Enrichment Period Research Articles

37 Key learnings from the improving pig survivability project

Abstract The Improving Pig Survivability Project has completed 5 yr encompassing research, education, and extension with the goal of reducing overall mortality in the U.S. commercial swine industry. The project is funded by National Pork Board and Foundation for Food and Agriculture Research, and continues through 2026. Team members represent institutions including Iowa State University, Kansas State University, and Purdue University. The project is guided by an advisory board consisting of US swine producers and allied industry partners. Research efforts seek to identify factors contributing to swine mortality in commercial production, and to develop strategies and information that can be utilized to reduce mortality and maximize pig survivability. Key economic findings include the first publicly available economic tool for swine producers to input their specific production information and costs, creating a farm level specific cost of mortality for both the breeding herd and post-weaning to market. Key strategies found to reduce sow mortality include: understanding late gestation body condition as thin sows in late gestation are more likely to prolapse compared with normal or overweight sows; Early intervention to monitor and treat lameness resulted in 25.4% relative reduction in annualized sow mortality in commercial settings tested; Feeding sows four 1.5-pound meals reduced farrowing assistance and reduced piglet deaths compared with ad libitum intake for 3 to 5 d before farrowing; perineal score, genetics, and microbiome risk factors for pelvic organ prolapse were identified. Key strategies found to reduce pre-weaning mortality include: colostrum should be 300 to 350 g per piglet, and a milky cheese addition during enrichment period. Key strategies found to reduce wean to finish mortality include: whole-herd analysis of 2,568 WTF closeouts revealed sow farm parameters associated with improved livability were sow farm health status and productivity associated with lower WTF mortality; Increased mortality was associated with Streptococcus suis, Glaeserella parasuis, PRRSv, Mycoplasma hyopneumoniae and PEDv; early maturing duroc sired pigs had reduced stress, greater feed intake, decreased % losing body weight post weaning, and greater gain during the nursery period; enrichment cubes to pigs post-weaning reduced the percentage losing body weight after weaning; feeding large pellet creep feed in lactation improved nursery pig growth and decreased fallout rates; mat feeding reduced mortality and removals; sensory attractant powder before and after weaning reduced percentage that lost body weight the first 3 d after weaning, and linoleic:linolenic acid ratio can impact gilt growth and the use of lower energy diets appears to reduce joint inflammation. In addition to grant funding, 22 additional projects were supported by in-kind industry donations/partnerships worth over $1.6 million. Resources generated are available in peer-reviewed publications, factsheets (English and Spanish), short informational videos, and podcasts (PigX). Project outcomes are available at the Improving Pig Surviability website (www.piglivability.org).

Rapid and Ultrasensitive Colorimetric Biosensors for Onsite Detection of Escherichia coli O157:H7 in Fluids.

This study presents a breakthrough in the field of onsite bacterial detection, offering an innovative, rapid, and ultrasensitive colorimetric biosensor for the detection of Escherichia coli (E. coli) O157:H7, using chemically modified melamine foam (MF). Different from conventional platforms, such as 96-well plates and fiber-based membranes, the modified MF features a macroporous reticulated three-dimensional (3D) framework structure, allowing fast and free movement of large biomolecules and bacteria cells through the MF structure in every direction and ensuring good accessibility of entire active binding sites of the framework structure with the target bacteria, which significantly increased sensitive and volume-responsive detection of whole-cell bacteria. The biosensing platform requires less than 1.5 h to complete the quantitative detection with a sensitivity of 10 cfu/mL, discernible by the naked eye, and an enhanced sensitivity of 5 cfu/mL with the help of a smartphone. Following a short enrichment period of 1 h, the sensitivity was further amplified to 2 cfu/mL. The biosensor material is volume responsive, making the biosensing platform sensitivity increase as the volume of the sample increases, and is highly suitable for testing large-volume fluid samples. This novel material paves the way for the development of volume-flexible biosensing platforms for the record-fast, onsite, selective, and ultrasensitive detection of various pathogenic bacteria in real-world applications.

Optimization of phosphate oxygen isotope pretreatment measurement method based on phosphate in situ enrichment blanket.

