Low Ammonium Concentrations Research Articles

Partial replacement of soybean meal with microalgae biomass on in vitro ruminal fermentation may reduce ruminal protein degradation

The objective of this study was to evaluate the effects of partially replacing soybean meal (SBM) with algal sources on in vitro ruminal fermentation. Using 6 fermenters in a 3 × 3 replicated Latin square with 3 periods of 10 d each, we tested 3 treatments: a control diet (CRT) with SBM at 17.8% of the diet dry matter (DM); and 50% SBM biomass replacement with either Chlorella pyrenoidosa (CHL); or Spirulina platensis (SPI). The basal diet was formulated to meet the requirements of a 680-kg Holstein dairy cow producing 45 kg/d of milk with 3.5% fat and 3% protein. All diets had a similar nutritional composition (16.0% CP; 34.9% NDF; 31.0% starch, DM basis) and fermenters were provided with 106 g DM/d split into 2 portions. After 7 d of adaptation, samples were collected for 3 d of each period for analyses of ruminal fermentation at 0, 1, 2, 4, 6, and 8 h after morning feeding for evaluation of the ruminal fermentation kinetics. For the evaluation of the daily production of total metabolites and for the evaluation of nutrient degradability, samples from the effluent containers were collected daily. Statistical analysis was performed with the MIXED procedure of SAS with treatment, time, and their interactions considered as fixed effects; day, square, and fermenter were considered as random effects. Orthogonal contrasts (CRT vs. algae; and CHL vs. SPI) were used to depict the treatment effect, and significance was declared when P ≤ 0.05. Fermenters that received algae-based diets had a greater propionate molar concentration and molar proportion when compared with the fermenters fed CRT diets. In addition, those algae-fed fermenters had lower branched short-chain fatty acids (BSCFA) and isoacids (IA), which are biomarkers of ruminal protein degradation, along with lower ammonia (NH3-N) concentration and greater nonammonia nitrogen (NAN). When contrasting with fermenters fed SPI-diets, fermenters fed based CHL-diets had a lower molar concentration of BSCFA and IA, along with lower NH3-N concentration and flow, and greater NAN, bacterial nitrogen flow, and efficiency of nitrogen utilization. Those results indicate that CHL protein may be more resistant to ruminal degradation, which would increase efficiency of nitrogen utilization. In summary, partially replacing SBM with algae biomass, especially with CHL, is a promising strategy to improve the efficiency of nitrogen utilization, due to the fact that fermenters fed CHL-based diets resulted in a reduction in BSCFA and IA, which are markers of protein degradation, and it would improve the efficiency of nitrogen utilization. However, further validation using in vivo models are required.

Energetic Physiology of the Caribbean Estuarine Clam Polymesoda arctata (Deshayes, 1854) Exposed to Different Environmental Conditions under Laboratory

The estuarine clam Polymesoda arctata is one of the commercially important bivalves of the Caribbean, which is currently considered endangered by overexploitation and habitat loss. With the purpose of gain knowledge about its environmental requirements for aquaculture and restocking purposes, its energetic physiology performance was evaluated under laboratory conditions in response to the variation of food concentration and water quality registered in their natural habitat. Different physiological variables, including the rates of filtration (FR), pseudofeces production (RR), ingestion (IR), absorption (AR), oxygen consumption (OCR), and ammonium excretion (UR), as well as absorption efficiency (AE) and scope for growth (SFG), were estimated in five successive experiments, where different concentration levels of food or particulate organic matter (1.8, 4.0, 7.3, and 13.0 mg L−1 equivalent to 2.3, 5.0, 9.3, and 16.6 mg of the microalgae Isochrysis galbana L−1), salinity (5, 15, and 25‰), temperature (27, 29, and 32°C), ammonia concentration (7, 48 and 77 µg NH3-N L−1), and dissolved oxygen saturation (24, 48, and 93%) were tested. Intermediate conditions of food concentration, salinity, and temperature resulted in higher values for most of the physiological variables measured, except for the higher values of OCR and UR obtained at low salinity, as well as the higher values of AE, AR, and SFG measured at low temperatures. Most of the physiological variables increased under conditions of lower ammonia concentrations and higher dissolved oxygen saturation in the water. Although this species exhibited physiological plasticity, tolerance, and enough energy for growth and reproduction under the environmental variations of its habitat, it also showed a high sensitivity to its environment, having the highest SFG values under intermediate conditions of particulate organic matter (7.2 mg L−1 or 9.3 mg of I. galbana L−1), salinity (15‰), and temperature (27–29°C), as well as at low ammonia concentration (7 μg NH3-N L−1) and high dissolved oxygen saturation (93%). Based on our results, we recommended the use of this values for reproductive conditioning of broodstock and juvenile culture in laboratory, and also as an input for selecting areas for aquaculture farming and restocking experiments.

