Ammonia Loading Research Articles

Nutrient recovery from source-separated urine via sorption and a comparative investigation on the improvement of the residual liquid quality

Human urine, a highly saline solution rich in plant-available nutrients, leaves behind significant organic matter after nutrient recovery, necessitating additional treatment for environmental protection. While nutrient recovery from human urine is well-documented in the literature, research on the safe handling of the residual liquid phase is notably lacking. This study investigates nutrient recovery from source-separated human urine using clinoptilolite for the ion exchange/adsorption process and evaluates the safe management of the residual liquid through anaerobic granular sludge and a second-stage of sorption. The results indicated that the ion exchange/adsorption process, using an ammonium loading of 15 mg NH4+/g clinoptilolite, removed the majority of nutrients, achieving 82% ammonium removal and 100% phosphorus removal, along with 30% removal of organic matter. The residual liquid phase from the nutrient removal stage was treated separately with anaerobic digestion and a second-stage of sorption for further processing. Results showed that anaerobic processing removed 68%–84% of organic matter, with no additional nitrogen removal observed as expected, and produced 0.20–0.46 L CH4/L urine. The second-stage of sorption removed 59%–62% of organic matter and nearly all nitrogen. Both processes effectively removed organic matter, with sorption also eliminating nitrogen and anaerobic processing potentially generating biogas, making them recommended for improving the quality of the residual liquid phase before final disposal.

Optimal Scheduling Strategy for Urban Distribution Grid Resilience Enhancement Considering Renewable-to-Ammonia Coordination

The integration of numerous distributed energy sources into the power system offers exciting opportunities to enhance the resilience of distribution networks. It is worth noting that the renewable-to-ammonia system has the potential to alleviate the multi-temporal and spatial imbalance of the power system. Therefore, this paper proposes a mathematical model for a renewable-to-ammonia system, taking into account the material balance and power balance of each unit. Based on this, this paper further explores the optimization scheduling method for flexible ammonia loads in distribution networks. A relaxation method for branch flow models in distribution networks based on second-order cone programming is proposed. An optimization scheduling model for flexible ammonia loads in distribution networks is constructed to minimize network loss. Moreover, considering the environmental advantages of the renewable-to-ammonia system, this paper compares the changes in hydrogen production technologies under different carbon emission constraints. Finally, a case study of the IEEE 33-node system is adopted to verify the effectiveness of the proposed model and method. It indicates that the renewable-to-ammonia system has environmental benefits and can reduce network loss to a certain extent.

Comparing the performance of microbial electrochemical assisted and aerated treatment wetlands in pilot-scale: Removal of major pollutants and organic micropollutants

The combination of treatment wetlands (TWs) with microbial electrochemical technologies (MET) is often studied in the lab to improve the performance and decrease the footprint of TWs. In this article we evaluated the long-term performance of four pilot-scale vertical sub-surface flow TWs for major pollutants' and organic micropollutants' removal from domestic wastewater. Three of them were filled with electroconductive material and operated under saturated (MET SAT), unsaturated (MET UNSAT) and unsaturated-saturated (MET HYBRID) conditions while the fourth one was a saturated intensified aerated system (AEW) filled with gravel. The MET-TWs achieved significant removals of COD (>78 %) with no clogging issues at the maximum applied OLR (249 g COD m−3 d−1) while under these loading conditions TSS removal exceeded 84 %. Among all electroactive TWs, UNSAT could remove 25 g NH4-N m−3 d−1 through nitrification when peak ammonium loading rate was applied; however this removal was significantly lower than AEW (35 g NH4-N m−3d−1). No important removal of P was observed in all systems with the exception of MET-SAT were precipitation reactions of P with iron occurred when anaerobic pretreated wastewater was used. The removal of the sum of studied organic micropollutants ranged between 70 ± 18 % (MET UNSAT) to 91 ± 4 % (AEW) and improved with feeding pulses increase. Moderate to high removal of specific microcontaminants was observed depending on the target compound, the studied system and the operational conditions. AEW and MET HYBRID systems complied with the limits set by EU for wastewater discharge to non-sensitive water bodies and for Class B water reuse. Scale-up calculations for a settlement of 500 PE showed that these systems require much less area per PE (0.51 m2 PE−1) comparing to conventional TWs while the operational cost was calculated to 0.07 € m−3 for the AEW and 0.02 € m−3 for the MET HYBRID.