Phosphate oxygen isotope analysis is an effective tool for investigating phosphorus migration and transformation in water bodies. Unfortunately, current pretreatment methods for this technology are significantly limited due to their demanding sample amount requirements, complex operation, and limited scope of application. In order to enhance the efficiency of the pretreatment process, hydrated zirconia was synthesized through liquid-phase precipitation. Zeolite, D001 macroporous resin, activated carbon, and ceramsite were chosen as possible candidate materials for loading purposes. The optimal zirconium loading material was identified through a combination of field enrichment and laboratory elution experiments. The ideal in situ enrichment duration, material dosages, and elution time were ascertained using response surface methodology. The findings showed that D001 resin exhibited superior selective adsorption and elution capacity for phosphate. The response surface optimization yielded the optimal parameters for the in situ phosphate-enrichment blanket: a mass of 13 g for zirconium-loaded D001 resin, an enrichment period of 360 min, and an elution period of 853 min. The attainment of a bright yellow Ag3PO4 solid after purification served as proof of the reliability of the optimization method. The obtained results provide a fundamental basis for the preparation and application of phosphate oxygen isotope analysis in freshwater ecosystem.

Effects of the Alga Aurantiochytrium mangrovei FIKU008-Enriched Artemia on Early Stages of the Green Tiger Shrimp, Penaeus semisulcatus

The first aim of the present study was to determine appropriate artemia enrichment levels by using Aurantiochytrium mangrovei FIKU008 served as DHA enrichment source and secondly to test the effects of enriched-Artemia on growth and survival during the early larval stages(M1-PL7) of Penaeus semisulcatus. In the 1st experiment, four different enrichment levels of AUR (0.0,0.6,0.8 and 1.0g/L) against a control commercial solution (S-presso) were tested for 12/24-hours enrichment while in the 2nd experiment, three levels (0.0, 0.6 and 0.8g/L) of AUR enriched-Artemia were fed to larval stages. At the end of both enrichments, DHA and EPA levels were found to be significantly enhanced by using AUR at 0.6 and 0.8g/L. In the 2nd experiment, fatty acid composition of the PL was significantly affected by AUR and the PL fed with enriched diets showed higher n-3 LC-PUFA accumulation in their tissues. The larvae grown from M1 to PL7 displayed higher survivals and growth in the enriched AUR-groups compared to the control(0.0AUR). In conclusion, this study has demonstrated that the use of AUR as enrichment significantly elevated EPA and DHA levels to 0.6-0.8g/L enrichment periods and the enriched-Artemia at such levels were proven to effectively improve growth and survival of the early larval stages of P. semisulcatus.

Controlling the microbial competition between hydrogenotrophic methanogens and homoacetogens using mass transfer and thermodynamic constraints

The reduction of CO2 allows the synthesis of platform molecules for the chemical and energy industry. Anaerobic microbial consortia contain homoacetogenic microorganisms (HAC) capable of reducing CO2 to acetate. However, one of the obstacles to their use is the understanding and management of their functional diversity. In particular, managing the competition between HAC and hydrogenotrophic methanogens (HM) that convert CO2 into methane is crucial to selectively produce acetate.This study contributes to bring new knowledge on the competition between HAC and HM. This microbial competition is encountered in numerous anaerobic systems, and it is necessary to know how to manage it. In this sense, mass transfer between the gas phase where the substrates are located, and the liquid phase which contains the microbial catalysts, as well as kinetic and thermodynamic aspects of biological reactions have been integrated in this work. The microbial competition between HM and HAC was studied in successive batches. The effect of temperature between 25 °C and 35 °C was investigated, as well as different states of mass transfer limitation in the system.A clear effect of temperature between 25 °C and 35 °C on the outcome of the competition between HM and HAC was highlighted, as well as the effect of mass transfer limitation. Enrichment of Acetobacterium homoacetogens and elimination of hydrogenotrophic methanogens was possible at 25 °C without mass transfer limitation. Acetate product selectivity was of 100% by the end of the enrichment period in successive batches. On the contrary, under mass transfer limitation, and/or at 35 °C, Methanobacterium hydrogenotrophic methanogens were promoted with 100% of methane selectivity by the end of the enrichment. This study contributes to identify specific process parameters influencing the selection of HAC over HM and should help in the design of experiments depending on the target product from H2/CO2. Furthermore, the results obtained could be applied to continuous acetate producing systems, at a larger scale, and they can also be useful in other gas fermentation systems and processes.

