[USCC] Leachate management - Anaerobic Digestion - Analyses

[Fengyu Wang]

Hi Jérémie Verdier,

To answer your question, here are some simple leachate management ideas for compost world to discuss:

What's the best management with *leachate from green waste composting*?
First of all, try to minimize the generation of the leachate by,
1. Not over water the compost piles, and turn the compost piles within one hour after applied water.
2. Use ComposTex (breathable cover, rain will not go in the piles) during the heavy raining season.

A. Could it generally have a good *fertilizer value?*
Yes. But it may smell bad if you do not get rid of it fast.

And could it have any *negative effects* when spreading to land?
It may have *negative effects* if the leachate have heavy salt content or other contaminations, such as lead. 
It also may *negative effects* to surface and possible ground water if it runs off.
You may need to consult local regulators before spreading.

B. What treatment would you propose before spreading to land? / send it to sewer?
If the leachate is only from compost piles, recommend use it back to the compost piles when water is needed. The fertilizer value will be back to your compost. 
However, you may only use the leachate at the beginning of the compost process, not after the pathogen reduction process, absolutely not during the curing process.

C. Would leachate from any mixed green/Kitchen waste be suitable for Anaerobic Digestion? To produce the electricity for the plant to be self sufficient?
Yes, it is an excellent feedstock for anaerobic digester, especially leachate from food waste.

D. In order to decide, what are the key elements to analyze?
Simple tests would be:
For land application: nutrients, salts, pH and metals.
For Anaerobic digestion: BOD (or Volatile solids), total solids, salts, pH and metals.

Best Regards,

Fengyu Wang
Norcal Waste Systems Inc.
6426 Hay Road
Vacaville, CA 95687
Phone: (707)678-4718 ext.26
Fax: (707)768-5695
Email: fwang at norcalwaste.com




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