Total Ammonia Nitrogen Concentrations Research Articles

The absolute concentration and bioavailability of trace elements: Two vital parameters affecting anaerobic digestion performance of chicken manure leachate

It is currently unclear whether trace elements (TEs) deficiency is due to low bioavailability or low absolute TEs concentrations, especially in high-pH anaerobic digestion (AD) systems. A mixed solution of TEs and EDTA-Na2 were used separately in mono-AD of chicken manure (CM) leachate to investigate this research gap. The results showed relatively low bioavailability of Fe, Mn, and Zn. The bioavailability of all TEs remained stable along with a gradual increase in total ammonia nitrogen concentration. Both TE and EDTA-Na2 supplementation improved the bioavailability of TEs, but TEs supplementation also gave a high proportion of soluble TEs. Adding TEs improved methane production efficiency (+38.3%) and decreased the H2S content. The exchangeable fraction of specific TE (Mo) in H2/CO2 pathway was higher in the TEs treatment. TEs bioavailability and absolute concentrations of available TEs are critical aspects that need to be scrutinized to assess the risk of TEs deficiency.

Comparison of metabolic kinetics during high and low solids anaerobic digestion of fecal sludge.

High solids anaerobic digestion (HS-AD) is an attractive energy-producing technology; however, high total solids (TS) content may inhibit methanogens due to high volatile fatty acid (VFA) and total ammonia nitrogenconcentrations. The objective of this paper is to quantify rate-limiting metabolic kinetic parameters to determine the influence of TS content during anaerobic digestion of fecal sludge. Two TS content:11% and 17% microcosms were analyzed. Good performance was observed in both systems, with volatile solid(VS) removalgreater than 50%, CH4 yield between 0.44 and 0.56 m3 CH4 /g VS added and cumulative CH4 production between 1.78 and 2.03 m3 CH4 /m3 digester-day. At 11% TS VFA consumption and VS removal had a positive correlation to CH4 production while the 17% TS microcosm had a negative correlation with both. This is the first study to determine the kinetic parameters for hydrolysis, VFA consumption, and methanogenesis during digestion of fecal sludge. These kinetic parameters are necessary in the design and operation of anaerobic digestion systems treating fecal sludge.

Effect of thermophilic microbial agents on nitrogen transformation, nitrogen functional genes, and bacterial communities during bean dregs composting.

This study explored how a thermophilic microbial agent altered nitrogen transformation, nitrogen functional genes, and bacterial communities during bean dregs composting with (T) and without (CK) a thermophilic microbial agent for 15days. The results showed that the maximum temperature in T reached 73°C and remained above 70°C for 8days, while that in CK was only 65°C. The pH in T had essentially stabilized on day 7, while that in CK was still increasing. On day 15, the seed germination index (GI) of T (95%) reached maturity (defined by GI ≥ 85%), while the GI of CK was only 36%. The concentrations of total nitrogen, water-soluble nitrogen, ammonia nitrogen, and nitrate nitrogen in T (2.5%, 18.9g/kg, 8.75g/kg, and 1.69g/kg) were all lower than those in CK (3.6%, 28.9g/kg, 12.75g/kg, and 6.82g/kg). During composting, Bacillus played a major role in nitrogen reduction, nitrogen mineralization, denitrification, and the conversion between nitrite and nitrate. Weissella played a major role in nitrogen assimilation. Komagataeibacter and Bacillus played a major role in nitrogen fixation in CK and T, respectively. Nitrification was not observed during composting. The nosZ gene, which converts nitrous oxide to nitrogen, was found only in T. Network analysis suggested that the average number of neighbours in T was 3.30% higher than that in CK and the characteristic path length in T was 14.15% higher than that in CK. Therefore, the thermophilic microbial agents could cause nitrogen loss but promote the maturity of bean dregs, which have great potential application.

