Total Ammonia Nitrogen Levels Research Articles

Insight into critical water quality factors and gill function of large yellow croaker (Larimichthys crocea) during packaging bag transport

To investigate the effects of the interaction between water quality and gill function of large yellow croaker during transportation in packaging bags, a total of 186 large yellow croakers weighing 120.0 ± 28.0 g were randomly divided into two groups: a control group (tanks with a water treatment system to maintain normal water quality) and treatment groups subjected to simulated transport for 0, 6, 12, 18, and 24 hours at a temperature of 20°C. The results revealed that prolonging the transport duration (beyond 6 hours) caused significant changes in dissolved oxygen (DO), total ammonia nitrogen (TAN) and pH levels in the water. Beyond 6 hours of transport, gill tissue damage increased, and the histomorphological characteristics of the gills were altered. Regarding osmoregulation, the activities of Ca2+/Mg2+-ATPase and Na+/K+-ATPase were notably reduced in the treatment groups, indicating compromised osmoregulatory function of the gill tissue during transport. However, changes in lactic acid (LD) and lactate dehydrogenase (LDH) were not statistically significant, and fish did not experience hypoxia during packaging bag transport. In terms of antioxidant activity, the treatment groups exhibited significantly lower activities of catalase (CAT) and superoxide dismutase (SOD) after 24 hours, as well as increased malondialdehyde (MDA) content after 18 hours. This reduction in antioxidant capacity led to cellular membrane damage in the gill tissue. Furthermore, acid phosphatase (ACP) activity showed a notable decline from 12 hours onwards in immune indicators, while lysozyme (LZM) activity experienced a substantial decrease at 24 hours. Correlation analysis revealed a significant correlation between the osmoregulation, antioxidant capacity, and immune response of gill tissue with elevated TAN levels and reduced pH. In conclusion, the levels of TAN and pH experience notable alterations after 6 hours of transportation, which may lead to impairment of gill function in large yellow croakers. Hence, we advise limiting the transportation of large yellow croakers to less than 6 hours at 20°C.

Interactive effects of water temperature and dietary protein on Nile tilapia: growth, immunity, and physiological health

Optimizing fish performance depends on several factors, with dietary protein levels and rearing temperature playing important roles. In this study, Nile tilapia fingerlings (Oreochromis niloticus) weighing an average of 20.00 ± 1.26 g were divided into nine groups (in three replicates). Each group was subjected to different water temperatures (26 °C, 28 °C, and 30 °C) and received one of three dietary protein levels (20%, 25%, and 30%) for two months. Our findings indicate that higher temperatures, particularly at 30 °C, increased water electrical conductivity and total dissolved salts, especially noticeable in fish fed 25% or 30% crude protein (CP). Lower total ammonia nitrogen levels were observed at 28 °C with 25% CP, 30 °C with 30% CP, and 26 °C with 30% CP. Hepatic growth hormone receptor 1 and insulin-like growth factor 1 expression gradually rose with higher dietary CP percentages in fish at 26 °C but declined in those at 30 °C, albeit remaining higher than in the 28 °C groups with 25% CP. Fish at 28 °C showed the best final body weights and growth performance when fed 20% or 25% CP, with no significant difference between these groups. Hepatic leptin expression did not differ significantly among groups, but hepatic fatty acid binding protein expression notably increased in fish fed 30% CP at both 26 °C and 30 °C compared to those at 28 °C with 25% CP. Within the same temperature group, fish fed 30% CP exhibited higher globulin levels, particularly thriving at 28 °C or 30 °C. Hepatic mucin-like protein expression significantly increased across all groups, especially in fish at 30 °C with 30% CP compared to those at 28 °C with 25% CP. Hepatic lysozyme expression also increased notably in fish at 30 °C with 30% CP. Notable changes in superoxide dismutase, catalase, and glutathione peroxidase expression were observed, with the highest serum superoxide dismutase and catalase activities recorded in fish at 30 °C with 25% CP. Overall, dietary protein levels of 25% and 30%, combined with temperatures of 28 °C and 30 °C, yielded favorable outcomes, particularly favoring 28 °C with 25% protein.

