Monthly Archives: May 2020

Since the Miami-Dade project was dismantled in the late 1990s, research has continued but not as pilot projects. rior research from the 1970s and 1980s demonstrated that high energy electrons can alter the physical properties of wastewater sludge particles, thereby enhancing dewaterability and biodegradability through the action of free radical chemistry (Etzel et al. 1969; Kurucz et al. 1991; Sedlácek et al. 1985; Waite et al. 1997; Wang 1993). This research provided evidence that electron beams can be used to improve sludge quality to expand the ability to produce Class A biosolids for land application. The mechanism is via more consistent inactivation efficiency to eliminate potential human pathogens, a concern that resonates with potable reuse and beneficial reuse of biosolids in areas in contact with people, after NRC (2001) raised issues about resistant microorganisms such as viruses, protozoan cysts, and bacterial spores being applied to land application sites where vegetables are being grown.  The main competition is from advanced thermal oxidation or incineration. Some utilities run a pelletizing plant to turn the material into a granular fertilizer product, such as Millorganite or Green Edge. Another final stabilization process could be composting.

However, this previous work showed that the electron beam processing of wastewater or biosolids has demonstrated a potential to completely mineralize organic constituents of concern including pharmaceuticals, personal care products, endocrine disrupting compounds, pesticide residues, petroleum hydrocarbons, nutrients, toxic metals, nanoparticles, and disinfection byproduct precursors. The mechanism is by direct and indirect action of short-lived but powerful oxidants and reducers induced in the matrix including hydroxyl radical, hydrogen radicals, aqueous electrons, superoxides, peroxy radicals, and ozone, without requiring chemical additives (Cooper et al. 1998). Undesirable halo-carbons found in waste-water can be decomposed by electron beams (Cooper et al 1990). Geiringer and Eschweiler (1996) noted that electron beams would be enhanced by ozone in creating OH radicals. Wang (2015) found it was effective for bromate removal. The E-beam process disinfects with electron beam and stabilizes with oxidants, chlorine dioxide and/or ferrate depending on the intended end use. The process can produce a Class A product that is at a neutral or acidic pH range and is also ideal for the Western United States (Reimers,,2005).  Several studies have proposed that e-beam (EB) processing could be a good method to remove nonbiodegradable pharmaceutical products from waste waters, as these are not efficiently removed by conventional waste water plant treatments (Getoff, 1996; Kimura et al., 2004; Kurucz et al., 1995). Trojanowicz et al (2017) found the electron beam with AOP reduces contaminants of emerging concern.  Slegers and Tilquan (2005) reported the ebeam was effective for removal of metaprolo tartate.  A full scale water treatment facility at a textile manufacturing plan uses an accelerator with three beam to eliminate the residuals from a textile manufacturing plant (Kim, et al 2000, Han et al 2005).

The only western hemisphere project proposed was in Mexico.  This would be the first electron irradiator in Mexico and would focus on sludge treatment at the sewage water treatment plant located north of Toluca in the State of Mexico. This treatment plant is mainly used for domestic wastewater and produces an approximate volume of 70 ton d-1 liquid sewage sludge. The consideration was a 50 kW power of a 10 Mev electron linear accelerator, an irradiation dose of 5 kGy and a treatment capacity of 346 tons per day (Moreno et al 2002), but it is unclear if the facility was installed. These findings open a window for far greater implementation of electron beams.


For example, given that in 2017, there were 14,748 wastewater treatment plants in the United States (ASCE 2017) treating around 32-40 billion gallons of wastewater per day and generating approximately 5.6-7.0 million dry tons per day of treated sewage sludge.  The vast majority of systems (80%) treat less than 1 MGD, but an important fraction (17%) of the wastewater treatment plants in the US treat 1-10 MGD, while over 500 facilities treat between 10-100 MGD and 51 treat over 100 MGD (USEPA 2015). Treatment plants in large US cities such as Miami, Chicago, Dallas, Los Angeles, and Washington D.C. routinely treat between 150-400 MGD. Theoretically, facilities that process more than 100 MGD have the manpower, infrastructure, and budgetary capacity to be able to manage electron beam systems, but to process this amount of flow, the number of accelerators and the electrical power needs would be extremely cumbersome without major innovations in the technology. Opportunities should extend well beyond the treatment of sludge.  Many areas of the country are looking at forms of potable reuse.  It would appear that the electron beam might be a useful tool as a part of the treatment process for potable reuse given its ability to destroy pathogens and emerging contaminants.

Therefore, the target market given the present state of the technology would most likely be the large-sized facilities that treat 10-100 MGD (n ≈ 500).  The costs are high, as are the power demands, but a paper by Meeroff et al (2018) showed that the costs are similar to current treatment technologies, and therefore we should perhaps begin to explore this issue further.



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Today is the Day that America remembers those fallen heroes that fought to protect our freedoms.  Memorial Day is supposed to be a time to reflect on those that made the ultimate sacrifice for our country.  These people, and the many veterans that served with them understood that what was important was protecting our country and our way of life.  Sacrifices needed to be made, and they made them.  It was not easy – no one said it would be.  FDR noted that the only thing we have to fear, is fear itself as we navigated the Great Depression, then WW2, both full of sacrifices at home and abroad.  The overarching goal of protecting our country was more important that the needs of individuals.  Sacrifices the Greatest Generation tried to make sure their descendants never faced.  We have not inherited the mantle and duty to protect the greater “us.”  That is patriotism.