Effects of different growth form submerged macrophyte assemblages on biomass accumulation and water purification

种植水生植物，尤其是沉水植物，是目前广泛应用于受损水体的最主要的生态修复方法之一. 研究不同生长型沉水植物组合对水体理化因子的影响及营养物质的去除效率可为受损水生生态系统修复提供重要的科学依据. 本研究以我国水体修复中常用的3种不同生长型沉水植物苦草(Vallisneria natans)、黑藻(Hydrilla verticillata)和穗状狐尾藻(Myriophyllum spicatum)为研究对象，采用1种生长型种植和2种生长型及3种生长型混种模式，研究不同生长型沉水植物组合及其不同生长阶段对实验系统水质指标及氮、磷等营养物质去除率的影响. 结果表明，所有植物组合处理均显著提高了系统中总氮、总磷和氨氮去除率; 在实验前中期总氮、总磷和氨氮去除率最高. 从本实验受试物种组合来看，1种和2种生长型组合比3种生长型组合具有更高的生物量累积量和总氮去除率. Pearson相关性分析显示，实验系统中的pH、DO浓度与植物总生物量呈显著正相关，总氮、总磷、氨氮浓度均与植物总生物量呈显著负相关. 建议在受损浅水水生态系统修复过程中，根据生态修复不同阶段考虑不同生活型、生长型和功能群的水生植物组合; 在生态修复过程中需加强管理，如水生植物收割等，才能达到最好的修复效果.;Aquatic plants are important components of freshwater ecosystems and constitute a dominant actor in many shallow lakes. Planting aquatic plant, especially for submerged macrophytes, is one of the most important ecological restoration methods widely used in damaged shallow freshwater bodies. However, previously studies have mainly focused on the effects of macrophyte richness on biomass and water quality. Little is known about the effect of different assemblages with various growth form submerged macrophyte on biomass accumulation and water purification. In this study, three different growth form submerged plants, Vallisneria natans, Hydrilla verticillata and Myriophyllum spicatum, which are commonly used in water ecological restoration in China, were selected to test the effect of different growth form submerged macrophyte assemblages on water quality and nutrients removal rate. Our results showed that all different growth form assemblages have obvious purification effects on total nitrogen, total phosphorus and ammonia nitrogen, and higher purification effects were observed in the early and middle stage of the experiment. From different combinations, one and two growth form combinations have higher biomass accumulation and higher total nitrogen removal efficiency than three growth form combinations. Pearson correlation analysis showed that the pH, and DO in the experimental system were significantly positively correlated with the total biomass, and the concentrations of total nitrogen, total phosphorus and ammonia nitrogen were significantly negatively correlated with the total biomass. Our results suggest that in order to get the best restoration results, we need to take various factors into consideration during the process of ecological restoration, including different life form and growth form aquatic plant assemblages, harvesting aquatic macrophytes, etc.

Model-based identification of biological and pH gradient driven removal pathways of total ammonia nitrogen in single-chamber microbial fuel cells

Experimental data that allow for a precise identification of the total ammonia nitrogen (TAN) elimination pathways in single-chamber microbial fuel cells (SC-MFCs) are still very rare. However, nitrification–denitrification and ammonia volatilization are commonly reported as the two main removal mechanisms. This work presents a mathematical model to quantify the contribution of volatilization to TAN removal in SC-MFCs. For model verification, three different experimental settings were performed with TAN concentrations of 57 to 111mgNL−1: (i) biotic tests using sealed cathode chambers with variable oxygen supply, (ii) biotic tests for determination of the pH gradient within the cathodic microenvironment and (iii) pH-induced abiotic gas release tests. In biotic tests, the TAN removal rate in closed-circuit was 29–37% higher compared to open-circuit mode, which indicated additional electrochemical conservation processes. A limitation of oxygen availability on the air-facing side of the cathode (0.1%) resulted in negligible TAN removal rates. In contrast, an atmospheric oxygen content of 21% increased the biological oxidation rate of TAN to 653–730mgNm−2Catd−1and the electrochemical ammonia stripping rate to 210–241mgNm−2Catd−1 at 22 °C. During electricity generation, a peak pH value of 9.6 was measured by microelectrode measurements, which might lead to free ammonia nitrogen concentrations of 39–40mgFANL−1 nearby the cathode surface. Based on the proposed model and assuming an inhibition of ammonium-oxidizing bacteria, a maximum TAN removal rate via ammonia volatilization of 785mgNm−2Catd−1 (T = 22 °C) at a current density of 322 mA m−2Cat is estimated.