Response and recovery of nitrifying moving bed biofilm reactor systems exposed to 1°C with varying levels of ammonia starvation

This study investigated the impact of varying total ammonia nitrogen (TAN) feed levels along with water temperature decreases on the performance of nitrifying moving bed biofilm reactor (MBBR) at 1 °C and its recovery at 3 °C. Five MBBR reactors were operated with different TAN concentrations as water temperature decreased from 20 to 3 °C: reactor R1 at 30 mg N/L, reactor R2 at 20 mg N/L, reactor R3 at 15 mg N/L, reactor R4 at 10 mg N/L and reactor R5 at 0 mg N/L. The corresponding biofilm characteristics were also analyzed to understand further nitrifying MBBR under different TAN feeding scenarios. The findings revealed that the higher TAN levels were before reaching 1 °C, the better nitrification performance and the more biomass grew. However, the highest TAN concentration (30 mg N/L) might negatively affect the nitrification performance, the activity of nitrifiers, and the growth of biofilms at 1 °C because of the toxic effects of un-ionized or free ammonia (FA). It was observed that the activities of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were affected by FA concentrations ranging from 0.2 to 0.7 mg N/L at 1 °C, but they could gradually be adapted to such inhibitory environment, with NOB recovering more quickly and robustly than AOB. The study identified 20 mg N/L (67 % of maximum influent TAN at 1 °C in R2 as the optimal TAN feeding concentration, achieving over 90 % TAN removal and a surface area removal rate (SARR) of 0.78 ± 0.02 g N/m2·d at 1 °C. Meanwhile, R2 also exhibited the highest biofilm mass, with total solids at 13.3 mg/carrier and volatile solids at 11.3 mg/carrier. As TAN was removed, nitrite accumulation was observed at 1 °C, and higher influent TAN concentrations prior to 1 °C appeared to delay the accumulation. When water temperature increased from 1 °C to 3 °C, nitrification performance improved significantly in all reactors without nitrite accumulation, and the higher TAN feeding in the previous stage led to faster recovery. Compared with 20 °C, biofilm became thinner and denser at 1 °C and 3 °C. Furthermore, this study revealed significant shifts in microbial community composition and nitrifier abundances in response to changes in water temperature and influent TAN levels. The dominant nitrifiers were identified as Nitrosomonadaceae (AOB) and Nitrospiraceae (NOB). At 1 °C, the nitrifier abundances were significantly correlated with SARRs, FA, and biofilm density. R2, which exhibited the best nitrification performance, maintained higher nitrifier abundances at 1 °C.

Ammonia concentration and recovery in an up-scaled electrochemical cell through screening of cation exchange membrane

An intensifying global alarm over excessive total ammonia nitrogen (TAN) calls for innovative recovery strategies. Although electrochemically-driven TAN concentration and recovery have been explored, limited research on upscaling lab-scale advancements with careful system engineering leaves a notable gap in practical application. Here, in the context of implementing an upscaled electrochemical system, we carefully chose a suitable cation exchange membrane to ensure the best ammonium migration, energy efficiency, and stability. Systematically examining the effects of applied current density and loading rate using Neosepta CSE, we achieved final concentrated TAN levels in the receiving catholyte, reaching 836.7 mM (4.4-fold), 778.8 mM (3.5-fold), and 980.4 mM (2.8-fold), with nitrogen flux values of 801, 817, and 955 g-N m−2 d−1 for synthetic, food, and livestock wastewater, respectively, at a current density of 25 mA cm−2 and a loading rate of 2.5 mL cm−2 h−1. Successful upscaling to an 8-cell stack, capable of treating 100 L every 20 h (recovering 207 g-N d−1) of synthetic wastewater, showcases the feasibility of upscaled electrochemical systems for TAN recovery.

