacial rock powder provides an excellent supply of minerals that can be used by the microbes when needed. With glacial rock powder readily available in 50 lb bags - it is used by organic farmers - you can often solve issues with lacking micronutrients by adding glacial rock at a rate of 5 - 10 pounds per million gallons flow ~ 0.7 - 1.2 parts per million (PPM).
To conclude - There is no such thing as a bug steroid. If you are found lacking micronutrients, add the lowest cost source of these minerals which is often glacial rock or even a metal salt (example magnesium sulfate).
Of course, if someone has a bug steriod and can tell me how it works on a cellular basis, I am willing to evaluate how it can help improve waste treatment.
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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