Growth and nitrogen uptake by Arthrospira platensis cultured in aquaculture wastewater from Nile tilapia reared in biofloc system

This study aimed to evaluate the growth of Arthrospira (Spirulina) platensis cultivated in Zarrouk culture medium and effluent from Nile tilapia (Oreochromis niloticus) reared in biofloc system. Four treatments were used: Control (100% Zarrouk), E50 (50% Zarrouk + 50% Tilapia effluent), E75 (25% Zarrouk + 75% Tilapia effluent), and E100 (100% Tilapia effluent), and the experiment lasted 10 days. Growth parameters such as maximum cell density (MCD), doubling time (DT), and growth rate (K) were daily evaluated, as well as pH and water temperature. In addition, the concentrations of total ammonia nitrogen (TAN), nitrite-N (NO2-N), and nitrate-N (NO3-N) were analyzed in order to compare nitrogen absorption. Among treatments, E50 and E75 obtained higher maximum cell densities and presented an exponential growth rate similar to the control treatment. Regarding the concentrations of nitrogen compounds, a significant reduction was observed in all treatments, with an NO3-N uptake of 99%, followed by 80% of TAN and 90% of NO2-N. Thus, giving the results obtained, besides being able to grow in wastewater, A. platensis can also be used in bioremediation processes, confirming the potential of this species.

Simultaneous effect of cathode potentials and magnetite concentrations on methanogenesis of acetic acid under different ammonia conditions

Electromethanogenesis (EM) is a system that facilitates direct interspecies electron transfer (DIET) in anaerobic digestion (AD) by providing an external power supply to favor desired reactions. Substrates of AD commonly contain ammonia (NH3) as biodegradation product of nitrogen-rich compounds that can deteriorate the stability of AD process. Optimized cathode potential (VCAT) and magnetite (Mag) concentration ([Mag]) are expected to improve AD efficiency in the presence of NH3. Response surface analysis with central composite face-centered design was used in this study to investigate the effect of VCAT and [Mag] under different total ammonia nitrogen concentration ([TAN]). Highest cumulative methane production was achieved at VCAT = -737.4 mV, [Mag] = 18.2 mM, and [TAN] = 1.5 g/L; highest acetate degradation rate was achieved at VCAT = 757.6 mV, [Mag] = 21.4 mM, and [TAN] = 1.5 g/L. The study demonstrated that VCAT promotes either microbial growth or electrochemical NH3 removal. A Shift from acetoclastic to hydrogenotrophic pathway was also observed by the increase of hydrogenotrophic methanogen populations at the end of experiment. This study is beneficial for process control of AD under different NH3 conditions.

Ammonia Recovery from Digestate Using Gas-Permeable Membranes: A Pilot-Scale Study

The reduction and recovery of nitrogen (N) from anaerobically digested manure (digestate) is desirable to mitigate N-related emissions, mainly ammonia and nitrate, derived from digestate land application in nutrient-saturated zones. This work reports the results of a gas-permeable membrane (GPM) pilot-scale plant to recover ammonia from digestate in the framework of the EU project Ammonia Trapping. The total ammonia nitrogen (TAN) concentration in digestate was reduced by 34.2% on average (range 9.4–57.4%). The recovery of TAN in the trapping solution in the form of a (NH4)2SO4 solution averaged 55.3% of the removed TAN, with a TAN recovery rate of 16.2 g N m−2 d−1 (range between 14.5 and 21.0 g N m−2 d−1). The TAN concentration in the trapping solution achieved a value of up to 35,000 mg N L−1. The frequent change of the trapping solution has been proven as an efficient strategy to improve the overall performance of the GPM technology.

The biochemical mechanism of enhancing the conversion of chicken manure to biogenic methane using coal slime as additive

To improve the efficiency of methane production from chicken manure (CM) anaerobic digestion, the mechanism of coal slime (CS) as an additive on methane production characteristics were investigated. The results showed that adding an appropriate amount of CS quickened the start of the fermentation and effectively increased the methane yield. In addition, the pH changed in a stable manner in the liquid phase, and the concentrations of total ammonia nitrogen (TAN) and free ammonia nitrogen (FAN) were reduced. Moreover, organic matter was decomposed and volatile fatty acids (VFAs) were consumed effectively. The abundance of Bacteroides in the bacterial community and Methanosarcina in the archaea was increased. In addition, the reduction of CO2 was the main methanogenic pathway, and adding CS raised the abundance of genes for key enzymes in metabolic pathways during methane metabolism. The results provide a novel method for the efficient methane production from CM.

