Mitigating odors from animal facilities using biofilters

Mitigating odors from livestock sites using biofilters was addressed in this dissertation which is organized in paper format and comprises a literature review paper and two original research papers. In the first literature review paper, both the laboratory and field research from 1997 to 2008 was reviewed to give an up-to-date perspective of studies on the mitigation of odors and volatile organic compounds (VOCs) relating to agricultural facilities using biofilters. A mobile biofiter testing system was developed which can be used at field conditions to evaluate biofilter performance at variable media types, empty bed residence times (EBRT) and media moisture contents. A field study for mitigating odors and odorous compounds from a deep-pit swine finishing facility in central Iowa was conducted to test two types of wood chip media (western cedar and two inch hardwood) using the mobile biofilter testing system. The biofilter testing system was continuously operated and evaluated at different media moisture content levels and different air flow rates resulting in a variable EBRT from 1.6 to 7.3 sec. A dynamic forced-choice olfactometer was used to evaluate odor concentrations from both the control plenum and biofilter treatments. Hydrogen sulfide and ammonia concentrations were also measured from these olfactometry samples. Solid-phase microextraction fibers were used to extract VOCs from both the control plenum and biofilter treatments. Analyses of VOCs and its corresponding individual odors were carried out using a gas chromatography-mass spectrometry-olfactometry (GC-MS-O) system. Pressure drop characteristics through the biofilters packed with western cedar and hardwood media were monitored. The reduction efficiency and pressure drop characteristics obtained with the wood chip-based biofilters indicate the feasibility of farm-level applications of wood chip-based biofilters for reducing swine building odors. The results also showed that both a proper media moisture content and a minimum EBRT were critical to a successful wood chip-based biofilter

A Two-Stage Wood Chip-Based Biofilter System to Mitigate Odors from a Deep-Pit Swine Building

A mobile biofilter testing laboratory was developed where two-stage biofilters filled with western cedar and hardwood chips were examined to treat odor emissions from a deep-pit swine finishing facility in central Iowa. An automatically controlled water supply system was tested and used to control media moisture content. Odor concentrations from theinlet and biofilter treatments, gas flow pressure drop, leachate pH and ammonia concentration, and water consumption were monitored.Results indicate that the water supply system tested in this study can keep wood chip media at a high and stablemoisture content of 72% ± 3% (western cedar) and 62% ± 3% (hardwood)with a 6.4 L/m3-day water supply. Western cedar (WC) chips achieved an average reduction efficiency of 51%, 83%, and 41% for odor, H2S, and NH3, respectively, when keeping the WC moisture content at 72% and the empty bed residence time (EBRT) between 3.7 and 5.5 s. A linear relationship between media unit pressure drop and unit airflow rate was observed with two-stage biofilters having an advantage in potentially reducing media compaction.Leachate pH and NH3 concentration were measured with pH levels in the 7.2 to 7.9 range with the NH3 concentration in the 198 to 1300 mg/L as N range.The effects of three different levels of media moisture content shows that proper moisture content is a key factor for the success of wood chip biofilters, but is not a substitute for inadequate EBRT

Mitigating Odors from Agricultural Facilities: A Review of Literature Concerning Biofilters

This article reviews literature on biofilter research both in laboratories and at confined livestock facilities. The purpose is to give an up-to-date review of biofilters used to mitigate of odors and volatile organic compounds (VOCs) from agricultural facilities using biofilters. More specifically the article addresses: 1) Factors concerned in design and operation of biofilters such as media property, empty bed residence time, media moisture measurement and control, microbial ecology, construction, and operation cost; and 2) Biofilter performance such as odor/VOC reduction efficiency (RE), and air pressure drop. Lab-scale, pilot-scale, and full-scale biofilter studies were reviewed. Biofilter design and odor/VOC REs were summarized in tables for easy reference and for a perspective on the current state of the art. The relationship between the biofilter configuration/operation factors and biofiter performance was discussed. This literature study indicates: 1) Biofilters can be used as an effective technology for reducing odor/VOC emissions from animal facilities (RE up to 99% for odor and up to 86% for 16 odorous VOCs reported); 2) The three most important factors effecting biofilter performance are packing media, media moisture content, and empty bed residence time; 3) Removal efficiency, air pressure drop, and construction/operation cost are three parameters of concern when a biofilter is installed and operated; and 4) Further studies such as developing precise media moisture measurement and control technologies, bacterial structure, and long time full-scale biofilter tests are needed to better understand the biofiltration process and improve biofilter applications for agriculture

