High Ammonia Concentrations Research Articles

Sludge from Arapaima Gigas Culture as an Alternative Culture Medium for Lipid Production in Nannochloropsis Sp

Objective: The objective of this work was to evaluate the use of sludge generated during the culture of Arapaima gigas as an alternative medium for Nannochloropsis sp. Theoretical Framework: Microalgae are photosynthetic micro-organisms with the ability to transform organic waste or effluents into valuable biomass. They are currently of great interest for their use in the food and pharmaceutical industry. Nannochloropsis sp. is a valuable microalga due to its excellent lipid profile. Method: The sludge used was collected from A. gigas culture ponds at the CITE Acuícola Pesquero Ahuashiyacu (Tarapoto-Peru). An aqueous extract of sludge (EAL) was obtained from the sample by a thermal procedure, which was dosed into the cultures at concentrations of 100, 150 and 200 mL/L. The experimental units followed the traditional batch culture arrangement under laboratory conditions. Guillard F/2 medium was used as control treatment. The characterisation of metals in the medium was performed by coupled plasma induction (ICP) and the determination of ammonium and nitrite by colorimetric tests. In addition, population density, productivity and total lipid content were estimated. Results and Discussion: Chemical analyses revealed high concentrations of calcium, sodium, magnesium, iron, potassium, phosphorus, ammonium and nitrite (655, 648, 283, 67, 32, 17, 1.5, and 10 ppm, respectively). Likewise, the best growth (3590.00 ± 91.24 x 104 cells/mL) and productivity (0.69 ± 0.01 g/L) was obtained with 200 mL/L of EAL, presenting significant statistical differences (p < 0.05) with respect to the other treatments. In contrast, the highest lipid production (29.67 ± 1.53 %) was observed in the control treatment, far exceeding the EAL cultures; however, no significant statistical difference was observed between EAL treatments. Research Implications: These results demonstrate the feasibility of using EAL as an alternative medium for the production of Nannochloropsis sp. with a positive environmental and economic impact on the production of A. gigas. Originality/Value: The use of sludge generated in fish culture, in particular A. Gigas, has not been reported previously. In this study, we demonstrate for the first time the feasibility of using this sludge in the culture of the microalga Nannochloropsis sp. which also has a high potential for use in fish larviculture.

Arrested development and increased incidence of sandprawn embryonic aberrations along an intertidal human recreation gradient.

Anthropogenic pressures are increasing in coastal ecosystems globally, yet identifying robust indicators of change and managing coastal resources can be complicated by phenotypic plasticity and differential life-history responses of key organisms. We illustrate this using biogeochemical and sandprawn (Kraussillichirus kraussi) response metrics along a human recreation gradient (trampling, sandprawn harvesting) in a South African lagoonal ecosystem. Benthic compaction, oxygen depletion and high porewater ammonia concentrations were associated with greatest recreation intensity. Sandprawn abundance was similar across the recreation gradient and body condition was counter-intuitively greater in areas with maximum recreation, but with higher frequencies of embryonic aberrations and arrested development. These findings suggest different vulnerabilities of life-history stages of sandprawns to recreation, with embryonic stages being highly susceptible. We suggest that embryonic aberrations and developmental changes in endobenthic crustaceans may be sensitive bioindicators of recreation-induced changes in sedimentary systems.

Ammonia removal and nitrogen preferences evaluation of indigenous Malaysian microalga Halamphora sp. on white shrimp Penaeus vannamei wastewater