Study of On-Site Upgraded Livestock Biogas Production and Carbon Emission Reduction By Substituting Coals For Thermal Power Generation

The objective of this project is to integrate a farm-scale bio-desulfurization facility with a novel biogas hollow fibre adsorption module for biogas desulfurization and bio-natural gas production. In this study, the desulfurization experimental results showed that the bio-desulfurization system can remove 96.7 ± 6% of H2S from the biogas after an approximately two-month enrichment period. The average CH4, N2, and CO2 concentrations in raw biogas were 63.4, 15.2, and 21.1%, respectively. As for biogas upgrading experiments, the inlet biogas flow rates were applied from 5 to 20 L/min. The removal efficiency of CO2 under all biogas flow rates was 100%. Meanwhile, methane was promoted from 60% to nearly 94% (i.e. 57% increase in methane concentration). The replacement of anthracite and coking coal by upgraded biogas might reduce 44.4% and 42.5% of CO2 equivalent, respectively. The achievement of this project pursues the mitigation of carbon dioxide emissions by using upgraded pig biogas which can be enlarged and extended to all decentralized pig farms worldwide.

Study of on-site upgraded livestock biogas production and carbon emission reduction by substituting coals for thermal power generation

The objective of this project is to integrate a farm-scale bio-desulfurization facility with a novel biogas hollow fibre adsorption module for biogas desulfurization and bio-natural gas production. In this study, the desulfurization experimental results showed that the bio-desulfurization system can remove 96.7 ± 6% of H2S from the biogas after an approximately two-month enrichment period. The average CH4, N2, and CO2 concentrations in raw biogas were 63.4, 15.2, and 21.1%, respectively. As for biogas upgrading experiments, the inlet biogas flow rates were applied from 5 to 20 L/min. The removal efficiency of CO2 under all biogas flow rates was 100%. Meanwhile, methane was promoted from 60% to nearly 94% (i.e. 57% increase in methane concentration). The replacement of anthracite and coking coal by upgraded biogas might reduce 44.4% and 42.5% of CO2 equivalent, respectively. The achievement of this project pursues the mitigation of carbon dioxide emissions by using upgraded pig biogas which can be enlarged and extended to all decentralized pig farms worldwide.

Micro Raman spectroscopy combined with chromatographic effect and OPLS-DA for time-resolved detection of stamp inks

Ink type identification and ink formation time play a significant role in document examination. Current methods for dating stamp inks in questioned documents primarily rely on the analysis of volatile ink components. However, there is a dearth of literature on the investigation of ink distribution in the initial stages of stamp impressions. Such studies are scarcely reported, despite their potential significance in the field of forensic document examination. This study aims to explore the feasibility of ink diffusion based on Raman spectra monitoring and to identify the ink types using orthogonal partial least squares discrimination analysis (OPLS-DA) multivariate modeling. The kinetics of ink diffusion can be elucidated by the interplay of chromatographic effects and diffusion equilibrium. The diffusion boundary of the ink is visualized using a microscope, and 21 specific locations at varying distances from the boundary are designated for time-resolved spectrum acquisition. Typically, the diffusion process can be separated into two distinct phases an enrichment period followed by an equilibrium period. As the diffusion distance increases, the Raman peak intensity and ink concentration progressively diminish. Following the pre-processing of spectral data, any outliers were removed prior to utilizing the orthogonal partial least squares discrimination analysis method for classification purposes. The OPLS-DA model demonstrated 100% accuracy in differentiating between all types of stamp inks, affirming the significant potential of Raman spectroscopy for forensic science applications.

Optimization and evaluation of a multiplex PCR assay for detection of Staphylococcus aureus and its major virulence genes for assessing food safety.

