Kathy P. Moore

Removal of Solids and Major Plant Nutrients from Swine Manure Using a Screw Press Separator

A screw press separator was temporarily installed on a commercial swine farm in Horry County, South Carolina. The separator had a 0.5 mm screen and was operated with a single 40 kg weight on each pressure plate arm. Prediction equations were developed from the data to describe the removal of total solids (TS), total volatile solids (VS), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), ammonium nitrogen (NH4 –N), organic nitrogen (organic–N), and total phosphorus (TP). Separated solids were analyzed to determine the percent total solids and the concentration of major plant nutrients. The concentration of total potassium (TK) in the separator influent and effluent was the same within measurement error. The removal of TS, VS, N, and P was found to vary significantly with the TS concentration of the influent manure. Therefore, building management and the methods used to implement the machine in the manure handling system would have a significant impact on separator performance. The prediction equations were used to calculate separator performance for a typical pit–recharge swine building based on observed characteristics on the cooperator’s farm. The screw press would be capable of removing 14.9% of the TS, 19.6% of the VS, 34.9% of the COD, 9.2% of the TKN, 16.0% of the organic–N, and 14.8% of the TP from the manure added by housed swine.

Using Broiler Litter as an Energy Source: Energy Content and Ash Composition

Broiler farms produce large amounts of litter that is typically spread on nearby cropland or is sold to other farmers for use as a fertilizer substitute. Burning litter biomass to provide energy for space heating in broiler houses or for off-site electric generation has been viewed as an attractive alternative to land application and a source of renewable energy. A large litter sample was obtained from a commercial broiler farm following clean-out to evaluate the energy content, ash yield, and characteristics of ash following combustion. Litter ash was evaluated as a possible lime substitute and fertilizer. The energy content of the broiler litter was 14,425 kJ/kgDM and had an ash content of 24.7% dry basis. Broiler litter ash contained large amounts of Ca and a pH of 11.6, however the calcium carbonate equivalency (CCE) was only 32.4% on a dry basis. It was determined that broiler litter ash should not be used as a liming agent since it would result in excessive application of P2O5, K2O, Cu, Zn, and Na. Small applications of litter ash, on the order of 2 t/ha or less, can provide the P or K needs of a crop and can serve as a source of key micronutrients without application of large amounts of Zn, Cu, or Na. A 1-MW litter fueled electric power plant would provide enough P2O5 in litter ash to fertilize only 1600 ha at a rate of 100 kg P2O5/ha. It was also estimated that only 59% of the electrical generating capacity would be available for use by the distribution system over and above the electricity required by the broiler houses that supply litter to the plant. The amount of litter produced on broiler farms is theoretically adequate to provide enough heat to eliminate the purchase of propane for space heating but is limited by heating system efficiency. The amount of land needed to accommodate the ash from an on-farm litter furnace was estimated to be about 20 ha per broiler house. Many technical and economic obstacles need to be overcome to see large scale use of litter as a source of biomass fuel.

Geotextile Filtration Performance for Lagoon Sludges and Liquid Animal Manures Dewatering

Maintenance and control of liquid levels in anaerobic lagoons and storage ponds is enhanced by pretreatment with liquid-solid separation or periodic removal of accumulated sludges. Until local disposal or nutrient recycling options become available, sludges can be contained, dewatered, and stored using geotextile filtration. A geotextile filtration testing method termed a hanging-bag test was used to treat dairy lagoon sludge, swine lagoon sludge, liquid dairy manure, and liquid swine manure. Hanging-bag performance was evaluated by: (1) determining solids and plant nutrient mass retention efficiencies (MRE), (2) quantifying the overall volume reduction, and (3) characterizing the dewatered manure. After three fill-dewater cycles, geotextile filtration performed similarly for the sludges, retaining an average 87.6% of total solids (TS), 58.4% of total ammoniacal nitrogen (TAN), and 86.7% total phosphorous (TP). Geotextile filtration was also effective in dewatering and concentrating the sludges; by highly concentrating the retained solids, it reduced the total influent sludge volume requiring disposal to less than 18.5%. Despite relatively high MRE values for liquid swine manure (70.2% of TS, 65.1% of TAN, and 75.7% of TP), geotextile filtration was ineffective as a primary liquid-solid separation, with 60.3% of the total influent volume remaining. For liquid dairy manure (TS = 0.71%), geotextile filtration reduced the total influent volume to less than 1%, concentrated the solids and nutrients in the dewatered material 16 to 21 times greater than the influent, and retained 38.4% of TS, 25.8% of TAN, and 45.0% of TP, making this an effective liquid-solid separation technique.