Effects of stocking density during simulated transport on physiology and behavior of largemouth bass (Micropterus salmoides)

AbstractThe live transport of farmed fish is an important practice in Chinese aquaculture due to consumer preferences in its domestic market. However, live transport can be stressful for fish and may cause many welfare issues. This study aimed to examine the effects of transport density on the welfare of largemouth bass (Micropterus salmoides). Adult fish were allocated to four experimental treatments in a two‐factor design (N = 5 groups per treatment). Factor one was stocking density of either 39 (low density) or 78 (high density) g L−1. Factor two was transport, with half of the fish groups exposed to simulated transport stress for 3 h using a motion platform, and the other half kept in static tanks for the same length of time. Baseline behavior and physiology were determined from a subset of fish after acclimation but before selection into groups and application of transport. To determine the effects of transport, stocking density, and their interaction on the experimental groups, physiological sampling and behavioral recording were carried out immediately after simulated transport, and water quality was measured both before and after transport. Changes in water quality were observed between two timepoints, with decreased dissolved oxygen levels and increased water temperature. Total ammonia nitrogen levels significantly increased in all treatments over time, particularly in the high‐density groups. Fish ventilation rates were significantly elevated in the groups kept at a high stocking density regardless of whether they also experienced transport stress. Fish transported at a high stocking density also showed more fear‐related behaviors such as freezing and thigmotaxis than non‐transported groups. Serum cortisol, catalase, and aspartate transaminase levels were significantly higher in the transported treatment groups compared to the baseline fish, but no difference was found for serum glucose, lactate, and glutathione peroxidase. We concluded that 3 h of simulated transport was stressful to largemouth bass kept at 78 g L−1, as evidenced by altered fish physiological and behavioral indicators of stress, as well as deteriorated water quality. Additionally, we identified a positive correlation between serum and skin mucus samples for cortisol, glucose, and lactate in transported fish, providing important information for developing less invasive methods for the welfare assessment of largemouth bass.

Effects of environmentally relevant concentrations of micro(nano)plastics on aquatic microorganisms: Changes in potential function but not in overall composition

Micro(nano)plastics (MNPs) are a growing problem as persistent environmental pollutants. Here, we investigated the impact of MNPs on microorganisms in aquatic microbial floc exposed to NPs (80 ​nm) and MPs (8 ​μm) for 35 days. Water quality indicators were tested weekly and microbiological analyses were conducted on Day 7 and 28 after exposure. The results showed that there were significant differences in the levels of total ammonia nitrogen or nitrite between the MNPs groups and the control group, spanning from Day 7 to Day 28. For the microbial response, microbial community richness in the NPs and MPs groups were significantly increased at Day 7. Functional prediction showed that the relative abundances of bacteria associated with the “Forms Biofilms”, “Potentially Pathogenic”, “Plastic Degradation” and nitrogen cycle processes were significantly different after MNPs exposure. The results suggest that MNPs had no significant effect on the microbial diversity of mature microbial flocs. Findings suggest MPs could cause an increase in the relative abundance of potentially pathogenic bacteria, while NPs do not. In addition, stress associated with MNPs affected the nitrogen cycle of microorganisms, and NPs exerted greater impacts than MPs. Findings from this study further our understanding of the impact of MNPs at environmentally relevant concentrations on microorganisms in aquatic ecosystems.

Evaluation of High Stocking Densities on the Water Quality and Growth Performance of Pacific White Shrimp Litopenaeus vannamei Reared in a Mixotrophic Biofloc Nursery System

The present study aimed to explore the effects of intensive culture densities on the water quality and growth performance of the Pacific white shrimp Litopenaeus vannamei reared in a mixotrophic biofloc system (heterotrophic/chemoautotrophic) at three stocking rates of 5,000, 4,000, and 3,000 PL/m3 (namely G5000, G4000, and G3000, respectively) for 21 days. At the end of the study, the mean values of water temperature, dissolved oxygen, dissolved oxygen saturation level, pH, oxidation-reduction potential, free carbon dioxide, alkalinity, total ammonia nitrogen (TAN), nitrite-nitrogen (NO2-N), nitrate-nitrogen, and settleable solids did not substantially differ among study groups ( p > 0.05 ). In addition, the highest mean levels of TAN and NO2-N recorded were 1.27 mg/l (G4000) and 9.23 mg/l (G3000), respectively. The results of growth performance revealed that final body weight, weight gain, weekly growth rate, and specific growth rate were not affected by the studied densities ( p > 0.05 ). Although no significant differences were observed ( p > 0.05 ), the G3000 treatment exhibited the highest survival rate (80.66% ± 8.56%), followed by G4000 (75.05% ± 0.31%) and G5000 (71.63% ± 2.11%). However, the shrimp yield was meaningfully higher for G5000 treatment (1.72 ± 0.0.09 kg/m3, 0.69 ± 0.03 kg/m2) compared with G3000 group (1.27 ± 0.0.12 kg/m3, 0.48 ± 0.04 kg/m2) ( p < 0.05 ). Our results indicate L. vannamei can be reared at intensive nursery densities of up to 5,000 PL/m3 (2,000 PL/m2) until reaching 0.5 g without significant retardation in water quality, growth, and survival.