Advanced modelling to determine free ammonia concentrations during (hyper-)thermophilic anaerobic digestion in high strength wastewaters

Anaerobic digestion is an attractive treatment technology for concentrated waste streams. However, high ammonia concentrations cause inhibition of methanogenesis, especially when operated at elevated temperatures like (hyper-)thermophilic (55 and 70 °C) anaerobic digestion. These emerging (hyper-)thermophilic technologies are beneficial due to high conversion rates and pathogen removal, but are more susceptible for ammonia toxicity as consequence of a temperature-induced pKa shift. Determination of NH3-N (free ammonia nitrogen (FAN); toxic form) concentrations is conventionally based on an equilibrium model and the total ammonia nitrogen concentration (TAN). However, the conventional equilibrium model overestimates the FAN concentration and therefore we developed an Ionic Activity Model which takes the ionic strength and organic matter interactions into account. The difference between the two models could mainly be attributed to the high ionic strength of the waste stream, whereas interactions with organic matter had a smaller effect. Based on this Ionic Activity Model and batch experiments at hyper-thermophilic conditions, we found that acetoclastic methanogenesis was completely inhibited at FAN concentrations exceeding 588 mg/L, whereas hydrogenotrophic methanogenesis could produce methane up to 925 mg/L. During thermophilic and hyper-thermophilic black water treatment, the ionic strength and organic matter interactions resulted in NH3 concentrations below the inhibitory threshold.

Stacked conservation practices reduce nitrogen loss: A paired watershed study

Combinations of best management practices (BMPs) are needed to achieve nutrient reduction goals in the Mississippi/Atchafalaya River Basin (MARB), but field results are crucial to encourage stacked adoption of BMPs. A paired catchment-scale study (2015–18) was done to assess the impact of (i) BMPs, (ii) precipitation patterns, and (iii) seasonality on nitrogen (N) export. Flow-weighted samples were collected and analyzed for total ammonia nitrogen (TAN), nitrate (NO3–N), and total nitrogen (TN). Catchments Low-BMP 11 and High-BMP 12 had 27.6% and 87.6% areal coverage of BMPs, respectively. No significant difference (p > 0.05) in TAN concentrations was found between Low-BMP 11 (0.023 mg L−1) and High-BMP 12 (0.020 mg L−1). However, NO3–N and TN concentrations were significantly higher (p < 0.05) at Low-BMP 11 (NO3–N: 26.0 mg L−1, TN: 28.7 mg L−1) than at High-BMP 12 (NO3–N: 8.8 mg L−1, TN: 9.2 mg L−1). Two precipitation factors that affected N export patterns were observed. First, N flushing could continue for several years after a drought as elevated NO3–N concentrations were observed in 2015 (i.e., two years after the 2011–2013 drought). Second, higher annual N export was observed when more precipitation occurred during the pre-planting or early-growing season versus later periods. For both catchments, the highest 50% of flows were responsible for majority of the NO3–N export. We estimated that 33–37%, 61–62%, and 82–85% of the NO3–N loads occurred in the 90th, 75th, and 50th flow percentiles, respectively. As demonstrated in High-BMP 12, stacked BMP application effectively lowered NO3–N and TN loads by 60.3% and 59.1%, respectively, relative to Low-BMP 11. Although 27.6% BMP coverage area in Low-BMP 11 was considered low for this study, this coverage area is higher than many other parts of the MARB. This research highlights the importance of joint efforts between landowners in a watershed to meet downstream water quality goals.

The design of multi-stage open-loop hollow fiber membrane contactor and its application in ammonia capture from hydrolyzed human urine

Hollow fiber membrane contactor (HFMC) is a promising technology for removing or recovering wastewaters' volatile components. Developing a rational design method is very important for guiding its further application. In this study, we proposed a method to design the multi-stage open-loop hollow fiber membrane contactor (HFMC) employing shell-side influent. In addition, a three-stage HFMC was designed to capture ammonia from real hydrolyzed human urine. A continuous 1344 h performance was conducted. The results showed that the experimental effluent total ammonium nitrogen (TAN) concentration and ammonia mass transfer coefficient matched the predicted results well, which indicated that the design method was feasible and accurate. The three-stage HFMC showed excellent ammonia capture capacity with a TAN recovery efficiency of 93.29%, and the final effluent TAN concentration was 30.98±14.70 mg/L which met our design requirement (lower than 50 mg/L). More than 98.92% of the inorganic ions and 96.85% of the organic matter were retained in the effluent. The stripping solution after ammonia capture was the high-purity ammonium sulfate solution with low concentration of small molecular weight hydrophilic organic substances. The inorganic and organic membrane fouling was mild and randomly distributed. The inorganic membrane fouling was attributed to the deposition of calcium-, magnesium-, phosphate-related inorganic compounds, while the organic membrane fouling was mainly protein and carbohydrate. After the ammonia capture process, the surface hydrophobicity and pore properties of the membranes had no significant changes. These results demonstrated that the multi-stage open-loop HFMC could be a potential alternative for ammonia recovery from the high concentration of ammonium nitrogen wastewater.

