Liquid Animal Manure Research Articles

Effect of anaerobic digestion on odor and ammonia emission from land-applied cattle manure

High ammonia (NH3) and odor emission can occur after land application of liquid animal manure. This study was aimed at evaluating NH3 loss and odor nuisance after field application of cattle manure and how it is affected by two anaerobic digestion strategies: i) digestion of cattle manure alone and ii) digestion with catch crops and dilution by water. A system of dynamic chambers with online measurements of NH3 and odorous compounds (summarized as odor activity value, OAV) was used. Two experiments were conducted under different temperature conditions. The results demonstrated that anaerobic digestion did not affect NH3 loss but did decrease OAV. Addition of catch crops and water to the digestion process reduced both NH3 loss and OAV. Cool temperature in one of the experiments had a large effect on both NH3 and odor emissions, and at high temperature the differences between treatments increased.

Changes in carbon and phosphorus storages and humic substances in a Ferralsol, after tillage and animal manures applications

The evaluation of the dynamics of storage and loss of soil organic carbon (OC) and available phosphorus, associated with humic substances, in areas under no-tillage (NT) that receive solid or liquid animal manure, has been little reported in the literature. This study aimed to evaluate the effect of different doses of liquid (liquid swine slurry) and solid (poultry manure) animal manures on OC and available phosphorus (PAV.) storages and humic substances (fulvic and humic acids, and humin) of a Ferralsol recently managed under a no-tillage system (four years). The experiment was carried out in a very clay Ferralsol. Two periods were sampled: in 2011, before tillage for incorporation of chemical fertilizer (CF) and start of the NT system, and in 2015, after four years of NT management and animal manure applications. Poultry manure (PM) and liquid swine slurry (LSS) were applied in three rates as follows: 2.00, 5.00, and 8.00 t ha−1 of PM and 45.00, 90.00, and 135.00 m3 ha−1 of LSS semi-annually applied without CF complementation. The CF was used as a reference. The use of LSS recovered the OC content of the 0.00–0.10 m depth at levels similar to those observed in 2011, indicating the interaction of the liquid form with the soil. The similarity of humic substance between CF and animal manures of the 0.00–0.10 and 0.10–0.20 m depths was mainly due to LSS use, which contents of fulvic and humic acids were significantly higher than those observed in the soil that received PM. Although the use of the LSS increased the SOC content, no difference in storage was observed among the treatments. Soil tillage for NT system start and CF use resulted in a PAV storage loss of − 2 kg ha−1 yr−1 in 0.10–0.20 m depth from 2011 to 2015. The LSS promoted PAV. sequestration of up to 33.50 Kg ha−1 yr−1 at 0.00–0.10 m depth and 19.93 Kg ha−1 yr−1 at 0.10–0.20 m depth. The LSS was more effective in increasing PAV. storage at the two soil depths compared to CF and PM. The fulvic and humic acids were more than two times higher in LSS than in the PM applications at 00.00–0.10 and 0.10–0.20 m depths. Thus, the liquid form has a greater potential to recover OC content and PAV storage after short-term of NT start (four years), indicating that it is more suitable for the recovery of Ferralsols recently tillage or degraded.

Effect of storage and field acidification on emissions of NH3, NMVOC, and odour from field applied slurry in winter conditions

Land spreading of liquid animal manure (slurry) is a major source of atmospheric emissions. Ammonia (NH3) emission is of concern, as it is one of the main contributors to ambient air pollution and nitrogen deposition. Storage and field acidification of the slurry prior to application is used to mitigate NH3 emission, but the effect of acidification on emissions of odorous non-methane volatile organic compounds (NMVOC) has not been investigated, and there is a scarcity of data investigating the effect of field acidification. Four field experiments, two with cattle slurry and two with pig slurry, were performed. Ammonia and NMVOC emissions were measured simultaneously in a system of dynamic chambers and online measurements by cavity ring-down spectroscopy (CRDS) and proton-transfer-reaction mass spectrometry (PTR-MS). The system allowed for a high time resolution and low variation. All four experiments were performed under cold conditions (<10°C average temperature). Storage and field acidification significantly lowered the NH3 emission by 79 ± 18% and 30 ± 6% on average, respectively. The NMVOC cumulative emission increased by 202 ± 133% and 17 ± 16% on average after storage and field acidification, respectively, even if the increase was only significant for storage acidification. Storage acidification significantly increased the emissions of odour at most measuring times. The increases of cumulative NMVOC emissions and odour was primarily caused by higher emissions of volatile fatty acids.

