Biochar from solid fraction of pig manure: Evaluation of phosphorus release rate

Transcription

1 Biochar from solid fraction of pig manure: Evaluation of phosphorus release rate Stéphane Godbout J. H. Palacios, P. Brassard, L. Rochefort, L. Potvin, P. Dubé, J-P Larouche, R. Pouliot and S. Hogue-Hugron Biochars, Composts, and DigestatesInternational Conference October 17 to 20, Bari (Italy)

2 Context In Quebec, before 1998, the manure management plan was based on nitrogen plant demand; End of 90 s, new regulation (Quebec Canada) based on phosphorus; Impact: The amount of manure that can be spread on the soil is restricted by the P fertilization rate; Consequently, in some regions, pig producers were facing an excess of pig manure which must be managed on a different and sustainable way. 2

3 Context Different solutions have been studied; A potential sustainable solution: The separation of the solid and liquid fraction by different means like; In-barn; Mechanical separator; Etc. 3

4 Environmental manure management Raw pig manure Solid fraction Dried solid fraction? Biochar mg P /kg mg P /kg 4

5 Environmental manure management - New biomass; - Compost was not a avenue at that time due to the price relatively low and the saturated market; - After many discussions, we decide to go through an energetic * approach; - But, we need dried biomass (more than 80%) - biodryer; - Pyrolysis was selected to produce energetic products with the dried solid fraction of pig manure (screw reactor); 5

6 Environmental manure management In the first approach, we produced mainly biooil(process reach 63% of biooil 20% of biochar); But quickly biocharsubproductappeared interesting (100% of P in around 20% of initial dried mass) (for the * present study we change process parameters) ;!!Warning: heavy metal like Cu and Zn are also concentrated in this biochar!! This aspect could be an issue when the pig manure is used 6

7 Phosphorusconcentration? Raw pig manure Solid fraction Dried solid fraction Biochar 810 mg P /kg mg P /kg mg P /kg mg P /kg 7

8 Environmental manure management Agronomists and biologists interested by the biochardue to his P concentration and other potential benefit effects (soil composition, water retention, nutrient uptake, crop field, carbon sequestration, N 2 O reduction, etc); * Particularly, peatland restoration research group: Companion plant (polytrichum) need phosphorus (first year) to create ground cover; In second year, no (or less) phosphorus is needed (shagnum no need to add P) 8

9 Could the biochar be used as fertilizer in peatlandrestoration? Could the biocharbe used as fertilizer in rehabilitation projects such as in peatland restoration? Biochar could replace the phosphate rock (usually used * to create ground cover during the restoration process); P needs to be slowly released during first year only; Objective of the study : to determine the release rate of P from biochar of pig manure in peatland conditions. 9

10 Methodology 1 Samples of moss (68 g) were immersed in 100 ml demineralised water and mixed up with biochar (22 g). Crop Sphagnum mosses Medium * Aerobic Anaerobic Temperature 20 C 30 C 20 C 30 C Control samples were prepared with sphagnum moss only (without biochar). 10

11 Methodology P from the aqueous phase was analyzed during 14 weeks (every 2 weeks); 2 Additionally, the total leachable phosphorus from biochar was analyzed by TCLP-1311 method for contaminant materials (ph=2.8 during 18h). 11

12 Composition of the biochar from the solidfraction of pigmanure Characteristic Units Total Raw material (driedsolidfraction) Biochar Dry matter % 87,7 99,5 Ash content % 13,2 32,6 C % 44,2 61,9 H % * 5,4 1,17 N % 3,08 3,66 P mg/kg ph 6,5 10,4 Soluble N-NH 4 mg/kg ,20 N-NO 3 mg/kg 4,29 0,269 P Olsen mg/kg P soluble mg/kg

13 Results P released/ P total (%) 10,0% 8,0% 6,0% 4,0% 2,0% 0,0% * Week Aerobic Aérobie 20 C Aérobie Aerobic 30 C ~1700 to 1900 mg P /kg were released in the first 24 h; No significant effect of the temperature. 13

14 Results P released/ P total (%) 10,0% 8,0% 6,0% 4,0% 2,0% 0,0% * Week Anaerobic Anaérobie 20 C Anaerobic Anaérobie 30 C 1900 to 2000 mg P /kg were released in the first 24 h (representing 7,5% of the P total contained in the biochar); And the temperature as no significant effect (only 4%) 14

15 Results P releasedaccumulated(mg/kg) * Anaerobic 20 C Anaerobic 30 C Aerobic 20 C Aerobic 30 C Week Aérobie 20 C Aérobie 30 C Anaérobie 20 C Anaérobie 30 C P leachable : ~6660 mg / kg biochar or 27% of the initial total P (TCLP-1311 leaching method ph 2.8 Env. Department regulation for pot. contaminant material) 15 30% 20% 10% 0% P released/ P total (%)

16 Results Medium Treatment T P total released (mg P /kg biochar ) P released /P total (%) P released / P leachable (%) P release rate (mg P /weekkg biochar ) Aérobie Anaérobie Sphaigne control Sphaigne + biochar Sphaigne control Sphaigne + biochar 20 C 3,8 ~0,0% 0,1% 0,3 30 C 10,5 ~0,0% 0,2% 0,8 * 20 C ,8% 85,2% C ,5% 84,0% C 13,3 0,1% 0,2% 1,0 30 C 21,2 0,1% 0,3% 1,5 20 C ,1% 93,7% C ,1% 90,3%

17 Conclusions Almost all the content (80 to 94 %) of leachable phosphorus was released in a 14 week period, equivalent to standard growing period were P is needed by companion plant (first year) ; After 14 weeks, the P release rate seems to be very low no phosphorus for the next years; The biocharfrom the solid fraction of pig manure could be used as fertilizer in peatland restoration. 17

18 Conclusions Is the measured release rate ( mg P /kg*week) adequate for the plant demand? (on going study); The optimal doses have to be determined (on going study) Be careful: no long time period study has been done to confirm that no P will be release on a long term base; 18

19 Acknowledgement Quebec environment department and IRDA for the funding; IRDA and L. Rochefort group (U. Laval) staffs; CecilienBerthiaume(barn owner in-barn separation system); All co-authors 19

20 Thankyou? 20