Ammonia is ubiquitous in aquaculture systems and its removal is important for maintaining water quality and the health of the cultured animals. Microalgae are effective at removing ammonia from water, but the effectiveness of different microalgae species may vary. In this study, indigenous Malaysian microalgae isolated from shrimp ponds were screened for their ability in removing ammonia from synthetic culture media. The most efficient microalga’s nitrogen preferences and its growth and nitrogen removal in the early and late stages of shrimp culture wastewater were explored. It was found that four microalgae species namely Halamphora sp. BpSpD2, Chaetoceros sp. BpSpD3, Chlorella sp. BpSpG3 and Desertifilum sp. BpSpC1 were able to eradicate ammonia after 14 days of cultivation. Further investigation showed that Halamphora sp. BpSpD2 was able to remove 100 % ammonia within 5 days of culture. The nitrogen preferences of Halamphora sp. BpSpD2 indicated a preference for ammonia over nitrate as evidenced by the higher growth and removal efficiency of the treatments. Nitrogen removal efficiency of over 70 % was observed in treating 4 to 12 mg L-1 of TAN and nitrate. When tested in shrimp-cultured wastewater, Halamphora sp. showed a higher growth and 100% ammonia removal efficiency in the late stage of shrimp-culture wastewater. It also effectively removed 59% to 80% of nitrogen throughout both the early and late stages of shrimp culture wastewater. The results suggested that the microalga Halamphora sp. BpSpD2 has a significant potential to treat the effluent of an aquaculture system containing high concentrations of ammonia and nitrate.

Improved Anaerobic Digestion of Food Waste under Ammonia stress by Side-Stream Hydrogen Domestication

High ammonia concentration inhibits archaea's activity, causing the accumulation of H2 and acetate, which suppresses methane production in anaerobic digestion (AD). The study aimed to enhance microbial hydrogen metabolism through a side-stream hydrogen domestication (SHD) strategy, which involves applying hydrogen stimulation to a portion of the sludge separately. SHD maintained a stable methane yield of 407.5 mL/g VS at a high total ammonia nitrogen (TAN) concentration of 3.1 g/L. In contrast, the control group gradually decreased and stopped methane production at a TAN concentration of 2.3 g/L. Further analysis using enzyme activity assays, flow cytometry, and metagenomics explored the mechanisms underlying ammonia tolerance of SHD-treated group. SHD reshaped the microbial community, enriching homoacetogens and Methanosaeta-dominated methanogenic archaea. Key metabolic pathways including homoacetogenesis, butyrate degradation, propionate degradation, and methane production were enhanced. The activity of related enzymes also increased. Gene abundance in energy-generating pathways, such as glycolysis, was enhanced, ensuring adequate ATP production. Additionally, the high gene abundance of ion transport systems contributed to regulating proton imbalance and supplementing intracellular K+. This study provides important insights and practical guidance for developing novel techniques in the field of anaerobic digestion.

Distribution of Air pollutant Concentration and Ammonium conversion rate in Livestock Areas: Focusing on Boryeong

Objectives:The association between the generation of fine particulate matter (PM2.5) and ammonia is well-established, highlighting the importance of managing ammonia as a primary means to reduce particulate matter. However, domestic research on ammonia emissions, particularly in livestock areas, which are major sources of ammonia, is insufficient. This study aims to contribute to pollutant management on a national scale by conducting air pollutant measurements and analyses in livestock areas. Methods:Real-time analysis and monitoring of air and weather conditions were carried out in Boryeong, Chungcheongnam-do, from 2021 to 2022. Statistical analysis was then employed to investigate the correlation between observed air pollutants (ammonia, nitrogen oxides, sulfur oxides, ozone and particle matters) and PM2.5. Results and Discussion:As a result of the analysis, the concentration of air pollutants in Boryeong showed a seasonal tendancy to decrease in summer and increase after that. Most substances such as NO2, SO2, and PM10 were observed within the standard values. In the case of ammonia, domestic air environment standards are not in place, but the annual average was found to be 61.5 ± 55.3 ppb, higher than in other research results. This discrepancy is attributed to the influence of nearby livestock houses. It was also observed that PM2.5 exceeded the annual standard value of 15 μg/m3 in spring (30.1 μg/m3), summer (18.3 μg/m3), autumn (25.3 μg/m3) and winter (31.7 μg/m3), respectively. During this period, ammonium (NH4+, 32.8%), nitrate (NO3-, 35.9%), and sulfate (SO42-, 19.7%) comprised the majority of particulate pollutants in PM2.5. The ammonia-ammonium conversion rate (NHR) was 0.08 annual average, and it was found that gas/ion phase changes were affected by seasonal weather conditions (temperature and relative humidity). As a result of analyzing the NHR according to the PM2.5 concentration, it was found that the higher the PM2.5 concentration, the higher the NHR. Furthermore, although the measurement area of this study exhibited high ammonia concentration, the NHR was low. This suggests that the contribution rate of ammonia to PM2.5 was relatively low compared to the other studies.Conclusion:As a result, there is a need for measures to reduce the high concentrations of ammonia in livestock areas. Simultaneously, considering the diverse mechanisms involved in particulate matter formation, it is suggested that management of pollutants such as nitrogen oxides, sulfur oxides including ammonia should be implemented.