Response of subsurface C and N stocks dominates the whole-soil profile response to agricultural management practices in a cool, humid climate

Subsoil contains about half of the soil organic carbon (C) at the global scale. However, C and nitrogen (N) in the subsoil are assumed to be relatively stable, and their response to agricultural management practices is uncertain. This study compared the effect of 20 different management systems, combining two tillage regimes (inversion tillage vs minimum tillage), two crop residue managements (retained vs harvested) and five different fertilizer sources (liquid swine manure, liquid dairy manure, solid poultry manure, complete mineral fertilizer (NPK) and a no-N control (PK)) on C and N stocks of two Brunisols with contrasting textures (sandy loam and silty clay). We compared C and N stocks of multiple soil layers (0–15, 15–30, 30–45 and 45–60 cm depths) on the 8th year of this field trial. Overall, stock differences among management systems were relatively small in the top 15 cm, varying from 0.36 to 0.76 kg C m−2 and 0.01–0.04 kg N m−2. In subsurface soil layers (15–30, 30–45 and 45–60 cm), however, management practices considerably influenced C and N stocks (differences of up to 3.9 kg C m−2 and 0.3 kg N m−2 between treatments) in ways different than those observed in the topsoil. In the subsurface (> 15 cm) layers of the sandy loam soil, systems combining inversion tillage, residue retention, and liquid animal manure (especially swine manure) resulted in the greatest C and N stocks. Conversely, in systems combining inversion tillage and mineral fertilizer, C and N stocks in the subsurface layers were higher when residues were harvested than when they were not. Subsurface C and N stocks therefore appeared to be particularly responsive to different combinations of fertilizer sources and residue management practices under inversion tillage in the coarse-textured sandy loam soil. In the silty clay, irrespective of tillage treatments, N stocks were the highest in the 30–45 cm layer when residues were harvested, and liquid swine manure was used. Ultimately, management-differences in subsurface C and N stocks were so large compared to those in the topsoil, that they dominated the response of the whole soil profile to management practices in both soil types. These results demonstrate that subsurface C and N dynamics must be considered and that recommendation for C stock management in agricultural soils should include deep soil layers, at least under certain pedoclimatic conditions.

Analysis of the effect of air temperature on ammonia emission from band application of slurry

Field application of liquid animal manure (slurry) is a significant source of ammonia (NH3) emission to the atmosphere. It is well supported by theory and previous studies that air temperature effects NH3 flux from field applied slurry. The objectives of this study was to statistically model the response of temperature at the time of application on cumulative NH3 emission. Data from 19 experiments measured with the same system of dynamic chambers and online measurements were included. A generalized additive model allowing to represent non-linear functional dependences of the emission on the temperature revealed that a positive response of the cumulative NH3 emission on the temperature at the time of application up to a temperature of approximately 14 °C. Above that, the temperature effect is insignificant. Average temperature over the measuring period was not found to carry any additional information on the cumulative NH3 emission. The lack of emission response on temperature above a certain point is assumed to be caused by drying out of the slurry and possible crust formation. This effect is hypothesized to create a physical barrier that reduce diffusion of NH3 to the soil surface, thereby lowering the emission rate. Furthermore, the effect of the interaction between soil type and application technique and the effect of dry matter content of the slurry was derived from the model, and found to be significant on cumulative NH3 emission predictions.