Kelimpahan plankton Prorocentrum sp. pada tambak intensif udang vaname (Litopenaeus vannamei)

Introduction: Prorocentrum sp. is one of the harmful algae genera that often grows in the aquatic ecosystems of vaname shrimp (L. vannamei) ponds. The purpose of this study was to determine the abundance and dynamics of the Prorocentrum sp. during the shrimp culture period of vaname shrimp (L. vannamei) in intensive ponds. Method: This research was conducted on 4 ponds with a size of 3,200 m2 and a stocking density of 120 fish/m2. The research variables observed were water quality parameters and Prorocentrum sp. which is carried out every 7 days during the shrimp cultivation periods. Result: Based on the results of study, the water quality parameters during the shrimp culture period tend to be stable, except for the water pH parameters which have relatively high afternoon pH fluctuations. Prorocentrum sp. genera during the shrimp culture period, the plankton genus was the most dominant compared to other genera of the Dinoflagellate class. The dynamics of the Prorocentrum sp. abundance on the intensive pond, there was a significant correlation between the solubility of TAN (Total Ammonia Nitrogen) content of 74.8% and the water temperature of 83.3%. Conclusion: The abundance dynamics of Prorocentrum sp. genera during aquaculture period of vaname shrimp (L. vannamei) fluctuated dynamically following the solubility trend of TAN (Total Ammonia Nitrogen) levels and water temperature flux in the pond ecosystem

Effects of Ocimum basilicum essential oil and ginger extract on serum biochemistry, oxidative stress and gill tissue damage of pearl gentian grouper during simulated live transport.

This study explored the effects of the essential oil of Ocimum basilicum (EOOB) and ginger extract (GE) during the transportation of pearl gentian grouper from water quality, serum biochemistry, oxidative stress, meat flavor, and gill tissue morphology. Fish (450 ± 50g) were allocated to the following 5 treatments: control group (fish transported in water only), 5mg/LEOOB, 10mg/LEOOB, 3mg/LGE, and 6mg/LGE and transported in insulation boxes (66 × 51 × 37.8cm) for 72h. Samples were taken at 0, 12, 36, 60, and 72h immediately after transport. It was found that 10mg/LEOOB and 6mg/LGE could reduce the levels of total ammonia nitrogen (TAN), dissolved oxygen (DO), water pH, serum glucose (GLU), cortisol (COR), liver superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and glutathione peroxidase (GPX), increase the activities of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH), as well as significantly increase the total free amino acid (TFAA) content in muscle compared to the control group (P < 0.05). In addition, by observing the microstructure of gill tissue, it was found that compared with untreated grouper, the morphological damage of gill tissue in EOOB and GE treatment was alleviated. These results indicated that adding appropriate amounts of EOOB and GE to transport water could improve the water quality, relieve stress, and lower energy metabolism of grouper during transport. The results of this research will help to improve the survival rate of grouper after transportation and decrease economic losses to fishery.

