Soomin Shim

Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.

Recently, circulating biologically treated manure in slurry pits has been used as an odor reduction technology, but few successful results have been reported, due to the lack of proper control strategies for bioreactors. This study was conducted to investigate the performance of the developed real-time controlled bio-liquor circulation system (BCS) at farm scale. The BCS was operated sequentially as per swine manure inflow (anoxic, aerobic, and settling) circulation to the slurry pit. Each operational phase was self-adjusted in real-time using a novel algorithm for detecting the control point on the oxidation reduction potential (ORP) and pH (mV)–time profiles, the nitrogen break point (NBP), and the nitrate knee point (NKP) in the aerobic and anoxic phases, respectively. The NH₄-N in the slurry manure was thoroughly removed (100%) in the bioreactor, optimizing the duration of each operational phase by accurately detecting real-time control points. The newly developed real-time BCS decreased the nitrogen and organic matter in the slurry pit by >70%, and the potential ammonia and methane emissions by 75% and 95%, respectively. This study highlights that improved BCS that utilizes ORP tracking and pH (mV)–time profiles can effectively optimize BCS operation, and thereby reduce malodor and GHG emissions from swine farms.

The aim of this study was to investigate the performance of the developed real-time controlled bio-liquor circulation system (BCS) on a farm-scale to optimize bioreactor operation for manure treatment, and to subsequently reduce both manure-related malodor and greenhouse gas (GHG) emissions from slurry pits. The BCS was operated sequentially as per swine manure inflow (anoxic, aerobic, and settling) circulation to the slurry pit. The duration of each operational phase was self-adjusted in real-time using a novel algorithm for detecting the control point on the oxidation-reduction potential (ORP) and pH (mV)-time profiles, the nitrogen break point (NBP), and the nitrate knee point (NKP) in the aerobic and anoxic phases, respectively. The NH₄-N in the slurry manure was thoroughly removed (100%) in the bioreactor, optimizing the duration of each operational phase by accurately detecting real-time control points. The newly-developed real-time BCS decreased the nitrogen and organic matter content in the slurry pit manure by > 70%, and the potential ammonia and methane emissions by 75% and 95%, respectively. This study highlights that the this improved BCS that utilizes ORP tracking and pH (mV)-time profiles can effectively optimize BCS operation, and thereby reduce malodor and GHG emissions from swine farms.

The livestock industry, especially swine production, has been pressurized by vicinity complaints about odor in Korea. Therefore, a lot of effort has been undertaken regarding reducing the odor emissions from pigsties, widely carried out and the washing out manure in slurry pit by liquid-phase compost has particularly been spotlighted with outstanding performance of odor reduction. However, such a washing out manure called bio-liquor circulation system (BCS) has been controlled by a timer with designated reaction time, which cannot guarantee the system performance. This research proposes an effective real-time control technology for BCS, which circulates bio-liquor to the slurry pit of swine barns. The real-time control system was operated through accurate detection of the designated control points on the oxidation reduction potential (ORP) and pH time profiles for the nitrate knee point (NKP) and nitrogen break point (NBP) in anoxic and aerobic conditions with 100 and 99.6% performances, respectively. The duration of the anoxic and aerobic phases was also automated and noticeably lowered the concentration of nutrients in the manure in the slurry-pit, which served as a source of malodor. The real-time control strategy may be an innovative way to reduce odor and simultaneously produce liquid fertilizer, and provides a reference for the optimization of the industrial scale.

In this study, an attempt was made to develop a real-time control strategy using oxidation–reduction potential (ORP) and pH (mV) time profiles for the efficient operation of bio-liquor circulation system (BCS) in swine farms and its effectiveness in reducing odor emission through improving manure properties in the slurry pit was evaluated. The lab-scale BCS used in this study comprised a bioreactor and a slurry pit. The bioreactor was operated in a sequence of inflow of swine manure → anoxic phase → aerobic phase → circulation to the slurry pit. The improvement in swine manure properties was elucidated by comparing the results of the BCS slurry pit (circulation type, CT) and conventional slurry pit (non-circulation type, NCT). The results revealed that the ORP time profile successfully detected the nitrate knee point (NKP) in the anoxic phase. However, it was less stable in detecting the nitrogen break point (NBP) in the aerobic phase. The pH (mV) time profile showed a more efficient detection of NBP. Compared to the NCT slurry pit, concentrations of ammonium nitrogen (NH₄-N) and soluble total organic carbon (STOC) and other analyzed swine manure properties were much lower in the CT slurry pit. In the aspect of odor reduction, around 98.3% of NH₃ was removed in the CT slurry pit. The real-time controlled BCS can overcome the drawbacks of fixed time-based BCS operation and therefore can be considered as a useful tool to reduce odor emission from intensive swine farming operations. However, further studies and refinement in control algorithms might be required prior to its large-scale application.