Development of Standardized Fertilizer Recommendations for Corn Grown in the Mid‐Atlantic Region of the United States

Abstract Crop fertilizer recommendations often differ between soil test laboratories operating within a given physiographic region, due to differences in chemical method used, laboratory techniques, soil test interpretation, and philosophy of making recommendations. In 1998, the Mid‐Atlantic Soil Testing and Plant Analysis Work Group, comprised of representatives from government (university/state) and commercial/industrial laboratories, evaluated differences in corn N, P, and K fertilizer recommendations in an effort to achieve more uniformity. For P and K, comparisons were made for four popular extractants at key strategic soil test levels. These levels were 1) the “zero” extractable nutrient level to indicate the maximum amount of fertilizer recommended by each laboratory, 2) the soil test level of no further crop response to applied fertilizer (optimum/maximum yield) to indicate the maintenance fertilizer rate each laboratory was using, and 3) the soil test level above which no further fertilizer would be recommended. The extractable nutrient values each laboratory was using at each strategic soil test level were compared, and then a standard set of strategic soil test levels and fertilizer recommendations were developed. Regarding N recommendations, a range in application rates was selected for an appropriate target yield applicable to soils in the region. These recommendations were designed for gradual implementation by the laboratories in the work group.

Fractionation of Solids, Plant Nutrients, and Carbon as a Result of Screening Broiler Litter

Broiler farms have significant quantities of litter and more environmentally responsible alternatives for its utilization are needed. Treatment of broiler litter by screening will produce two fractions, a screened fraction and a retained fraction. The screened fraction has the potential to have an increased available nitrogen (AN) to P2O5 ratio to meet crop requirements when mixed with an inorganic source of nitrogen. An enhanced carbon-nitrogen ratio may be obtained from the retained fraction, which could possibly provide a more economical substrate for composting. Screening significantly concentrated many constituents in the screened fraction but it did not significantly increase AN:P2O5 ratios. A significantly higher C:N ratio was observed in the retained fraction. A screened litter-34% inorganic N blend could be created to meet the AN:P2O5 requirements of corn. This blend will reduce the amount needed to be hauled and land applied by 72% when compared to untreated broiler litter.

Chemical and Physical Properties of Potting Media Containing Varying Amounts of Composted Poultry Litter

Composted poultry litter (CPL) was obtained from a commercial composting operation in South Carolina. The proprietary recipe included broiler breeder litter, cotton gin trash, and wood shavings. A common base mix for woody ornamentals of 8 parts pine bark and 1 part sand was compared with 3 other mixes that contained 20%, 40%, and 60% compost (v/v). The remaining fraction of these three mixes was the base mix (bark and sand). Samples of the bark and CPL were analyzed to determine the following mineral concentrations: nitrogen (organic and soluble), P2O5, K2O, Ca, S, Mg, Mn, Cu, Zn, and Na. The chemical characteristics of the three compost-based potting mixes was calculated based on a mass basis. The aeration porosity, total porosity, water holding capacity and bulk density of the four mixes were measured using a chamber that was constructed to facilitate measurement of the physical properties of potting media. The results indicated increasing the percentage of compost in potting media caused the desired decrease in aeration porosity, and total porosity. However, volumetric water holding capacity was not significantly influenced by the addition of CPL. Including CPL in potting media created a substantial increase in valuable plant nutrients and minerals. The normalized evaporation rate from the four mixes was measured by placing three replicate pots containing equal volumes of each mix in a room with common temperature and convective conditions. The pots were brought to saturation and were allowed to dry for four days. It was determined that media composition did not affect the evaporation rate, but the addition of CPL increased the mass of water in a pot at all water contents included in the experiment. It was concluded that adding 20% to 40% CPL to a screened bark base mix would provide the majority of the improvements in fertilizer value, physical properties, and mass of water in a container for a growing plant.