Electronic structure and bonding properties of cobalt oxide in the spinel structure

The spinel cobalt oxide Co3O4 is a magnetic semiconductor containing cobalt ions in Co2+ and Co3+ oxidation states. We have studied the electronic, magnetic and bonding properties of Co3O4 using density functional theory (DFT) at the Generalized Gradient Approximation (GGA), GGA+U, and PBE0 hybrid functional levels. The GGA correctly predicts Co3O4 to be a semiconductor, but severely underestimates the band gap. The GGA+U band gap (1.96 eV) agrees well with the available experimental value (~ 1.6 eV), whereas the band gap obtained using the PBE0 hybrid functional (3.42 eV) is strongly overestimated. All the employed exchange-correlation functionals predict 3 unpaired d electrons on the Co2+ ions, in agreement with crystal field theory, but the values of the magnetic moments given by GGA+U and PBE0 are in closer agreement with the experiment than the GGA value, indicating a better description of the cobalt localized d states. Bonding properties are studied by means of Maximally Localized Wannier Functions (MLWFs). We find d-type MLWFs on the cobalt ions, as well as Wannier functions with the character of sp3d bonds between cobalt and oxygen ions. Such hybridized bonding states indicate the presence of a small covalent component in the primarily ionic bonding mechanism of this compound.Comment: 24 pages, 8 figure

First principles study of intrinsic point defects in hexagonal barium titanate

Density functional theory (DFT) calculations have been used to study the nature of intrinsic defects in the hexagonal polymorph of barium titanate. Defect formation energies are derived for multiple charge states and due consideration is given to finite-size effects (elastic and electrostatic) and the band gap error in defective cells. Correct treatment of the chemical potential of atomic oxygen means that it is possible to circumvent the usual errors associated with the inaccuracy of DFT calculations on the oxygen dimer. Results confirm that both mono- and di-vacancies exist in their nominal charge states over the majority of the band gap. Oxygen vacancies are found to dominate the system in metal-rich conditions with face sharing oxygen vacancies being preferred over corner sharing oxygen vacancies. In oxygen-rich conditions, the dominant vacancy found depends on the Fermi level. Binding energies also show the preference for metal-oxygen di-vacancy formation. Calculated equilibrium concentrations of vacancies in the system are presented for numerous temperatures. Comparisons are drawn with the cubic polymorph as well as with previous potential-based simulations and experimental results

Krüppel-like factor 8 promotes aerobic glycolysis in prostate cancer cells by regulating AKT/mTOR signaling pathway

Purpose: To investigate the effects of Krüppel-like factor 8 (KLF8) in prostate cancer (PCa) cell viability and glycolysis, and explore its role as a regulatory factor.Methods: Immunoblot assays were conducted to assess the expression of KLF8 and proteins in AKT/mTOR pathway in PCa cell lines PC-3 and DU145. Cell Counting Kit-8 assays were performed to assess the effect of KLF8 on PCa cell viability. The glycolysis capacity of PCa cells was determined by measuring the levels of glucose intake, lactic acid production, and cellular ATP levels.Results: Depletion of KLF8 decreased the survival of PCa cells in vitro (p < 0.05). KLF8 depletion also inhibited aerobic glucose metabolism in PCa cells (p < 0.05). Further studies confirmed that KLF8 contributed to the growth and glycolysis of PCa cells via the regulation of AKT/mTOR pathway.Conclusion: KLF8 regulates glycolysis in PCa cells by regulating AKT/mTOR signaling pathway and is thus a promising therapeutic target for PCa treatment. Keywords: Krüppel-like factor 8 (KLF8), Prostate cancer (PCa), Aerobic glucose, AKT/mTOR signaling pathway, Therapeutic targe