Ammonium Removal and Recovery from Industrial Wastewater Using Distillation Method

:Industrial wastewater contains high ammonium concentration, leading to difficulties in the treatment process using conventional methods. This study used the heat distillation method following the alkalization of wastewater to remove and recover ammonium from the wastewater of an industrial plant. The influent wastewater has a pH 6.41 and a very high ammonium concentration (28000 mgN/L). The distillation system was designed to consist of heating, cooling, and recovery units. After alkalinization, the wastewater sample was boiled using an electric stove, the ammonia vapor passed through the cooler and condensed into liquid ammonia, and was recovered. The controlling factors for the removal efficiency including solution pH (7-12) and distillation time (0.5, 10, 15, 30, 60 and 90 min) were investigated. Experimental results show that the optimal conditions for ammonium treatment from wastewater are at pH 12 and distillation time of 30 min, corresponding to 100% of removal efficiency. In terms of liquid ammonia recovery, the ice cooling mode was more efficient than the tap water cooling and vacuum evaporating modes. Final ammonia concentration reached 215 mgN/L that has potential for industrial production.

Time-course analysis of the transcriptome of Arabidopsis thaliana leaves under high-concentration ammonium sulfate treatment

ABSTRACT Ammonium fertilization is of great interest for future agriculture, as unlike nitrate, ammonium use efficiency does not decrease in C3 plants, even in environments with elevated CO2 concentrations. However, excess ammonium often results in toxic effects such as growth suppression and chlorosis, i.e. ammonium toxicity. The addition of nitrate, a major source of nitrogen commonly found in soils, has been shown to alleviate these toxic effects. Understanding the mechanisms of ammonium toxicity in the presence of nitrate is crucial for the effective use of ammonium fertilizers in crop cultivation. To elucidate these responses, a time-course analysis of the transcriptome was performed on A. thaliana leaves treated with high concentrations of ammonium sulfate in the presence of sufficient nitrate. The expression of nitrate-inducible genes tended to be downregulated by the treatment. The expression of genes relating to abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), and membrane trafficking was upregulated, whereas that of photosynthesis-, auxin-, and cytokinin-related genes involved in growth and development was downregulated. The induction of many osmotic stress-responsive genes and nitric oxide (NO)-inducible genes suggests the involvement of osmotic stress and NO signaling in the response. This study provides a novel and comprehensive overview of transcriptional changes occurring in response to high ammonium sulfate concentrations with sufficient nitrate, and sheds light on potential pathways involved in ammonium toxicity under these conditions.

Influence of antioxidant and chelate compound on milk productivity and milk quality of lactating cows during denitrification