Changes in Selected Water Quality Parameters in the Utrata River as a Function of Catchment Area Land Use

Surface waters are very important for society, as they are a source of potable water, as well a water supply for agricultural, industrial and recreational purposes. This paper presents changes in the quality of the water in the Utrata River, along its entire length, as a function of the catchment area’s land use. Water-quality measurements were carried out once a month for a total period of one year (April 2019–March 2020) at 24 measurement points. The concentrations of the following compounds were measured: total phosphorus, ammonia nitrogen and nitrate nitrogen, dissolved oxygen, and chemical oxygen demand. The results were compared with the limit values specified in the Regulation of the Minister of Maritime Economy and Inland Navigation. In order to determine the impact of land use on water quality in the Utrata River, principal component analyses (PCA) were conducted. The research demonstrated a considerably negative impact of agricultural land use and the presence of urban areas on the water quality of the Utrata River, with elevated concentrations of total phosphorus, ammonia nitrogen, nitrate nitrogen and COD, and decreasing concentrations of dissolved oxygen. The presented results point to the need for effective strategies to mitigate the adverse impact of agriculture and urbanisation on the environment and surface waters.

Stabilization of Source-Separated Urine Using Electrochemically Synthesized Hydrogen Peroxide

Separate urine collection and treatment is an attractive alternative to current wastewater treatment strategies, though urea hydrolysis presents challenges for collection and storage. In this study, we demonstrated proof-of-concept for a method to stabilize source-separated urine with electrochemically synthesized hydrogen peroxide (H2O2). Samples of synthetic urine were stored following electrochemical treatment and monitored for changes in total ammonia nitrogen (TAN), H2O2, and pH. TAN formation from urea hydrolysis was inhibited by the deactivation of the urease enzyme by H2O2 in all experiments. We evaluated the effects of current density, treatment time, and final pH of the synthetic urine. Higher current densities and longer treatment times resulted in slightly lower final concentrations of TAN, while pH had no observable effect on final TAN concentrations. A neutral pH resulted in a slower degradation of H2O2 within treated samples compared to alkaline samples. Direct urea measurements showed that as much as 78.9% of the initial urea was preserved after 140 days of storage at room temperature. These results confirm that electrochemically synthesized H2O2 is an effective method for source-separated urine stabilization and present a basis for investigating this process beyond bench-scale experiments.

Retrofitting Sea Cucumber Nursery Tanks to Recirculating Aquaculture Systems for Highly Intensive Litopenaeus vannamei Aquaculture

Designing good recirculating aquaculture systems (RASs) is challenging in shrimp aquaculture. In this study, two sets of RASs were constructed using sea cucumber nursery tanks for rearing Litopenaeus vannamei. Recirculating aquaculture was supported by key technologies such as sewage collection and aeration systems adapted to the rectangular tanks and technologies for the removal of sewage, shrimp shells, and dead individuals. Six-hundred and eighty-five thousand juveniles were selected for rearing in the newly constructed RASs, where the average stocking density was 1013 shrimp/m3. During the recirculating aquaculture period of 53 days, the water temperature of the tanks was 24–31 °C, the salinity was 25–32‰, the pH was 6.4–8.2, the DO was ≥ 4.9 mg/L, the concentration of total ammonia nitrogen (TAN) was maintained between 0.17 and 4.9 mg/L, the concentration of nitrite nitrogen (NO2-N) was between 0.12 and 4.7 mg/L, and the total number of Vibrio bacteria remained between 330 and 9700 cfu/mL. At the end of the experiment, the final average weight of individual shrimp was 13.43 g, and the average yield reached 12.92 kg/m3. The great improvement in growth performance marks a breakthrough in RAS technology of shrimp, and it supports the use of an innovative methodology for the retrofitting and utilization of idle sea cucumber nursery tanks.