Staphylococcus aureus is a natural commensal microflora of humans which causes opportunistic infections due to its large arsenal of exotoxins, invasion, immune evasion, and antibiotic resistance mechanisms. The primary goal of this study is to develop a multiplex PCR (mPCR) assay for simultaneous detection of Staphylococcus aureus (nuc) and its virulence genes coding for prominent exotoxins namely alpha hemolysin (hla), enterotoxins A (sea), enterotoxin B (seb), toxic shock syndrome toxin (tsst-1), and the gene coding for methicillin resistance (mecA). A competitive internal amplification control (IAC) was included in the assay to exclude the false negative outcomes. Highly specific primer pairs were designed for the target genes using in silico resources. At the outset, monoplex PCRs were standardized using reference S. aureus strains. Primer specificity to the target genes was authenticated through restriction digestion analysis of amplified PCR products. Multiplex PCR was optimized in increments of one gene starting with nuc and IAC amplified simultaneously using one pair of primers (nuc) in a competitive manner. The mPCR assay was found to be highly sensitive with a detection limit of ~10 CFUs per reaction for pure cultures. Multiplex PCR assay was further evaluated on the retail and processed food samples to test the prevalence of S. aureus and study their exotoxin profiles. Of the 57 samples examined, 13 samples (22.80%) were found to be contaminated with S. aureus whose DNA was extracted after a 6-h enrichment period. Among these, a high percentage of hemolytic and enterotoxin A positive strains were encountered. The mPCR assay developed in this study would be a useful tool for rapid and reliable monitoring of S. aureus for food quality testing and from clinical infections.

Comparison of Gold Biosensor Combined with Light Microscope Imaging System with ELISA for Detecting Salmonella in Chicken after Exposure to Simulated Chilling Condition.

In this study, the performance of a gold biosensor combined with light microscope imaging system (GB-LMIS) was comparatively evaluated against enzyme-linked immunosorbent assay (ELISA) for detecting Salmonella under simulated chilling condition. The optimum concentration of anti-Salmonella polyclonal antibodies (pAbs) was determined to be 12.5 and 100 μg/ml for ELISA and GB-LMIS, respectively. GB-LMIS exhibited a sufficient and competitive specificity toward three tested Salmonella among only. To mimic a real-world situation, chicken was inoculated with Salmonella cocktail and stored under chilling condition for 48 h. The overall growth of Salmonella under chilling condition was significantly lower than that under non-exposure to the chilling condition (p < 0.05). No significant differences in bacterial growth were observed between brain heart infusion and brilliant green broth during the enrichment period (p > 0.05). Finally, both GB-LMIS and ELISA were employed to detect Salmonella at every 2-h interval. GB-LMIS detected Salmonella with a competitive specificity by the direct observation of bacteria on the sensor using a charge-coupled device camera within a detection time of ~2.5 h. GB-LMIS is a feasible, novel, and rapid method for detecting Salmonella in poultry facilities.

Real-Time Detection of Circulating Tumor Cells in Bloodstream Using Plasmonic Fiber Sensors.

Circulating tumor cells (CTCs) are single cancer cells or cancer cell clusters that are present in the circulatory system. Assessing CTC levels in patients can aid in the early detection of cancer metastasis and is essential for the purposes of accurate cancer prognosis. However, current in vitro blood tests are limited by the insufficient blood samples and low concentration levels of CTCs, which presents a major challenge for practical biosensing devices. In this work, we propose the first surface plasmon resonance (SPR) fiber probe to work intravenously, which offers a real-time detection of CTCs in bloodstreams. By exposing the protein-functionalized fiber probe to circulating blood, a continuous capture of CTCs ensures a constant increase in enrichment and hence greatly enhances enumeration accuracy. The performance of our plasmonic fiber probe was demonstrated to specifically detect Michigan Cancer Foundation-7 (MCF-7) breast cancer cells in flowing whole mouse blood. Further, a detection limit of ~1.4 cells per microliter was achieved by using an epithelial cell adhesion molecule (EpCAM) antibody-based receptor layer and a 15 minute enrichment period. This pilot study validates real-time CTC detection directly in the bloodstream by using plasmonic fiber probes, which exhibit promising clinical potential for in vivo diagnostic tests involving low concentration biomarkers in circulating blood.