The purpose of the research was to study the eff ect of the antioxidant Epofen and chelate calcium citrate feed additives on milk productivity, physicochemical and technological properties of milk from lactating cows fed by rations with subtoxic nitrate content. It was found that the highest degree of denitrifi cation with a simultaneous increase in the technological qualities of milk was facilitated by joint feeding of Epofen at a dose of 3 g/head and chelate calcium citrate at a dose of 1.0 g/100 kg of live weight. Due to this, the fat and protein content in the milk of cows in the 3rd experimental group was significantly higher by 0.23 and 0.26 abs.% compared to the control group (P > 0.95). The highest ammonia content was in the milk of cows in the 3rd experimental group 3.552 mg/l, which was 62.1 % more than in the control group (P > 0.95), with a simultaneous reliable (P > 0.95) decrease in nitrates by 52.9 % and nitrites by 60.0 %. At the same time, joint feeding of Epofen and calcium citrate allowed to ensure the highest yield of cheese mass from the milk raw materials of cows in the 3rd experimental group 10.84 kg, which was 13.3 % more than in the control group (P > 0.95). With joint additions of the tested drugs, cheese samples from the milk of cows in the 3rd experimental group compared to the control samples contained more protein soluble nitrogen by 6.87 abs.% (P > 0.95), and non-protein soluble nitrogen by 2.63 % (P > 0.95) less. Compared to the control samples, in the samples of cheese mass from the milk of cows of the 3rd experimental group, there was a signifi cant (P > 0.95) decrease in the content of nitrates by 72.3 % and nitrites by 74.3 %.

Treating liquid anaerobic digestate using natural zeolite and Arthrospira platensis cyanobacteria: From laboratory to pilot-scale

Over the past decade, using liquid digestate as a nutrient source for microalgae cultivation has gained considerable attention. However, its high ammonium concentration and turbidity often inhibit algal growth. To address this, natural zeolite was explored as a novel approach to reduce digestate toxicity before microalgae cultivation at both laboratory and pilot-scales. Clinoptilolite, a type of natural zeolite, was applied in adsorption columns at a ratio of 0.5 kgzeolite.L-1 to treat 0.45 L of liquid digestate. After 24 h of treatment, ammonium levels decreased significantly from 2273 to 115 mgN.L-1, corresponding to a 95 % removal efficiency and an adsorption capacity of 4.31 mg.gzeolite-1. Arthrospira platensis demonstrated strong growth in the treated digestate with minimal dilution (≤5x), in contrast to the high dilution (≥20x) required for the untreated digestate. Laboratory-scale results were effectively scaled up to pilot scale, detoxifying 15.5 L of digestate with similar performances. The pretreated digestate was subsequently used as a culture medium for Arthrospira platensis in flat panel photobioreactors without further dilution, achieving a final concentration of 0.82 gDW.L-1 and a biomass productivity of 33 mg.L-1.d-1. These findings underscore the potential of natural zeolite in enhancing microalgae-based processes for digestate detoxification and CO2 mitigation.

Two factors facilitate the cost-effective and harmless cementation of rare earth slags through MICP technology: Carbonic anhydrase bacteria and endogenous calcium ions

Microbially induced carbonate precipitation (MICP), a solidification/stabilization technique that doesn't interfere with recycling and can reduce the migration of pollutants, has been employed to cement rare earth slags (RES). Currently, the MICP process of the urease/carbonic anhydrase pathway has attracted considerable attention. However, the MICP process of the urease pathway may produce high concentrations of ammonia, which can cause secondary contamination; the addition of a calcium source (calcium chloride) may increase the cost of the treatment process. In this study, two factors, carbonic anhydrase bacteria and endogenous calcium ions (Ca²⁺), facilitated the MICP technology to cost-effectively and harmlessly cement RES and stabilize contaminants. The findings indicated that strain Z1 could utilize endogenous Ca²⁺ to cement the RES, thereby enhancing its unconfined compressive strength, reducing the disintegration rate, radiation dose, and wind erosion intensity, and facilitating the stabilization of heavy metals and radionuclides. In comparison to the CK group, the leaching concentrations of Cu2+, Pb2+, Zn2+, Cd2+, Th(Ⅳ), and U(Ⅵ) in the C1 group were reduced by 42.37 %, 20.20 %, 18.77 %, 22.53 %, 12.32 %, and 23.66 %, respectively. The treatment effect can be further enhanced by adding exogenous Ca2+. This study's findings can help reduce the potential environmental risks in the long-term sequestration of RES, while also providing technical support for the sustainable development of the rare earth industry.

