- Crop Production: nutrient cycling
Disposal of livestock wastewater effluent (LWE) is a costly expense for dairy and hog farmers in New Jersey (NJ). LWE contains high levels of orthophosphate (OP), ammonium (NH4-N), nitrate (NO3-N), total suspended solids (TSS) and biochemical oxygen demand (BOD). These contaminants are regulated by the Clean Water Act, limiting the discharge of untreated LWE into surface water. One approach for disposal of LWE is to release the effluent to the topsoil of crop fields as fertilizer by spraying, a costly addition to the farm production costs. This can contribute to leaching of NO3-N into groundwater, and erosion and deposition of particulate OP to surface waters, with negative environmental impacts. We evaluate a treatment approach for reclaiming LWE using an aerated fluidized bed reactor (AFBR), coupled with constructed wetland treatment (CWT). The first step of the AFBR-CWT process is to precipitate OP and NH4-N as struvite (MgNH4PO4*6H2O) fertilizer from LWE using AFBR. The second step reduces BOD and TSS levels to meet primary wastewater treatment requirements using CWT. Therefore, AFBR-CWT produces fertilizer to grow livestock feeding crops and refurbished water for irrigation. This treatment will reduce operation costs for the small-scale dairy producer and improve sustainability.
Project objectives from proposal:
1. Assessment of LWE properties to determine AFBR-CWT requirements:1. Assessment of LWE properties to determine AFBR-CWT requirements:The study locations: Fulper farm, Hunterdon County and Rutgers New Brunswick (RU-NB) animal science farm, NJ. An on-site study will characterize the LWE, including TSS, BOD and nutrient content, in order to design the most suitable CWT layout.
2. Produce struvite fertilizer for crop production by recycling nutrients from LWE:The AFBR will be used to recover OP and NH4-N from LWE by induced precipitation of struvite, to be recycled on-site as fertilizer. The measurement of success for AFBR treatment is >70% OP removed with >60% struvite content in the precipitated salt for dairy LWE and >90% OP removed with >90% struvite content in the precipitated salt for swine LWE.
3. Implement CWT to meet primary treatment water discharge requirements:While traditional LWE treatment does not contribute to farm water balance, CWT can reclaim the bulk of effluent water for irrigation by removing remaining nutrients and contaminants. The current standard for primary effluent treatment is 30/30 mg/L BOD/TSS. CWT will need to reduce the BOD/TSS concentrations accordingly if the water is to be reused. The assumption is that if a consistent and stable CWT system can be constructed to remove nutrients, BOD/TSS requirements can be attained by expanding the system in a series of CWT structures. The measurement of success for CWT is therefore meeting the effluent discharge requirements, making treated LWE usable for crop irrigation.
4. Industry outreach: Dissemination:The AFBR-CWT method will be promoted by hosting on-site tours of the AFBR-CWT treatment facility for local producers, high school students and researchers at the RU-NB farm site, and by attending agronomy expo events.
5. STEM outreach: Undergraduate student research:To encourage more students to engage in STEM-related sustainability research, undergraduate students will be directly involved in the project. These students will be supported by National Science Foundation (NSF) Research Experiences for Undergraduates (REU), and Garden State-Louis Stokes Alliances for Minority Participation (GS-LSAMP) programs at Rutgers University-Newark (RU-N). The students will conduct on-site research at the RU-NB farm, compile reports, and present results at local conferences.
6. Scientific and public outreach: Publication and presentation:Findings will be published in scientific peer-reviewed journals as part of Mr. Rabinovich’s dissertation. Results will be presented at national meetings, such as the American Chemical Society (ACS) meetings. Presentations at local events will inform the general public.