Benefits
- ACTIVE DISINFECTION: Kills pathogens by at least six logs (99.9999%)
- Creates a full-stabilised earthy-like final product, which meets the "USEPA Class A" biosolids standard with a commercial value as a fertiliser-aid
- Destroys up to 95% of man-made complex compounds including EDCs and PAHs and eliminates contamination concerns for drinking water
- Resulting in a 70% reduction in biosolids volume (compared to a 40% reduction with conventional aerobic digestion).
- Obtain the above results in 3 to 5 days hydraulic retention time (as opposed to 15 to 30 days with conventional aerobic digestion)
- Obtain the above results while using about 25% less energy than conventional aerobic digestion
OZOLIZ
OZOLIZ is a proprietary method for accelerated aerobic digestion (lysis) of sludge (biosolids) from small and medium-size wastewater treatment plants; provides total disinfection of pathogens while removing the vast majority of man-made anthropogenic compounds and emerging contaminants (CECs).
The vast majority of existing water pollution control plants (WPCPs) use aerobic digestion to treat sludge. Until all of these small to medium-sized plants are upgraded to utilize anaerobic digestion methods with high CAPEX, there is a need for disinfecting aerobically digested sludges so that re-contamination risks can be minimized after disposal.
Innovation
The patented method intermittently applies ozone (O3) into biosolids to destroy a small portion of microorganisms and make them "readily digestible food" for the remaining microorganisms by promoting aerobic digestion. Basically, the process involves cycles of partial microbial destruction with ozone and subsequent aerobic digestion, thereby achieving superior disinfection and producing a highly-stabilized fertilizer substitute.
Summary on the state of the art
The sequentially intermittent method for ozone-assisted aerobic digestion of biosolids is novel and surpasses various "tried" ozone methods for reducing sludge. Biological treatment has utilized ozone for decades; therefore, the incorporation of ozone into a mainstream bioreactor is not new. However, sequentially intermittent ozone application using the OZOLIZ process in an aerobic digester tank is unique and has never been reported before. In addition to this, OZOLIZ is explicitly implemented in the excess sludge (biosolids) digestion reactor, which is separate from the mainstream aeration reactor.
Why should sludge be disinfected?
Biological wastewater treatment produces organic residuals, so-called biosolids. These biosolids contain essential nutrients that, when properly treated, can be used as fertilizer. The EU currently uses only 37% of its treated biosolids for farm land due to an insufficient or non-existent treatment process. Ideally, this waste product can be converted into a sanitized, nutrient-rich, bio-fertilizer that replaces synthetic chemical fertilizers.
Antidepressants have also been found in fish brains in the Great Lakes region (ref: http://aware-simcoe.ca/2017/08/antidepressants-found-in-fish-brains-in-great-lakes-region/) Treatment and disinfection of biosolids before disposal are important to prevent such incidents.
Some municipalities have already implemented premium biosolids treatment processes and produced high-quality biosolids; however, the numbers are limited. For example, A bio-fertilizer product (anaerobically treated) sold by DC Water (Washington, DC, USA) can be purchased by the public for approx. 7.5 $US per cubic yard (10 $US per m3), and they plan to pack and sell the product in small quantities.
Ref: Chris Peot, Director of Resources Recovery, September 2017
Full-Scale Pilot Demonstration
A full-scale demonstration of the patented ozone-assisted aerobic digestion process is necessary to prove its feasibility and performance. Full-scale operating results will validate bench-scale results. Scaling up the technology will demonstrate to potential customers that it will create a nutrient-rich, sanitized, bio-fertilizer product that will safely replace synthetic chemical fertilizers with a comparable commercial value.
When biosolids are returned to farms, they complete a natural food cycle: farm's produce is consumed by humans, who create waste, which, when properly treated, can be used to offset input costs and maximize yields. Soil remediation, horticulture, crop production, sod farming, and other farm applications benefit from this process.
Need for Sludge Disinfection Regulation
As passionate proponents of biological biosolids sanitation and safe biosolids recovery, we are convinced that new biosolids sanitation guidelines are necessary. While disinfection of treated wastewater effluent is strictly regulated, why not legislate disinfection of biosolids before disposal or land application?
For biosolids sanitation, it's time to move from the Biosolids Pathogen and Vector Attraction Reduction Guidelines from two decades ago to a "New Biosolids Disinfection and Safe Reuse Guideline". Technological advances have been made to improve the efficiency and effectiveness of aerobic digestion and anaerobic digestion. In the absence of regulations with incentives or penalties, it seems that no one is adapting these technologies voluntarily. As a result, regulators need to update existing legislation and guidelines to reflect new technologies.
Anthropogenic compounds and contaminants of emerging concern (CECs) aside, pathogen accumulation and subsequent re-activation in sewage sludge storage after conventional aerobic digestion seem to be a significant problem. The following article may also help increase public awareness of the pathogens and other unwanted substances accumulating in biosolids. Further interest in this topic can only spark further research, perhaps leading to a new Biosolids Disinfection Legislation.
Linkedin's article below goes into greater detail regarding why conventional aerobic digestion systems should be improved.
Post COVID-19 Biosolids: Discard or Recover How?
www.linkedin.com/pulse/post-covid-19-biosolids-discard-recover-how-ishin-kaya/
