White Paper | May 13, 2014

A New Paradigm In Aeration Technology: DO2E Capabilities Explained

Source: DO2E

The DO2E organization sprang from one individual’s attempt to solve an aeration problem in a fish hatchery and realizing that his device to do so had many other applications as well. This device broke up algal blooms as well as aerating, and it was only a short step to modify it into breaking up FOG (fats, oils, and grease) deposits in grease traps and lift stations. This device was patented, thus DO2E was born.

The DO2E organization offers a variety of cost-effective devices designed to address aeration and other issues in both water and wastewater treatment as well as in environmental remediation. Following is a general description that applies to many of them, and we shall describe the particular devices as relevant to several applications.

All of these devices contain similar structural design features. All of them are designed to have no moving parts; all of them are air-driven; all of them have electrical components far from the platform that enters the water; and, safety to the operator is of paramount consideration as is current draw for the device as a whole. All of them are constructed of heavy-duty, non-corrodible material, and all of them have within the design parameters the capability of being modified to address particular situations that are encountered.  All of them, furthermore, are oxidizing systems relying primarily on atmospheric oxygen, but all of them can be adapted as well to co-deliver ozone or modified ozone (AOP) or even other gaseous or liquid components as part of a package.

Currently, efforts are underway to extend this technology to introduction of microparticulates into process systems. This may have surprising implications in areas as diverse as biological and environmental remediation and in aquaculture and various related areas. Other areas of our current investigations are fracking fluids, ballast water, and mining wastes.

The first device DO2E introduced was the “Digester”, which was marketed under the name of the Little John Digester™.  It was designated as a “Digester” because it was designed to break up and eliminate FOG deposits in the collection side of the treatment process.  Functionally, it is an aerobic mixer that breaks up deposits (including FOG) into microparticulates, aerates them, and recirculates them so that the particles get ever finer and therefore more reactive — hence the term “Digester”. This results in a pre-digestion step in the collection process as these smaller particles are more reactive because of their increased surface area and rugose (wrinkled/cracked) surface profiles. Although it was designed for grease traps and lift stations for the removal of FOG deposits, it can also be helpful in control of excessive sludge deposits as well as in odor control in some cases.

Because the compounds present in FOG deposits are so recalcitrant to chemical degradation (and, of course, microbial degradation as well), it was incumbent on DO2E to provide a means for removing these microparticulates (pumping them out, that is) so that they would be easily pumpable and would not settle out in the lines.  We understood that charged particulates would remain suspended and would address this particular concern, and we knew that ozone-charged particulates retained their charge for extended periods of time. To that end, we began our “balancing act” of ozonizing just enough to charge the engendered particulates without removing beneficial bacteria from the collection system, and worse yet, affecting downstream microbial populations. By manipulating the type of ozone and the amount provided, we could make these particulates stable in suspension; while, removing odor-causing formation of H2S in the lift stations and grease traps and, to some extent, even in force mains in the collection system.  As these microparticulate suspensions traveled through the collection system, they became increasingly degraded to smaller organic compounds, CO2, and water.  There have been various estimates to what extent this occurs, but we have evaluated several large systems and consider that probably 60 to 65 percent of these particulates are degraded before arrival at the waste treatment plant. These are approximations only as some FOG, as a result of their composition, are more difficult to biologically/chemically digest (decompose) than others.

One realization that we had was that ozone, particularly AOP treatment (ozone + free-radical hydroxyl ions), was able to be applied via the “Digesters” deep within the water column despite the rapid reaction rate with waste species as well as with water.  Because of this, we were able to markedly affect the formation rate of H2S in several situations which had previously been either costly or ineffective to apply.  Ozone (and its AOP iteration) had limitations within the collection system as they also negatively impacted activated sludge; however, there was another device that we developed that was ideally suited to other applications of ozone oxidation.

