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Abstract "Heft 32"


Freiburger Bodenkundliche Abhandlungen

Schriftenreihe des

Institut für Bodenkunde und Waldernährungslehre
der Albert-Ludwigs-Universität Freiburg i.Br.
Schriftleitung: F. Hädrich


Heft 32


Peter Schalk

Einsatz von Rindenfilterkörpern zur biologischen Güllebehandlung


Freiburg im Breisgau 1993

ISSN 0344-2691


Summary:

The liquid manure of a piggery farm was treated in a trickling fdter process. The pilot plant consisted of an anoxic predenitrification and two postsequent stages of treatment with aerobic trickling filters. Different filter mediums (bark of norway spruce, pine and plastic packing FLOCOR) were tested in three units over a period of several months.

The grinded bark is applicant to a biological filter medium for growing-up the fixed biofilm, to an adsorptive agent and filter material for the compounds of liquid pig manure. The investigations focus to the biological removal of carbon and nitrogen compounds and the adsorptive elimination of phosphorus and postassium.

The biological degradation of BOD and COD achieved in all units an effiency of over 95 %. The nitrogen compounds TKN and ammonia were removed by nitrification and denitrification to a rate of 85 % in the units with bark filter medium and 78 % in the unit with plastic elements. Comparing the removed load within 100 experimental days the units with bark filled trickling filters achieved a purification of carbon and nitrogen compounds which is several times higher than which one of plastic packing. Within the bark filter medium the nitrogen removal is characterized by simultaneous processes of nitrification and denitrification. In combination with the adsorption of buffering compounds of the pig slurry the bark filter preserves a most favourable pH-value (moderate alkaline) for the microbiological processes especially the nitrification.

The use of bark filters is temporary restricted by his degradation and the clogging caused by dry substances of the liquid manure. The trickling filter filled with bark of spruce was saturated after 120 Operation days. The outlet of excess sludge and the application of pine bark increased the Operation permanence to more than 250 days.

The bark biofilter separated the dry substances and removed phosphorus and potassium of the liquid manure by adsorption and biosorption. Twice the total flow of pig slurry than the filter volume the bark filter medium eliminated 55 % phosphorus and 58 % potassium. The exchange of saturated bark material provides an organic substance which is enriched especially with phosphorus and potassium but poor content in nitrogen. The exchanged bark can be spread on agricultural land to improve soil with organic matter.

The liquid manure is purified to a point that the effluent can be recycled as a process water or discarded on agricultural land for irrigation.

To many cases disposable agricultural lands don't suffice any longer for the removal of liquid manure out of animal fattenings. Conifer bark as a filter medium in tnckling filters is applicable to treat the waste liquid manure which cannot be used as a fertilizer without risk of environment pollution.



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