groundswell -reprocessing to manage e-coli result

8/7/2019 Groundswell -Reprocessing to Manage E-coli Result

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i n f o r m a t i o n s h e e t

reprocessing to manage a high E-coli result 

E-coli is a naturally occurring bacteria that is used as an ‘indicator’ species. The idea is that high levelsof E-coli may mean that high levels of other more harmful bacteria may have survived the composting orfermentation process.

The most eective way to ensure E-coli levels in the fnished compost batches are within acceptable thresholdsis to maintain the correct composting process. This means keeping piles wet and covered and monitored ortemperature. It also means spraying with the correct dosages and using non- chlorinated or de-chlorinated waterduring the composting process.

Even with good management o the composting process, it will not be possible to eliminate all E-coli bacteria and

there will always be the chance that a grab sample will show a poor result.

I a sample returns an unsatisactory result ie more than <100 MPN per gram (dry weight), the ollowing remedialprocess should be undertaken:

The pile will be re-covered and allowed to incubate for a further 7 days. After 7 days, new samples will be takenand the sample will be re tested.

I a similar result is ound, the pile will be turned completely and re-inoculated.

Process for re-inoculation:

Prepare inoculants as per normal spraying (see table 1)

For each litre o inoculant, add 1 litre o molasses (see table 1)

Spray diluted inoculant and molasses mix throughout pile.

Add water to the pile until the total moisture level reaches 40% o the weight o the pile

Recover the pile and allow to incubate or a urther 7 days

Ater 7 days, re-test pile or E-coli. Make sure testing methodology prevents cross contamination.

I there is still E-coli contamination ater this (unlikely), the pile should be disposed o at an appropriate acility.

Table 1 Dilution Rates

Feedstock Start Seeding Molasses Water Quantity of culture agent Feedstock

Composting with 1 litre 1litre 2 litres 10 litres For every 10m3 green waste (cubic meters)

Composting with 2 litres 2 litres 4 litres 10 litres For every 10m3 

sewage sludge (cubic meters)

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For updates and more information on the Groundswell project go to: www.groundswellproject.blogspot.com

Written by Simone Dilkara, 2010. Graphic design/illustration by Carolyn Brooks

This work is licensed under the Creative CommonsAttribution 3.0 Unported License and can be reproducedproviding the Groundswell project is acknowledged asthe original source.

The Groundswell Projectwas assisted by the NSWGovernment through itsEnvironmental Trust