title: Composting process control based on interaction between microbial heat output and temperature.
abstract: Rational composting process control involves the interrelated factors of heat output, temperature, ventilation, and water removal. The heat is released microbially at the expense of organic material; temperature is an effect and, because it is a determinant of microbial activity, it is also a cause of heat output; ventilation supplies oxygen and removes heat, mainly through the vaporization of water; water removal results from heat removal. These relationships were implemented in a field-scale process of static-pile configuration, using a mixture of sewage sludge and wood chips. Heat removal was matched to heat output through a temperature feedback control system, thereby maintaining biologically favorable temperatures. The observations indicate that fundamentally there are two kinds of composting systems: those that are and those that are not temperature self-limiting. The self-limiting system reaches inhibitive temperatures (>60 degrees C) which debilitate the microbial community, suppressing decomposition, heat output, and water removal. In contrast, non-self-limiting temperatures (<60 degrees C) support a robust community, promoting decomposition, heat output, and water removal.
authors.affiliation: Department of Environmental Science, Cook College, Rutgers University, New Brunswick, New Jersey 08903.
authors.forename: S T
authors.initials: ST
authors.lastname: Macgregor
authors.forename: F C
authors.initials: FC
authors.lastname: Miller
authors.forename: K M
authors.initials: KM
authors.lastname: Psarianos
authors.forename: M S
authors.initials: MS
authors.lastname: Finstein