Composition of Animal Manure Compost and Utilization Implications

Six compost products were obtained for the purpose of evaluating the plant nutrient, carbon, and organic matter contents. The composts included in the study were a yard waste compost (containing no animal manure), two cow manure based products, mushroom compost (containing manure and straw), and two compost products that contained 25% and 33% separated swine solids. The carbon sources used ranged from wood waste to cotton gin trash. Statistical analysis indicated that the nutrient contents of the compost products were significantly different depending on whether or not animal manure was included in the mix, the type of manure used (cow vs. swine), and the amount of manure included in the mix. The organic matter content (VS/TS) ranged from 0.289 to 0.540 indicating high levels of decomposition. The two products with the lowest organic matter contents (0.289 and 0.366) had the highest values of C:N (18.5 and 24.6), indicating that C:N was not a reliable indicator of compost stability. Nutrient balancing calculations were used to estimate the constituent application rates resulting from the use of the compost products for erosion control blankets, and to provide the pre-plant N, P2O5, and K2O requirements for tomatoes. It was concluded that the amount of compost used in a compost blanket mix should be determined based on the major plant nutrient contents, and the fertilization recommendations for roadside turf. The data and nutrient balancing calculations for tomatoes point out that application recommendations based on a prescribed volume (blanket depth) or mass per unit area (t/ha) are not useful. Instead, compost application rates need to be determined based on analysis of the plant nutrients in a compost product, soil-test results, the nutrient requirements of the crop to be grown, and the amount of material required.

Composition and Settling Characteristics of Milking Center Wastewater: A Case Study

Milking center wastes are often included with manure from the animal housing areas for treatment, storage, and land application. On a grazing dairy, milking center wastewater is often handled independent of other manure generated on farm. Very little data are available on the composition and settling characteristics of milking center wastewater. Large milking center wastewater samples were collected from a storage pit on a grazing dairy farm in South Carolina on two different days. The samples were analyzed to determine the concentrations of the following constituents: TS, VS, TKN, TAN (NH4 +-N, + NH3-N), Org-N, NO3-N, total-P, total-K, Ca, Mg, S, Zn, Cu, Mn, and Na. The large amount of waste milk present on day 2 resulted in significantly higher dry basis concentrations for most constituents than on day 1. In particular, the waste milk introduced 217% more Na, 75% more Ca, and 51% more P. Gravity settling and thickening experiments were performed for the two milking center waste samples (7165 and 17,024 mgTS/L). Gravity settling was effective at removing a fraction of all of the defined constituents. The greatest mass removals were for TS, VS, Org-N, P2O5, S, Cu, and Zn. The mass removal efficiency for the soluble constituents, TAN, K2O, and Na, was a consequence of volume fractionalization and not a change in concentration.

Determination of products of combustion from fires involving solvents commonly carried by rail

Abstract The apparatus and protocols used to determine the semi-volatile products of combustion from controlled laboratory-scale fires are presented. Products of combustion were collected in a sampling train consisting of a filter (heated to 160°C) and Tenax and charcoal sorbent tubes. The Tenax tubes were extracted with cyclohexane and the extracts analyzed. Quantitative measurement of the semi-volatile components was made using gas chromatography/flame ionization detection and identification of the products was performed using gas chromatography/mass spectrometry. The results for sixteen solvents commonly carried by rail are presented.

Determination of rates of product consumption and soot formation during combustion of solvents commonly carried by rail

Abstract A two-phase study of the combustion of solvents carried in large quantity by rail was performed. The first phase involved development of protocol and apparatus for determining the amounts of soot produced and heats of combustion for several commonly carried commodities under varying conditions of oxygen availability. In the second phase, the rate of product consumption, hereafter referred to as the “burnrate“, was measured for solvents under controlled conditions. This paper presents a description of the combustion apparatus, the protocols used and the burnrate data obtained. The possibility of developing a predictive model for burnrate or amount of soot generated based on physical and chemical properties of the solvent is explored.