Intensified partial nitrification and microbiome response in a membrane pulsing-aerated biofilm reactor

Membrane aerated biofilm reactor (MABR) has been developed as an energy-saving process for nitrogen removal in municipal sewage treatment, even in high ammonia wastewater. However, the impact of aeration pattern on biofilm microbiome assemblage and nitrification is not well understood. In this study, MABR and membrane pulsing-aerated biofilm reactor (MpABR) were established for partial nitrification under high ammonium loadings. The MABR and MpABR exhibited a 95 % nitrite accumulation rate (NAR), with over 60 % ammonium removal and nitrite conversion achieved after the start-up phase. The MABR and MpABR gradually adapted to the substantial increase in ammonium loading (350 mg NH4+-N·L-1), resulting in stable and high NAR (96 %), ammonium removal efficiency (70 %), and nitrite conversion efficiency (67 %). Orthogonal experiments revealed that ammonium loading rate (ALR) was the primary factor regulating nitrite conversion and oxygen levels. A moderate ALR was preferable to achieve ideal partial nitrification and energy saving. Furthermore, the integrated MpABR-anaerobic ammonium oxidation (Anammox) maintained high total nitrogen (TN) removal (> 90 %) under high ALR conditions. Microbiome analysis revealed that nitrifiers (Nitrosomonas) and denitrifiers (Stenotrophomonas and Arenimonas) alternately dominated the biofilms at different stages. These findings highlight the potential for achieving efficient partial nitrification effects using a MpABR. The excellent TN removal performance of the MpABR-Anammox suggests its wide applicability in energy-efficient wastewater treatment.

Regulatory mechanisms of biochar alleviating ammonia inhibition to methanogenesis during long-term operation of anaerobic membrane bioreactor treating swine wastewater

Anaerobic Membrane Bioreactor (AnMBR) is regarded as an advanced technology for the anaerobic digestion (AD) of swine wastewater. However, the high ammonia level in swine wastewater is a crucial issue to inhibit methane production. This study aimed to establish a biochar-assisted AnMBR (BC) to mitigate ammonia inhibition during AD of swine wastewater. As the gradual ammonia loading rate (ALR) increased from 3.0 g/L to 6.0 g/L, BC maintained methane yields ranging from 74.9 % to 48.1 %, which were 9.1 % to 33.3 % higher than those of a regular AnMBR (CT). Moreover, the COD removal efficiency steadily surpassed 80 %. Although the increase in ALR had negative effects on both BC and CT, the presence of biochar enhanced the methanogenic activity of bulk sludge, specifically accelerating processes involved in syntrophic acetate oxidation and CO2-reducing methanogenesis under high ALR conditions. Integrated characterizations using PARAFAC-based EPS analysis, INT-ETS, and WO3 probe-based extracellular electron transfer (EET) activities indicated that biochar stimulated the secretion of humic-like and aromatic protein-like compounds in the TB-EPS, which likely established a redox-active matrix with biochar between VFA oxidation bacteria and CO2-reducing methanogens to facilitate EET. This potentially made the syntrophic VFA oxidation with favorably thermodynamic kinetics under high ammonia stress. Furthermore, the analysis of microbial community coupling prediction of functional genes associated with methanogenic pathways revealed that as ALR increased, the presence of biochar re-shaped the microbial communities by enriching electro-active Syntrophomonas and Methanosarcina/Methanospirillum, which mainly triggering EET-based syntrophic methanogenesis by accelerating the intracellular enzymatic transformation from Formylmethanofuran to 5,10-Methylenetetrahydromethanopterin process. We expect the major findings of this study provide new insights to understand the mechanisms of biochar alleviating ammonia inhibition during long-term operation of AnMBR.

Effect of ammonia energy ratio and load on combustion and emissions of an ammonia/diesel dual-fuel engine

Ammonia is receiving increasing attention as a zero-carbon fuel. However, it is difficult to use alone because of its high auto-ignition temperature. Therefore, in this paper, the effects of four ammonia energy ratios (15 %, 30 %, 45 %, and 60 %) on the combustion and emission characteristics of the engine at different loads were studied by using the ammonia/diesel dual-fuel strategy. The results indicated that the presence of ammonia lowered the combustion temperature at all loads, thereby lowering the cylinder temperature and cylinder pressure. In addition, the HRR first increased and then decreased as the ignition delay increased with the increase in ammonia energy ratio. In terms of emissions, at 100 % load, the CO2 and NO of the D40A60 were 65.5 % and 88.14 % lower than that of the D100. The decrease in CO2 was due to more carbon-based fuels being replaced by ammonia. The decrease in NO was due to the decomposition of NO by the thermal deNOx reaction resulting from the lower combustion temperature. The emissions of N2O produced by partial ammonia oxidation offset the greenhouse gas emission reduction effect caused by the reduction of carbon dioxide emissions. Further optimization of the engine combustion strategy is still needed in the future.

