[Digestion] pathogens which might create a health hazard

'Mark Wells' mark at gaiacooperative.com
Thu Jul 14 02:04:14 CDT 2011


Another way to sterilize digester effluent is to dilute with irrigation
water and treat this mixture in shallow 30cm deep high rate algal ponding.  

 

If you don’t stir the ponds you will need a 30 day retention time in the
pond. 

 

If you stir the ponds the retention time drops to 3 to 4 days. Stirring
takes place with an eight fin paddle wheel powered with a mere 200 to 300
watt motor for a typical 500m2 algal raceway (4meter wide paddle wheel).

 

In daylight periods of algal photosynthesis the digester effluent in the
pond will become highly oxidized and the pH will elevate up to levels as
high as pH11, effectively destroying pathogens and cracking viruses. 12
years of rigorous tests at EBRU in South Africa confirm this. 

 

Stirring encourages the growth of non-toxic algae as well as the creation of
algal floccs that enable 70% of the algal biomass to be easily settled out
using simple small settling pond. The nutrient rich oxidized effluent form
the algal ponds can be used for irrigation or for aquaculture, creating a
second cycle of nutrients in zooplankton and fish waste. Aquaculture waste
is perfect for irrigation of aquaponic/hydroponic production of food.

 

Algal biomass is an excellent fertilizer containing plant growth hormones.
Also makes a good foliar feed when the cells are cracked open.

Algal biomass also makes for good biogas production. And recent tests done
by EBRU on the AD of algal biomass indicate a  general improvement of about
10% in biogas production when algal biomass is codigested, as it seems that
the algal biomass makes for healthy and happy AD bacteria.

 

Mark

 

  _____  

From: digestion-bounces at lists.bioenergylists.org
[mailto:digestion-bounces at lists.bioenergylists.org] On Behalf Of Johan
Carels
Sent: 13 July 2011 09:55 PM
To: digestion at lists.bioenergylists.org
Subject: [Digestion] pathogens which might create a health hazard

 

Dear Johan,

Regarding  “pathogens which might create a health hazard. There are reports
on pathogens for man, animal, and plant, which might survive the biogas
process. As  the input material of any biogas plant which is not operated on
a farm level may contain many different types of pathogens you may
accumulate these germs even if they are in a low number in the digestate.”

 

Suggest to pasturise  ( heating at 70°C during 60 minutes)  all the
digestate since you hav e this heat available from the cogenerater [cooling
water, turbocooling, exhaust gase-heat]. This will kill all pathogens.

 

K rgds

Johan Carels

www.jcarels.be

 

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