Calculation of NH3 Emissions, Evaluation of Backward Lagrangian Stochastic Dispersion Model and Aerodynamic Gradient Method

Two campaigns measuring ammonia (NH3) emissions with different measurement techniques were performed on a large grass field (26 ha) after the application of liquid animal manure. The aim was to compare emissions from a confined area estimated from either (i) concentration measurements, both point and line-integrated measurements, combined with backward Lagrangian stochastic (bLS) dispersion modeling or by (ii) estimation of the vertical flux by the aerodynamic gradient method (AGM) with and without footprint correction approximated by the bLS model estimates of the flux footprint. The objective of the comparison is to establish the best practice to derive NH3 emissions from a large field. NH3 emissions derived from bLS agreed well when comparing point and line-integrated measurements. Simple point measurements combined with bLS yield good emission estimations for the confined area. Without footprint correction, the AGM underestimates the emissions by up to 9% compared to the footprint-corrected AGM results. The sensitivity of the measurement methods makes it possible to quantify NH3 emissions with diurnal patterns even five days after a field application of liquid animal manure under wet conditions. The bLS model proves to be a strong tool to determine the NH3 emissions from point concentration measurements inside a large field after a slurry application.

The overlooked role of diffuse household livestock production in nitrogen pollution at the watershed scale

Livestock production has become a primary source of nitrogen pollution in China due to the rapid socio-economic development. While intensive production operations are the major sources, small livestock breeding units (diffuse livestock production) potentially also contribute to water quality impairments because of their dispersed nature and lack of appropriate waste treatment facilities. However, little is known about how diffuse livestock production affects the surface water quality due to the difficulty isolating its influence from other agricultural activities. In this study, the fate of diffuse livestock-derived N transported through the watershed (i.e., both amount and flow path by which diffuse livestock-derived nitrogen is delivered to the watershed mouth) across flow conditions was investigated by using a new approach that accounted for aquatic nitrogen retention during transport. Its contribution to watershed nitrogen export was also unraveled and isolated from other sources. Overall percentage of diffuse livestock-derived nitrogen that was transported to surface waters was 8.7%, 58.2% of which was delivered to the receiving water bodies (i.e., the watershed mouth). The fate of diffuse livestock-derived nitrogen that was loaded to surface waters (7.6–8.0% under baseflow, and 10.8–16.4% under stormflow) and exported to the watershed mouth differed across flow regimes (3.9–4.4% under baseflow, and 7.4–12.1% under stormflow). Further, majority of livestock nitrogen was mobilized by the direct discharge of urine (82.2%) due to the farmer’s water-flushed operation, whereas, only 17.8% of livestock-derived nitrogen flux was from the loss of manure and urine during storage. The contribution of diffuse livestock to watershed nitrogen flux varied across flow conditions with higher contributions under baseflow conditions (67.9–74.9%) than under stormflow conditions (49.5–54.5%). The diffuse household livestock production can substantially degrade the stream water quality as do concentrated livestock production facilities, which was overlooked in the previous studies. A fully coupled mode that recycles both solid and liquid animal manure should be highly regarded as for the sustainability of livestock production. The findings provide important information for source identification and the management of the diffuse livestock production.

Ammonia Volatilization Losses during Irrigation of Liquid Animal Manure

Ammonia loss resulting from land application of liquid animal manure varies depending on the composition of the manure and the method used to apply manure to cropland. High levels of ammonia volatilization result in an economic loss to the farmer based on the value of the nitrogen and have also been shown to be a source of air pollution. Using irrigation as a method of applying liquid manure to cropland has generally been accepted as a method that increases the volatilization of ammonia. However, only three studies available in the literature measured the amount of ammonia lost during the irrigation process. Only one of the three studies concluded that ammonia loss during irrigation was significant. A pooled statistical and uncertainty analysis of the 55 available observations was performed to determine if ammonia loss occurred during irrigation of animal manure. Data on the total solids content of the manure were also included as an indicator of evaporation losses. Volatilization losses during irrigation were not found to be statistically significant, and evaporation losses were small, 2.4%, and agreed with previous studies on irrigation performance. Furthermore, the range of ammonia loss reported in previous studies was determined to be within the errors associated with the measurement of total ammoniacal nitrogen concentrations and the calculation of per cent differences.

