José R. Bicudo

Upflow biological aerated filters for the treatment of flushed swine manure

Abstract A pilot plant with capacity to treat up to 8 m 3 /day of supernate from settled flushed swine wastes was monitored for 12 months. The main system is composed of two upflow aerated biofilters connected in series. The aerated biofilters, operated under warm weather conditions (average temperature of 27°C), were able to remove about 88% of biochemical oxygen demand (BOD), 75% of chemical oxygen demand (COD), and 82% of total suspended solids (SS) with loading of 5.7 kg COD/m 3 /day of biofilter media. The total Kjeldahl nitrogen (TKN), total ammonia nitrogen (NH 3 -N), and total nitrogen (Total-N) reductions averaged 84%, 94% and 61%, respectively, during warm weather, with a significant portion of the NH 3 -N being converted to nitrite plus nitrate nitrogen (NO 2 +NO 3 -N). At higher organic loading (over 9 kg COD/m 3 /day) during September, the biofilters had only slightly lower percentage removal rates. Operation at lower temperatures (average of 10°C) resulted in lower performances. The COD, TKN, NH 3 -N, and Total-N removal averaged 56%, 49%, 52%, and 29%, respectively, in December through March. The COD mass removal rate was linear with loading rate over the range of approximately 2–12 kg COD/m 3 /day of filter. A mass balance average for the 12 months indicated that about 30% of the influent volume, 35% of Total-N and 60% of total phosphorus (Total-P) are removed with the biofilter backwash. Management and utilization of the backwash are important factors in implementing this type of system on farms. The unaccounted-for nitrogen was about 24% and could have been lost as ammonia volatilization or possibly through denitrification within the biofilm.

AIR QUALITY AND EMISSIONS FROM LIVESTOCK AND POULTRY PRODUCTION/WASTE MANAGEMENT SYSTEMS

The objective of this paper is to summarize the available literature on the concentrations and emissions of odor, ammonia, nitrous oxide, hydrogen sulfide, methane, non-methane volatile organic carbon, dust, and microbial and endotoxin aerosols from livestock and poultry buildings and manure management systems (storage and treatment units). Animal production operations are a source of numerous airborne contaminants including gases, odor, dust, and microorganisms. Gases and odors are generated from livestock and poultry manure decomposition (1) shortly after it is produced, (2) during storage and treatment, and (3) during land application. Particulate matter and dust are primarily composed of feed and animal matter including hair, feathers, and feces. Microorganisms that populate the gastro-intestinal systems of animals are present in freshly excreted manure. Other types of microorganisms colonize the manure during the storage and treatment processes. The generation rates of odor, manure gases, microorganisms, particulates, and other constituents vary with weather, time, species, housing, manure handling system, feed type, and management system. Therefore, predicting the concentrations and emissions of these constituents is extremely difficult. Numerous control strategies are being investigated to reduce the generation of airborne materials. However, airborne contaminants will continue to be generated from livestock and poultry operations even when best management systems and/or mitigation techniques are employed. Livestock and poultry buildings may contain concentrations of contaminants that negatively affect human and animal health. Most of these health concerns are associated with chronic or longterm exposure to gases, dust, or microorganisms. However, acute or short-term exposures to high concentrations of certain constituents can also have a negative effect on both human and animal health. For example, the agitation and pumping of liquid manure inside a livestock building can generate concentrations of hydrogen sulfide that are lethal to humans and animals. Once airborne contaminants are generated they can be emitted from the sources (building, manure storage, manure treatment unit, or cropland) through ventilation systems or by natural (weather) forces. The quantification of emissions or emission rates for gases, odor, dust, and microorganisms from both point sources (buildings) and area sources (beef and dairy cattle feedlot surfaces, manure storage and treatment units and manure applied on cropland) is being intensely researched in the U.S., in many European countries, Japan, and Australia. However, the accurate quantification of emissions is difficult since so many factors (time of year and day, temperature, humidity, wind speed, solar intensity and other weather conditions, ventilation rates, housing type, manure properties or characteristics, and animal species, stocking density, and age) are involved in the generation and dispersion of airborne materials. Furthermore, there are no standardized methods for the collection, measurement and calculation of such constituents, resulting in significant variability and large ranges in the published literature. In fact, emission rates of only a few airborne contaminants have been investigated. Ammonia, hydrogen sulfide, and methane emissions have been more thoroughly studied than other gases and compounds because of the negative environmental impacts or human health concerns associated with them. Unfortunately, there is very little emission data for other contaminants such as odor, nitrous oxide, non-methane volatile organic compounds, dust, and endotoxins. The long-term impacts of these constituents on the environment and on human health are also not known.