Organic and inorganic nitrogen amendments reduce biodegradation of biodegradable plastic mulch films

Abstract. Biodegradable mulch films (BDMs) are a sustainable and promising alternative to non-biodegradable polyethylene mulches used in crop production systems. Nitrogen amendments in the form of fertilizers are used by growers to enhance soil and plant-available nutrients; however, there is limited research on how these additions impact the biodegradation of BDMs tilled into soils. A 4-month laboratory incubation study using soil microcosms was used to investigate the effects of inorganic (ammonium nitrate) and organic (urea and amino acids) nitrogen application on biodegradation of BDMs. We investigated the response of soil bacterial, fungal, and ammonia-oxidizing microbial abundance along with soil nitrogen pools and enzyme activities. Microcosms were comprised of soils from two diverse climates (Knoxville, TN, USA, and Mount Vernon, WA, USA) and BioAgri, a biodegradable mulch film made of Mater-Bi®, a bioplastic raw material containing starch and poly(butylene adipate-co-terephthalate) (PBAT). Both organic and inorganic nitrogen amendments inhibited mulch biodegradation, soil bacterial abundances, and enzyme activities. The greatest inhibition of mulch biodegradation in TN soils was observed with urea amendment where biodegradation was reduced by about 6 % compared to the no-nitrogen control. In WA soils, all nitrogen amendments suppressed biodegradation by about 1 % compared to the no-nitrogen control. Ammonia monooxygenase amoA gene abundances were increased in TN soils in all treatments but reduced for all treatments in WA soils. However, a significantly higher nitrate concentration and a lower ammonium concentration were seen for all nitrogen treatments compared to no-nitrogen controls in both TN and WA. This study suggests that the addition of nitrogen, particularly inorganic amendments, could slow down mulch biodegradation but that mulch biodegradation does not negatively affect soil nitrification activity.

Sub-lethal Ammonia Toxicity in Fingerlings of <i>Catla catla</i> (ham.) and <i>Labeo rohita</i> (ham.): Effect on Certain Haematological Parameters and Enzymes Activities

Fingerlings of catla and rohu were exposed to ambient sub-lethal total ammonia-nitrogen concentrations of 1, 2, 4, 8, 11.8 and 16 mg/l for 96 hours to study the toxic effect. Haematological parameters such as TEC and TLC increased in both species in lower concentration of ambient ammonia but decreased in higher concentration while haemoglobin and serum protein content decreased and blood glucose level increased with increasing ammonia concentration. Elevation of LDH, ALAT and ASAT activities were observed in serum and different tissues while inhibition was recorded in AChE activity in brain and liver with increasing ammonia concentration. Comparison of the haematological responses of the two major carps revealed catla to exhibit significant alteration in almost all haematological parameters at relatively lower ammonia concentrations compared to that of rohu. The study on enzymes also revealed lower alteration in AChE, LDH, ALAT and ASAT activities in rohu suggesting better tolerance of the species to higher ambient ammonia than catla, corroborating catla to be more susceptible to environmental stress than rohu.

Application of the fermented broiler chickens manure under different aeration regimes during vermiculture cultivation