Total ammonia nitrogen removal and microbial community dynamics in an outdoor HDPE-lined shrimp pond with no water discharge

This study assessed the characteristics of a zero-discharge outdoor high-density polyethylene (HDPE)-lined demonstration aquaculture pond (400 m2) in terms of water quality variables, total ammonia nitrogen (TAN) removal and oxygen net primary production (NPP) indices, and photosynthetic microbiome over a 76-day crop cycle. The shrimp harvest yield was 4.1 t/ha/crop with an average daily gain (ADG) of 0.15 g/day and a feed conversion ratio (FCR) of 1.49. During shrimp cultivation with a semi-intensive stocking density (40 shrimp/m2), there were low levels of TAN (<1.01 mg-N/L), nitrite (<0.21 mg-N/L), and nitrate (<2.79 mg-N/L). Ammonia removal was mainly mediated by photoautotrophic uptake, as evidenced by the consistent estimated TAN uptake rate of 0.05 ± 0.02 g-N/m3 h, which was calculated based on photosynthesis. The overall TAN removal rate of 0.10 ± 0.08 g-N/m3 h was maintained by suspended microorganisms in water, which exceeded that of microorganisms attached to the HDPE liner surface. A positive oxygen NPP of 0.24–1.16 g-O2/m3 h during light availability indicated prevailing autotrophic conditions. The bacterial community in the water was dominated by Phyla Pseudomonadota (Proteobacteria; 16–32%), Bacteroidota (Bacteroidetes; 15–29%), Cyanobacteria (7–35%), and Actinomycetota (Actinobacteria; 3–39%). The chloroplast amplicon sequence variants (ASVs) indicated abundances of Bacillariophyta (27–97%) and Chlorophyta (0.4–67%). High centric diatom populations (Bacillariophyta) were detected throughout cultivation, while the proportion of green algae (Chlorophyta) was positively correlated with increased TAN availability when feeding was increased. The findings enabled estimations of TAN removal and oxygen NPP rates and provided an understanding of correlations between environmental variables and bacterial and phytoplankton populations in the outdoor lined shrimp pond.

Using some natural essential oils and their nano-emulsions for ammonia management, anti-stress and prevention of streptococcosis in Nile tilapia, Oreochromis niloticus

The current study aimed to investigate the efficacy of dietary thyme essential oil (TEO), Nigella sativa essential oil (NSEO), thyme essential oil nano-emulsion (TEO-NE), and Nigella sativa essential oil nano-emulsion (NSEO-NE) in reducing total ammonia nitrogen (TAN), improving immune response, mitigating stress, and acting as anti-inflammatory agents as well as preventing streptococcosis infection in Oreochromis niloticus (O. niloticus). Fish (N = 330, 14 ± 2 g) were divided into 10 groups of 11 fish each, with three replicates in each group. The negative and positive controls were fed a control diet, while the third group was given 1% TEO. Moreover, the fourth group of fish was given 2% TEO. The fifth and sixth groups were fed 1% TEO-NE and 2% TEO-NE, respectively. The seventh, eighth, ninth, and tenth groups were fed 1% NSEO, 2% NSEO, 1% NSEO-NE, and 2% NSEO-NE, respectively. After dietary intake of TEO, NSEO, and their nano-emulsions for 28 days, the mean values of TAN levels in the water of fish aquaria had a significant reduction in the group fed 2% TEO-NE compared to the control group. On the contrary, NSEO-NE at the same concentration had no significant effect on TAN levels. The levels of lysozyme, complement 5, and IgM increased in all feeding groups compared to the control group. Concerning cortisol level as a stress indicator, it was decreased in all feeding groups compared to the control. Also, the current experiment overall showed a significant decrease in the expression level of pro-inflammatory tumor necrosis factor (TNF-α) gene in the gills of fish groups fed TEO, TEO-NE, NS, and NS-NE relative to the β-actin gene. Oppositely, there was an increase in the expression level of the anti-inflammatory transforming growth factor (TGF-β). In the current study, TEO-NE and NSEO-NE showed a better effect on preventing streptococcosis in O. niloticus with no mortality than 1% TEO and NSEO, respectively. Furthermore, there was a 12.5% mortality rate and an 84.99 RPS in the group fed 1% TEO and injected with Streptococcus inae. On the other hand, the groups fed 1 and 2% NSEO showed 37.5 and 25% mortality rate, respectively and 54.99 and 69.99 RPS. In conclusion, the nano-emulsion either TEO or NSEO had the superior effect. For bulk status, the TEO had superior effect than NSEO. The study needs more investigations for ammonia, either on the mode of action or over a longer period.