Selective aqueous ammonia sensors using electrochemical stripping and capacitive detection

AbstractManaging waterborne ammonia–nitrogen pollution requires monitoring distributed wastewater nitrogen discharges. In this study, we demonstrated and investigated a proof‐of‐concept sensor that combines selective electrochemical separation and sensitive capacitive detection for sensing total ammonia nitrogen (TAN). By varying TAN concentration in synthetic ammonia‐polluted water (up to 50 mg/L), we selectively separated ammonia nitrogen from feedwater into a sulfuric acid solution, in which capacitance decreased linearly with increasing TAN (R2 &gt; 0.99). Experimental observations were supported by theoretical explanations for the decrease in capacitance as ammonia absorbs into the sulfuric acid solution and abstracts protons. Capacitive detection facilitated TAN sensing at higher acid concentrations (up to 0.5 M H2SO4) than conductivity detection (up to 0.01 M H2SO4), which enables sensitive sensors with larger TAN detection ranges, longer deployment, and less complexity. Results from this study provide evidence of the use of selective separations and their transport mechanisms for environmental sensing applications.

Application of alginate-immobilized microalgae beads as biosorbent for removal of total ammonia and phosphorus from water of African cichlid (Labidochromis lividus) recirculating aquaculture system.

Immobilized microalgae are a promising approach to incorporate microalgae in recirculating aquaculture system (RAS) for water purification. In the present study, two types of biosorbents including sodium alginate-immobilized Scenedesmus spp. and Chlorella spp. beads (algal beads) and sodium alginate beads without microalgae (alginate beads) were prepared. In the first experiment (static test), the potential of two biosorbents to remove different concentrations of total ammonia nitrogen (TAN) and total phosphorus (TP) from water was investigated. In the second experiment, two prepared biosorbents were used as biofilter in a RAS for rearing African cichlid (Labidochromis lividus) for 30 days. The survival rate and growth indices of fingerling fish and removal efficiency of two biosorbents for TAN, NO3-N, and TP were determined. The results of static test showed that the removal efficiency and uptake capacity of the two biosorbents for TAN and TP increased during 30 days of the experiment, and these values for the algal beads were higher than the alginate beads. The TAN removal efficiency of the two biosorbents increased with increasing TAN concentration from 0.5 to 5 mg L-1. The application of algal beads in the RAS improved the survival rate, final weight, final length, weight gain, and daily growth index (DGI%) indices of fish compared to those cultured in the RAS containing the alginate beads and the control (P<0.05). The algal and alginate beads decreased the TAN concentration by 42.85% and 28.57% compared to the control after 30 days of cultivation period, respectively. The uptake of nitrate was not observed by the two biosorbents during cultivation period. The TP removal efficiency of algal beads reached 44.90% after 30 days. The findings of this study indicated that the sodium alginate-immobilized microalgae could be considered as a suitable biofilter to be incorporated into a RAS to improve water quality and consequently enhance the growth and health of fish.

Effects of oral administration of timothy hay and psyllium on the growth performance and fecal microbiota of preweaning calves

The objective of this study was to evaluate the effects of oral administration of fiber from the first week of life on the growth and hindgut environment of preweaning calves. Twenty newborn female Holstein calves were divided into 2 groups as control and treatment. Calves in both groups were reared under the same feeding program except for oral fiber administration. Timothy hay and psyllium were mixed at a 50-to-6 ratio as a treatment diet for oral fiber administration. Calves in the treatment group were orally administered 50 g of fiber daily from 3 to 7 d of age and 100 g of fiber from 8 d of age until weaning. Feed intake and occurrence of diarrhea were recorded daily, and body weight (BW) was recorded weekly for the individual calf. Fresh feces were collected from calves at 7, 21, 35, 49, and 56 d of age to analyze fermentation parameters and microbiota to characterize the hindgut environment. Higher fiber intake in the treatment group due to oral administration of timothy and psyllium did not affect the starter intake and achieved higher BW at 21 d of age. The fecal pH, total volatile fatty acid, lactate, and ammonia nitrogen concentrations were not affected by oral fiber administration; meanwhile, the molar proportion of propionate was higher in the treatment group at 7 d of age. The difference in fecal microbiota in the calves subjected to the oral administration of fiber was observed within 21 d of life; Lactobacillus spp. and Prevotella spp. showed higher abundance, whereas that of Clostridium perfringens was decreased. These higher abundances of beneficial bacteria and lower abundance of pathogenic bacteria during early life may partly explain the higher BW of calves in the treatment group at 21 d of age. Furthermore, no adverse effect was observed for the BW and health status in the treatment group throughout the preweaning period. Therefore, early fiber feeding via oral administration potentially contributes to improving the hindgut environment in newborn calves, which leads to better growth of calves during the early stage of life.

