SUSTAINABILITY OF LAND-APPLICATION OF CLASS B LIQUID BIOSOLIDS
Ian L. Pepper, Director, University of Arizona, Environmental Research Laboratory, USA
(free)
Currently about 60% of all biosolids are land applied in the United States, with most of the land receiving Class B biosolids. Class B biosolids may contain pathogenic viruses, bacteria, protozoan parasites and helminths, and public concern in some areas of the United States has resulted in the banning of Class B biosolids. Much of the concern is due to the limited amount of data on the fate and transport of pathogens after land application. However, indirect routes of exposure such as contact with bioaerosols away from the land application sites, or consumption of groundwater contaminated with pathogens have been evaluated via research conducted at the University of Arizona.
We have also evaluated the overall benefits and risks of biosolids on the soil microbial community
following 20 years of land application of liquid Class B biosolids. Having an agricultural field with a 20
year history of biosolids application provided a unique opportunity for the long-term effects of biosolids on various biological parameters including: soil microbial numbers; microbial diversity; and microbial activity.
KEYWORDS
Biosolids; Fate and Transport of Pathogens; Sustainability of Land Application
