Proceedings available at: http://www.extension.org/67621 Dry-lot feedlot wastes have historically been a challenging feed-stock for digestion due to the dry recalcitrant nature of the waste, and the presence of settleable sand. Leach-bed dry digestion systems could theoretically circumnavigate these difficulties but poor hydraulic conductivities are noted in the literature. In addition to the poor hydraulic conductivities there are often serious problems with system stability and operation. A leach-bed based design which addresses the hydraulic limitations of previous systems and utilizes a multiple process stages to enhance system stability is currently under development. By adding readily available inert shear stabilizers and biodegradable porosity improvers, hydraulic improvements have been demonstrated to be an order of magnitude higher than without the modifications. By utilizing a multiple stage process the liquid leachategenerated from the leachate beds is treated through two stages, the buffering/storage tank and the high rate methanogenic reactor. The buffering tank is a tank for the leachate to reach chemical equilibrium and to store the leachate before it is precisely metered into the methanogenic tank. Within the high rate methanogenic reactor compounds with the leachate are converted into methane which is removed and combusted. This system is demonstrated in a 48’ long refrigeration transport trailer which is essentially energy independent under continuously operation. This system will provide support for the validation of the technology with various wastes and will also serve as a research vessel for the continual optimization of this technology.

1. Demonstration of a Pilot
Scale Leach-bed
Multistage Digester for
Treating Drylot Wastes April 4, 2013
Lucas Loetscher
Sybil Sharvelle
Department of Civil and Environmental Engineering
Colorado State University

2. The Feedstock- Mount Manure

3. Ag/Waste Generation in
Colorado

6. Colorado Manure Wastes % TS
BCMP L CH4/kg
Waste
Dry scrape dairy manure 53.1% 23.2
Freshly horse manure 29.9% 35.2
Dairy/horse manure 31.3% 15.6
Wet scrape dairy manure 18.7% 14.0
Dry scrape dairy manure 88.7% 15.9
Dry scrape dairy manure w/ straw 78.8% 49.5
Diluted dry scrape dairy manure 30.9% 13.7
Highly Variable - Yet Promising BCMP
Manure Waste Characteristics

7. Colorado Manure Wastes % TS
BCMP L CH4/kg
Waste
Dry scrape dairy manure 53.1% 23.2
Freshly horse manure 29.9% 35.2
Dairy/horse manure 31.3% 15.6
Wet scrape dairy manure 18.7% 14.0
Dry scrape dairy manure 88.7% 15.9
Dry scrape dairy manure w/ straw 78.8% 49.5
Diluted dry scrape dairy manure 30.9% 13.7
As excreted most of these manures are below 12% TS
Manure Waste Characteristics

8. Digester Types

9. Colorado Manure Wastes % TS
BCMP L CH4/kg
Waste
Dry scrape dairy manure 53.1% 23.2
Freshly horse manure 29.9% 35.2
Dairy/horse manure 31.3% 15.6
Wet scrape dairy manure 18.7% 14.0
Dry scrape dairy manure 88.7% 15.9
Dry scrape dairy manure w/ straw 78.8% 49.5
Diluted dry scrape dairy manure 30.9% 13.7
As excreted most of these manures are below 12% TS
Manure Waste Characteristics

10. Compositing
Tank
Leachate Bay
Leachate Bay
Leachate Bay
Leachate Bay
Fixed Film
Reactor
Leachate Flow Path
Biogas Flow
Hydrolysis Reactors
Acetogenic Reactor
Hydrolysis Reactors
Methanogenic Reactor
The Proposed Solution

11. Leachate Bay 1
Leachate Bay 2
Leachate Bay 3
Leachate Bay 4
LeachateStorage
WastewaterSource
FixedFilmDigesters
Simplified System Flow

12. Potential System Advantages
 Reduced water requirements
 Substrate flexibility
 Potential for reduced capital costs
 Superior process control
 Process upset is easy to correct

13. Biogas Production for Various
Wastes

14. Pilot Scale System
 Mobile demonstration and research unit
 System Validation on ~1/100 scale
 Provides data on how to scale process
 Able to be self powered and portable

16. Gas System & Generator

17. Power

18. Electrical Panels (2 of 7)

21. Status of Project
 Have filled a single LBR to begin FFR inoculation
 Start operation after 1 month inoculation phase
 Power will be shifted to main panel within the month
 Controls and calibrations to be completed by June
‘13
 Data for scaling the process to be collected by
August ‘13

22. Tentative Plans for Full Scale
System

23. Full Scale Representation

24. Vision for Future Developments

25. Acknowledgments
Colorado Agriculture Experiment Station
Colorado NRCS
Colorado Bioscience Discovery Grant
Colorado Governors Energy Office
Jesse Bergdolt
Bryan Grotz
James Hansen