Isotopic evidence that aestivation allows malaria mosquitoes to persist through the dry season in the Sahel.

Data suggest that the malaria vector mosquito Anopheles coluzzii persists during the dry season in the Sahel through a dormancy mechanism known as aestivation; however, the contribution of aestivation compared with alternative strategies such as migration is unknown. Here we marked larval Anopheles mosquitoes in two Sahelian villages in Mali using deuterium (2H) to assess the contribution of aestivation to persistence of mosquitoes through the seven-month dry season. After an initial enrichment period, 33% of An. coluzzii mosquitoes were strongly marked. Seven months following enrichment, multiple analysis methods supported the ongoing presence of marked mosquitoes, compatible with the prediction that the fraction of marked mosquitoes should remain stable throughout the dry season if local aestivation is occurring. The results suggest that aestivation is a major persistence mechanism of An. coluzzii in the Sahel, contributing at least 20% of the adults at the onset of rains. This persistence strategy could influence mosquito control and malaria elimination campaigns.

Development of a Label-Free Immunosensor for Quantitative, Electrical Detection of Target Antigens

Point-of-care immunoassays require rapid, sensitive, and user-friendly operation. The most common example is an at-home pregnancy test, which falls under a class of diagnostics called a lateral flow assay (LFA). However, LFAs present many disadvantages such as poor sensitivity and a difficulty for users to interpret test results accurately. The gold standard immunoassay, ELISA, exhibits excellent limits of detection (LOD) and limits of quantitation (LOQ). However, barriers to the implementation of ELISA must be considered, such as the consumption of large amounts of expensive reagents, the need for trained personnel to perform the assay, and the possibility of false positives or negatives due to improper washing or procedure. A clear demand exists for a label-free immunological sensor with high sensitivity and specificity, requiring only a small amount of sample and with fully automated operation. Previous work in our group has demonstrated the successful label-free detection of nucleic acids in a microfluidic device with an embedded 3D porous electrode by their hybridization to a bed of bioconjugated microbeads. An increase in conductivity, observed by a current-voltage curve, was attributed to the negative charge added to the beads upon hybridization of the target nucleic acids. In this presentation, we demonstrate label-free sensing of antibody targets by an analogous method despite their low net charge under the conditions employed. In this system, biotinylated goat anti-rabbit IgG immobilized on streptavidin-modified beads serves as the capture antibody. The analyte, Rabbit IgG, is introduced into the channel and incubated for 30 min. A current-voltage curve (CVC) is obtained before and after incubation to detect and quantify binding of Rabbit IgG to the bead surface. We evaluated the sensitivity of this method and found that the LOD is approximately 5 nM. Following validation of this method, we examined binding kinetics by obtaining CVCs at several time points during incubation. Next, to improve the LOD in this device, faradaic ion concentration polarization (fICP) was employed to electrokinetically enrich the negatively charged IgG over the bead bed test line. After an enrichment period of 30 min, the antigen was preconcentrated over 100-fold, which resulted in greater sensitivity. Finally, we characterize the impact of ionic strength on the sensor and evaluated its performance in a simulated biofluid, saliva, under several conditions: neat, spiked with Tris, and diluted. Ongoing research in our group will translate this method to biomarkers relevant to viral diagnostics. The authors gratefully acknowledge the Roy J. Carver Charitable Trust for the funding of this project.

Endothelin Receptor Antagonists for Kidney Protection: Lessons from the SONAR Trial.

Endothelin Receptor Antagonists for Kidney Protection: Lessons from the SONAR Trial.

