Colorado State University's (CSU) Diagnostic Laboratory (DL), located at the Veterinary Teaching Hospital, diagnoses the causes of animal mortality. Some of the carcasses contain prions, the infectious agents of Transmissible Spongiform Encephalopathies (TSEs.). The DL initially disposes of its mortalities in an alkaline digester, which destroys the infectivity of pathological organisms, including prions, after six hours. The end products of the digestion process are bones and more than 130,000 gallons annually of liquid effluent, an odiferous, alkaline (pH 10) solution of small peptides, amino acids, sugars and soaps, which is also high in potassium from potassium hydroxide used in the digestion process. No satisfactory, economical method exists to directly dispose of the effluent. Research is underway to examine composting the effluent with horse manure mixed with wood shavings, a waste product from the Equine Teaching and Research Center (ETRC) at CSU. The final end product, compost, will be used on the CSU campus as a soil amendment. Five composting mixes, including digester effluent, manure, wood shavings and food wastes from CSU were replicated four times in large composting bins. Laboratory results showed that the compost had acceptable values for pH and soluble salts. The average ratio of total carbon to total nitrogen was 36:1, which is higher than the acceptable range in compost that would be useful on campus. The high level of carbon in the finished compost was due to the high initial levels of carbon in the wood shavings and manure feedstock. Further research will examine how to lower the amount of carbon in the finished compost to an acceptable level by increasing the initial amounts of nitrogen through the use of a higher proportion of digester effluent and food wastes and by exploring other bedding options at the ETRC.