Au. Ahmed et Dl. Sorensen, AUTOHEATING AND PATHOGEN DESTRUCTION DURING STORAGE OF DEWATERED BIOSOLIDS WITH MINIMAL MIXING, Water environment research, 69(1), 1997, pp. 81-94
Long-term storage with occasional mixing of biosolids was investigated
for its ability to meet Class A, pathogen destruction requirements fo
r unrestricted beneficial use of biosolids on land as de fined by the
Environmental Protection Agency. Field studies were conducted to evalu
ate the survival of pathogenic bacteria (Salmonella typhimurium, Yersi
nia enterocolitica, and Campylobacter jejuni), and Ascaris suum eggs i
n stored, digested, dewatered, and air-dried wastewater biosolids. Scr
een-enclosed biosolids columns, seeded with the pathogens, were incorp
orated into elongated, triangular biosolids-storage piles established
at five wastewater treatment plants in Utah. Storage piles were either
nonmixed, mixed once a month, or mixed twice a month. Biosolids piles
at the Central Weber wastewater treatment plant that were mixed once
and twice each month were autoheated to 50 degrees C and 57 degrees C,
respectively. Pathogenic organisms were reduced to below detection le
vels in all the piles within a year irrespective of whether the piles
were turned or if autoheated temperatures were attained. Storage time
was most important in the destruction of A. suum eggs.