Management of inorganic nitrogen compounds in a closed aquaculture system during imitation for nursery of Litopenaeus vannamei under brackish condition

It was aimed to estimate the efficiency of management of inorganic nitrogen compounds under a closed system condition, via addition of carbon source. For this purpose, an imitation experiment for nursery of Litopeanaeus vannamei postlarvae under a brackish condition was conducted, in two closed systems with a salinity of about 18‰: systems with (CS) and without (control) addition of carbon source (molasses) at a carbon to nitrogen ratio (C:N) of 20:1. The levels of total ammonia nitrogen (TAN, 1.39±0.14 mg L−1), nitrite (0.023±0.003 mg L−1) and nitrate (0.49±0.06 mg L−1) in CS system were significantly lower than those in the control system (6.92±0.60, 0.809±0.050 and 2.39±0.47 mg L−1, P < 0.05). The results indicated that carbon source addition to the closed system imitating nursery of L. vannamei postlarvae under a brackish condition well managed the level of inorganic nitrogen compounds during experiment, making it possible to environment-friendly culture L. vannamei at inland areas under a closed condition.

Polyculture of sea grape (Caulerpa lentillifera) with different stocking densities of whiteleg shrimp (Litopenaeus vannamei): Effects on water quality, shrimp performance and sea grape proximate composition

The polyculture of sea grape with whiteleg shrimp is considered as one of the strategic approaches to sustainable shrimp production. This is the first study to investigate the effects of integrating sea grape (Caulerpa lentillifera) with different densities of whiteleg shrimp (Litopenaeus vannamei) on water quality, shrimp performances and sea grape proximate composition. The experiment was executed in indoor tank systems, comprising five treatments in randomly designed triplicate tanks, with five levels of shrimp densities (100, 200, 300, 400, and 500 individuals m−3) integrated with sea grape (1 kg m−3) for 56 days. The results showed that the polyculture of sea grape with shrimp significantly enhanced sea grape biomass and proximate composition in terms of protein, lipid and ash contents while maintaining adequate levels of total ammonia nitrogen (TAN), nitrite (NO2−), nitrate (NO3−), and phosphate (PO43−) in the rearing tanks at high shrimp densities. Shrimp growth rates (weight gain, daily weight gain, and specific growth rate) tended to decrease at higher density levels, but there were no statistical differences (p > 0.05) among treatments at stocking densities ranging from 200 to 400 individuals m−3. Although shrimp survival was significantly reduced as stocking densities increased from 400 individuals m−3 upward; the lowest and highest shrimp yields were obtained at densities of 100 and 400 individuals m−3, respectively. Feed conversion ratios were higher at higher shrimp density; however, no significant difference was not observed between 300 and 400 individual m−3 groups. These findings indicated that polyculture of sea grape with whiteleg shrimp can perform up to 400 individuals m−3 while maintaining suitable water quality parameters and sustaining improved production efficiency in the culture unit.

Artificial Neural Network and Near Infrared Light in Water pH and Total Ammonia Nitrogen Prediction

Water quality plays an important role in aquaculture. The operation of a freshwater aquaculture fish farming is highly dependent on the ability to understand, monitor, and control the physical and chemical constituents of the water. pH and total ammonia nitrogen (TAN) levels are two critical water quality parameters that affect fish growth rate and health. However, pH and TAN levels are affected by uncontrollable factorse.g.weather, temperature, and biological processes occurring in the water. Therefore, it is important to monitor changes in pH and TAN levels frequently to maintain optimal conditions for freshwater habitats. Near infrared spectroscopy (NIR) has been extensively investigated as an alternative measurement approach for rapid quality control without sample preparation. Therefore, this research aims to evaluate the feasibility of machine learning combined with NIR light in predicting the water pH and TAN values of a fish farming system. The proposed system contains three main components i.e.a multi-wavelength light emitting diode (LED), a light sensing element, and a machine learning model i.e.artificial neural network (ANN). First, the transmitted NIR light with different wavelengths of water samples was measured using the proposed system. Then, the actual pH and TAN values of the water samples were quantified using conventional methods. Next, ANN was used to correlate the measured NIR transmittance with the pH and TAN values. The results show that ANN with four hidden neurons achieved the best prediction performance with a mean square error (MSE) of 0.1466 and 0.3136 and a correlation coefficient (R) of 0.8398 and 0.9560 for the pH and TAN predictions, respectively. These results show that ANNcoupled with NIR light can be promisingly developed for in situ water quality prediction without sample preparation.