Correction: A Higher Stomatal Aperture is Associated with the Growth Promotion of Centipedegrass (Eremochloa ophiuroides (Munro) Hack.) Under High Concentrations of Ammonium

Correction: A Higher Stomatal Aperture is Associated with the Growth Promotion of Centipedegrass (Eremochloa ophiuroides (Munro) Hack.) Under High Concentrations of Ammonium

Formation of zinc tetraammine difluoride and dinitrate and conversion to zinc oxide and zinc hydroxyfluoride under ambient conditions

The zinc tetraammine complexes [Zn(NH3]4]F2 (ZAF) and [Zn(NH3]4](NO3)2 (ZAN) have been isolated from methanolic ammonia and characterized by single crystal X-ray diffraction and Raman spectroscopy. As determined from Raman data, the tetrahedral structure of the zinc tetraammine cation complex is sustained in solutions that contain high concentrations of ammonia. Dilution of ZAF or ZAN solutions in bulk water results in the deposition of ZnO as determined by X-ray powder diffraction (XRD). Lower dilution, as when aqueous ZAF is applied to wet surfaces, results in Zn(OH)F deposition as identified by XRD. These mineral products are readily obtained from zinc tetraammine solutions under ambient conditions and lend themselves to biomedical and materials applications.

Assessing the aerobic/anoxic enrichment efficiency at different C/N ratios: pilot scale polyhydroxyalkanoates production from waste activated sludge

Polyhydroxyalkanoates (PHA) can be produced using fermentation products of an excess sewage sludge fermentation process. An efficient method to enrich a PHA-producing community is an aerobic-feast/anoxic-famine enrichment strategy. The effect of different carbon to nitrogen (C/N) feed ratios of 1, 2 and 3.5 g COD/g N on the process performance was studied. The study was executed on a pilot plant scale using fermented waste activated sludge as the organic carbon source. The system's performance was monitored in terms of removing contaminants, producing PHA, and reducing N2O emissions. The results indicated that a lower C/N ratio results in lower PHA production, with PHA content in the sludge of 20, 24 and 36 % w/w for C/N ratios of 1, 2 and 3.5 g COD/g N, respectively. At the lowest C/N ratio, the highest nitrite accumulation rate (77%), nitrification efficiency (89%) and denitrification efficiency (89%) were observed, but the N2O production was also the highest (0.77 mg N2O-N/L). The long-term comprehensive monitoring carried out in this study revealed high carbon and ammonia removal efficiencies (never below 80%) despite the C/N shifts and high COD and ammonia concentrations. At the same time, the system showed relatively low PHA production and high environmental impact in terms of high gaseous N2O emission. These findings question the sustainability of the aerobic-feast/anoxic-famine enrichment strategy for PHA production in full-scale plants.

Start-up of a full-scale two-stage partial nitritation/anammox (PN/A) process treating reject water from high solid anaerobic sludge digestion (HSAD)

High solid anaerobic digestion (HSAD) achieves the benefits of high volumetric loading rates and lower reject water production, which, however, results in much more concentrated reject water with a remarkable increase in organics and nitrogen compared with that from conventional AD with low solid content. The high concentrations of ammonium (2000–3500 mg/L) and COD (3000–4000 mg/L) were reported to exert inhibition on anammox bacteria (AnAOB), posing challenges to the application of the partial nitritation/anammox (PN/A). To date, no cases of PN/A process start-up for sludge HSAD reject water were reported. This study demonstrated the start-up process of a 480 m3/d PN/A project without anammox sludge inoculation and treating HSAD reject water from a centralized dewatered sludge treatment plant. The project did not construct new infrastructures but utilized previously constructed tanks to upgrade the process from existing short-cut nitrification-denitrification to a two-stage PN/A process. Although no external anammox sludge inoculation was performed to save seeding sludge cost, the start-up was successfully achieved in about 9 months (273 days) based on a three-step method of “AnAOB enrichment - sludge acclimation - capacity doubling”. During start-up, the relative abundance of AnAOB (Candidatus_Kuenenia) increased from near zero to 12.0%. After start-up, the total inorganic nitrogen (TIN) removal load reached 0.74 kgN/(m3•d), with a total nitrogen removal efficiency of over 90%. Compared to the traditional nitrification-denitrification process, the PN/A process remarkably reduces the addition of organic chemicals and aeration energy consumption, saving approximately 4.2 million yuan (RMB) in operational costs annually. In summary, this research provides a full-scale reference for the start-up of the PN/A process treating sludge HSAD reject water.