Effects of humic acid on the nitrogen utilization efficiency and microbial communities in aquaponic systems

Aquaponic systems consisting of recirculating aquaculture systems and hydroponic beds. Raft-floating aquaponics integrated with a moving-bed biofilm reactor (MBBR) was established. Humic acid (HA) was added to the aquaponic systems to promote nutrient recovery. An elementary analyzer was used to determine the nitrogen content of fish, plants, and sediments to calculate the NUE. High-throughput sequencing and quantitative polymerase chain reaction (qPCR) were conducted to reveal the influence of HA on microbial communities and nitrification genes. During an 80 day experimental period, the effects of water quality parameters, nitrogen utilization efficiency (NUE), and microbial communities in variable concentrations of HA-based aquaponic systems were compared. Among the HA-based systems, the one with an optimal concentration of 15 ppm indicated the best performance. In HA-based aquaponic systems with 15 ppm concentration, the maximum concentrations of total ammonia nitrogen and NO2−–N were 6.02 mg/L and 12.693 mg/L, which were significantly lower than those in aquaponic systems with 0 ppm and 30 ppm. However, the accumulation of nitrate in the HA-based aquaponic systems with 15 ppm was greater than that in the others. The NUE of the 15 ppm HA-based aquaponic system was 58.34%, which was significantly higher than that of the 0 ppm (50.83%) and the 30 ppm (47.25%) systems. Consequently, the threshold concentration of HA was established as 15 ppm. The microbial communities of different HA-based systems revealed the presence of denitrifying and nitrifying microbial populations for nitrogen recovery in moving bed biofilm reactors (MBBRs); higher levels of these microbial populations thrived in the 15 ppm HA system than in the other systems. However, there was no significant difference in microbial communities from root samples. The highest copies of amoA and nxrB were found at 15 ppm for both MBBRs and roots, indicating that the addition of HA to the aquaponic systems yielded more products and improved water quality and NUE by changing the composition of microbial communities based on the threshold for HA input concentration. This study provided that HA show enormous potential for an interesting research and the development of green technologies for biological wastewater treatment and bioremediation.

Effect of Biofloc product‐Rapid BFT TM vs. clear water system in improving the water quality and growth performances of Pacific Whiteleg shrimp, P. vannamei , cultured in indoor aquaculture system

Biofloc technology was known to improve the shrimp growth performance and water quality in several ways. The application of bacterial booster was proven to accelerate the development of biofloc in the culture treatments as well as help improve the water quality, shrimp growth performance and yield production. Due to its importance, a study was conducted to identify the effect of biofloc application using Rapid BFTTM microbial booster formulation versus clear water system to improve shrimp growth performance and water quality condition. Study was conducted for 80 days with every 7 days of interval of data collection. Overall, biofloc treatments were identified successfully in improving the shrimp growth performance and also effectively reduced the nutrient concentrations of total ammonia nitrogen (TAN) from the biofloc culture treatments until the end of culture periods. Nitrate (NO3−) from biofloc treatments was also identified in lower concentration as compared to control of clear water system. The average daily growth (ADG) was at 0.12g much better from biofloc treatments as compared to control with ADG 0.08g of clear water system. The specific growth rate (SGR) was 5.47%/day in biofloc and 2.82%/day in control treatments which identified higher and much better from biofloc about 2.65%/day differences between biofloc and clear water. Meanwhile, the final body weight achieved was much higher from biofloc about 9.55 grams compared with control about 7.06 grams from the same day of culture, DOC80 which recorded at the end of cultured period. The first sampling was started at DOC7 where the average initial weight of shrimp in biofloc treatment was 0.117 grams and 0.077 grams identified in control. The highest biomass achieved from biofloc treatments also much better around 11.0 kg compared with control that produced 7.1 kg as the higher biomass produced. There was only yellow and green colony of Vibrio identified from the TCBS culture and no occurrence of luminescent colony from harmful Vibrio harveyi detected. Therefore, it can be concluded that biofloc technology of Rapid BFTTM help improves the water quality of ammonia nitrogen level in water columns and inhibits pathogenic Vibrio to the culture species as well as help improving the shrimp growth performances in more effective way.