NUTRIENT CONTENT AND SLUDGE VOLUMES IN SINGLE-CELL RECYCLE ANAEROBIC SWINE LAGOONS IN NORTH CAROLINA

Fifteen single-stage anaerobic lagoons representing four types of swine production farms (farrow-to-feeder, crossing, farrow-to-finish, and finish) were monitored during two years to evaluate performance. Lagoon liquid and sludge were characterized for all sites. Lagoon loading rates, percent of lagoon volume occupied by sludge, sludge accumulation and age of lagoon at the time of evaluation were determined. The mean annual lagoon liquid Total Kjeldahl Nitrogen (TKN) increased with increase in average daily live animal weight per cubic meter (LAW/m3) of lagoon volume, and the rate of increase depended upon the type of production farm. The monthly supernatant TKN concentration varied as much as 50% over two years for the same lagoon, generally showing a cyclic pattern with highest concentration in mid-summer. Of the nutrient mass contained in the lagoon, about 30% of TKN and more than 90% of Total Phosphorus (Total-P) and volatile solids (VS) were contained in the sludge. The accumulation of TKN and Total-P in the sludge increased linearly with time. Sludge accumulation was found to be impacted both by age of lagoon and loading rate. Based on total sludge accumulated and the age of lagoon, it was determined that sludge accumulated at an approximate rate of 0.003 m3/yr per kg of LAW. This is higher accumulation rate than reported from a study in Missouri, but lower than reported by a study in South Carolina. It is approximately 25% of the value predicted by ASAE Engineering Practice EP 403.2 and ASAE DATA D384.1. Additional data is needed on sludge accumulation rates in swine lagoons and characterization of sludge, especially considering likely changes in swine nutrition to improve nutrient utilization and reduce nitrogen and phosphorus excretion.

GEOTEXTILE COVERS TO REDUCE ODOR AND GAS EMISSIONS FROM SWINE MANURE STORAGE PONDS

Odor, hydrogen sulfide (H2S), ammonia (NH3), and volatile organic compounds (VOC, GC/MS analytes) were measured between May and October 2000, and between April and October 2001 at sites representing three different swine production facilities (8000-head nursery, 2000-head finishing, and 3000-head finishing) in southwestern Minnesota. For each facility type, two farms were tested. The paired farms had similar manure storage ponds, production phases, herd sizes, genetics, and diet formulations. A manure storage pond from each pair of farms was selected as treatment (with geotextile cover, Biocap.), and the other as control (without cover). Results showed reductions in odor, H2S, and NH3 flux rates due to the geotextile cover, but performance in reducing odor and H2S deteriorated during the second year of the study. No significant differences in VOC (GC/MS analytes) emissions from covered and non-covered manure storage ponds were observed during the two-year study. Analysis of ambient H2S data suggested the covers were effective in reducing ambient H2S concentrations near manure storage ponds located at the two finishing units. Odor and gaseous flux rates were poorly correlated with relevant manure parameters (NH3 -N, sulfides, and VOC).