Single cell protein production from methane in a gas-delivery membrane bioreactor

Single cell protein (SCP, or microbial protein) is one of the emerging alternative protein sources to address the global challenge of food insecurity. Recently, the SCP produced from methane has attracted substantial attention since methane is a renewable resource attainable from anaerobic digestion. However, the supply of methane, an insoluble gas in water, is one of the major challenges in producing methane-based SCP. This work developed a novel bioreactor configuration, in which hollow fiber membrane was used for efficient methane supply while microorganisms were growing in the suspended form favourable for the biomass harvest. Over a 312-day operation, the impacts of three critical parameters on the SCP production were investigated, including the ratio of methane loading to ammonium loading, the ratio of methane loading to oxygen loading, and the sludge retention time (SRT). Under the condition of 4 g CH4/g NH4+, 4 g O2/g CH4, and SRT of 4 days, the highest SCP production yield was observed and determined to be 1.36 g SCP/g CH4 and 5.05 g SCP/g N, respectively. The protein content was up to 67 %, which is higher than the majority of reported values to date. Moreover, the methane and ammonium utilization efficiencies were both close to 100 %, suggesting the highly efficient utilization of substrates in this new bioreactor configuration. A high relative abundance of essential amino acids (EAA) above 42 % was achieved, representing the highest EAA content reported. These findings provide valuable insights into SCP production using methane as a feedstock.

Ammonia-dependent reducing power redistribution for purple phototrophic bacteria culture-based biohydrogen production

The global energy crisis has intensified the search for sustainable and clean alternatives, with biohydrogen emerging as a promising solution to address environmental challenges. Leveraging photo fermentation (PF) process, purple phototrophic bacteria (PPB) can harness reducing power derived from organic substrates to facilitate hydrogen production. However, existing studies report much lower H2 yields than theoretical value when using acetate as carbon source and ammonia as nitrogen source, primarily attributed to the widely employed pulse-feeding mode which suffers from ammonia inhibition effect on nitrogenase. To address this issue, a continuous feeding mode was applied to avoid ammonia accumulation in this study. On the other hand, other pathways like carbon fixation and polyhydroxyalkanoate (PHA) formation could compete reducing power with H2 production. However, the reducing power allocation under continuous feeding mode is not yet clear. In this study, the reducing power allocation and hydrogen production performance were evaluated under various ammonia loading, using acetate as carbon source and infrared LED at around 50 W·m−2 as light source. The results show that (a) The absence of ammonia resulted in the best performance for hydrogen production, with 44 % of the reducing power distributed to H2 and the highest H2 volumetric productivity, while the allocation of reducing power to hydrogen production stopped when ammonia loading was above 7.6 mg NH4-N·L−1·d−1; (b) when PPB required to eliminate reducing power under ammonia limited conditions, PHA production was the preferred pathway followed by the hydrogen production pathway, but once PHA accumulation reached saturation, hydrogen generation pathway dominated; (c) under ammonia limited conditions, the TCA cycle was more activated rendering higher NADH (i.e. reducing power) production compared with that under ammonia sufficient conditions which was verified by metagenomics analysis, and all the hydrogen production, PHA accumulation and carbon fixation pathways were highly active to dissipate reducing power. This work provides the insight of reducing power distribution and PPB biohydrogen production variated by ammonia loading under continuous feeding mode.

Start-Up Performance and Process Kinetics of a Two-Stage Partial Nitrification–Anaerobic Ammonium Oxidation Reactor

The study of two-stage partial nitrification–anaerobic ammonium oxidation (PN/A) reactors, which are advantageous in engineering applications, still lacks research on process kinetics. Therefore, in this study, the start-up performance and process kinetics of a two-stage PN/A reactor were evaluated by controlling the reaction conditions, for which the two reactors were inoculated with sludge, incubated separately, and then operated in tandem. Increasing the ammonia load of the reactor during the 60 d stabilization period resulted in a nitrogen accumulation rate of 96.93% and a [NO2− − N]Eff/[NH4+ − N]Eff ratio of 1.33, which is close to the theoretical value of 1.32. Successful initiation of the A reactor was achieved after 55 d of operation by inoculating with anammox-activated sludge and granular activated carbon, and the PN and A reactors then successfully operated in combination for 20 d, with an average NH4+ − N efficiency of 99.04% and the NH4+ − N load of the A reactor showing an “S-shaped” curve. An analysis of the microbial growth kinetic models indicated that the removal of NH4+ − N could be successfully described by the logistic, modified logistic, modified Gompertz, and modified Boltzmann models. A strong association between the model and the dependent variable was observed. The process kinetic analysis showed that the removal of NH4+ − N from reactor A could be simulated under steady-state conditions, using the Grau second-order model. The parameters obtained from the model analysis are expected to help predict the denitrification performance of the reactor, facilitate operational management and control, and thus provide a promising research basis for the introduction of automated control systems.

Nitrite accumulation performance and microbial community of Algal-Bacterial symbiotic system constructed by Chlorella sp. And Navicula sp.