Recoupling Industrial Dairy Feedlots and Industrial Farmlands Mitigates the Environmental Impacts of Milk Production in China.

Dairy production is becoming more industrialized globally, especially in developing countries. The large amount of animal wastes from industrial feedlots cannot be fully used on nearby farmlands, leading to severe environmental problems. Using China as a case study, we found that most dairy feedlots employ a semicoupled mode that only recycles solid manure to farmlands, and only a few dairy feedlots employ a fully coupled mode that recycles both solid and liquid animal manure. To produce 1 ton of milk, the fully coupled mode could reduce greenhouse gas (including carbon dioxide, methane, and nitrous oxide in this paper) emissions by 24%, ammonia emissions by 14%, and N discharge into water by 29%, compared with the semicoupled systems. Coupling feedlots with constructed wetlands can further result in greater mitigation of N leaching into groundwater. However, the fully coupled system has not been widely used due to the low benefit to farmers and the institutional barrier that the feedlot owners have no right to use adjacent farmlands. Since a fully coupled system improves net ecosystem services that favor the public, a policy that supports removing the economic and institutional barriers is necessary. Our approach provides a template for mitigating environmental impacts from livestock production without sacrificing milk production.

Improving DNDC model to estimate ammonia loss from urea fertilizer application in temperate agroecosystems

Process-based biogeochemical models such as the DeNitrification–DeComposition (DNDC) model can provide reliable estimations of agricultural nitrogen loss, information necessary for developing better management practices. The Canadian version of the model (DNDC v.CAN) was recently developed to predict NH3 volatilization after the field application of liquid animal manure; however it did not include a mechanism for simulating soil pH buffering or fertilizer application at depth. Using published data collected from four studies in Quebec, Canada, this research included the effects of urea hydrolysis and buffer capacity on soil pH in DNDC v.CAN. The improved model was tested for estimating NH3 loss after surface and incorporated urea applications. Owing to the developments, the NH3 loss estimations of the improved DNDC v.CAN model better correlated to observations in all four field studies (r = 0.95 for P ≤ 0.05) compared to the previous model versions (0.63 and 0.47 respectively). Soil pH predictions were also better correlated (r = 0.56) while the other versions had poor correlations of −0.27 and −0.33, respectively. An assessment of environmental and management factors on NH3 losses using scenario and sensitivity analyses was also carried out. The scenario assessment suggested that incorporated urea application had the highest reduction in cumulative NH3 loss and the sensitivity analysis indicated that soil pH and temperature had the greatest influence on estimates of NH3 loss under the incorporated and split scenarios. The improvements to the mechanisms regulating N losses in DNDC v.CAN will have positive implications to accurately simulate N cycling in agro-ecosystems.

Greater accumulation of soil organic carbon after liquid dairy manure application under cereal-forage rotation than cereal monoculture

As opposed to the well-known positive effect of solid animal manure on soil organic carbon (SOC) stocks, the effect of liquid animal manure is less clear. In addition, few long-term studies have measured the combined effects of animal manure application and management practices such as tillage or the inclusion of perennial forages in annual cropping systems on SOC stocks. The objective of this paper was to determine the response of SOC stocks along a 0–50cm soil profile to 21 years of liquid dairy manure (LDM) application compared to mineral fertilizer in combination with two fall primary tillage practices (moldboard plowing vs. chisel plowing), and two crop rotations (cereal monoculture vs. cereal-perennial forage rotation) on a silty clay soil at Normandin, Quebec, Canada. The effects of LDM application on SOC stocks were apparent only in the top 20cm of the 0–50cm soil profile, with overall higher SOC stocks compared to mineral fertilizer. The magnitude of the LDM-induced change in SOC was also dependent on the crop rotation, with a 15% greater SOC accumulation in the 0–30cm soil profile in the cereal-perennial forage rotation than in the cereal monoculture. The large retention of LDM-induced C under the cereal-perennial forage rotation could be explained by (1) slower C decomposition resulting from the lower tillage frequency in the cereal-forage rotation (every three years) compared to the cereal monoculture (yearly operation), and/or (2) greater C stabilization promoted by the presence of a high-quality labile litter (perennial legume) in the rotation. We conclude that LDM-induced changes in SOC can be strongly modulated by the inclusion of perennial forages in annual cropping systems, and may not be just the consequence of manure characteristics.