Effects of water activity, ammonia and Corynebacterium urealyticum on the survival of Salmonella Typhimurium in sterile poultry litter.

This study examined the effects of water activity (aw ), ammonia and Corynebacterium urealyticum on the survival of Salmonella Typhimurium in sterile poultry litter. Sterile poultry litter inoculated with S. Typhimurium was adjusted to pH 9.0, various aw levels (0.84, 0.92 and 0.96), and total ammonia nitrogen levels were increased either by the addition of ammonium sulphate or C. urealyticum inoculation with 1% urea added. All litter treatments were incubated at 30°C and sampled daily for five days. Similar results were observed at each aw level in both experiments. At 0.84 and 0.92 aw , S. Typhimurium populations in litter fell below 1logCFUg-1 within 5days, with no significant differences between the controls and increased ammonia treatments. At 0.96 aw , Salmonella populations treated with increased ammonia levels were significantly lower than control treatments on days 1-5. This study showed that C. urealyticum can produce ammonia in litter at higher aw levels with sufficient available urea and that the antimicrobial efficacy of ammonia is dependent on high aw (~0.96) in litter. These results provide insights into the production of ammonia in litter, its antimicrobial efficacy in litter and the importance of aw in this interaction.

Biochar from Corn Waste as Biofilter in a Recirculating Aquaculture Systems

Abstract: The use of biofilter with the application of biochar technology for the improvement of water in a recirculating aquaculture system (RAS) provides a lot of advantages in aquaculture production. The research aimed to devise a biofilter system for the enhancement of TAN and un-ionized ammonia levels in a RAS using biochar from corn cobs for Nile tilapia Oreochromis niloticus production. It has five main parts: fish tank, biochar filtration tank, sediment filter, sludge filter and pump. The fish tank used is a 1 m 3 plastic cubical tank. The biochar filtration tank with a height of 85 cm and a diameter of 30 cm. The sludge filter has a height of 52 cm with a diameter of 13 cm. An electric water pump was used to recirculate the water. The system was fabricated and were able to effectively enhance the level of total ammonia nitrogen (TAN) at a rate of 0.56 ppm per hour for every 1kg biochar and 0.72 ppm per hour for the reduction of un-ionized ammonia. The devised biofilter proved to reduce the level of TAN by 9.45 ppm and un-ionized ammonia levels by 2.18 ppm in 6 hours and 30 minutes using corn cob biochar. Keywords: Biochar, Biofilter, Recirculating Aquaculture Systems (RAS), Total Ammonia Nitrogen (TAN), Un-ionized ammonia

Bioaugmentation with a propionate-degrading methanogenic culture to improve methane production from chicken manure

Volatile fatty acid (VFA) accumulation caused by high ammonia concentrations is often encountered during the anaerobic digestion (AD) of ammonia-rich substrates. In this study, propionate-degrading methanogenic cultures were introduced to augment the semi-continuous AD of chicken manure under high ammonia levels. Introduction of a methanogenic culture enhanced the methane yield in the bioaugmented digester by 17–26% when the organic loading rate (OLR) was 2–4 g L-1d-1 compared to that in the control. When the OLR was further increased from 4.0 L-1d-1 to 5.0 g L-1d-1, and bioaugmentation ceased, methane yield improved by 15–18% under a high total ammonia nitrogen level of 5.0–8.4 g NH4+-N/L. Moreover, bioaugmentation reconstructed the methanogenic community in the digester, promoting the dominance of hydrogenotrophic Methanobacterium and slightly increasing the abundance of aceticlastic Methanothrix and the syntrophic propionate-oxidizing bacteria Syntrophobacter, which were the key contributors to the improved AD under high ammonia concentrations.