Objective: Due to rapid economic return, mixed crop-swine farming systems in Korea have become more intensive. Intensive farming practices often cause nutrient surpluses and lead to environmental pollution. Nutrient budgets can be used to evaluate the environmental impact and as a regulatory policy instrument for nutrient management. This study was conducted to select a nutrient budgeting approach applicable to the mixed crop-swine farms in Korea and suggest an effective manure treatment method to reduce on-farm nutrient production.Methods: In this study, we compared current and ideal gross nutrient balance (GNB) approaches of Organisation for Economic Co-operation and Development and soil system budget (SSB) approach with reference to on-farm manure treatment processes. Data obtained from farm census and published literature were used to develop the farm nutrient budgets.Results: The average nitrogen (N) and phosphorus (P) surpluses were approximately 11 times and over 7 times respectively higher in the GNB approaches than the SSB. After solid-liquid separation of manure, during liquid composting a change in aeration method from intermittent to continuous reduced the N and P loading about 50% and 47%, respectively. Although changing in solid composting method from turning only to turning+aeration improved the N removal efficiency by 30.5%, not much improvement in P removal efficiency was observed.Conclusion: Although the GNB approaches depict the impact of nutrients produced in the mixed crop-swine farms on the overall agricultural environment, the SSB approach shows the partitioning among different nutrient loss pathways and storage of nutrients within the soil system; thus, can help design sustainable nutrient management plans for the mixed cropswine farms. The study also suggests that continuous aeration for liquid composting and turning+aeration for solid composting can reduce nutrient loading to the soil.

The agricultural sector is considered one of the major sources of greenhouse gas (GHG) emissions globally. The livestock industry as a significant contributor, is accounting for about 18% of GHG emissions measured in carbon dioxide (CO₂) equivalent from agricultural practices. Depending on farming practices and climatic conditions, GHGs such as methane (CH₄) and nitrous oxide (N₂O) emissions from livestock agriculture can vary significantly. Country-specific emission factors are, therefore, needed for a precise estimation of GHG emissions and to avoid uncertainties. This study was aimed at estimating the CH₄ and N₂O emission fluxes from Hanwoo (the most famous and popular Korean native cattle) manure management systems. CH₄ and N₂O emission fluxes from litter in the Hanwoo cattle barn and composting lot were monitored and calculated for 52 weeks using the dynamic chamber method. The calculated monthly average fluxes of CH₄ and N₂O from litter in the cattle barn ranged from 0.0 to 30.0 ± 13.7 and 0.896 ± 0.557 to 2.925 ± 2.853 μg/m² s, respectively during the whole measurement period. While during the composting period, the monthly average of CH₄ and N₂O emission fluxes were varied from 1.449 ± 0.783 to 86.930 ± 19.092 and 0.511 ± 0.410 to 2.629 ± 1.105 μg/m² s, respectively. The calculated emission fluxes of CH₄ and N₂O from manure management systems in this study were almost 5.4 and 2.1 times, respectively higher than the values reported for the Asian, South and North American countries in the 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories. Overall, this study initiates the process along with signifies the importance of developing country-specific GHG inventories for the effective reduction of GHG emissions from the livestock sector in Korea.

In this study, a novel treatment approach combining biological treatment, struvite crystallization, and electrochemical treatment was developed and its efficiency for the simultaneous removal of pollutants and recovery of nutrients from high strength swine wastewater (SWW) was verified. For all the parameters, maximum removal efficiencies in the lab-scale test were obtained in the range of 93.0–98.7% except for total solids (TS) (79.4%). Farm-scale process showed overall removal efficiencies for total nitrogen (TN), total phosphorus (TP), soluble total organic carbon (sTOC), and color as 94.5%, 67.0%, 96.1%, and 98.9%, respectively, while TS, suspended solids (SS), ammonium nitrogen (NH₄-N), and ortho-phosphate (O-P) concentrations were reduced by 91.5%, 99.6%, 98.6%, and 91.9%, respectively. Moreover, the struvite recovered from SWW showed heavy metal concentrations within the range of the Korean standard for fertilizers and feedstocks and thus, suggesting its potential application as fertilizer and in animal feed production. Using the proposed process, the SWW was converted to liquid compost as a quick-acting fertilizer, struvite as a slow-release fertilizer, and the decolorized and disinfected effluent after electrochemical treatment was safe for discharge according to Korean standard. Therefore, the novel integrated treatment process used in this study can be considered as a solution for SWW management and for the simultaneous removal and recycling of nutrients (N and P).