Electricity generation and nutrients removal from high-strength liquid manure by air-cathode microbial fuel cells

ABSTRACTAir-cathode microbial fuel cells (MFCs) are widely tested to recover electrical energy from waste streams containing organic matter. When high-strength wastewater, such as liquid animal manure, is used as a medium, inhibition on anode and cathode catalysts potentially impairs the effectiveness of MFC performance in power generation and pollutant removal. This study evaluated possible inhibitive effects of liquid swine manure components on MFC power generation, improved liquid manure-fed MFCs performance by pretreatment (dilution and selective adsorption), and modeled the kinetics of organic matter and nutrients removal kinetics. Parameters monitored included pH, conductivity, chemical oxygen demand (COD), volatile fatty acids (VFAs), total ammoniacal nitrogen (TAN), nitrite, nitrate, and phosphate concentrations. The removals of VFA and TAN were efficient, indicated by the short half-life times of 4.99 and 7.84 d, respectively. The mechanism for phosphate decrease was principally the salt precipitation on cathode, but the removal was incomplete after 42-d operation. MFC with an external resistor of 2.2 kΩ and fed with swine wastewater generated relatively small power (28.2 μW), energy efficiency (0.37%) and Coulombic efficiency (1.5%). Dilution of swine wastewater dramatically improved the power generation as the inhibitory effect was decreased. Zeolite and granular activated carbon were effective in the selective adsorption of ammonia or organic matter in swine wastewater, and so substantially improved the power generation, energy efficiency, and Coulombic efficiency. A smaller external resistor in the circuit was also observed to promote the organic matter degradation and thus to shorten the treatment time. Overall, air-cathode MFCs are promising for generating electrical power from livestock wastewater and meanwhile reducing the level of organic matter and nutrients.

Apparatus for the Ammonium Recovery from Liquid Animal Manure

<abstract><title><italic>Abstract. </italic></title> Nitrogen present in animal manure can be a limiting factor when considering manure application rates onto arable land. EU-regulations triggered the development of a new ammonia exchange apparatus for the recovery of ammonia. The described apparatus has a liquid to liquid ammonia mass transfer coefficient of 0.0058 m/s. The results were fitted using a simple first order ammonia exchange model with constant time step that additionally predicted that 80% of the ammonia could be recycled from the liquid fraction of animal manure within a residence time of 10 h with addition of 0.2 M NaOH to the manure, yielding a liquid artificial fertilizer with a calculated achievable maximum concentration of about 18 % nitrogen.

Life Cycle Assessment of Segregating Fattening Pig Urine and Feces Compared to Conventional Liquid Manure Management

Gaseous emissions from in-house storage of liquid animal manure remain a major contributor to the environmental impact of manure management. Our aim was to assess the life cycle environmental consequences and reduction potential of segregating fattening pig urine and feces with an innovative V-belt system and to compare it to conventional liquid manure management, that is, the reference. Moreover, we aimed at analyzing the uncertainty of the outcomes related to applied emission factors. We compared a reference with two scenarios: segregation with solid, aerobically, stored feces and with liquid, anaerobically, stored feces. Results showed that, compared to the reference, segregation reduced climate change (CC) up to 82%, due to lower methane emission, reduced terrestrial acidification (TA) and particulate matter formation (PMF) up to 49%, through lower ammonia emission, but increased marine eutrophication up to 11% through nitrogen oxide emission from storage and nitrate leaching after field application. Fossil fuel depletion did not change. Segregation with liquid feces revealed lower environmental impact than segregation with solid feces. Uncertainty analysis supported the conclusion that segregating fattening pig urine and feces significantly reduced CC and additionally segregation with liquid feces significantly reduced TA and PMF compared to the reference.

