Determination of Nutrient Concentrations in Simulated Rainfall-Runoff from Poultry House Dust Deposited Adjacent to Exhaust Fans

Until recently, little attention has been given to the loss of nutrients that may occur in stormwater runoff from poultry houses. Dust emitted from poultry house fans and deposited near the fans has been shown to contain similar amounts of phosphorus (P) and nitrogen (N) as in poultry litter, thus, there is need for information on the potential of runoff to transport deposited dust off-site. The objectives of this study are to quantify P and N in simulated rainfall-runoff from sites immediately adjacent to fans (sidewall and tunnel) from a commercial poultry house in northwest Arkansas. Runoff from fan plots range in total P (TP) and total N (TN) concentration from 1.0 to 26.0 mg·L-1 and from 5.1 to 189 mg·L-1. The concentration of P and N in runoff from plots adjacent to sidewall fans is significantly lower (P < 0.05) during warmer (June to August;1 and 2 mg·L-1 for TP and TN, respectively) than cooler months (November through March;3 and 7 mg·L-1 for TP and TN, respectively). In contrast, TP and TN concentrations of runoff from tunnel fan plots are significantly greater (P < 0.05) during warm (14 and 170 mg·L-1, respectively) than cool months (5 and 60 mg·L-1, respectively). The results of this research indicate that conservation practices are needed around poultry production houses to minimize the potential for runoff of nutrients in emitted dust entering nearby surface waters.

Liming Characteristics of a High-Calcium Dry Flue Gas Desulfurization By-Product and a Class-C Fly Ash

Due to coal’s availability and low cost, coal combustion continues to be the United States’ primary energy source. However, coal combustion produces large quantities of waste material. Some coal combustion by-products (CCBs) have chemical and physical characteristics that make them potentially useful as soil amendments. The objectives of this study were to characterize a relatively new, high-calcium dry flue gas desulfurization (DFGD) by-product and compare its agronomic liming potential to a Class-C fly ash (FA) and reagent-grade calcium carbonate (CaCO3). Calcium car-bonate equivalence (CCE), degree of fineness (DOF), and effective neutralizing value (ENV) for each CCB were determined using standard methods. The CCBs and CaCO3 were also incubated with an acidic (~4.5) clay sub-soil at application rates equiva-lent to 0, 0.5, 1, and 2 times the soil’s lime requirement and compared to an una-mended control. Soil pH was then measured periodically during a 40-day incubation. The ENV of 79.4% for the DFGD by-product and 57.3% for the FA were comparable to those of commercially available liming materials, but were significantly lower (P < 0.05) than that of reagent-grade CaCO3. After 40 days of incubation at the 0.5× ap-plication rate, both CCBs raised the pH of the clay soil to only 5.0, while the CaCO3 raised the pH to 6.5. After 40 days at the 1× rate, all three materials had raised the soil pH to between 6.5 and 7.0, although the FA increased the soil pH more slowly than did the other two materials. At the 2× rate, both CCBs increased the soil pH to between 7.5 and 8.0, while the CaCO3 increased the soil pH to only 7.0. Both CCBs appear to be useful as soil liming materials, although care should be taken to avoid over-application, as this may make the soil too alkaline for optimum plant growth.

Optimizing Hydraulic and Chemical Properties of Iron and Aluminum Byproducts for Use in On-Farm Containment Structures for Phosphorus Removal

Phosphorus (P) transported in runoff from broiler production areas is a potential source for nutrient enrichment of local surface waters. Capturing nutrients prior to runoff leaving the production area could reduce the risk of transport. Commercially available systems for nitrogen (N) and P removal from stormwater are available but too expensive for widespread adoption on small, privately owned farms. The P adsorption capacities and hydraulic conductivities of locally-sourced iron red mud (RM) and aluminum water treatment residual (WT) were determined for potential on-farm treatment use. The byproducts were air-dried and separated into ≤2-, ≤6-, and ≤12.5-mm particle size fractions. Saturated hydraulic conductivity (HC) was determined for each particle-size fraction and results evaluated for the material’s ability to transmit a 25-year, 30-min rainfall of 6.6 cm. While the HC of ≤6-mm particles of each byproduct did not differ (p > 0.05;4.1 and 4.6 cm·min-1), for ≤12.5-mm particles it was greater (p > 0.05) for WT than RM (15.4 and 8.0 cm·min-1, respectively). However, all byproduct size fractions transmitted flow sufficiently to accommodate the baseline storm. Phosphorous adsorption maxima of ≤2-mm fraction for RM and WT were 25 and 10 g·P·kg-1, respectively. Using a solution containing 6 mg·P·L-1, rep-resenting the measured runoff-P concentration from areas adjacent to poultry house ventilation fans, the ≤2-mm fraction of RM removed 98% of added P and WT 84%. The ≤6-mm fraction of RM and WT removed 56% and 57% of added P, respectively, while the ≤12.5-mm fraction adsorbed only 28% and 10%. Results indicate the potential use of low-cost RM and WT byproducts to sequester P in runoff prior to P leaving poultry farm production areas.

