Development of a Real-Time Controlled Bio-Liquor Circulation System for Swine Farms: A Lab-Scale Study

Abstract

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.

Real-Time Control Technology for a Bio-Liquor Circulation System in a Swine Barn with Slurry Pit: Pilot Scale Study

“…An algorithm based on a previous lab study [ 12 ] was applied on a newly built pilot scale. The performance of the designed algorithm was evaluated using the detectability of NKP and NBP on the ORP- and pH-time profile, respectively.…”

“…Swine manure management practices in Korea differ significantly from those of livestock farming in EU and other parts of the world, owing to the weather, geography, and limited available land. In Korea, swine manure undergoes several processes before final disposal, while in European countries, the slurry is transferred to bio-gasification facilities after a short period in the storage tank [ 12 , 13 ]. The floor structure of the swine barn in Korea mostly consists of the slurry pit where feces and urine, as well as washing water, are aggregated beneath the floor.…”

“…Despite these systemic limitations, the attempts to optimize the operation of the bioreactor in the BCS process have not been carried out, at least on a farm scale. The optimization of BCS is significantly limited because treatment efficiency is affected by various factors such as the complex nature of manure, climate, season, microbial activity, feed, pig age, gender, slurry pit sizes, and liquid composting facilities [ 12 ].…”

Optimization and Modeling of Ammonia Nitrogen Removal from High Strength Synthetic Wastewater Using Vacuum Thermal Stripping

“…The vapor and stripped (free) NH 3 from the evaporating flask entered to the cooling section (condenser) through a vapor duct. The free NH 3 was drawn to a 500 mL Büchner flask having 200 mL H 2 SO 4 (2 N) using the vacuum pump [49]. As the thermal energy of the vapor was transferred to the coolant fluid (ice water), it recondensed and deposited in a receiving flask; thus, the issue related to condensation of water vapor in the acid solution was solved.…”

Measuring the Economic Value of the Negative Externality of Livestock Malodor in South Korea

“…One of the negative aspects of the livestock industry causing conflict and drawing a large number of complaints from local residents is livestock malodor associated with manure [ 7 , 8 , 9 , 10 , 11 , 12 ]. In Korea, livestock odor complaints have increased significantly from 2838 cases in 2014 to 12,631 cases in 2019, an increase of 19.2% to 30.9% of the total odor complaints (Ministry of Environment (MOE); , last accessed on 24 January 2021).…”