Our expectations of our government have been that our government will protect and uplift us in time of need.  Virtually all government legislation notes that the intent is the protection of the public health, safety and welfare, or something akin to that.  The US Constitution addresses this as well in the first paragraph – “promote the general Welfare.”  Laws and rules are made to reinforce that concept of the greater good.  Likewise, we look to governments in the aftermath of natural disasters, terrorist attacks, etc. to protecting the greater good by bringing much needed help for the greater good.

So, let’s remember the sacrifices that those who have fought for this country have made, let’s remember those sacrifices so they are not in vain.  Likewise, let’s resist recognizing false patriots who’s real agenda is their personal desires, something that our forefathers would view as anti-American, and would view with disgust.

In 1980, Miami-Dade County undertook a major regionalization effort that required expansion of the three major wastewater treatment facilities (South District, Central District, and North District), upgrades to new wastewater disposal solutions, and consolidation of many small-sized treatment plants that were replaced by master lift stations, while expanding service to a rapidly increasing population of 1.6 million people.  At the time, the Central District Wastewater Treatment Facility was generating approximately 100 dry tons of raw sludge per day, which was reduced to about 65 dry tons per day after digestion.  In the 1980s, the County created an alternative solids plan that included use of an electron beam prototype unit procured with 95% funding provided by USEPA. Thus, a pilot-scale electron beam system was installed and operated at the Miami-Dade County Central District Wastewater Treatment Plant in Virginia Key, FL. The installation was designed to achieve pathogen reduction and removal of organic priority pollutants in sludge and wastewater. This system was a 1.5 MeV, 75 kW (50 mA) unit capable of delivering 8.3 kGy at 120 gpm, which was only 0.1% of the plant’s capacity. The beam was scanned out to a window with dimensions of approximately 150 cm × 5 cm (60″ × 2″) in a horizontal configuration that passed through a constant flow over a weir. The wastewater fell by gravity through the electron beam with treatment achieved in less than one second exposure. The efficiency of this system was measured to be 66% (Kurucz et al. 1995).

During pilot testing operations, both pathogens and viruses were evaluated. The anaerobic digestion process generated a product with ~10,000 mg/L of ammonia, which is a concentration that is known to inactivate pathogens and viruses. Spiking sludge with viruses to monitor direct treatment performance was not acceptable with the regulatory agency (Florida Department of Heath). The facility achieved a 5-7 log reduction in bacteria, but it could not demonstrate effectiveness on Ascaris ova because of limited analytical capabilities. Likewise, because there were no viruses in the feed sludge, effectiveness on viruses could not be demonstrated. Similarly, with respect to organic priority pollutants, they were detected consistently but the removal efficiency could not be determined because concentrations were near zero initially and spike tests could not be performed (Cooper et al. 1998; Kurucz et al. 1995).

Laboratory and pilot tests were conducted in 1998-2001 using electron beam treatment of sludge collected from multiple sampling points at this facility (Meeroff et al. 2004). Operational improvements were investigated with respect to bulking control, thickening enhancement, anaerobic stabilization, and dewaterability. Electron beam processing caused permanent effects in measured sludge parameters including solids content, chemical oxygen demand, ammonia-nitrogen, zeta potential, specific surface area, resistance to filtration, sludge volume index, pH, organic acid production during anaerobic digestion, and digester gas evolution and methane content. Findings from sludge parameter analyses indicated that treatment should enhance certain flocculation and settling mechanisms by permanently altering electrokinetic sludge properties, rupturing cells, and increasing biodegradability of recalcitrant material.

For doses higher than 10 kGy, pilot testing generally showed a reversal of dose-response trends indicating undesirable effects. At moderate doses (3-4 kGy), pilot testing demonstrated several benefits:

  • Ammonia nitrogen stayed below toxic levels (<1000 mg/L as N)
  • COD solubilization increased slightly (3%)
  • Surface charge became more neutral by 40%
  • Specific surface area decreased by 30%
  • Resistance to filtration was reduced by 50%

Taken together, these results indicated that treatment induced more efficient compaction and improved filterability; however, the rate of water release did not necessarily show a corresponding improvement, and bench scale settling tests were not sensitive enough to detect any differences, such that surface area requirements and loading rates in settling column studies were not affected, indicating no adverse impacts to sludge thickening. With respect to bulking control, feasibility was deduced from relative inactivation kinetics. Since the indicator filament Sphaerotilus natans (D10 = 0.66 kGy) was inactivated at a lower dose than the bulk flora (D10 = 0.94 kGy), selective elimination of bacterial filaments is possible. In summary, pilot testing results suggest that electron beams will enhance operational efficiency of certain processes within an activated sludge wastewater treatment plant with residuals processing. Analysis of beneficial effects from preliminary studies and pilot tests demonstrate that a dose of 2-3 kGy would be potentially successful for bulking control and to a lesser degree, enhanced thickening and improved anaerobic digestion. A cost analysis based on preliminary tests determined that a centralized electron beam accelerator in an integrated approach could potentially pay for itself at an estimated annual savings of $0.2-2.7 million depending upon the application (Meeroff et al. 2004).

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