Environmental consequences of processing manure to produce mineral fertilizer and bio-energy

Liquid animal manure and its management contributes to environmental problems such as, global warming, acidification, and eutrophication. To address these environmental issues and their related costs manure processing technologies were developed. The objective here was to assess the environmental consequences of a new manure processing technology that separates manure into a solid and liquid fraction and de-waters the liquid fraction by means of reverse osmosis. This results in a liquid mineral concentrate used as mineral nitrogen and potassium fertilizer and a solid fraction used for bio-energy production or as phosphorus fertilizer. Five environmental impact categories were quantified using life cycle assessment: climate change (CC), terrestrial acidification (TA), marine eutrophication (ME), particulate matter formation (PMF), and fossil fuel depletion (FFD). For pig as well as dairy cattle manure, we compared a scenario with the processing method and a scenario with additional anaerobic digestion of the solid fraction to a reference situation applying only liquid manure. Comparisons were based on a functional unit of 1 ton liquid manure. System boundaries were set from the manure storage under the animal house to the field application of all end products. Scenarios with only manure processing increased the environmental impact for most impact categories compared to the reference: ME did not change, whereas, TA and PMF increased up to 44% as a result of NH3 and NO(x) emissions from processing and storage of solid fraction. Including digestion reduced CC by 117% for pig manure and 104% for dairy cattle manure, mainly because of substituted electricity and avoided N2O emission from storage of solid fraction. FFD decreased by 59% for pig manure and increased 19% for dairy cattle manure. TA and PMF remained higher compared to the reference. Sensitivity analysis showed that CH4 emission from manure storage, NH3 emission from processing, and the replaced nitrogen fertilizer by the mineral concentrate were important parameters affecting final results. It was concluded that processing fattening pig and dairy cattle manure to produce mineral fertilizer increased overall environmental consequences in terms of CC (except for dairy cattle manure), TA, PMF, and FFD compared to current agricultural practice. Adding the production of bio-energy reduced CC and FFD. Only when NH3 emission from processing was low and bio-energy was produced, overall equal or better environmental performance was obtained for TA and PMF. It was emphasized that real time measurements should be done to enhance the environmental assessment of manure processing technologies. Results of this study present the full environmental consequences of manure processing and key parameters affecting the environmental impact of manure management. Outcomes can be used for decision making and further tackling of environmental problems related to manure management.

Methane emissions from stored liquid dairy manure in a cold climate

Climate change has been linked to increasing concentrations of greenhouse gases including CH4, which has a global warming potential 25 times greater than CO2. Stored liquid animal manure is an important emissions source of CH4 globally and in Canada. As part of ongoing efforts to mitigate CH4 emissions, it may be beneficial to obtain field scale flux estimates which can be used to verify CH4 emission factors. The objective of this study was to measure CH4 fluxes from a liquid dairy manure storage tank and compare measured fluxes with predicted values using US EPA methodology. Fluxes were measured from a circular concrete tank 11.25m in diameter storing liquid dairy manure in Bright, Ontario, Canada. Measurements were conducted semi-continuously from January through July 2003, using a tunable diode laser and the non-interfering micrometeorological mass balance method. Monthly average CH4 flux ranged from 11μg/m2/s in June after the tank had been emptied, to 153μg/m2/s in July. Large bubble flux events occurred in February and March that coincided with surface thawing. Predicted emissions using the US EPA approach with carryover of volatile solids showed overestimation unless a substantial correction factor was used. In contrast, if volatile solids were not carried over, predicted fluxes had acceptable agreement with measurements.This article is part of the special issue entitled: Greenhouse Gases in Animal Agriculture – Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors: K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson.

