Daniel S. Andersen

Performance of Six Vegetative Treatment Systems for Controlling Runoff from Open Beef Feedlots in Iowa

Beef feedlots of all sizes are looking for more cost-effective solutions for managing feedlot runoff. Vegetative treatment systems (VTSs) are one potential option that has been proposed. Iowa State University (ISU) has monitored the performance of six VTSs on open beef feedlots throughout Iowa since 2006. These feedlots have interim, National Pollution Discharge Elimination System (NPDES) permits that allow the use of VTSs to control and treat feedlot runoff. As part of the permit requirements for these feedlots the effluent volumes, nutrient concentrations, and nutrient masses exiting each component of the VTS were monitored. This paper describes the VTSs and monitoring methods used in this study and evaluates the effectiveness, in terms of both effluent concentration and nutrient mass transport reductions, of each system. During the three-year monitoring period, results have shown that VTSs are capable of reducing the nutrient mass exiting the VTSs by 65 – 99% as compared to a settling basin only system, with performance varying by both site and year. In addition to overall mass transport reductions, nutrient concentrations were also reduced, typically reduced by 50-90%, during treatment. Furthermore, monitoring results have shown a consistent improvement in system performance during the three years of the study. Much of this improvement can be attributed to improved management techniques and system modifications that addressed key performance issues.

Summary of performance data for technologies to control gaseous, odor, and particulate emissions from livestock operations: Air management practices assessment tool (AMPAT)

The livestock and poultry production industry, regulatory agencies, and researchers lack a current, science-based guide and data base for evaluation of air quality mitigation technologies. Data collected from science-based review of mitigation technologies using practical, stakeholders-oriented evaluation criteria to identify knowledge gaps/needs and focuses for future research efforts on technologies and areas with the greatest impact potential is presented in the Literature Database tab on the air management practices tool (AMPAT). The AMPAT is web-based (available at www.agronext.iastate.edu/ampat) and provides an objective overview of mitigation practices best suited to address odor, gaseous, and particulate matter (PM) emissions at livestock operations. The data was compiled into Excel spreadsheets from a literature review of 265 papers was performed to (1) evaluate mitigation technologies performance for emissions of odor, volatile organic compounds (VOCs), ammonia (NH3), hydrogen sulfide (H2S), particulate matter (PM), and greenhouse gases (GHGs) and to (2) inform future research needs.

Impact of system management on vegetative treatment system effluent concentrations

Beef feedlots of all sizes are looking for more cost-effective solutions for managing feedlot runoff. Vegetative treatment systems are one potential option, but require performance evaluation for use on concentrated animal feeding operations. The performance of six vegetative treatment systems on open beef feedlots throughout Iowa was monitored from 2006 through 2009. These feedlots had interim, National Pollution Discharge Elimination System permits that allowed the use of vegetative treatment systems to control and treat runoff from the open feedlots. This manuscript focuses on making within site comparisons, i.e., from year-to-year and component-to-component within a site, to evaluate how management changes and system modifications altered performance. The effectiveness, in terms of effluent concentration reductions, of each system was evaluated; nutrient concentration reductions typically ranged from 60 to 99% during treatment in the vegetative components of the vegetative treatment systems. Monitoring results showed a consistent improvement in system performance during the four years of study. Much of this improvement can be attributed to improved management techniques and system modifications that addressed key performance issues. Specifically, active control of the solid settling basin outlet improved solids retention and allowed the producers to match effluent application rates to the infiltration rate of the vegetative treatment area, reducing the occurrence of effluent release. Additional improvements resulted from system maturation, increased operator experience, and the addition of earthen flow spreaders within the vegetative treatment area to slow flow and provide increased effluent storage within the treatment area, and switching to active management of settling basin effluent release.

Impact of fiber source and feed particle size on swine manure properties related to spontaneous foam formation during anaerobic decomposition

Foam accumulation in deep-pit manure storage facilities is of concern for swine producers because of the logistical and safety-related problems it creates. A feeding trial was performed to evaluate the impact of feed grind size, fiber source, and manure inoculation on foaming characteristics. Animals were fed: (1) C-SBM (corn-soybean meal): (2) C-DDGS (corn-dried distiller grains with solubles); and (3) C-Soybean Hull (corn-soybean meal with soybean hulls) with each diet ground to either fine (374 μm) or coarse (631 μm) particle size. Two sets of 24 pigs were fed and their manure collected. Factors that decreased feed digestibility (larger grind size and increased fiber content) resulted in increased solids loading to the manure, greater foaming characteristics, more particles in the critical particle size range (2-25 μm), and a greater biological activity/potential.

Lab-assay for estimating methane emissions from deep-pit swine manure storages

Methane emission is an important tool in the evaluation of manure management systems due to the potential impact it has on global climate change. Field procedures used for estimating methane emission rates require expensive equipment, are time consuming, and highly variable between farms. The purpose of this paper is to report a simple laboratory procedure for estimating methane emission from stored manure. The test developed was termed a methane production rate (MPR) assay as it provides a short-term biogas production measurement. The MPR assay incubation time is short (3d), requires no sample preparation in terms of inoculation or dilution of manure, is incubated at room temperature, and the manure is kept stationary. These conditions allow for high throughput of samples and were chosen to replicate the conditions within deep-pit manure storages. In brief, an unaltered aliquot of manure was incubated at room temperature for a three-days to assay the current rate of methane being generated by the manure. The results from this assay predict an average methane emission factor of 12.2 ± 8.1 kg CH4 head(-1) yr(-1) per year, or about 5.5 ± 3.7 kg CH4 per finished animal, both of which compare well to literature values of 5.5 ± 1.1 kg CH4 per finished pig for deep-pit systems (Liu et al., 2013). The average methane flux across all sites and months was estimated to be 22 ± 17 mg CH4 m(-2)-min(-1), which is within literature values for deep-pit systems ranging from 0.24 to 63 mg CH4 m(-2)-min(-1) (Park et al., 2006) and similar to the 15 mg CH4 m(-2)-min(-1) estimated by (Zahn et al., 2001).

