Improved water quality and reduction of odorous compounds in anaerobic lagoon columns receiving pre-treated pig wastewater

Authors: Szogi, Ariel; Loughrin, John; Vanotti, Matias

Submitted to: Environmental Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2017
Publication Date: 8/14/2017
Citation: Szogi, A.A., Loughrin, J.H., Vanotti, M.B. 2017. Improved water quality and reduction of odorous compounds in anaerobic lagoon columns receiving pre-treated pig wastewater. Environmental Technology. https://dx.doi.org/10.1080/09593330.2017.1363294.

Interpretive Summary: Confined swine production generates large volumes of wastewater typically stored and treated in anaerobic lagoons. Although anaerobic lagoons are designed to degrade organic waste loads, still foul odors may be emitted. Moreover, odor emissions beyond the boundaries of swine production operations have been associated to the decline of quality of life for rural residents in the proximity of these facilities. An alternative to resolve this environmental problem is pre-treatment of liquid swine manure prior to lagoon input to control foul odor emissions from lagoon structures and during land application of lagoon liquid. We evaluated the effect of manure pre-treatment on water quality improvements and reduction in concentration of selected malodor compounds in the influent using: 1) chemically (flocculant) enhanced solid-liquid separation (SS), and 2) solid-liquid separation plus biological N treatment using nitrification-denitrification (SS+NDN). A conventional anaerobic lagoon treatment was included as a control. Concentrations of five selected malodorous compounds (phenol, p-cresol, 4-ethylphenol, indole, and skatole) usually found in swine manure were determined in liquid samples from both lagoon influent and effluent. The SS and SS+NDN pre-treatments differed in their efficiencies to reduce concentrations of single odor compounds in the lagoon inflow. The SS+NDN pre-treatment had the greatest improvements in reducing by about 99% the concentrations of all selected compounds in liquid stored in the lagoon. As indicators of water quality improvement, reductions in concentrations of ammonium-nitrogen and chemical oxygen demand had a strong correlation with reductions in total malodor levels. The potential exists to use pre-treatment technologies such as SS+NDN to eliminate the associated ammonia and malodor emissions from lagoon liquid during both lagoon storage and land application.

Technical Abstract: Large volumes of wastewater from confined pig production are stored in anaerobic lagoons. Control methods are needed to reduce air pollution by foul odors released from these lagoons. In a pilot-scale experiment, we evaluated the effect of pig wastewater pre-treatment on reducing the concentration of selected malodor compounds in lagoons receiving liquid from: (1) flocculant enhanced solid–liquid separation (SS), and (2) solid–liquid separation plus biological N treatment using nitrification-denitrification (SS+NDN). A conventional anaerobic lagoon was included as a control. Concentrations of five selected malodorous compounds (phenol, p-cresol, 4-ethylphenol, indole, and skatole) and water quality parameters (ammonia-nitrogen and chemical oxygen demand) were determined in lagoon effluents. The SS+NDN pretreatment was more efficient than the SS in reducing odorous compounds in the lagoon liquid. The SS+NDN reduced by about 99% the liquid concentrations of all selected compounds. An odor panel test revealed that SS was ineffective to reduce the human sense of malodor with respect to the control. Whereas the SS+NDN had the significant lowest odor intensity and unpleasantness. These results are supported by the strong correlations found between the sum of odorous compound concentration with odor panel results and concentrations of both ammonium nitrogen and chemical oxygen demand in lagoon liquid samples.