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This question was posed by an ALN reader. We asked Shanon D. Jones of BioSAFE Engineering and Christopher Kiley of Merrick to offer information on this chemical process.

By definition, alkaline hydrolysis is a chemical process where the reaction of elevated pH breaks down animal carcasses or cadavers into a liquid form. This process was first recorded in the 1800s by Amos Herbert. His original patent called for elevated temperatures, the addition of 5-10% potash (or other caustic) of the animal weight, and a form of agitation. This is the recipe that current technologies use, however, there are varieties depending on the system selected given the process itself has given way to a small market with several companies providing these systems.

Today’s Technology
In the past, local codes and waste water treatment plant guidelines prevented the use of alkaline hydrolysis in some areas as a means for waste water treatment. However, today’s technology helps address many of these issues.

Previously, the negative effect of using alkaline hydrolysis was the batch discharge into sanitary systems. When discharging older systems, the sanitary system was being hit with the volume of waste now liquefied, containing extremely high levels of BOD. In addition, the waste sometimes contains higher levels of other nutrients, such as phosphates and potassium, which could be difficult for local waste treatment plants to process. There are many more options now available for the removal of the effluent from these systems including; storage for fertilizer, discharge and hold as a solid waste, and discharge to sanitary sewer (possibly through a holding or blending tank to mix with effluent from other parts of a building or campus). Each of these options do present their own unique challenges and must be closely coordinated with the respective local authorities.

The process of converting the carcass into liquid also meant the bones and cellulose would require manual or automated carting off, adding to the complexity of engineering the system into a building. There are a lot of issues that will need to be addressed for any carcass disposal system including; utility infrastructure, waste stream disposal, storage of material and carcasses, throughput of the system, bedding removal, etc. So, the overall point is that while the alkaline hydrolysis process is the chemical decomposition of the animal carcasses, the impact to a facility of using such a system (or any system for carcass disposal) should be taken into consideration.

Over time, this technology has had multiple studies conducted on the efficacy of the process, which has been approved for the inactivation of prions. This testing was originally conducted in Europe and once it was proven to inactivate prions, the process was written into their guidelines as an acceptable method to process contaminated materials, which was followed by USDA, CDC, and NIH guidelines. It is important to request third party testing data from vendors and consult with your team to compare the process recipe with guideline compliancy if selecting alkaline hydrolysis as a means to sterilize and dispose of carcasses.

Leaving you readers with one last note, the process has been proven to be a green method of carcass disposal because the unit is contained in a closed vessel. There is no venting to the atmosphere until the cycle has been completed, and as opposed to incineration, there is no carbon release. Also with the new recipes and internal agitation versions of the system, less water and caustic is used, reducing costs per pound and a significant reduction in time to process.

If You Use It
If you are looking for more information, currently there are a few vendors in the industry that use alkaline hydrolysis. The market has expanded beyond laboratory use of the technology including veterinarian clinic, human cadaver systems in replacement to cremation, hospitals for amputee tissue disposal, and meat and dairy ranches.

When considering the application, always conduct a risk assessment first. Remember, it is a proven chemical process, but does require human interface and stored caustic in itself requires a methodical detailed plan and carries risks which need to be evaluated. Lastly, contact your vendor and get as much information upfront as possible. This will help your team select the type of unit based on regulatory compliancy, recipe design, and sizing.

Our thanks to Shanon D. Jones, Director of Life Sciences, BioSAFE Engineering, www.biosafelifesciences, and Christopher Kiley, PE, Director of Life Science Engineering, Merrick, www.merrick.com, for taking the time to respond to this question.

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