best available technologies for manure treatment - Baltic Green Belt

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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 Best Available Techniques for manure treatment - for intensive rearing of pigs in Baltic Sea Region EU Member States Technical Report "Best Practice Manure Handling, Phase 2" Ref No. 23 Temperature and pressure treatment Brief description Description of the effect on leaching (positive or negative) of N and P Treatment of slurry by raising the temperature to more than 72 degrees shall be made on a number of Danish biogas plants, as this is a veterinary requirement. The slurry is hygienic and at the same time a bigger portion of the organic matter is made accessible to biological degradation afterwards. This can increase the biogas yield if the slurry is subsequently used in biogas plants. A combination of high pressure and high temperature (pressure cooking) has been used for pretreatment of the fibre fraction of separated slurry. By the treatment a hygienic product is made and at the same time higher proportions of cellulose and hemicelluloses is made available for subsequent biological treatment. The process is very energy consuming and ammonia is discharged with the exhaust air and has to be collected, to prevent air pollution. No direct effect. However, the treatment will, in case it is applied to plant fibres, make the anaerobic treatment more efficient because it opens the cell structures so the anaerobic bacteria can digest the substrate more efficiently. It is claimed that the biogas production in this way can be increased with 20 - 60%. A larger part of the N would similarly be converted to the more readily available ammonium N, wherefore the digestate would have relatively higher field effect. As a standalone treatment this form of treatment cannot be recommended but can be beneficial in some cases in combination with biogas plants. The process is also called hygiening in case the treated material is comprised by EU’s Animal Byproducts Directive. Temperature and pressure treatment can be done of biomass substrates with high cellulose and lignin content in order to obtain a higher biogas yield of such fractions. Innovation stage Research Pilot Practice Major references Foged, 2009 Investment price, Basic Variable Operational costs, per tonnes 50.000 (?) - 5 (?) Condition for leaching reduction effect The digestate is used to fertilise crops according a fertiliser plan. Certainty of information Prices Low Effect on leaching High per kg saved N or P leaching Depends on the situation of the individual farm. Complexity of implementation High –this is typically part of a complex livestock manure treatment facility 58 Page 59 58
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 Best Available Techniques for manure treatment - for intensive rearing of pigs in Baltic Sea Region EU Member States Technical Report "Best Practice Manure Handling, Phase 2" Ref No. 24 Adding other chemical to manure, here under enzymes Brief description Description of the effect on leaching (positive or negative) of N and P Under the generic denomination of manure additives are a group of products made up of different compounds that interact with the manure, changing its characteristics and properties. These products are applied to the pig manure in the pits, and the following effects are described to different degrees in the label of every product: 1. a reduction in the emission of several gaseous compounds (NH3 and H2S) 2. a reduction of unpleasant odours 3. a change in the physical properties of the manure to make easier its use 4. an increase in the fertilising value of the manure The effects on leaching in concerning N related with the additive effect on emission on ammonia and other N compounds. Less emission of ammonia emissions means that less N could return as atmospheric deposition and that more N is re-circulated in the agricultural production rather than ending in the environment. The effect on P leaching is associated with the use of additives in processes to separate the manure in fractions, allowing the fibre fraction with a high content of P to be exported to areas with a low livestock density. 5. a stabilisation of pathogen micro-organisms. Usually, the items 2 and 3 are the main reasons for their use at a farm level. Below the techniques 1 – 5 are detailed. 1. Additives for reducing the emission of several gaseous compounds: The decrease in gaseous emissions achieved through its use (mainly NH 3 and H 2 S) is one of the most interesting yet controversial points. It has been well documented that up to 90 % of the N produced by the pigs is as urea. When the urease produced by faecal micro-organisms comes into contact with urea, the following reaction occurs: CO(NH 2 )2 + 3 H 2 O 2 NH 4 + HCO 3 + OH This reaction is highly influenced by temperature and pH, for example, under 10 °C or at a pH below 6.5 the reaction stops. 2. Additives for reducing unpleasant odours: Odour results from the mix of different compounds under anaerobic conditions. More than 200 substances involved have been identified, such as: volatile fatty acids alcohols (indol, skatole, p-cresol, etc) H 2 S and derivatives ammonia other N compounds (amines and mercaptans). There is a huge variation in the proportion and concentration of every substance depending on the type of farm, nutrition and nutritional management, and climatic conditions. This could explain why in many instances the effectiveness of these compounds against odours could not be proven under farm 59 Side 60 59
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