Distribution of residence time in rotary-drum composting and implications for hygienization

Dayanand Sharma, Ibrahim Saadi, Shlomi Oazana, Ran Lati, Yael Laor

Research output: Contribution to journalArticlepeer-review

Abstract

Rotary drums enable rapid composting compared to static systems. Residence times (RT) of 3–5 days are commonly applied to fulfill sanitary requirements and ensure the initial stabilization of organic matter. Practically, RT distribution (RTD) implies that a portion of the feed is discharged earlier than the mean RT, which may not guarantee safe application of the end product. This study assessed RTD and other physical–chemical and biological parameters of cattle manure and green waste composted in an EcodrumTM rotary drum (∼10 m3). Two types of tracers were used: pieces of plastic tubing and lumps of raw material in which plant seeds were buried, which were packed in nylon socks. A transient-state during which less than 50 % of the drum volume was occupied was distinguished from a steady-state stage, during which the drum operated with its optimal loading of about two-thirds of its volume. Starting temperatures inside the drum were close to ambient when the drum was mostly empty and then increased up to 60–65 °C as the occupied volume approached 50 %. The two types of tracers seemed to provide complementary measurements; under steady-state conditions, actual RTs were 60 % of the mean RT for 10 % of the feed material. The viability of plant seeds which were included in tracers was somewhat dependent on the specific RT. Under transient-state conditions, even shorter RTs (relative to the mean RT) are expected, coupled with non-thermophilic conditions, reducing the likelihood of adequate destruction of pathogens.

Original languageEnglish
Pages (from-to)22-31
Number of pages10
JournalWaste Management
Volume179
DOIs
StatePublished - 30 Apr 2024
Externally publishedYes

Keywords

  • Markers
  • Pathogen elimination/persistence
  • Residence time distribution (RTD)
  • Retention time (RT)
  • Rotation
  • Solid flow
  • Tracers
  • Weed seed viability

ASJC Scopus subject areas

  • Waste Management and Disposal

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