Tangential flow separation and chemical enhancement to recover swine manure solids, nutrients and metals

Abstract A mobile unit of a tangential flow separator (TFS) system was installed at a swine farm. System performance was evaluated through tests conducted on 11 different occasions between February and August of 1997 with flushed wastes and lagoon liquid. The TFS unit consists of a lime slurry tank, a pre-floc mixing tank, a TFS tank, a thickening tank and associated pumps and flow meters with a processing capacity of 110 m3/d. Previously screened wastes were mixed with lime in the pre-floc tank, ferric chloride and polymer injected into the flow after pre-floc tank, and flow introduced to the TFS tank tangentially to the wall, creating a circular motion within the tank. The fluid dynamics tends to concentrate solids to the center of the tank where they settle to the bottom. Approximately 75% of incoming flow are discharged at the top as treated effluent, with reduced organic and nutrient content, and flow to a storage lagoon. The settled solids that accumulate at the bottom of the TFS tank flow into a thickening tank of similar design to the main unit in order to further concentrate the solid material (up to 5% total solids). System performance expressed as percentage reduction is better when flushed wastes are processed compared to lagoon liquid. Total phosphorus (Total-P) removal can be higher than 90% depending on the amount of chemicals used. The system can remove an average of 22% total Kjeldahl nitrogen (TKN), 49% chemical oxygen demand (COD), 50% volatile solids (VS), 82% total suspended solids (TSS) and 87% copper (Cu) and zinc (Zn). Percentage reductions obtained with lagoon liquid are generally lower than with flushed wastes. However, the concentrations in effluent from the TFS system are lower for lagoon liquid than for flushed wastes. Typical concentrations of chemicals are about 2000 mg/l of hydrated lime, 400 mg/l of ferric chloride, and 20 mg/l of polymer. Chemical costs can be significant and must be balanced with improvements in effluent quality and potential economic value of sludge.

Streambank Erosion Associated with Grazing Practices in the Humid Region

The effects of cattle grazing on stream stability have been well documented for the western portion of the U.S., but are lacking for the east. Stream and riparian damage resulting from grazing can include alterations in watershed hydrology, changes to stream morphology, soil compaction and erosion, destruction of vegetation, and water quality impairments. However, few studies have examined the successes of best management practices (BMPs) for mitigating these effects. The objective of this project was to assess the ability of two common BMPs to reduce streambank erosion along a central Kentucky stream. The project site consisted of two replications of three treatments: (1) an alternate water source and a fenced riparian area to exclude cattle from the stream except at a 3.7 m wide stream ford, (2) an alternate water source with free stream access, and (3) free stream access without an alternate water source (i.e., control). Fifty permanent cross-sections were established throughout the project site. Each cross-section was surveyed monthly from April 2002 until November 2003. Results from the project indicated that the incorporation of an alternate water source and/or fenced riparian area did not significantly alter stream cross-sectional area over the treatment reaches. Rather than exhibiting a global effect, cattle activity resulted in streambank erosion in localized areas. As for the riparian exclosures, changes in cross-sectional area varied by location, indicating that localized site differences influenced the processes of aggradation and/or erosion. Hence, riparian recovery within the exclosures from pretreatment grazing practices may require decades, or even intervention (i.e., stream restoration), before a substantial reduction in streambank erosion is noted.

Using a Wind Tunnel to Determine Odor and Gas Fluxes from Manure Surfaces

A standard wind tunnel design for measuring gas fluxes from area sources is needed. This paper documents an attempt to design and test such a wind tunnel. Key parameters evaluated were tunnel wind speed, horizontal and vertical velocity profiles, and filter efficiency. Bulk speed in the wind tunnel can be varied between 0.1 and 1.2 m/s. The velocity profiles in the tunnel are fairly uniform and consistent. The activated charcoal filter on the inlet side of the wind tunnel reduced odor up to 85%, ammonia by 99% and hydrogen sulfide by 99%. Limited data on VOC reductions showed up to 100% reduction in some compounds but increases in other compounds.