Effects of environmental enrichment on behaviours and faecal glucocorticoid levels in captive sun bear (Helarctus malayanus)

AbstractStereotypic behaviour is correlated to stress in wild animals in captivity. When wild animals are exposed to stress repeatedly, they may experience a chronic elevation of glucocorticoids (G.C.s), especially for captive sun bears. This study aimed to investigate the stress in captive sun bears by analysing the cortisol level using Faecal Glucocorticoid Metabolite (FGM) analysis before and after introducing environmental enrichments. 57 samples of faecal captive sun bears were collected from four selected study sites around Malaysia. The behavioural data were collected with an instantaneous sampling method. While for FGM analysis, glucocorticoids were analysed using enzyme immunoassays. As predicted, the stereotypic behaviour increased in pre and post enrichment and decreased during the enrichment period. For FGM analysis, the cortisol level was high in pre-enrichment and low in the enrichment period. In conclusion, the outcome of this study indicated that environmental enrichment might help reduce chronically elevated cortisol concentrations that are generally associated with distress in mammals.

Environmental enrichment decreases anxiety-like behavior in zebrafish larvae.

The development of anxiety disorders is often linked to individuals’ negative experience. In many animals, development of anxiety‐like behavior is modeled by manipulating individuals’ exposure to environmental enrichment. We investigated whether environmental enrichment during early ontogenesis affects anxiety‐like behavior in larval zebrafish. Larvae were exposed from hatching to either an environment enriched with 3D‐objects of different color and shape or to a barren environment. Behavioral testing was conducted at different intervals during development (7, 14, and 21 days post‐fertilization, dpf). In a novel object exploration test, 7 dpf larvae of the two treatments displayed similar avoidance of the visual stimulus. However, at 14 and 21 dpf, larvae of the enriched environment showed less avoidance, indicating lower anxiety response. Likewise, larvae of the two treatments demonstrated comparable avoidance of a novel odor stimulus at 7 dpf, with a progressive reduction of anxiety behavior in the enriched treatment with development. In a control experiment, larvae treated before 7 dpf but tested at 14 dpf showed the effect of enrichment on anxiety, suggesting an early determination of the anxiety phenotype. This study confirms a general alteration of zebrafish anxiety‐like behavior due to a short enrichment period in first days of life.

Soil microorganisms facilitated the electrode-driven trichloroethene dechlorination to ethene by Dehalococcoides species in a bioelectrochemical system

Bioelectrochemical dechlorination using organohalide-respiring bacteria (ORBs) is a promising technique for remediating contaminated groundwater. Generally, a longer enrichment period is required for selecting the ORB consortia to achieve bioelectrochemical dechlorination. However, the full dechloriantion is difficult to be achieved due to the absence of functional species (e.g. Dehalococcoides) in previously used enrich cultures. To overcome these challenges, bioelectrochemical dechlorination using a culture enriched with the pre-augmented Dehalococcoides was performed for the first time in this study. A two-chamber bioelectrochemical system (BES) inoculated with a pure Dehalococcoides culture and paddy soil with an applied voltage of −0.3 V (versus a standard hydrogen electrode) as the sole electron donor was used to achieve dechlorination. The ethene formation rate was 10–100 times higher than that in previous studies, indicating that inoculating the system with a pure Dehalococcoides culture and soil microorganisms gave effective full dechlorination performance. Microbial community analysis and bioelectrochemical analysis indicated that Desulfosporosinus species may have facilitated dechlorination through syntrophic interactions with Dehalococcoides. The results indicated that adding Dehalococcoides cells before operating a bioelectrochemical system is an effective way of achieving full dechlorination.

Nitrogen Removal by an Anaerobic Iron-Dependent Ammonium Oxidation (Feammox) Enrichment: Potential for Wastewater Treatment