Locally Sourced Iron and Aluminum Byproducts Decrease Phosphorus Leached from Broiler House Dust Deposited near Ventilation Fans

Freshwater impairment by eutrophication, as a result of excessive phosphorus (P) inputs from runoff in particular, remains a ubiquitous environmental concern. A common issue with systems designed to remove P and nitrogen (N) from runoff is their reduced effectiveness under high-flow conditions. To over-come this, P removal from broiler-house fan dust would be more effective if removal occurred at the nutrient source, where the water volume is limited to direct rainfall. The P removal efficiencies of different thicknesses of locally sourced, iron-rich red mud (RM) generated during the manufacture of steel belts for tires and alum-based drinking water treatment residual (WT) byproducts were investigated. Byproduct thicknesses of 4, 8, and 12 cm were tested using 57-L leaching columns. The columns were filled with the specified byproduct thickness and a 3-mm thickness of poultry house dust was surface applied prior to receiving six, 30-min simulated rainfalls (at 7 cm·hr-1) at 1-day intervals. The 8-cm thickness of both RM and WT outperformed the other thicknesses in terms of sorbing P released from the added broiler house dust, removing 99 and 96% of the added P, respectively, over the six simulated rainfall events. The 12-cm thickness of both RM and WT showed no additional benefit for P removal over the 8-cm thickness. As the 4-cm-thick WT treatment was less effective (89% of added P removed), the 8-cm thickness was the optimal thickness for field testing. Locally sourced materials with large P-sorbing capacities can offer a convenient, relatively inexpensive alternative for P removal from areas around poultry houses impacted by P-containing, exhausted broiler house dust.

Nutrient Composition of Dust Emitted from Poultry Broiler Houses in Northwest Arkansas

A substantial body of research has been conducted on the potential water quality impairments associated with land application of poultry broiler litter. However, until recently, little attention has focused on the potential for nutrient runoff from dust emitted from broiler production houses despite related air quality concerns raised by the United States (US) Environmental Protection Agency. The objective of this study was to characterize the composition of broiler house dust (BHD) and compare BHD composition to that of broiler litter (BL). Dust composition varied significantly (P < 0.05) among facilities operated by different integrator companies, likely due to differences in feed and house management among integrators. Specifically, BHD pH was lower (P < 0.05) in Facility 1 than in Facilities 2 and 3, which did not differ, whereas BHD K and Ca were greatest (P < 0.05) in Facility 1 and 2, respectively. The facility average moisture content of BHD was at least 1.9 times lower than that for the BL from the same facility. The facility average total phosphorus (TP) and water extractable phosphorus (WEP) concentrations in BHD were at least 1.2 and 1.6 times greater, respectively, than that for BL from the same facility. The greater WEP in BHD than in BL is of particular environmental importance given that extensive research shows WEP to be a major variable influencing P runoff risk. The facility average total nitrogen (TN) concentration in BHD was at least 3.0 times greater than that for BL from the same facility. As TP, WEP, and TN are greater in BHD than in BL, there is a greater risk of nutrient enrichment of runoff from an equivalent mass of BHD than BL. The results of this study highlight the need for careful management of dust emissions from broiler houses and a need for conservation practices to minimize the risk of BHD increasing nutrient runoff and its loss to waters of the US.

Extraction Characteristics of Selenium as Affected by Coal Fly Ash Type, Water Extractant, and Extraction Time

Selenium (Se) contamination can be a potential groundwater concern near un-lined coal ash landfills. Of all the Environmental Protection Agency’s priority and non-priority pollutants, Se has the narrowest concentration range considered beneficial and detrimental for aquatic and terrestrial organisms. The effects of ash type (i.e., fresh and weathered), water-extractant type (i.e., deionized water, rainwater, and groundwater), and extraction time (i.e., 2 and 6 hours) on Se, arsenic (As), and chromium (Cr) concentrations were investigated from Class C, subbituminous coal fly ash produced at the Flint Creek Power Plant (Benton County, AR). Water-extractable Se concentrations differed (p = 0.03) between ash types across water-extractants, but were unaffected (p > 0.05) by extraction times. Unexpectedly, fresh ash water-extractable Se concentrations were below minimum detection limits (i.e., 2.0 μg·L-1) for all treatments. In contrast, averaged over extraction times, the water-extractable Se concentration from weathered ash was greatest (p < 0.05) with groundwater and rainwater, which did not differ and averaged 60.0 μg·L-1, compared to extraction with deionized water (57.6 μg·L-1). Selenite SeO32- was greater (p ·L-1) than in the weathered ash (0.70 mg·kg-1), while selenate SeO42- concentration was greater (p < 0.001) in the weathered (0.67 mg·kg-1) than in fresh ash (0.48 mg·kg-1). Results from this study indicate that environmental weathering of Class C, subbituminous fly ash promotes oxidation of selenite, to the less toxic, but highly mobile selenate. The formation of hydrated ettringite [Ca6Al2(SO4)3(OH)12·26H2O] and calcium selenite (CaSeO3) likely acted as a sink for weathered ash selenite. Implications of this research include a better understanding of the past, present, and future environmental and health risk potential associated with the release of watersoluble Se, As, and Cr to aid in the development of sustainable fly ash management strategies.