The growth of poultry population in Ukraine and in the world leads to a number of environmental problems such as concentration and accumulation of large masses of manure without litter and manure mixed with organic litter. A rational way to dispose poultry manure, including broiler chickens’ manure, is to produce vermicompost from it by growing there a hybrid of local red worm or Eisenia fetida. Unfermented broiler manure contains a high concentration of nitrogen-containing compounds, including ammonia, which has a negative effect on worms. Even at low ammonia concentrations in the organic biomass, the worms die. Traditional methods can take more than 17 months to compost broiler manure. One of the ways to speed up composting is to apply bioprocessing devices and aeration of the manure. The effectiveness of growing vermiculture on the fermented broiler manure with a biodegrader and different aeration regimes remains insufficiently studied. For the experimental cultivation of worms, we used the broiler chicken manure fermented for 160 days, which was enriched with air once every 10 days by mechanical mixing (control), 15 minutes a day using a compressor (I experimental group) and twice a day for 15 minutes using a compressor (II experimental group). The study determined the number of adult and immature worms, their weight, the number of cocoons and their weight. It has been experimentally found that fermented broiler chicken manure under different aeration regimes with litter as part of the vermiculture substrate has an effect on the reproduction and weight of worms and their cocoons. Growing worms on a substrate from fermented broiler chickens' litter with a daily one-time air enrichment with a compressor increases the number of mature worms by 15.7 % compared to the control group. The largest mass of mature worms was recorded in the first experimental group. It was proved that the use of fermented broiler manure with active aeration (experimental group I) as a substrate increased the number and weight of immature worms by 10.3 and 33.3 %, respectively, compared to the control. The largest number of cocoons has been found in the first experimental group.

Multi-Function Sensory System for Detection of Ammonia

Ammonia is a highly toxic gas with implications for human and animal health. This effort aims to develop a low-cost multi-array orthogonal sensor for detecting a low concentration of ammonia in a poultry house. To approach this problem, a novel multi-array electro-thermal and Metal oxide solid state gas sensor are developed. Its design consists of a microfabricated suspended MEMS bridge, a resistance temperature detector (RTD), a low-pass loop filter H(s), and a heater amplifier for the micro-oven. The resistive element is used as the micro-oven heater. The sensing platform comprises of a low-cost thermal conductivity sensor (TCD), and Metal oxide (ZnO, NiO-ZnO, Au-ZnO) solid-state sensors. From this study. we concluded that the thermal conductivity sensor provides a linear level of detection(LOD) of 1 ppm at 30-80 % relative humidity with 100 ns response time and 5 years of lifetime while the Au-ZnO solid state sensor has sub ppm limit of detection and response time of ~ 2 minutes. Figure 1

