Expanding the Feasibility of On-Farm Anaerobic Digestion Operations: An Innovative Application of Thermal-Alkaline Hydrolysis and Combined Digestion and Storage of Livestock Manures

On-farm anaerobic digestion (AD) is an established technology for sustainable manure management that offers farmers the opportunity to produce renewable biogas and reduce the carbon footprint of their operations. Digesters are generally located on large dairy farms, with 250 to 1,000 cattle, that solely digest dairy manure as a liquid slurry or co-digest with commercial organic wastes. Dairy farms are optimal sites for AD because their daily operations meet the requirements of digestion applications: -Dairy manure is typically a low-solids liquid or slurry that is easily digested; -Dairy manure contains minimal bedding like straw or shavings; and -Manure collection occurs daily and can be continually fed to a digester. On-farm AD is less common for other livestock operations as the manure may be considered to be too high in solids, heterogeneous, contain too much cellulo-lignose bedding materials, or manure collection may only occur intermittently, thus inhibiting continuous feed to the digester. Feasibility of on-farm digesters is further dependent on final outlets for biogas utilization. Typically the biogas is used in on-farm operations (dairy farms have larger on-farm demand to power or heat milking operations and general farm buildings), to generate electricity for sale to the local utility, or is upgraded to renewable natural gas (RNG) and injected and sold to a local natural gas pipeline. Lystek's patented Thermal-Alkaline Hydrolysis Process (Lystek THP®) uses high-speed shearing, low-pressure steam heating, and alkali addition of potassium hydroxide within a Reactor to hydrolyze biological cells and particulate organic matter to release water trapped in the organic matrix. This hydrolysis process transforms dewatered or solid feedstocks into a low-viscosity material with liquid properties while maintaining a high total solids content, typically up to 16%. This technology enhances the digestibility of organics through multiple mechanisms: particle size reduction, feedstock homogenization, and solubilization of recalcitrant organic carbon. The hydrolyzed substrate has demonstrated greater digestion kinetics. The application of this technology to improve AD performance has been well demonstrated with biosolids, food and beverage processing residuals, as well as source-separated organics. This technology has been applied in a pre-feed (THP upstream of mesophilic AD), refeed (post-THP with a recirculation loop), and more recently in an innovative combined digestion and storage application. In this passive digestion application hydrolyzed biosolids are intermittently discharged to sealed anaerobic reservoirs, with no supplementary heating or mixing, and anaerobic digestion is efficiently occurring. The purpose of this study is to gain an understanding of how a range of livestock waste feedstocks are transformed using this technology and if/how the AD potential is affected. This research is funded by Natural Resources Canada under the Energy Innovation Program to investigate renewable resource opportunities in rural farming communities. The project has included over 30 samples from a range of livestock types, including dairy and beef cattle, swine, sheep, goats, broiler meat chickens, egg layer hen chickens, and turkeys. The variety of livestock types were selected to generate a large data set that can inform general trends of where this technology is most technically applicable and operationally feasible. All testing and laboratory analysis in the LysteMize Livestock Waste Characterization Study was completed in 2025. This paper will summarize the findings across all livestock manure samples provided and include depth discussion of select feedstocks that were further analyzed in Phase Two of this research. Bench-scale processing demonstrated the ability to transform multiple feedstocks, typically considered to not be operationally feasible for AD, into a liquified slurry with reduced viscosity sufficient for AD. Biochemical methane potential (BMP) testing and characterization was completed to quantify the rate, quantity, and quality of biogas from each sample, comparing the hydrolyzed sample to the unprocessed manure sample. Enhancement of dairy cattle manures is presented below in Figure 1 with average methane generation from materials that have been processed through laboratory-scale hydrolysis compared to unprocessed samples. The dairy manure, a common substrate for on-farm digestion, demonstrated a 70% increase in methane yield on average across the samples collected from two dairy farms with similar infrastructure. The homogeneity of the final manure product after hydrolysis is shown in Figures 2 and 3 to highlight the concentrated nature of the high-solids liquid. Solid dairy manure would typically be considered to have too many large particles, bedding or straw, that would require removal upstream of a conventional digester. The THP process effectively blends the material into a homogenous thickened liquid that is easily pumpable and, therefore, transportable. A critical drawback of conventional AD is that it produces a dilute liquid effluent. While the liquid is rich in nutrients, its dilute nature makes storage and application of the material expensive, operationally cumbersome, and inefficient. The final residual from this application is a concentrated liquid product that can be more efficiently stored and land applied using conventional equipment. Less typical on-farm digestion substrates include poultry manures due to their higher solids content, higher baseline ammonia levels, and infrequent collection methods that are incompatible with conventional AD. Samples from multiple turkey, broiler meat chicken, and egg layer hen chicken were analyzed, with more focus on layer hens as the study progressed to investigate the ammonia effects on digestion. The hydrolyzed, high-solids liquid manure sample in Figures 4 and 5 show a 40% methane yield increase and improved digestion kinetics without inhibitory effects observed from ammonia as high as 5,700 mg/L. Many poultry farms face challenges managing large volumes of solid, nutrient-rich manure. The excessive nitrogen or phosphorous concentrations in poultry manure can limit land application rates to ensure nitrogen or phosphorous limits defined by local agricultural regulations or best management practices are not exceeded. The thickened liquid nature of the hydrolyzed manure product offers opportunities for on-farm digestion to the poultry industry where it was not previously feasible with a solid material, as well as a more convenient manure management strategy that mitigates intensive nutrient concentrations in solid layer hen manure. Co-digestion of poultry manure feedstocks with low-solids liquid cattle and swine manure was also considered in the project to emulate a regional approach to on-farm digestion. This regional approach will further broaden the accessibility for on-farm digestion in rural communities. Solid and liquid manure feedstocks co-processed effectively to generate a homogenous, concentrated liquid feedstock for anaerobic digestion. Preliminary analyses of co-digested animal manures demonstrate comparatively positive increases in methane yield and digestion kinetics as the digestion of these feedstocks independently. A regional, co-digestion approach of various animal manure feedstocks not online increases the scale of the on-farm digestion operations but will optimize processing by increasing the solids concentrations of typically more dilute feedstocks (liquid dairy manure) and dilute high-solids manures with substantial cellulo-lignose concentrations (such as solid poultry manures up to 49%TS). This research demonstrates an increasing scope of size and type of livestock operations whereby AD is an accessible pathway to renewable energy generation via biogas production from manure wastes. Hydrolysis can be used on large cattle farms which have existing anaerobic digestion infrastructure to boost gas production. The THP system also offers other livestock farms with less conventionally digestible feedstocks, such as poultry manure, another approach to AD and biogas collection by transforming the material into a high-solids liquid that can be handled more efficiently. When considering the expanded operational feasibility of on-farm AD, this technology can be easily started and stopped to align with intermittent manure collection activities without losing process efficiency. Conventional digestion requires continuous operation and meticulous care to ensure the health and productivity of the bacterial mass. This technology remains effective with a more hands-off operational approach, which allows discontinuous manure collection methods or smaller scale farms access to digestion technology and energy production without impacts to their major farming activities.