Distribution and Characteristics of Ammonia Concentration by Region in Korea

In this study, the characteristics of ammonia and their effects on secondary particulate matter (PM) formation were analyzed by region in Korea in 2020. The NH3 concentration was high in GJ (11.4 ppb), a neighboring agricultural area, followed by DJ (9.0 ppb) and SE (8.6 ppb), which are located in urban areas. On the other hand, BI (2.6 ppb) and JI (4.5 ppb), which are background regions, demonstrated a lower concentration than other areas. Seasonally, ammonia was high in spring and summer, and it generally increased when human activities are active. Therefore, it is believed that the ammonia in the atmosphere not only changes depending on local emissions, but also based on temperature-dependent phase distribution characteristics. For SE and GJ, regions with relatively high ammonia concentrations, investigations into the effect of ammonia on secondary PM formation were conducted. In both regions, the ammonium-to-sulfate mole ratio tended to increase with increasing ammonia or PM2.5 concentration. It can be assumed that the PM2.5 concentration increases as nitrates are formed under the ammonia-sufficient condition. The adjusted gas ratio is generally greater than 4, indicating that there is a lot of free ammonia. Thus, it is estimated that a reduction in ammonia would not be effective to restrain nitrate formation.

Feasibility of riverbank filtration in Vietnam

Riverbank filtration (RBF) could contribute to meeting the growing demand for drinking water in Vietnam. This study investigates the feasibility of implementing RBF in different regions of Vietnam, with a focus on the Red River Delta (RRD) and Binh Dinh (a province in central Vietnam). Although Vietnam’s extensive river network and shallow aquifers generally provide favorable hydrogeological conditions for RBF, regional variations in hydrogeology introduce specific challenges. In the RRD, complex hydrogeological settings, such as thick clay layers near the surface and low hydraulic conductivity in the Holocence aquifer, can limit the effectiveness of RBF in maximizing the portion of bank filtrate and improving water quality. In contrast, Binh Dinh generally presents more favorable conditions, with absence of clay layers on top and higher hydraulic conductivity leading to successful RBF implementation. Water quality issues such as high concentrations of ammonium, arsenic, and other pollutants persist in both RBF and groundwater in the RRD, requiring careful site-specific evaluations. The study also highlights that while surface water remains underutilized compared to groundwater, its use may be economically preferable in regions where groundwater quality is compromised. Lessons learned from the RRD and Binh Dinh can serve as good practice for RBF implementation in other parts of Vietnam. The findings indicate that while RBF holds significant promise for enhancing water supply in Vietnam, its application needs to be carefully tailored to local hydrogeological and water quality conditions.

Assembly process and co-occurrence network of microbial community in response to free ammonia gradient distribution.

The research presented in this paper explores how varying concentrations of free ammonia impact microbial communities in aquatic ecosystems. By employing advanced gene sequencing techniques, the study reveals significant changes in microbial diversity and network structures in response to increased ammonia levels. Key findings indicate that high ammonia concentrations lead to a decrease in microbial richness and diversity while increasing community dissimilarity. Notably, certain microbial groups, like Actinobacteria, show resilience to ammonia stress. This research enhances our understanding of how pollution affects microbial ecosystems and underscores the importance of maintaining balanced ammonia levels to preserve microbial diversity and ecosystem health.