Physical and Chemical Properties of Runoff Effluent from Beef Feedlots in Iowa

Beef feedlot runoff is a potential environmental contaminant. As such, it should be managed properly to preserve water quality. Primary treatment of feedlot runoff often relies on sedimentation techniques; thus, accurate knowledge of feedlot runoff physical properties is required. This study characterized the physical and chemical properties of runoff effluent from earthen and concrete beef feedlots in Iowa with the objective of providing the necessary information to improve solid settling basin design and performance. Results, although not statistically significant (p = 0.11), indicated that solids in runoff from concrete lots tended to settle more slowly than solids from earthen lots. Particle size distribution and particle density measurements indicated that the poorer settleability of concrete lot runoff was primarily caused by lower particle densities: 1.47 ±0.17 g cm-3 (average ± SD) for concrete lots as compared to 1.89 ±0.11 g cm-3 for earthen lots. Runoff composition was analyzed before and after settling to relate nutrient reduction to solids removal. Results indicated an average of 41 g total Kjeldahl nitrogen per kg total solids and 16 g total phosphorus per kg total solids were removed during settling.

Phosphorus Retention, Accumulation, and Movement in Six Feedlot Runoff Vegetative Treatment Areas

Increased environmental awareness has prompted the need for improved feedlot runoff control. Vegetative treatment systems (VTSs) provide a cost effective option that may enhance environmental security. Vegetative treatment systems are typically designed on the basis of hydraulic performance, which may result in over-application of nutrients, especially phosphorus. This study assessed the retention, accumulation, and movement of phosphorus in vegetative treatment areas used for runoff control on six Iowa feedlots over a four year period. Phosphorus loadings and retention were calculated based on measured settled feedlot effluent, or vegetative infiltration basin, and vegetative treatment area runoff volumes and phosphorus concentrations. Results indicated that between 61 and 89% of all applied phosphorus was retained within the treatment area, resulting in phosphorus loadings of 124 to 358 kg P/ha-yr. Measurements of harvested vegetation phosphorus concentration and yield indicated that between 13 and 61 kg P/ha-yr were removed with vegetation harvest. However, this only accounted for 6 to 13% of all applied phosphorus, which suggests that these systems have potential for rapid phosphorus accumulation in surface soil, which could potentially lead to reduced treatment and loss of soluble phosphorus. Projected soil phosphorus accumulation was compared to annual measurements of soil Melich-3 phosphorus concentrations increases. Both approaches found similar increases in soil phosphorus levels, indicating that the majority of the phosphorus retained in vegetative treatment areas was due to interaction and retention in the surface soil. Deep soil sampling (0 to 122 cm) was utilized to evaluate vertical phosphorus movement of phosphorus through the soil profile. Sampling indicated that most accumulation was in the surface soil, but that signs of vertical transport and leaching were occurring after four years of operation especially near the VTA inlet.

Use of the Soil-Plant-Air-Water Model to Predict Hydraulic Performance of Vegetative Treatment Areas Controlling Open Lot Runoff

Alternative treatment systems to control runoff from open beef feedlots may enhance environmental security and protect water quality. Several Midwestern states have issued National Pollution Discharge Elimination System permits allowing beef feedlots to use vegetative treatment systems (VTSs) to control and treat feedlot runoff. Monitoring VTSs has provided data to validate performance modeling strategies. The objective of this study was to evaluate the ability of the Soil-Plant-Air-Water (SPAW) model to predict the hydraulic performance of vegetative treatment areas (VTAs). Two approaches, one using the field module and the other the pond module of the SPAW model, were investigated. The model results from the SPAW field and pond modules were compared to monitored performance data from five VTAs in Iowa. Modeling statistics were calculated to evaluate SPAWs ability to predict VTA hydraulic performance. Based on the 18 site-years of data collected, the Nash-Sutcliffe efficiency (NSE), percent bias (BIAS), and ratio of the root mean square error to the standard deviation (RSR) were 0.95, 8%, and 0.22, respectively, on an annual basis. The NSE, BIAS, and RSR for the field module were 0.32, 32%, and 0.83, respectively. The results showed that the SPAW model could be used successfully to predict the hydraulic performance of VTAs, with the pond module being more successful than the field module.

Validation of a Low Cost Flow Measurement System for Monitoring Vegetative Treatment System Performance

In 2006, the Iowa Department of Natural Resources issued National Pollution Discharge Elimination System (NPDES) permits to six feedlots participating in research on the use of vegetative treatment systems (VTSs) to control beef feedlot runoff. While Iowa State University monitors releases from the research portion of these sites, the producers are required to monitor releases from the non-research portions. Additionally, non-research site producers with VTSs and NPDES permits are required to monitor system releases. They are required to measure release volume and collect a sample for analysis. Automated, research oriented open channel flow measurement systems typically cost

Vegetated Treatment System Models: Modeled vs. Measured Performance

7,500 to employ. Muhlbauer et. al (2007) developed a low cost monitoring system (LMS) designed to measure open channel flow from a VTS with a total cost of