Methods of Remote, Continuous Temperature Detection in Beef Cattle

Beef cattle core body temperature (CBT) was remotely and continuously measured over three ambient conditions (Period 1 at 30 °C, Period 2 at 20 °C, and Period 3 at 15 °C) at three sites: rectum, near the tympanic membrane, and peritoneal cavity. Ear surface measurements were taken under the same conditions with a temperature sensor placed on the ventral ear surface and were compared to the CBT measurements. Visual observation of the temperature measurements illustrated similar trends in the ear surface temperature and CBT measurements over time. A differencing method was used create a Temperature Index to detect the onset of fever in cattle. The use of the Index as a threshold showed promise. The animals’ baseline temperatures (Periods 1, 2 and 3) did not intersect this threshold until fever was present. A different threshold value was determined for rectal vs. ear surface temperatures. While promising, this system of detection needs improvements in hardware reliability and convenience before it can be implemented into a production setting.

Influence of BMPs on Cattle Position Preference

The beef industry is an important component of Kentucky’s agriculture accounting for approximately 15% of the state’s agricultural sales in 2000. Dairy also plays a prominent role in Kentucky’s agriculture (state rank of 18th). The state’s significant cattle production occurs primarily on small to mid-sized farms averaging between 25 and 40 head of cattle per operation. Considering this upward trend in cattle production along with Kentucky’s 140,000 km of rivers and streams, rolling pastures and karst geology, the potential for damage to riparian ecosystems from uncontrolled livestock access is high. The objective of this project was to determine the influence of alternate management strategies such as off-stream water, fencing, shade (permanent and movable), and pasture improvements on cattle behavior in grazed pastures of the humid region of the U.S. The project site, located on the University of Kentucky’s Animal Research Center, consisted of two replications of three treatments: control, selected BMPs with free access to the stream, and selected BMPs with limited access to the stream. Cattle placed on the research pastures were fitted with GPS collars to track their positions. The use of GPS collars for tracking animal movements and behaviors eliminates errors often introduced in human observations. GPS collar data was collected at five minute intervals for seven sampling events over a two year period. Results indicated that the BMP systems (i.e. treatments) did not affect cattle position preference, and as such, these BMP systems did not decrease the amount of time cattle spent along the streambanks. However, significant time effects were noted the cooling pasture feature trees as cattle sought relief from the heat and humidity. Increased cattle presence along the streambank during the daytime period was linked to longer day light hours, but the impractical nature of the model indicated that additional independent variables were required. For the nighttime data set, the significant seasonal variable was solar radiation, as decreases in solar radiation resulted in the model predicting that cattle would tend to avoid the pasture feature trees. The majority of non-zero solar radiation values, while relatively small in comparison to the daytime values, were in the periods dividing daytime and nighttime (i.e. dawn and dusk). Thus, the primary driving factor with regards to cattle position preference appeared to be a desire to avoid trees, a pasture feature often associated with loafing, possibly in favor of grazing. While the results of this study indicated that no significant treatment effects were present, the significant time effects suggest that the strategic development of 1) cooling features such as shade, wading ponds or water misters and 2) areas of high forage quality and quantity may influence cattle position preference.

A Two-Year Study of the Effectiveness of Geotextile Covers to Reduce Odor and Gas Emissions from Manure Storages

Odor, hydrogen sulfide (H2S), ammonia (NH3) and volatile organic compounds (VOC) were measured between May and October 2000, and between April and October 2001 at three sites in Southwest Minnesota. Each site consisted of a pair of farms (nursery N1A, N1B; 2,000-head finishing F2A, F2B; 3,000-head finishing F3A, F3B). A manure storage from each pair was selected as treatment, where a geotextile cover (BioCap .) was installed. Results showed that there was a significant deterioration of the performance of geotextile covers in reducing odor and gas emissions from manure storages on the second year of the study. Odor emissions were, in average, reduced by 48% over the two-year period. Emission rates were reduced by 90% in terms of H2S in the first year, but no significant differences were found between covered and non-covered manure storages in 2001. NH3 emissions were, in average, reduced by 44% in 2001. No significant differences in total-VOC emissions from covered and noncovered manure storages were observed during the two-year study. Analysis of the ambient H2S data suggested that the covers were effective in reducing ambient H2S concentrations near manure storages located at the two finishing sites. Odor and gaseous emission rates from all sites were poorly correlated with most manure characteristic parameters (nutrients, solids, organic matter, VOCs).