This is a past event.

Environmental Engineering Graduate Seminar

Karina Eyre, Environmental Engineering MS Student,  Michigan Technological University

Abstract:

In the United States, Class A biosolids are produced at water resource recovery facilities (WRRF) and treated to reduce pathogens sufficiently to allow for unrestricted land application. Class B biosolids are also treated to reduce pathogens, but to a lesser degree, and they do not have to meet guidelines for parasitic worm (helminth) ova and enteric viruses. Consequently, there are restrictions on access to, and use of, land on which Class B biosolids are applied, and many WRRFs are seeking to upgrade to Class A biosolids treatment. Pilot scale studies were conducted at two WRRFs in the upper peninsula of Michigan to: (1) determine if additional treatment of Class B biosolids via long term storage followed by air drying could be used to achieve Class A requirements for pathogen inactivation and (2) identify the pathogen inactivation mechanisms. Anaerobically digested and dewatered biosolids were stored in triplicate indoor and outdoor test beds for one or two years, and then formed into windrows and turned twice a week. Key physical and chemical parameters were measured to evaluate their effects on pathogen inactivation. Ambient weather conditions and biosolids temperature were also monitored. Attenuated human poliovirus and iable Ascaris ova were used as indicators for enteric virus and helminth ova, respectively, and fecal coliform bacteria were also monitored. Significant differences emerged in the physical and chemical properties of biosolids stored indoors and outdoors. Class A fecal coliform levels were achieved; however, the potential for regrowth is of concern after significant precipitation. Viable Ascaris levels decreased, particularly during the summer, but more than one year of storage will be required to achieve Class A helminth standards in northern climates. Volatile acids and competition from indigenous organisms may have contributed to Ascaris ova inactivation. Nitrification of biosolids ammonia and low pH levels meant that unionized ammonia likely did not contribute to pathogen inactivation.

Bio:

Karina is a second year master’s student in Environmental Engineering at Michigan Technological University. She graduated from the University of Idaho with a Bachelor’s Degree in Civil Engineering in spring of 2017. Her studies have focused on municipal wastewater treatment, and she participated in undergraduate research in biological phosphorus removal before moving to sustainable biosolids treatment research for her graduate degree. She was certified an engineer in training in 2017 and plans to enter the consulting field in water and wastewater engineering after completing her Master’s degree in spring 2019.