Compost SanitationDavid CrohnUniversity of California, Riverside

Thermophilic composting

Compost microorganisms

Illustrations: www.Digitalseed.com

Aerobic processes

Microbes, Microbes, Carbon, Carbon,

& Oxygen& Oxygen Carbon Carbon Dioxide, Dioxide, Water, Water,

Compost, Compost, &&HeatHeat

Thermophilic composting Microbes tend to specialize in the

temperatures they prefer. In California soils and in our bodies mesophiles

are most abundant. Pathogens are mesophiles.

Between 110°F and 155°F, thermophiles dominate.

Above about 160°F dieoff begins. Reliable pathogen kill occurs above 131°F. Heat greatly accelerates microbial efficiency.

Documented outbreaks, 1990 - 2004

CSPI 2006

September 14, 2006

E. coli O157:H7 outbreak announced Nationwide recall of produce packed by Natural Selection Foods More than 200 illnesses

Over 100 hospitalized 31 suffer hemolytic uremic syndrome (acute kidney disease) 3 deaths

Market drop Spinach 41% - $77,000,000 Salad products 8%

Linked to an August 14 spinach harvest in San Benito County A spinach farm located on a cattle ranch The crop was grown organically, but marketed as conventional Had received pelletized chicken compost which received intense

scrutiny

E. coli O157:H7 victims

Kyle Algood, age 2NY Times

Compost? Wildlife? Water?

Cal Dept Health Services and FDA (March 2007):

Compost ruled out

Pathogenic E. coli

E. coli O157:H7 waterborne and foodborne

outbreaks documented bloody diarrhea may cause acute kidney

failure, death Can survive if reintroduced

into compost Low infectious dose

Other pathogenic E. coli “traveler’s diarrhea” transmitted by contaminated

food, water may be minor to severe

November 3, 2006

FDA announces that fresh tomatoes served in restaurants had sickened 183 people in 23 states with Salmonella typhimurium

One of four such outbreaks during the 2005-2006 period

Salmonella

causes diarrhea, fever, cramps 12-72 hours after infection

illness lasts 4-7 days can also cause typhoid fever 40,000 cases reported annually;

1000 deaths annually 0.1% population excretes

Salmonella at a given time most common bacterial

pathogen in wastewater primarily foodborne (beef,

poultry, milk, eggs), but also transmitted by water

Arrows indicate Salmonella cells invading pig epithelium

Survival in the Environment

Depends on: type of

microorganismParasites>viruses>

bacteria temperature

0 10 20 30

Temperature (C)

Ra

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f In

ac

tiv

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Survival of Microorganisms in the Environment

Organism Time

Total coliform bacteria days - weeks

Fecal coliform bacteria days - weeks

Salmonella days - weeks

Shigella days

Enteroviruses months

Rotaviruses months

Giardia months - year

Cryptosporidium months - year

Ascaris years

Title 14 – Sampling – 8 weeks

Glassy winged sharpshooter eggs, Olive fruit fly larvae Compost sampling No pests lasted more than 14 d No pests survive more than 4 d at the 30 and 100 cm depths.

Neither of the pests survived 100 cm after 2 d. Armillaria mellea, Phytophthora cinnamomi, Sclerotinia

sclerotiorum, and Tylenchulus semipenetrans S. sclerotiorum survived at the pile surface and at 10, 30, and

100 cm within the pile for the entire 8 weeks in both fresh green waste (FGW) and aged green waste (AGW).

A. mellea and T. semipenetrans did not survive more than 2 days in FGW,

P. cinnamomi persisted for over 21 days in FGW.

GAP Metrics – Industry standard

“Do not use crop treatments that contain raw manure for lettuce or leafy green produce.”

“Verify that the time and temperature process…” “Maximize the time interval between the crop

treatment application and time to harvest.” “Segregate equipment used for crop treatment

applications or use effective means of equipment sanitation before subsequent use.”

June 2007

Precautionary Principal

Buyer’s attorneys and insurancecompanies hold influence

“Is it possible for compost tovector disease?”

“Is compost absolutely necessary to grow crops?”

“That’s good. One lessthing.”

Title 14 - Sampling

Compost sampling 1 composite sample for each 5000 cu yd Composite of 12 samples from different depths Fecal coliforms (<1000 MPN/dry g) Salmonella (<3 MPN/4 g)

Title 14 - Temperature

Turned windrow – 5 turns over 14 days at 55ºC Monitored at 12 – 24”

Static pile – 3 days at 55ºC with 6 – 12” insulation Monitored at 12 – 18”

Daily readings for every 120’ or 200 cu yds

GAP Metrics – Industry standard

Follow CIWMB requirements for compost process Requires E. coli O157:H7 analysis

Safety

Long track record Not controversial, but regularly investigated Used all over the world without problems Samples do occasionally reveal pathogens Best available alternative Cross-contamination Acute vs. chronic concern

The Seven HACCP Principals

(1) Assess hazards(2) Identify reliable safety measures (Critical Control

Points)(3) Assign acceptable performance parameters

(critical limits)(4) Monitor,(5) Maintain,(6) Verify, and (7) Document program performance.

Critical Control Point (CCP) Identification

CCPs are opportunities to eliminate a

significant hazard Must be both

essential and effective

Urban Yardwaste is a blend of everything green that is disposed of.

Yardwaste recycling is mandated

Dead plants are disposed of in yardwaste

Pathogens reside in dead plants

Composting is not necessarily a part of yardwaste recycling

Pathogen spread in yardwaste products is a concern.

Loading bags with mulch

Arranging bags for the pull dates

Piles are covered with yardwastes

Armillaria mellea, Phytophthora cinnamomi, Sclerotinia sclerotiorum, and Tylenchulus semipenetrans (citrus nematode)