Benchmarking Heterogeneous Photocatalysts for the Nitrogen Reduction Reaction

Ammonia is the key ingredient for living organisms, and artificial catalytic synthesis of ammonia (known as the Haber-Bosch process) is undoubtedly a milestone in scientific research in the 20th century and the cornerstone of today's society.[1] However, the Haber-Bosch process is energy-intensive (2% of the global energy consumption) and is accompanied by large CO2 emissions (1% of global CO2 emission).[2] To catch up with the goal of “Net Zero CO2 Emissions” by 2050, it is imperative to develop a carbon-free and sustainable ammonia production process. The photocatalytic ammonia synthesis method relies only on renewable feedstocks (water and air) and sustainable energy input (light) and can be operated under ambient conditions. The current progress in photocatalytic ammonia synthesis suggests, however, there exists a large gap in performance before commercial use is viable. To replace the Haber-Bosch process and produce commercial fertilizer, the solar-to-ammonia (STA) efficiency needs to be at least 0.1% and the highest reported efficiency carried out in a lab setting is approaching 0.04%[2][3] With advances in measurement techniques, recent studies in the field of electrocatalytic ammonia synthesis have shown that many reported highly active catalysts have later been shown to be inactive toward nitrogen reduction.[4] This false positive result is mainly due to the adventitious ammonia in the environment. A series of discussions were triggered, including identifying and eliminating contaminations, developing robust measurements for low-concentration ammonia detection, and establishing rigorous testing protocols.[4-7] At present, the ammonia yield of electrocatalysis is at least an order of magnitude higher than that of photocatalysis, so the problem of nitrogen contamination will only be more serious in the field of photocatalysis.[7] Unfortunately, such discussions have not received equal attention in this field, and few if any rigorous testing protocols have been employed in existing reports.It is imperative to benchmark and develop a robust testing protocol for the growing field of photocatalytic ammonia synthesis. Here, we developed a rigorous setup to suppress all known ammonia contaminations (e.g., ammonia and NOx), systematically discussed the effect of various gas pretreatment methods, and established the background contamination level in the system. We synthesized three highly active photocatalytic materials (Fe-BiOBr, OVs-TiO2, and Fe2O3/g-C3N4) from the literature and measured their ammonia yield using the setup with strict controls.[8-10] To avoid potential interference effects during the measurements, we cross-compared different ammonia-detecting methods (Indophenol blue method and ion chromatography).[6] In addition, we applied isotope labeling with quantitative NMR to confirm the genuine production of photo-fixed ammonia. Going a step further, we methodically compare the effects of two experimental parameters (temperature and gas flow rate) on the performance of photocatalytic ammonia synthesis. These parameters vary greatly across reports, making it difficult to objectively analyze their impacts on the production of photo-fixed ammonia. Based on our findings, we aim to provide a solid benchmark for this burgeoning field and draw more attention to the importance of rigorous testing. Reference: Smil, Vaclav. Enriching the earth: Fritz Haber, Carl Bosch, and the transformation of world food production. MIT press, 2004.Medford, Andrew J., and Marta C. Hatzell. "Photon-driven nitrogen fixation: current progress, thermodynamic considerations, and future outlook." Acs Catalysis4 (2017): 2624-2643.Yuan, Jili, et al. "Efficient Photocatalytic Nitrogen Fixation: Enhanced Polarization, Activation, and Cleavage by Asymmetrical Electron Donation to N N Bond." Advanced Functional Materials4 (2020): 1906983.Andersen, Suzanne Z., et al. "A rigorous electrochemical ammonia synthesis protocol with quantitative isotope measurements." Nature7762 (2019): 504-508.Choi, Jaecheol, et al. "Identification and elimination of false positives in electrochemical nitrogen reduction studies." Nature communications1 (2020): 1-10.Zhao, Yunxuan, et al. "Ammonia detection methods in photocatalytic and electrocatalytic experiments: how to improve the reliability of NH3 production rates?." Advanced Science8 (2019): 1802109.Iriawan, Haldrian, et al. "Methods for nitrogen activation by reduction and oxidation." Nature Reviews Methods Primers1 (2021): 1-26.Liu, Yang, Zhuofeng Hu, and Jimmy C. Yu. "Fe enhanced visible-light-driven nitrogen fixation on BiOBr nanosheets." Chemistry of Materials4 (2020): 1488-1494.Zhang, Guoqiang, et al. "Constructing a tunable defect structure in TiO 2 for photocatalytic nitrogen fixation." Journal of Materials Chemistry A1 (2020): 334-341.Mou, Hongyu, et al. "A one-step deep eutectic solvent assisted synthesis of carbon nitride/metal oxide composites for photocatalytic nitrogen fixation." Journal of materials chemistry A10 (2019): 5719-5725.

Impact of Varying Mass Concentrations of Ammonia Nitrogen on Biogas Production and System Stability of Anaerobic Fermentation

High ammonium release from chicken manure poses a significant limitation to aerobic digestion, impeding microbial processes and inhibiting biogas production. In this study, we conducted anaerobic digestion of a mixture consisting of chicken manure and corn straw as the fermented raw material. The inoculum used was obtained from the residue of previously fermented chicken manure. To assess the inhibitory effect, we varied the ammonia levels within the range of 750–4250 mg/L by introducing ammonium chloride. The efficiency of aerobic digestion was monitored through the measurement of volatile fatty acids (VFA), chemical oxygen demand (COD), total inorganic carbon (TOC), and methane yield. Our results indicated that elevated levels of ammonia nitrogen had a suppressive impact on methane release, and this decrease followed a linear relationship with the increasing ammonia nitrogen load. Moreover, the addition of ammonia led to a slower release, with the maximum daily ammonia concentration observed at 15 days compared to the 6th day at lower ammonia levels. Furthermore, on the 40th day of aerobic digestion, the cumulative methane production at 4250 mg/L was inhibited by 41% compared to the 750 mg/L condition. The patterns of VFA, inorganic carbon, and COD reduction were consistent across all ammonia levels, with VFA and TOC levels being highest at the highest ammonia concentration and lowest at the lowest ammonia concentration. The accumulation of VFA resulted in a decrease in pH and a decline in methanogenic activity. Additionally, high ammonia levels altered the relative abundance of methanogens. Acetoclastic methanogens (Methanosaeta) exhibited a decrease in abundance, while hydrogenotrophic methanogens (Methanosaeta, Methanoculleus) and methylotrophic methanogens (Candidatus Methanoplasma) demonstrated an increase in abundance. Overall, our findings highlight the inhibitory effects of high ammonia concentrations on biogas production, providing insights into the changes in microbial composition and activity during anaerobic fermentation.