Assessment of a Two-Stage Wood Chip-Based Biofilter Using Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry-Olfactometry

A mobile pilot-scale biofilter testing laboratory, which consisted of one- and two-stage biofilter reactor barrels, was developed where two types of wood chips (western cedar and hard wood) were examined to treat odor emissions from a deep-pit swine finishing facility in central Iowa. The biofilters were operated continuously from July 20 to October 17, 2007 at differe nt air flow rates resulting in variable empty bed residence times. During this test period, solid-phase microextraction 85 µm Carboxen/PDMS fibers were used to extract volatile organic compounds (VOCs) from both the control plenum and biofilter treatment. Analyses of VOCs were carried out using a multidimensional gas chromatography-mass spectrometry-olfactometry system. Reductions of nine odorous compounds were reported. An overall average reduction efficiency of 98.9% and 96.4% was achieved for two-stage western cedar and hardwood biofilters, respectively. The results showed that maintaining proper moisture content is critical to the success of wood chip-based biofilter

Odor reduction during biofiltration as affected by air flow rate and media moisture content

A mobile biofilter testing laboratory was developed where two types of wood chips (western cedar and hardwood) were examined to treat odor emissions from a deep-pit swine finishing facility in central Iowa. The biofilters were run continuously for 12 weeks at different air flow rates resulting in variable empty bed residence times. During this test period, a dynamic forced-choice olfactometer was used to evaluate odor concentrations from both the control plenum and biofilter treatments. Analyses of separated odors were carried out using a gas chromatography-mass spectrometry-olfactometer (GC-MS-O) system. Olfactometry results indicated that both types of chips achieved significant reductions in odor and hydrogen sulfide concentrations. GC-MS-O results showed both treatments reached high reduction efficiency for four main groups of odorous compounds. Effects of three different levels of media moisture content were also evaluated. The results showed that proper moisture content is a key factor for the success of wood chip-based biofilters

Performance evaluation and optimization of simultaneous phosphorus and nitrogen removal from anaerobically digested liquid dairy manure using an intermittently aerated extended idle sequencing batch

Wastewater from confined dairy operations requires efficient treatment to reduce its potential to pollute the surrounding environments. In this study, a novel intermittently-aerated-extended-idle sequencing batch reactor (IA-EI SBR) process was developed, evaluated, and optimized for simultaneously removing phosphorus (P) and nitrogen (N) from anaerobically digested liquid-dairy-manure (ADLDM) with lower carbon-to-nutrient-ratios. Four influential operating parameters including cycle-time of 5–9 h, intermittent-aeration strategy of 10–50 min/h, two feed-phases of 6–30 min, and idle-phase of 40–120 min were statistically analyzed using central-composite design coupled with response-surface methodology for optimal removal efficiencies of ortho-phosphorus (%OPremoval), total-phosphorus (%TPremoval), ammonia-nitrogen (%NH3-Nremoval), total-nitrogen (%TNremoval), and chemical oxygen demand (%CODremoval). Results showed that the interactions of cycle time-idle phase, and aeration strategy-feed phases were significant in affecting %TPremoval (p-value ≤ 0.005). The synergistic effect of aeration strategy-idle phase was significant for %TNremoval and %CODremoval (p-value ≤ 0.006), while the cycle time-feed phases interaction had significant effect on %NH3-Nremoval. The maximum simultaneous nitrification-denitrification (SND) efficiency of 85.7% was recorded under influent COD and TN loading of 3,999.2 and 785.7 mg L−1 at 30 min/h aeration time in 7 h. The quadratic regression models based on statistical analysis of the experimental results adequately described the IA-EI SBR performance and showed that the applied levels of operating parameters were highly correlated with all five responses (p-value ≤ 0.030). Operating conditions for optimal IA-EI SBR process efficiency determined by desirability analysis were cycle-time of 8 h, intermittent-aeration strategy of 36 min/h, feed-phases of 24 min, and idle-phase of 100 min. Under these optimal conditions, the corresponding removal efficiencies for OP, TP, NH3-N, TN, and COD of 82.64, 95.82, 92.92, 73.84, and 90.94%, respectively, were achieved in validation experiments