Sensitivity analysis and calibration of CN-SIM to simulate the mineralisation of liquid dairy manures

Abstract Scientific knowledge of carbon and nitrogen dynamics incorporated into soil organic matter (SOM) dynamic simulation models can be tested using experimental data from decomposition experiments. This possibility is particularly interesting for liquid animal manures, which are very heterogeneous materials. CN-SIM is a SOM model that was successfully applied for the short- and long-term simulation of C and N dynamics in the soil. The objective of this research was to test this model using results of a 180-d laboratory incubation of five liquid dairy manures in three soils. Initial sensitivity analysis indicated that model parameters that mostly impact net CO2 and soil mineral nitrogen concentration (SMN) are those that allocate manure C and N to model pools, their decomposition constants and soil parameters that describe microbial biomass and its residues. Automatic parameter optimisation was carried out with the downhill simplex method separately for 15 manure by soil combinations. After optimisation, CO2 respiration was well simulated for the entire period, while SMN was overestimated after day 40. Simulations overestimated the remineralisation of immobilised N in the first weeks. Simulated initial microbial immobilisation was the only possibility for the model to match the experimental decrease of SMN, while simulated N remineralisation after day 40 was necessary to enable a good simulation of respired CO2. Further work is needed to test whether these simulations can be improved by adding SMN sinks (such as denitrified N and clay-fixed ammonium).

Ozone Treatment of Animal Manure for Odor Control

Problem statement: The effectiveness of ozone in reducing odor emission from liquid animal manure was evaluated under batch and continuous treatment operations. Results: The results indicated that the use of ozone for the treatment of animal manure proved to be effective in reducing the odor offensiveness. A minimum 3.4 level out of 10 (66% reduction) was achieved in the continuous operation; while a minimum of 3.1 (69% reduction) was achieved in the batch operation. Increasing the level of ozone (O3) increased the level of offensiveness which was attributed to the presence of intermediate products due to the interaction between ozone and hydrogen sulfide and methylamine. Conclusion: The cost analysis indicated that the treatment is economical as a ton of manure could be treated at a cost of $ 0.23.

