|AS||Advanced Solids Separation|
|CNG||Compressed Natural Gas|
|DAF||Dissolved Air Flotation|
|MVC||Mechanical Vapor Compression|
|NTU||Nephelometric Turbidity Unit|
|TSS||Total Suspended Solids|
Manure and its associated nutrients can be valuable for crop production when it contributes to meeting plant nutrient needs. However, release of phosphorus (P), nitrogen (N), salts, and pathogens to the environment during manure management can contribute to numerous significant air and water quality concerns (Yorgey et al. 2014). As a result, dairies in many regions of the US are facing increased regulatory pressure (Rieck-Hinz et al. 2012). This is spurring government, industry, and farm interest in improving manure management and recovering manure nutrients through development and implementation of new technologies.
This review summarizes technological approaches to NR appropriate for use with dairy manure, particularly, but not exclusively, dairy effluent from AD. AD treatment changes the form of manure in ways that may be beneficial for some NR approaches, but make other approaches more difficult. Systems combining both AD and NR provide a wealth of environmental benefits beyond NR, including renewable energy or fuel, and reduction in odor, pathogen, and greenhouse gas emissions (US-EPA 2004; US-EPA 2005). More information about the integration of NR and AD may be found in The Dairy Manure Biorefinery (Yorgey et al. in review) and additional publications referenced therein. Thermal renewable energy approaches such as combustion, pyrolysis, hydrothermal carbonization and gasification are also viable technical approaches to both NR and renewable energy production but are beyond the scope of this publication. Additional information on thermal applications can be found elsewhere (e.g., Cantrell et al. 2008, Pelaez-Samaniego et al. 2017).
Throughout this publication, the focus is on classes of approaches, and reference to specific technology providers has been avoided. The publication is therefore meant to provide a broad view of the industry and should not be used for individual technology purchase or investment decisions. For each of the more common technical approaches being used or considered by the dairy industry, this publication aims to summarize important indicators:
- approximate performance and capital (CAPEX) and operating and maintenance (OPEX) expenses,
- co-product form and price, and
- impacts on manure management.