Modulation of struvite composition in full-scale nutrient recovery system using source-separated urine.

Using urine collected from a public restroom at a highway rest stop in Northern California, a full-scale nutrient recovery system involving a two-part system consisting of urine distillation followed by the precipitation of struvite crystals was characterized. The study examined the effects of different operational parameters of the coupled ammonium distillation and struvite process (CADSP) on the composition of struvite crystals and the overall nutrient recovery rates. System inputs that were investigated included the feed:steam (F:S), alkalinity source, and urinary pH. Overall, the findings demonstrate that the composition of the struvite produced can be varied by adjusting the preceding distillation unit process. Low F:S distillation operations result in high ammonium distillation rates which coincided with increased formation of magnesium potassium phosphate (MPP) while higher F:S operations led to conditions favorable to magnesium ammonium phosphate (MAP) precipitation. Therefore, low energy distillation operations (high F:S) are more conducive to MAP formation and high phosphorus recovery rates while high energy operations (Iow F:S) are more conducive to MPP formation. Sodium-based alkalinity sources should also be avoided in instances of low ammonium concentrations in the struvite precipitation tank to minimize the co-precipitation of magnesium sodium phosphate (MSP) with MPP.

A highly sensitive ammonia gas sensor based on non-covalent functionalized single-walled carbon nanotubes with Schiff Base polyphenylene polymer

Accurately detecting the NH3 gas is an important task in different fields. For this demand, high-purity of semiconducting single-walled carbon nanotubes (sc-SWCNTs) are ideal for gas sensing, but the cost of their preparation could limit the application of this material. In this paper, a copolymer of poly [9, 9-dioctylfluorene-N, N′ - (1, 4-phenyl dimethyl) bis (4-iodoaniline)] (FO-N-PA) was reported, which was used to separate and non-covalently functionalize the sc-SWCNTs by simple ultrasonication and centrifugation with over 99 % purity. Then, the sorted FO-N-PA@SWCNTs were used as a sensing material for the detection of ammonia vapors at room temperature. Eventually, the FO-N-PA@SWCNTs complex-based sensor demonstrates high sensitivity, fast response, and high selectivity for low concentrations of ammonia vapors in the natural air. The response of the FO-N-PA@SWCNTs complex-based sensor is improved by 14 times than that of the raw SWCNTs-based sensor. In particular, the FO-N-PA@SWCNTs complex-based sensor showed response values of 21.3 % and 73.3 % for 1 ppm and 35 ppm ammonia vapors, respectively. The limit of detection (LOD) of the FO-N-PA@SWCNTs complex-based sensor was calculated to be 75.78 ppb. The test results showed that sensors have high sensitivity at both low and high ammonia concentrations.

Digestibility and Palatability of the Diet and Intestinal Functionality of Dogs Fed a Blend of Yeast Cell Wall and Oregano Essential Oil.

Feed additives, such as prebiotics and essential oils, are used in pet foods and can affect digestibility, palatability, and intestinal functionality of dogs. The combined effects of yeast cell wall and oregano essential oil on apparent total tract digestibility (ATTD) and palatability of diet, intestinal fermentation products, and fecal microbiota in dogs were analyzed. Eighteen adult dogs were fed for 20 days with three dry extruded diets for adult dogs: control (without the additive), a diet containing 1.5 kg/ton of yeast cell wall and oregano essential oil (1.5YCO), and a diet containing 3.0 kg/ton of yeast cell wall and oregano essential oil (3.0YCO). The inclusion of both levels of YCO reduced the intake ratio. The addition of 3.0YCO reduced the ATTD of dry matter, compared to the control group (p < 0.05). There were greater putrescine and cadaverine concentrations and lower histamine and ammonia (p < 0.05) in the feces of dogs fed 3.0YCO. In addition, fecal odor of dogs fed YCO was less fetid than the control group (p < 0.05). There was greater fecal bacterial diversity in dogs fed with both dietary concentrations of YCO evaluated (p < 0.05). Dogs fed 1.5YCO and 3.0YCO showed higher relative abundance of Blautia and Faecalibacterium and lower abundance of Streptococcus (p < 0.05) in the feces, in comparison to the control group. Given the modulation of microorganisms considered beneficial and the lower fecal concentrations of histamine, phenols, and ammonia, the YCO blend resulted in indicators of improvement of intestinal functionality in dogs.

