The Pathogen Equivalency Committee (PEC) has recommended PFRP (process to further reduce pathogens) approval to BCR Environmental LLC and its Class A biosolids processing technology known as Neutralizer®.
The PEC is a federally sponsored technical group created by the EPA that provides technical assistance and recommendations on process equivalencies for pathogen reduction in sewage sludge to government and industry. The PEC reviews and makes recommendations to relevant federal and/or state permitting authorities on the merits of applications proposing that innovative or alternative sewage sludge pathogen reduction processes are equivalent to the processes currently listed in the 40 CFR Part 503D regulation.
The Neutralizer® system is a physical, chemical, batch process that incorporates the use of chemistry to generate a Class A biosolids that may be registered as a commercial fertilizer. The system is reported to use >95% less energy than alternative biosolid treatments such as digesters, dryers or incinerators, and lime stabilization. The active chemistry is chlorine dioxide and nitrous acid. The process provides for the disinfection and vector attraction reduction requirements as set forth by the CFR 40, part 503 for generation of Class A biosolids.
The process acquires source material, waste activated sludge (WAS), directly from the secondary clarifier which eliminates the need for standard digesters. The WAS is thickened prior to treatment to achieve a solids content of 3.5-4.0% solids. The thickened WAS is then directed to a continuously mixed batched process tank where it is subjected to the chemistry and treated to Class A standards in less than eight hours.
The chemical treatment is a simple two phase process. During the first chemical phase thickened WAS is dosed with chlorine dioxide and held for one hour. Next, the pH of the process tank is lowered in preparation for the second chemical phase, nitrous acid dosing. The nitrous acid phase is maintained for six hours. At the conclusion of the nitrous acid phase the pH is restored to the pH level desired by the end user of the treated product.
Ferric chloride can be added to the process tank during the process to aid in phosphorus removal from the wastewater treatment plant. After treatment, the process tank is evacuated and the biosolids dewatered by any preferred means of dewatering.
The Neutralizer® process produces a Class A/AA biosolid that may be registered as a commercial fertilizer. The system is designed to have minimal impact on local environmental conditions. It is a "zero-emission" process that takes place within a climate controlled building. The resulting treated biosolids are disinfected and deodorized without exposure to the surrounding environment. Many of BCR's current installations are in close proximity (<300 feet) to residential neighborhoods.
BCR's system relies on simple chemistry rather than on energy intensive treatments such as digesters, dryers, incinerators or gasifiers. The entire process has been designed using individual energy efficient (fractional horsepower) equipment to minimize the need for electricity.
Many WWTPs are having difficulty meeting strict regulatory requirements for phosphorus levels in effluent. By eliminating digestion, the nitrogen and phosphorus return and ammonia loading to the plant is greatly reduced. Additionally, the chemistry of the process binds phosphorus in the biosolid and has proven to be extremely effective at reducing phosphorus levels in the return effluent from dewatering.
Biosolids produced by the Neutralizer process have an extremely low P index (measurement of phosphorous leach-ability). In testing by Penn State University, the Phosphorus Source Coefficient of processed biosolids is 0.1.
System equipment includes a chemical dosing system, disk thickener, batch process tank, SCADA equipment and process control sensors.
The Neutralizer system has been in operation at three facilities in Florida for 3+ years. Two additional facilities are currently under construction. The PFRP recommendation opens the doors for broad adoption of the system throughout the U.S. and provides a basis for worldwide acceptance of BCR Environmental's technologies.
For more information on the system, visit BCR's website at: www.bcrenvironmental.com. WW
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