best available technologies for manure treatment - Baltic Green Belt

Best Available Technologies for manure treatment baltic sea 2020
Best Available Technologies for manure treatment baltic sea 2020
ANNEX E: TABLES WITH SHORT DESPRIPTION OF LIVESTOCK MANURE TREATMENT TECHNOLOGIES
Ref No. 10A Flocculation
Brief description Description of the effect on leaching (positive or negative)
of N and P
Flocculation is often used as a pre-treatment
technology to mechanical separation systems. In the
flocculation process, agents / flocculants aggregate
organic particles / fibres in the liquid manure into
bigger particles, whose size and other physical
properties makes them easier to separate from the
rest.
As flocculants are used for instance clay mineral
betonite (Henriksen at al., 1998). More conventionally
used flocculants are polymers like proprietary cationic
polyacrylamide (PAM). Polymers are often mineral oil
derivates, which according EU legislation is prohibited to spread on fields. Attention should also be given to
the fact that polymers in the nature are broken down to monomers, which can have carcinogen effect.
In case the livestock density in an area is the maximally
allowed according the Nitrates Directive, the application of
livestock manure would typically mean the double of the
needs of the crops concerning P.
By exporting the phosphorus rich fibre fraction to areas
with a low livestock density, an over-fertilisation and
leaching of excess P can be avoided.
Generally, flocculation is thus a technology that makes technologies for mechanical separation more efficient.
Hjorth (2009) reports trials, which shows that polymer flocculation and drainage of pig slurry leads to a fibre
fraction with 29% of the dry matter, 40% of the N, and 90% of the P, as compared to for instance pressurised
filtration, which makes the fibre fraction hold only 14% of the dry matter, 3% of the N and 15% of the P.
Flocculation can increase the amount of nutrients in the fibre fraction, compared to more simple separation
as screw pressing. In cases where it is necessary to reduce the application of P to the fields, the use of
flocculation as a technology would be worth considering. See further explanation at for instance Ref No. 14:
Filter pressing.
Innovation stage
Investment price,
Basic Variable
Operational
costs,
per tonnes
per kg
saved N
or P
leaching
Complexity of implementation
Research
Pilot
Practice
~ 50.000 No data ~ 0,80
Major references Condition for leaching reduction effect Certainty of information
1: Nielsen, 2008
2: European
Commission, 2003
Scenarios II – V Prices Medium
Effect on
leaching
High
Varying
with the
concrete
situation.
Medium
There are several commercial plants/technologies on the
market, which are quite easy to install on the farm,
provided stable systems, storage tanks etc. on the farm
are suitable for this. The investment complexity is fairly
high, due to the pre treatment flocculation typically being
part of a wider manure treatment system, comprising also
mechanical separation.
50
50