Inhibitory Effects of Ammonia on Archaeal 16S rRNA Transcripts in Thermophilic Anaerobic Digester Sludge

High temperatures exacerbate the ammonia inhibition of anaerobic digestion coupled with methanogenesis. The inhibition of methane production by ammonia has been observed in other studies. However, the underlying mechanism is not well understood and requires further investigation. This study explored the effect of ammonia stress on archaeal 16S rRNA transcripts in thermophilic anaerobic digester sludge. Different ammonium concentrations were checked for their influence on the methanogenic rate and hydrogen accumulation. Quantitative PCR was used to compare the changes in total archaeal 16S rRNA expression. A Monte Carlo permutation test within redundancy analysis (RDA) was adopted for exploring the relationship between environmental variables and archaeal 16S rRNA and their transcripts. The results showed that with the increase in ammonium concentration, the methanogenic rate decreased and hydrogen accumulation occurred. The total archaeal 16S rRNA genes and transcripts copy numbers decreased significantly in treatments with higher ammonium concentrations (7 and 10 g NH4+-N/L), but did not change much at lower ammonia concentrations (3 g NH4+-N/L) compared with the 0 g NH4+-N/L treatment. The RDA analysis further revealed that most environmental variables, including ammonia and methane, except for formate, were significantly correlated with the community structure activity of archaeal 16S rRNA transcripts rather than the community structure of their genes. The composition of archaeal 16S rRNA transcripts showed that the hydrogenotrophic methanogen Methanothermobacter dominated the methanogenic community activity in all incubations. It exhibited sensitivity to ammonia stress and should be responsible for the methanogenic inhibition under thermophilic conditions. Our findings suggested that archaeal 16S rRNA transcripts, rather than 16S rRNA genes, are key indicators of ammonia stress and methanogenic activity.

Purified Chlorine Dioxide as an Alternative to Chlorine Disinfection to Minimize Chlorate Formation During Postharvest Produce Washing.

The washwater used to wash produce within postharvest washing facilities frequently contains high chlorine concentrations to prevent pathogen cross-contamination. To address concerns regarding the formation and uptake of chlorate (ClO3-) into produce, this study evaluated whether switching to chlorine dioxide (ClO2) could reduce chlorate concentrations within the produce. Because ClO2 exhibits lower disinfectant demand than chlorine, substantially lower concentrations can be applied. However, ClO3- can form through several pathways, particularly by reactions between ClO2 and the chlorine used to generate ClO2 via reaction with chlorite (ClO2-) or chlorine that forms when ClO2 reacts with produce. This study demonstrates that purging ClO2 from the chlorine and ClO2- mixture used for its generation through a trap containing ClO2- can scavenge chlorine, substantially reducing ClO3- concentrations in ClO2 stock solutions. Addition of low concentrations of ammonia to the produce washwater further reduced ClO3- formation by binding the chlorine produced by ClO2 reactions with produce as inactive chloramines without scavenging ClO2. While chlorate concentrations in lettuce, kale, and broccoli exceeded regulatory guidelines during treatment with chlorine, ClO3- concentrations were below regulatory guidelines for each of these vegetables when treated with ClO2 together with these two purification measures. Switching to purified ClO2 also reduced the concentrations of lipid-bound oleic acid chlorohydrins and protein-bound chlorotyrosines, which are exemplars of halogenated byproducts formed from disinfectant reactions with biomolecules within produce.

Hexagonal/monoclinic phase junction modulated WO3 heterostructures for the detection of ammonia

Engineering the formation of phase junctions in the metal oxide is a powerful way to improve their gas-sensing performance. Here, we report a successful synthesis of different WO3 nanostructures. A simple and cost-effective hydrothermal technique was employed for the synthesis of monoclinic (m-WO3) and mixed hexagonal-monoclinic WO3 nanostructures (h-/m-WO3). The h-/m-WO3 exhibits a higher response than m-WO3 at 200℃. Among the various reducing gases, h-/m-WO3 is more sensitive toward ammonia whereas m-WO3 is sensitive toward H2S. The h-/m-WO3 device could detect a low ammonia concentration of 10 ppm and show spontaneous recovery, good repeatability, and long-term stability.