Nitrogen fate in riparian zones: Insights from experiments and analysis of sediment porosity and surface water-groundwater exchange

Riparian zones play a vital role in the river ecosystem. Solutes in vertical riparian zones are transported being by alternating hydraulic gradients between river water and groundwater, due to natural or human activities. This study investigates the impacts of porous sediments and alternating rate of surface water-groundwater on nitrogen removal in the riparian zone through experiments based on the field sampled. The experimental results, combined with dimensionless numbers (Péclet and Damköhler) and Partial Least Squares-Path Modeling, analyze the nitrogen fate responding to hydrodynamics changes. The results show that increased sediment porosity contributes to the ammonium removal, particularly when the oxygen content of river water is low, with the removal rate up to 72.57%. High ammonium content and dissolved organic carbon (DOC) in rural rivers lead to a constant low-oxygen condition (4 mg/L) during surface water-groundwater alternation, and promote denitrification. This threatens groundwater with ammonium pollution and causes accumulation at the top of vertical riparian zones during upwelling, potentially causing secondary river pollution. However, increasing the alternating rate hinders the nitrate denitrification and drastically changes in the redox environment of the riparian zone, despite contributing to ammonium removal. Rapid oxygen consumption during aerobic metabolism and nitrification in groundwater-surface water exchange created favorable conditions for denitrification. Floodplains sediment porosity is unfavorable for nitrification. This study improves understanding of coupled hydrologic and solute processes in vertical riparian zones, informing strategies for optimizing nitrogen attenuation and riparian zone construction.

Evaluation of black tilapia (Oreochromis niloticus) hatchery in UPT-Perikanan Budidaya Air Tawar (PBAT) Sukorejo, Malang

Abstract Black tilapia is a freshwater fish that has become a leading commodity in the UPT-PBAT (Unit Pelayanan Teknis-Pengembangan Budidaya Air Tawar) Sukorejo Freshwater Aquaculture Fisheries with an optimal selling price. The purpose of this study was to evaluate the hatcheries activity performance in UPT-PBAT Sukorejo. The method in this research used active participation and descriptive methods. The data collection method used was from primary and secondary data. Primary data taken in this study were fertilization rate, hatching rate, and survival rate while secondary data was from literature comparison and asking directly to the staffs of UPT-PBAT Sukorejo. The results of hatchery performance showed fertilization rate of 95%, hatching rate of 98.6%, and survival rate of 93%. Hatching was carried out naturally using a 1:3 ratio (50 male fish and 150 female fish per pond). The research results indicated that hatchery activity in UPT-Freshwater Aquaculture (PBAT) Sukorejo, Malang showed good performance. However, water quality (ammonia) needs more attention to prevent negative effect in the next aquaculture cycle activity since this study found the ammonia value reached minimum tolerable value. Ammonia that exceeds the limit can cause mortality to black tilapia. Changing water is important to avoid mortality due to high ammonia content.

Self-regenerable oxygen system using microalgae-bacterial consortium for ammonium removal from wastewater

This study investigated self-regenerable oxygen system using microalagae-bacterial consortium for ammonium removal from wastewater and its kinetic modeling based on a combined mechanistic and empirical approach. By mechanistic modeling using a simple microalgal-bacterial Monod model, based on algal growth due to NH4+, NO3− and NO2−, the nitrogen and DO profiles were accurately predicted under different nitrogen conditions (low, medium, and high NH4+ concentrations). The mathematical modeling results showed that sufficient oxygen was available for nitrification at low initial NH4+ ammonium concentration levels, even when dual nitrogen substrate (NH4+–NO2−, NH4+–NO3− or NO2−–NO3−) or all three in combination (NH4+–NO2−–NO3−) were used, compared with high initial ammonium concentration levels. The DO profile was successfully used to monitor N transformation and N uptake in the PSBR based on net O2 uptake rate, O2 production rate, and O2 saturation profile. By empirical modeling of the data obtained, the actual O2 produced by microalgae with the different N species was calculated based on N mass balance and empirical equations. The empirical model further revealed that low NH4+ concentration levels (up to 82.5 mg N/L) favored successful nitrification due to the sufficient production of O2 in the system. However, NH4+ concentration in the range 82.5–132.5 mg N/L affected the nitrification efficiency due to insufficient O2 produced in the system, whereas high ammonium concentration results in nitritation/partial nitrification due to the high demand of O2 by AOB and inhibition in the growth of NOB.