액상 가축분뇨의 처리 및 토양환원에 따른 악취 및 악취물질의 평가

효율적인 악취방지책을 수립하고 시행하는 것은 지속가능한 축산 뿐만 아니라 증가되는 악취 민원과 더욱 엄격해지는 법규에 대응하기 위해 필수적이다. 본 연구는 돈분뇨의 처리방법에 따른 액상분뇨 유래 악취 및 처리방법이 다른 액상분뇨를 토양에 살포시 발생하는 악취 및 악취물질을 평가하기 위하여 수행되었다. 시험에 사용된 액상분뇨는 신선 분뇨, 혐기성 소화 액상분뇨 및 고온 호기성 소화 액상분뇨를 이용하였고, 토양 특성이 다른 논/밭 토양을대상으로 총 6처리 5반복 설계 배치하였다. 시료 포집은 관능법과 기기분석법에 사용될 시료를 각각 주사기와 테들러 백을 이용하여 액상분뇨와 액상분뇨를 살포한 토양의 상부공간에서 채취하였다. 악취 분석은 관능법을 이용하여 악취강도 및 불쾌도를 평가하였고, 기기분석법으로는 질소화합물 악취물질인 암모니아를 흡광광도법, 황화합물 악취물질인 황화수소, 메틸머캅탄, 다이메틸설파이드 및 다이메틸다이설파이드를 GC-PFPD를 이용하여 분석하였다. 처리과정이 다른 액상분뇨의 악취 및 악취물질 발생 평가에서 고온 호기성 소화 액상분뇨가 신선 분뇨 및 혐기성 소화 액상분뇨에 비해 악취강도, 불쾌도 및 악취농도 저감 효과가 매우 두드러지게 나타났으며 통계적으로도 유의적인 차이가 인정되었다. 혐기성 소화 액상분뇨와 고온 호기성 소화 액상분뇨에서 발생되는 황화수소, 메틸머캅탄, 다이메틸설파이드, 다이메틸다이설파이드 및 암모니아의 평균농도는 각각 65.93 : 5.15 ppb, 18.55 : 0.97ppb, 5.26 : 0.80ppb, 0.33 : 0.56ppb 및 10.57 : 1.34ppm으로 분석되었다. 액상분뇨를 밭과 논 토양에 살포시 혐기성 소화 액상분뇨와 고온 호기성 소화 액상분뇨가 각각 51～94% 및 22～91%의 암모니아 저감 효율을 나타내었다. 본 시험의 결과를 종합할 때 고온 호기성 소화 액상분뇨가 악취 저감이라는 측면에서 다른 처리방법에 비해 우수한 것으로 나타났으며, 액상분뇨의 토양환원에서 발생되는 악취문제는 액상분뇨의 처리방법에 따른 악취발생 정도와 직접적인 연관이 있다고 사료된다. To comply with stricter regulations provoked by increasing odor nuisance, it is imperative to practice effective odor control for sustainable livestock production. This study was conducted to assess odor and odorous compounds emitted from liquid animal manure with different treatment methods such as Fresh Manure(without treatment, FM), Anaerobic Digestion(AD) and Thermophilic Aerobic Digestion(TAD) and their application to soil. Air samples were collected at the headspace of liquid manure, upland and paddy soil, and analyzed for odor intensity and offensiveness using an olfactometry; odor concentration index using odor analyser; nitrogen-containing compound such as ammonia(NH3) using fluorescence method; and sulfur containing compounds such as hydrogen sulfide(H2S), methyl mercaptan(MeSH), dimethyl sulfide(DMS) and dimethyl disulfide(DMDS) using gas chromatography-pulsed flame photometric detector, respectively. Odor intensity, offensiveness and concentration index from TAD liquid manure was statistically lower than those from FM and AD(p<0.01). Mean concentrations of H2S, MeSH, DMS, DMDS and NH3 were 65.93ppb, 18.55ppb, 5.26ppb, 0.33ppb and 10.57ppm for liquid manure with AD; and 5.15ppb, 0.97ppb, 0.80ppb, 0.56ppb and 1.34ppm for liquid manure with TAD, respectively. More than 60% of malodorous compounds related to nitrogen and sulfur were removed by heterotrophic microorganisms during TAD treatment. When liquid manure was applied onto upland and paddy soil, NH3 removal efficiencies ranged from 51 to 94% and 22 to 91% for AD and TAD liquid manure, respectively. The above results show that liquid manure with TAD is superior to AD and FM with respect to the odor reduction and odor problem caused by land applied liquid manure is directly related to the degree of odor generated by the manure treatment method.

Physico-Chemical P Removal from the Liquid Fraction of Pig Manure as an Intermediary Step in Manure Processing

Intensive animal farming has resulted in overproduction of manure in parts of the industrialized world. The localized excessive nutrient emission has detrimental effects on both ecology and economy. In response to European guidelines, Flanders (Belgium) has imposed obligations on the agricultural sector to process a portion of the produced animal manure. To achieve the stringent criteria for discharge of processed waste water, overly expensive engineering techniques are currently required (mostly membrane technology). This paper examines the potential of more economic physico-chemical techniques for P-removal from pre-treated liquid animal manure. Two techniques for dephosphatation were performed sequentially: (i) the use of flocculants (FeCl3, FeCl2, FeClSO4, Poly Aluminium Chloride (PAC), Na Aluminate) and subsequently, (ii) the use of substrates to further reduce P-levels by adsorption or precipitation (expanded clay (argex), Fe-oxide powder, clay, calcinated clay, alganite, sand). The P-removal efficiencies obtained in this research are promising to consider implementation of physico-chemical P-removal as an intermediary step in animal manure processing after secondary pre-treatment in an activated sludge reactor and before tertiary treatment.