Widely targeted metabolomics investigation of the meat taste of Eriocheir sinensis under ammonia exposure

Ammonia-nitrogen may accumulate in the aquaculture water of Eriocheir sinensis. This study investigated the effects of ammonia exposure during 48 h (0, 10.47, and 41.87 mg/L) on the meat taste of E. sinensis. Sensory analysis showed that the low-concentration ammonia group had the highest umami and the lowest bitterness scores. Metabolomics combined with quantitative analysis showed that ammonia increased the 5′-inosine monophosphate content and the equivalent umami concentration and reduced the arginine content, thereby enhancing umami and reducing crab meat bitterness. Exposure to high concentrations of ammonia reduced umami amino acids (glutamic acid and aspartic acid) and increased bitter amino acid levels (leucine, isoleucine, and tryptophan), which hindered the taste development of crab meat. The increased levels of sweet amino acids (glutamine and serine) in the high-concentration ammonia group may be key ammonia detoxification products. This study revealed that phospholipids and small peptides may participate in improving crab meat flavor after ammonia exposure.

Effect of initial ammonium concentration on a one-stage partial nitrification/anammox biofilm system: Nitrogen removal performance and the microbial community

One-stage partial nitrification coupled with anammox (PN/A) technology effectively reduces the energy consumption of a biological nitrogen removal system. Inhibiting nitrite-oxidizing bacteria (NOB) is essential for this technology to maintain efficient nitrogen removal performance. Initial ammonium concentration (IAC) affects the degree of inhibited NOB. In this study, the effect of the IAC on a PN/A biofilm was investigated in a moving bed biofilm reactor. The results showed that nitrogen removal efficiency decreased from 82.49% ± 1.90% to 64.57% ± 3.96% after the IAC was reduced from 60 to 20 mg N/L, while the nitrate production ratio increased from 13.87% ± 0.90% to 26.50% ± 3.76%. NOB activity increased to 1,133.86 mg N/m2/day after the IAC decreased, approximately 4-fold, indicating that the IAC plays an important inhibitory role in NOB. The rate-limiting step in the mature biofilm of the PN/A system is the nitritation process and is not shifted by the IAC. The analysis of the microbial community structure in the biofilm indicates that the IAC was the dominant factor in changes in community structure. Ca. Brocadia and Ca. Jettenia were the main anammox bacteria, and Nitrosomonas and Nitrospira were the main AOB and NOB, respectively. IAC did not affect the difference in growth between Ca. Brocadia and Ca. Jettenia. Thus, modulating the IAC promoted the PN/A process with efficient nitrogen removal performance at medium to low ammonium concentrations.

Comparison of the effects of probiotic-based formulations on growth, feed utilization, blood constituents, cecal fermentation, and duodenal morphology of rabbits reared under hot environmental conditions

Abstract The present study aimed to assess the effects of three probiotic-supplemented diets on growth, cecal fermentation, blood biochemical, and intestinal morphological features in growing rabbits reared under summer conditions. Rabbits were allotted into four groups: G1 rabbits were fed the basal diet (control), G2 rabbits received Enterococcus faecium (EF) and Clostridium butyricum (CB) complexes (1 × 108 and 2.5 × 106 cfu/kg diet, respectively), G3 rabbits were given CB (2.5 × 106 cfu/kg diet) and yeast complexes (1 g/kg diet), and G4 rabbits received EF (2 × 108 cfu/kg diet) and yeast (1 g/kg diet). G2 rabbits exhibited the highest performances in terms of enhanced body weight and weight gain, protein efficiency ratio and feed conversion ratio (P&lt;0.05). Serum total protein, globulin, immunoglobulin M, and highdensity lipoprotein concentrations were higher in probiotic-fed rabbits than those in controls. Additionally, lipid profile parameters were significantly reduced in the probiotic-fed rabbits, with the lowest concentrations measured in G4 rabbits (P&lt;0.05). Rabbits given EF and CB had the highest total volatile fatty acid (VFA ) and propionic acid levels and the lowest ammonia concentrations. Increased villi length and muscular layer thickness and reduced crypt depth were observed in rabbits receiving EF and CB compared with the values obtained in controls (P&lt;0.05). In summary, supplementing fattening rabbit diets with EF and CB, as a novel formulation, might be a promising and easy method to enhance growth performance under hot climate conditions by improving the feed utilization, immune response, serum lipid profile, cecal VFA production, and duodenal morphology.