Nitrogen pollution in water is a growing concern. Anthropogenic activities have increased the amount of nitrogen released into watercourses, which harms human health and the environment, and causes serious problems, such as eutrophication. Feammox is a recently discovered biological pathway associated with the nitrogen cycle that has gained scientific interest. This process couples anaerobic ammonium oxidation with iron reduction. This work presents a study on the Feammox mechanism from the enrichment of an activated sludge obtained from a sewage treatment plant. The enrichment was carried out at neutral pH to study the N2 pathway, that is, the Feammox process with the oxidation of ammonium (NH4+) directly to N2. In addition, different sources of iron were studied: iron chloride (FeCl3); ferrihydrite; and goethite. The characterization of the sludge showed the genes associated with ammonia monooxygenase, nitrate and nitrite reductases processes, along with relevant microbial species. The enrichment, carried out for 42 days and monitored every 14 days, showed that FeCl3 as a source of Fe was more effective for the coupled process of oxidation of NH4+ and the reduction of Fe(III) to Fe(II). At the end of the enrichment period, a removal of 31% and 32.2% of NH4+, and an increase in Fe(II) concentration by 52.4 and 63.9 times regarding the initial value were achieved in aerobic and anaerobic sludge, respectively. This study provides information on the potential of Feammox in the removal of N from wastewater, and the oxidation/reduction yields in the initial enrichment phase.

Enhanced bioelectrochemical nitrogen removal in flow through electrodes

In the past decade, bioelectrochemical systems (BESs) have been studied extensively for the generation of power and maximizing power densities. In recent years, it was noticed that BESs applications can critically improve wastewater treatment. Most of the previous BESs work has used varied reactor geometry and configuration, wastewater composition, electrolyte solution, and constant electrode size to maximize power generation. However, there is limited research investigating the influence of increased electrode size on the wastewater treatment process. We investigated the effect of increased electrode surface area on wastewater treatment efficiency and studied the mechanism of nitrogen removal. In this study, we developed a flow-through electrode in a 3-electrode bioelectrochemical reactor. The anodic biofilms were enriched on electrodes for one week. Following the anodic enrichment period, the reactor was operated in a semi-continuous mode with raw domestic wastewater. To investigate the wastewater treatment efficiency, the chemical oxygen demand (COD), total nitrogen (TN), ammonia (NH3-N), nitrite (NO2–-N), and nitrate (NO3–-N) concentrations were measured. We found that increased surface area of anode did not significantly contribute to COD removal rate, most likely indicating the limits of BES. On the other hand, the TN removal rate increased proportionally to the surface area of the anode in the BES. We also found that outlet NO3–-N and NO2–-N concentrations were 1.2 ± 0.2 and 3.2 ± 0.9 mg/L, respectively. Our results indicated that it is possible to remove COD and TN simultaneously. Analysis of the microbial community structure showed that nitrogen removal was dominated by sulfidogenesis, anodic ammonia oxidation, autotrophic and heterotrophic denitrification as well as reducing NO3–-N to NO2–-N usingGeobacterspecies in our system.

Weathering of Copper Deposits and Copper Mobility: Mineralogy, Geochemical Stratigraphy, and Exploration Implications

Abstract Weathering of pyrite and copper sulfide-bearing rocks produces a consistent series of iron- and copper-bearing minerals that reflect vertical and lateral geochemical changes as supergene solutions react with rock and experience loss of oxidizing capacity. Reactive host rocks, comprising feldspars, mafic minerals, chlorite, and carbonates, buffer pH values that limit copper mineral destruction, thus restricting the supergene transport of copper. Generally, rocks that have undergone well-developed hypogene or supergene hydrolysis of aluminosilicates promote copper mobility because they do not react substantially with low-pH supergene solutions generated by oxidation of pyrite and associated copper sulfides. Development of geochemical stratigraphy is characterized by physical and geochemical parameters that determine the maturity of a supergene profile, with cyclical leaching and enrichment periods critical for the production of economically significant copper accumulation. Evidence for multicycle enrichment is recorded by hematite after chalcocite, hanging zones of copper oxides that replace chalcocite, and hematitic capping overlying immature goethitic-pyritic capping. Because pyrite is the most refractory sulfide with respect to chalcocite replacement, geochemically strong supergene enrichment is independent of total copper added to protore and instead is indicated qualitatively by the degree to which chalcocite replaces pyrite. Covellite replacement of chalcopyrite indicates weak copper addition to protore and generally represents the base and lateral extent of supergene enrichment; covellite replacement of chalcocite indicates incipient copper removal by copper-impoverished supergene solutions. Exploration for, and delineation of, mature supergene enrichment profiles benefits from the recognition of paleoweathering cycles and consequent development of mature geochemical stratigraphy.