This device was the aerator. As the “Digesters” utilized different size openings in the air delivery manifold to aerate the wastestream and to power the Venturi that resulted in the microparticulates being formed; so, too, did the aerators with the primary function of them being to create a powerful Venturi draw and a many times increased aeration capacity that had been limited in the “Digesters.” Additionally, more powerful blowers could be employed so that more water could be aerated. The breakup of sludge particulates was a consequence of the increased turbulence from these more powerful blowers and not from the impaction mechanism that were operational in the “Digesters.”  All of the aerators that we manufactured drew in the wastestream at a depth of 46” from the surface as we had determined that this was optimal in managing the “draw” from the Venturi and the cost of the aeration per unit of water treated.

AOP was an important consideration of the aerators as it allowed us to destroy additional compounds that had proven troublesome, including pharmaceuticals, dangerous hydrocarbons, odoriferous compounds that were a nuisance (mercaptans and various other organics), and especially significant was the germicidal affects from aerosols engendered in remediation processes as well as affects on nuisance species contaminating ponds and water reservoirs of various kinds. Most of our aerators have an AOP capability.

However, we make those that employ only atmospheric oxygen as the oxidant.  These are designed for polishing ponds in which a client wishes to utilize environmental microorganisms to accomplish the degradation of wastestreams, and the aerator provides a “boost” in the dissolved oxygen that will allow the aerobic microorganisms to be more efficient while interfering with septicity resulting from anaerobes.

Common Sense And Ozone Regarding DO2E Devices

Pursuant to earlier remarks, we want to clarify what digestion with respect to wastestreams is and what it isn’t.  As the initial remark, digestion is used in the biological (not chemical) sense in that living organisms are involved, which is not the case with chemical digestion.  So, the DO2E “Digesters” are not digesters per se but rather aerobic mixers that facilitate biological digestion. They do this by providing an oxygen source from the atmosphere, which is diatomic oxygen — not ozone.

In so doing, one employing them in a waste treatment system actually uses them in a pre-digestion function so that the BOD5 is reduced within the collection system itself. Therefore, any diminution in BOD5 resulting from these DO2E devices are strictly the result of biological degradation by means of the resident microorganisms that are enhanced from the increased oxygen allowed from these devices.

Ozone, on the other hand, results in a chemical degradation as its presence excludes the organisms necessary for biological degradation.  A mixer equipped with an ozone capability is, by definition, not a “digester,” but rather a deliverer of an oxidizing agent.  Normally, this is used to reduce H2S levels in a wastestream, as an adjunct to stabilize a suspension (at very low levels), or as a method of chemical degradation of very recalcitrant molecular species that are not bio-degradable.

The DO2E devices are quite effective at delivering ozone to these deeper levels and thereby affecting the generation of H2S in wastewater enclosures of various sorts (grease traps, lift stations, wet wells, etc.). Usually, the delivery of ozone comes from a surface source, and this engenders all kinds of problems with equipment as ozone is a premier oxidant and corrodes and destroys over time most plastics, elastomers, polymers (coated surfaces), and metals — even those normally considered refractory to corrosion. 

Fortunately, most sulfides are not particularly soluble in aqueous milieu; the problem results from acidification of the aqueous phase and the concomitant breakdown of the sulfides to toxic H2S gas. This is a major problem in the “oil patch,” particularly in refineries, but is a nuisance problem and potential hazard in municipal wastestreams as well. Ozone and other oxidizers are used for this purpose; but, whatever oxidizer is used, care must be taken to avoid attack on the very microorganisms that are used to remediate the wastestream.  This is a “balancing act” for the most part.

Ozone generation and concomitant effects are always a controversial topic, but let us weigh in here on perspective regarding the so-called half-life of ozone and/or hybrid ozone (AOP) streams.  The half-life of ozone is not the same as a half-life for a radioactive isotope in that the radiation half-life is a fixed value.  The ozone half-life depends solely on the time it takes for the generated ozone to react with the wastestream substrate. This is, of course, highly variable depending on the wastestream’s nature and can vary from milliseconds to minutes depending on the “loading” of the wastestream.  This is of overriding importance as this understanding is crucial in preventing ozone or its degradation products to adversely affect the microbial degradation process.  Hence, the term sizing depends largely on the wastestream contents and flow characteristics.