Efficient cavity-enhanced adsorption and recovery of low-concentration ammonia on pillar[5]arenes

Ammonia (NH3) capture has great implications for environmental protection and resource recovery. Developing effective and recyclable adsorbent materials to remove low-concentration NH3 in industrial waste gas is critical. Here, solid adsorbents per-hydroxylated pillar[5]arene (OHP[5]) and pillar[5]quinone (P[5]Q) with well-designed functional groups were synthesized and evaluated for NH3 adsorption. The results showed that both materials have high NH3 uptake capacity and excellent cycle stability. P[5]Q showed higher NH3 capacity (15.4 mmol/g) than OHP[5] (11.5 mmol/g) at ambient conditions (293.2 K and 1.0 bar). Dynamic breakthrough experiments showed that P[5]Q had good separation performance on low concentration NH3. Characterizations (including FTIR, SEM, and XPS) and density functional theory (DFT) studies revealed that the adsorption strength for NH3 on P[5]Q possessing CO groups was stronger than OHP[5] composed of phenolic hydroxyls. Also, the electron-accepting CO groups on P[5]Q could change the intramolecular charge distribution, in which an amount of NH3 enters and stores in the electron-deficient internal cavity of P[5]Q. It is demonstrated that P[5]Q with the suitable cavity has good potential for separating low concentration NH3 from industrial waste gas.

Enhancing nitrogen removal efficiency and anammox metabolism in microbial electrolysis cell coupled anammox through different voltage application

The slow growth and difficulty in cultivating anammox bacteria limit the rapid start-up of anammox process and effective microbial enrichment. In this study, microbial electrolysis cell (MEC) was coupled with anammox to investigate the effects of different applying voltage methods on substrate removal efficiency and rates, microbial community structure, anammox metabolism and metabolic pathways. The results showed that applying voltage not only improved NH4+-N removal efficiency and removal rates, but also promoted electron transfer efficiency, key enzyme activity and extracellular polymeric substances (EPS) secretion in the systems. Step-up voltage was more conducive to the growth of Candidatus_Kuenenia in the cathode, which promoted the rapid start-up of anammox and treating wastewater with low ammonia concentration. The main metabolic pathway in step-up voltage operation was hydrazine to nitrogen, while in constant voltage operation was hydroxylamine oxidation pathway. These findings provided a new insight into the enhancement and operation of anammox system.

Simultaneous ammonium and water recovery from landfill leachate using an integrated two-stage membrane distillation

Resources recovery from landfill leachate (LFL) has been attracting growing attention instead of merely purifying the wastewater. An integrated two-stage membrane distillation (ITMD) was proposed to simultaneously purify LFL and recover ammonia in this study. The results showed that organics could be always effectively rejected by the ITMD regardless of varying feed pH, with COD removal higher than 99%. With feed pH increased from 8.64 to 12, the ammonia migration (50–100%) and capture (36–75%) in LFL were considerably enhanced, boosting the separated ammonia enrichment to 1.3–1.7 times due to the improved ammonium diffusion. However, the corresponding membrane flux of the first MD stage decreased from 13.7 to 10.5 L/m2·h. Elevating feed pH caused the deprotonation of NOM and its binding with inorganic ions, constituting a complex fouling layer on the membrane surface in the first MD stage. In contrast, the membrane permeability and fouling of the second MD were not affected by feed pH adjustment because only volatiles passed through the first MD. More importantly, it was estimated that ITMD could obtain high-quality water and recover high-purity ammonium from LFL with relatively low ammonium concentration at an input cost of $ 2–3/m3, which was very competitive with existing techniques. These results demonstrated that the ITMD can be a valuable candidate strategy for simultaneous water purification and nutrient recovery from landfill leachate.