Medical Waste Management at Cornell’s College of Veterinary Medicine

J. Paul Jennette
P.E. Biosafety Engineer
Cornell University College of Veterinary Medicine

In support of its mission to advance animal and human health, the College of Veterinary Medicine incinerates approximately 500,000 pounds of animal remains each year. In addition, the college ships over 100,000 pounds/year of regulated medical waste (RMW) to a commercial RMW management facility in Syracuse for treatment and disposal. Since the mid-1990s, the college has been working with members of the local community (and more recently with the State University Construction Fund) to evaluate waste disposal alternatives in response to concerns about the health impacts of incineration.

For the past two years, we have been working to develop a draft environmental impact statement (DEIS) for a proposal to replace our current medical waste disposal practices with innovative technologies that are safer and more environmentally sound.

What are we proposing?

For animal remains, we are proposing to use a new technology called alkaline hydrolysis, a process by which animal remains are dissolved under conditions of very high temperature, pressure, and pH. The process generates a liquid effluent, or hydrolysate, and solid, calcium-based bone fragments.

For RMW (as well as infectious animal bedding that is currently incinerated), we are proposing to use an advanced application of steam sterilization, the technology commonly used in autoclaves to sterilize medical equipment, surgical supplies, and laboratory wastes. Following treatment, the RMW would be shredded and shipped from the college to a permitted landfill.

What are the differences between the current and proposed methods for treating animal remains?

Fundamentally, incineration converts animal remains into “smoke” and other air emissions, while the alkaline hydrolysis converts remains into hydrolysate liquid. (A relatively small volume of bone fragments also is produced by both technologies). In contrast to the air emissions from incineration, hydrolysate is not discharged directly into the environment without additional treatment. At the existing installations of this technology, which include SUNY Binghamton, Albany Medical Center, Colorado State and University of Florida veterinary colleges, and two USDA facilities, among others, the hydrolysate is discharged to the local sanitary sewer system and treated at sewage treatment plants. We are proposing the same basic approach, except that we would prefer to haul the hydrolysate (about 2,000 gallons, the volume of two residential septic tanks, each day) to the Ithaca Area Wastewater Treatment Facility (IAWWTF) for pretreatment in their anaerobic digestion system. This system, which the IAWWTF uses to treat septage, industrial wastewater, and other high-strength wastes, generates methane from the controlled decomposition of the waste. Methane from the process is, in turn, used to generate heat and electricity for the facility. Effluent from the anaerobic system is then combined with the other wastewater that flows to the plant for treatment and treated a second time (Figure 1).

The Ithaca Area Waste Water Treatment Facility (IAWWTF) would process the hydrolizate byproduct from the Veterinary College using both anaerobic digestion and aerobic treatment processes. The treatment co-generates electricity and heat, used at the IAWWTF

How do we know this is safe?

First, we have the excellent operating history of the other alkaline hydrolysis installations and their corresponding sewage treatment facilities. A good example is at the University of Florida, where the effluent from alkaline hydrolysis units at their Veterinary and Medical Colleges is treated in a small sewage-treatment plant. While the amount of hydrolysate they generate is comparable to what we would generate, the sewage-treatment plant is less than a third the size of the IAWWTF. The effluent from that sewage plant is used for irrigation and groundwater recharge, and treating hydrolysate has not interfered with the plant’s operations.

Second, we (and other institutions and agencies) have performed detailed characterization studies on the hydrolysate generated during a pilot test at the college to assess its chemical composition and have found it to be highly treatable by typical sewage treatment facilities. As part of the development of the environmental impact statement for this project, the project’s consultants have performed an engineering evaluation of the IAWWTF and found it has ample capacity to treat the hydrolysate. In addition, the IAWWTF is currently performing a long-term pilot study to assess the treatability of the hydrolysate in the facility’s anaerobic digestion system. The preliminary results of that study are very encouraging.

Finally, the technology has passed the NYS Department of Health’s rigorous procedures for accepting alternative medical-waste technologies. These procedures include testing the destruction of a variety of microorganisms designed to represent potential pathogens. The process completely destroyed all the microorganisms tested, including giardia cysts and bacillus spores.

What about phosphorous (and other pollutants) getting into Cayuga Lake?

Hydrolysate contains phosphorous and other wastewater constituents commonly found in domestic sewage, but the total contribution of these constituents is relatively low compared to the total amount of wastewater treated at the IAWWTF each day. The increase in the total load on the IAWWTF is very low and well within the plant’s reserve capacity. The total phosphorous (TP) load, for example, from hydrolysate will amount to approximately three pounds per day, less than two percent of the plant’s average TP load of approximately 200 pounds per day. The IAWWTF currently removes 80 to 90 percent of the TP in the wastewater it treats, and planned upgrades to the plant will cut its TP discharges to Cayuga Lake in half. These impacts were studied in detail in the draft environmental impact statement and are being evaluated as part of the ongoing pilot treatability study at the IAWWTF.

What about "Mad Cow Disease?"

Bovine spongiform encephalopathy (BSE), commonly referred to as “mad cow disease,” is one of a class of fatal degenerative disorders that includes Creutzfeld-Jacolb disease (CJD) in humans, scrapie in sheep, and chronic wasting disease in deer and elk. These transmissible spongiform encephalopathies are caused by microscopic agents known as prions, which are highly resistant to many conventional treatment technologies. Because of the threat posed by these agents, the ability of treatment technologies to inactivate prions has been a key factor in the efforts to evaluate alternatives for the college. Only two available technologies are believed to inactivate prions — incineration and alkaline hydrolysis. Alkaline hydrolysis meets or exceeds the conditions established by the World Health Organization for prion inactivation. In addition, the (thus-far positive) results of a direct test using commercial alkaline hydrolysis equipment to inactivate prions at the UK Neuropathogenesis Laboratory will be published this spring.

Consequently, we are confident that if animal remains infected with “mad cow disease” or any other prion-based disease are treated at the college, any prions (along with any other infectious agent) will be inactivated before the resulting hydrolysate leaves our facility.

Are there any alternatives for animal remains?

Alternative methods for treating animal remains have been studied at length by Cornell, community members, and other agencies. For treating large quantities of animal remains, especially those from farm animals, there are only two other options appropriate to an institution like Cornell. Pressure rendering, an application of steam sterilization for bulk treatment of animal remains, is used at three institutions worldwide. This technology is limited, primarily, by its inability to destroy the agents that cause “mad cow disease ” and its inability to treat intact remains of farm animals. The other alternative is incineration.

What’s next?

The college hosted two public information sessions on the project this February. Members of the community were invited to learn about and share views on the project. The formal public review of the draft environmental impact statement began immediately thereafter and will conclude with a public hearing in mid-April. Pending final approval of the draft environmental impact statement, design of the new facility will take place this year, and, after an approximately two-year construction period, validation and startup of the new facility is expected in early 2005.