Effects of different carbon sources on growth performance of Litopenaeus vannamei and water quality in the biofloc system in low salinity

This study aimed to investigate the effects of different carbon sources on water quality and growth performance of Litopenaeus vannamei in the biofloc system under a salinity condition as low as 5‰. Three biofloc treatments with glucose (Glu), molasses (Mol) and starch (Sta) as carbon source, respectively, were designed to stocking shrimp juveniles (0.81 ± 0.02 g) at a density of 90 individuals m−3 for a 63-days culture experiment. Results showed that there was no significant difference on shrimp performance and water quality between Glu treatment and Mol treatment. The final mean body weight, weekly increment rate of body weight, specific growth rate, feed efficiency rate, productivity and survival rate of shrimp in Glu and Mol treatments, were all significantly higher than those in Sta treatment (P < 0.05). Significantly higher pH and carbonate alkalinity (P < 0.05), but significantly lower levels of total ammonia nitrogen, nitrite and nitrate (P < 0.05), were also found in Glu and Mol treatments, when compared to those in Sta treatment. The results indicated that in the biofloc system with a low salinity in the present study, soluble glucose and molasses are good carbon sources for grow-out culture of L. vannamei shrimp.

Consecutive batch anaerobic digestion under ammonia stress: Microbial community assembly and process performance

To reveal the effects of the degree and mode of total ammonia nitrogen (TAN) stress on community assembly, composition, and process performance, sequential batch experiments of anaerobic digestion (AD) of food waste were conducted with three different ammonia levels (1800, 3000, and 6000 mg/L) and two exposure modes (stepwise and direct). The selected TAN levels varied in the degree to which they inhibited the AD process. However, deterministic processes may play a larger role in shaping the microbial community than stochastic processes regardless of the level and mode of TAN stress. Under controlled conditions, long-term exposure can lead to the convergence of the community to a specific equilibrium state. The key link affecting community function was acetogenesis. The relative abundance of hydrolytic and acidogenic bacteria under the 1800, 3000, and 6000 mg/L TAN groups was 67.36 ± 3.59%, 68.54 ± 5.73%, and 77. 09 ± 2.69%, respectively. The resistance and redundancy of functional bacteria can maintain the hydrolysis and acidification function of the AD process. Methanogens can also maintain their metabolic performance through the transfer of dominant methanogens from Methanosaeta and Methanospirillum to Methanosarcina and Methanoculleus. Acetogens, especially Pelotomaculum, were inhibited at 6000 mg/L TAN. This led to a decrease in their abundance and the accumulation of longer-chain volatile fatty acids, which was the main reason for the deterioration of the AD process. A new method that promotes acetogenesis under high ammonia stress needs to be developed to achieve efficient AD performance.

Study of Biofilter Planted with Basil for Removal of Ammonia in Aquaponic Water

Abstract This experimental investigation of a laboratory scale aquaponic system included testing of a biofilter with basil plant as the biofilter part on aquaculture water quality. Irridescent shark was selected as aquaculture species. The biofilter consist of natural biomaterials such as coconut husk, coco peat, and coarse aggregates. The experiment was carried out for three short water recirculation durations of 2, 3, and 4 h/day. The influent and effluent ammonia NH3, total ammonia nitrogen (TAN), nitrites NO2 and nitrates NO3 levels were measured and analysed. The results showed that the biofilter effectively removed NH3 (65 - 71 %), TAN (34 - 58 %), and NO2 (60 - 67 %) from the aquaculture water. The dissolved oxygen (DO) levels were maintained between 3 - 7.0 mg/l during all the recirculation durations. The significance of water recirculation period was assessed by calculating the differences between the means of water quality parameters with a statistical test named one-way analysis of variance (ANNOVA) with significant level P taken as 5 %, i.e., P ≤ 0.5. The effluent mean NH3 levels 0.030 mg/l, 0.033 mg/l, and 0.022 mg/l exhibited significant difference at 4 h/d periods while effluent TAN levels 0.81, 0.77, and 0.77 showed no difference with varying periods.