Spring 2021 EN

Biogas Journal
| Spring_2021
English Issue
Thomas Karle explaining
the plant for the recovery of
phosphorous (phosphate)
and other substances.
operation since 2001. The gas
tank has been enlarged several
times, peak power has doubled.
The plant has a total of three
combined heat and power plants
(CHP plants). An ORC turbine to
convert the heat of exhaust gas
into electricity was installed in
the largest CHP in 2019 to increase
efficiency.
The purchase of heat from the
CHP plant has been fully secured
for years, says the director
Thomas Karle. Füßbach itself is
a real bioenergy village and has
been obtaining most of its energy,
electricity and heat from
its biogas plant. There is also a
hall on the company premises in
which grain and other substances
can be dehumidified for a fee.
NADU with a positive life
cycle assessment
Last but not least, the digestates
from the plant are dried there.
The product Agro Energie Hohenlohe
advertises in the Internet
is called “NADU Natural Fertilizer”:
“An innovative fertilizer
from Baden-Wuerttemberg that
is not only good for your plants,
but also for the environment.”
Because of its “positive life cycle
assessment, NADU has received
several sustainability awards! It
is produced by a controlled fermentation
process and is made exclusively out of raw
materials and products.”
The biogas plant in Füßbach differs from many others
when it comes to substrate material for the fermenter.
“Various fractions of animal manure – from cows,
pigs and horses. And added to that, mainly vegetable
by-products, such as grape marc or vegetable waste,”
Karle adds. The bulk of animal manure is provided by
full-time farmers from the small village and from a radius
of three kilometers, the plant remains come from
no more than 17 kilometers of the surrounding area.
Thomas Karle has been promoting the concept of getting
nutrients from land cultivation for a long time now.
“Where does it make sense to place the nutrients outside
of agricultural application?” So far, he has mainly
been trying to respond to this question by using the
NADU gained from the digestate. His involvement may
also be due to the fact that he is the honorary chairman
of Gütegemeinschaft Gärprodukte e.V. (GGG),
which cooperates closely with Fachverband Biogas e.V.
“The problem with the nutrients is exacerbated even
further by the fertilizer ordinance,” says Karle. And
while elsewhere digestate dewatering “usually only
reduces the volume, here something is filtered out, individual
tradable substances,” says the biogas plant
operator enthusiastically. And he points to the huge
plant with numerous containers and machines in what
used to be a pigsty.
NuTriSep – Technology on an industrial
scale
Basically, this system, which was developed by Geltz
and set up in 2019, is an upscaling of the container
prototypes that have already been tested here on an
industrial scale. But there is a small catch: The largescale
plant could process 70,000 tonnes (t) of liquid
per year, but the Agro Energie Biogas plant only has an
annual flow rate of 18,000 tonnes.
In 2019, the VR Banks in Baden-Wuerttemberg awarded
Geltz first prize at the Innovations Awards for the Nu-
TriSep development and the step towards the versatile
industrial scale, which was an achievement for the test
facility that was already in operation in Füßbach at the
time. Since January 2020, Isabella Maier, who works
for Geltz as a product engineer with a master’s degree
in environmental protection engineering, has been able
to demonstrate in real terms on tours of the plant that
the anticipated award was obviously justified. Even if
visitors do not really know straight away what there is to
see. The former pigsty has exactly 30 single units that
are consecutively numbered. Geltz describes this as
follows: “A sequence of several filtration, solution and
precipitation steps to extract nutrients from digestates
and gain uncontaminated residual water with-
Isabella Maier from Geltz Umwelttechnologie holding
various forms of phosphate sludge.
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