Chlorella sp. and Navicula sp. were separately used to construct an algal-bacterial symbiotic system in two identical sequencing batch reactors (R1 and R2) to explore the influence of algal species differences on nitrite accumulation. The Navicula-bacterial symbiotic system showed a higher nitrite accumulation efficiency of 85% and a stronger resistance to ammonia load. It secreted twice as many extracellular polymeric substances than the Chlorella-bacterial symbiotic system. Nitrospira and SM1A02 were the dominant functional genera of nitrite-oxidizing bacteria in R1. The dominant functional genus of ammonium-oxidizing bacteria and the dominant functional genus of denitrifying bacteria were Ellin6067 and unclassified_Saprospiraceae in R2, respectively. In general, this research provided some reference for the construction of an algal-bacterial symbiotic system and achieving nitrite accumulation through an algal-bacterial symbiotic system.

Nitrogen removal intensification of biofilm through bioaugmentation with Methylobacterium gregans DC-1 during wastewater treatment

The increasing concern for environmental remediation has led to a search for effective methods to remove eutrophic nutrients. In this study, Methylobacterium gregans DC-1 was utilized to improve nitrogen removal in a sequencing batch biofilm reactor (SBBR) via aerobic denitrification. This bacterium has the extraordinary characteristics of strong auto-aggregation and a high ability to remove nitrogen efficiently, making it an ideal candidate for enhanced treatment of nitrogen-rich wastewater. This strain was used for the bioassessment of a test reactor (SBBRbio), which showed a shorter biofilm formation time compared to a control reactor (SBBRcon) without this strain inoculation. Moreover, the enhanced biofilm was enriched in TB-EPS and had a wider variety of protein secondary structures than SBBRcon. During the stabilization phase of SBBRbio, the EPS molecules showed the highest proportion of intermolecular hydrogen bonding. It is possible that bioaugmentation with this strain positively affects the structural stability of biofilm. At influent ammonia loadings of 100 and 150 mg. L−1, the average reduction of ammonia and nitrate-nitrogen was higher in the experimental system compared to the control system. Additionally, nitrite-N accumulation was lower and N2O production decreased compared to the control. Analysis of the microbial community structure demonstrated successful colonization in the bioreactor by a highly nitrogen-tolerant strain that efficiently removed inorganic nitrogen. These results illustrate the great potential of this type of denitrifying bacteria in the application of bioaugmentation systems.

Impaired lysosomal acidity maintenance in acid lipase-deficient cells leads to defective autophagy

The lysosome is an acid organelle that contains a variety of hydrolytic enzymes and plays a significant role in intracellular degradation to maintain cellular homeostasis. Genetic variants in lysosome-related genes can lead to severe congenital diseases, such as lysosomal storage diseases. In the present study, we investigated the impact of depleting lysosomal acid lipase A (LIPA), a lysosomal esterase that metabolizes esterified cholesterol or triglyceride, on lysosomal function. Under nutrient-rich conditions, LIPA gene knockout (LIPAKO) cells exhibited impaired autophagy, whereas, under starved conditions, they showed normal autophagy. The cause underlying the differential autophagic activity was increased sensitivity of LIPAKO cells to ammonia which was produced from L-glutamine in the medium. Further investigation revealed that ammonia did not affect upstream signals involved in autophagy induction, autophagosome-lysosome fusion, and hydrolytic enzyme activities in LIPAKO cells. On the other hand, LIPAKO cells showed defective lysosomal acidity upon ammonia loading. Microscopic analyses revealed that lysosomes of LIPAKO cells enlarged, whereas the amount of lysosomal proton pump V-ATPase did not proportionally increase. Since the enlargement of lysosomes in LIPAKO cells was not normalized under starved conditions, this is the primary change that occurred in the LIPAKO cells, and autophagy was affected by impaired lysosomal function under the specific conditions. These findings expand our comprehension of the pathogenesis of Wolman's disease, which is caused by a defect in the LIPA gene, and suggest that conditions, such as hyperlipidemia, may easily disrupt lysosomal functions.

High ammonia loading rate and biofilm reattachment initiated partial nitrification and anammox in a membrane aerated biofilm reactor

Inhibition of nitrite oxidizing bacteria (NOB) is important for efficient wastewater treatment via anammox. Here, a novel strategy was demonstrated, which based on the detachment and reattachment of the biofilm to establish partial nitrification and anammox in a membrane aerated biofilm reactor (MABR). The results showed that using free ammonia as the sole inhibitor to start up partial nitrification took more time, and NOB acclimated to the free ammonia inhibition. Detaching the biofilm made it possible for free ammonia to contact NOB in deeper zones of the biofilm while at the same time washing NOB out of the reactor. Nitrite accumulation efficiency (NAE) increased to 70 % in 50 days when both high ammonia loading and biofilm reattachment were applied. With a short hydraulic retention time and high concentrations of ammonia and nitrite, anammox activity appeared in the reactor and resulted in a nitrogen removal efficiency of 60 %. Microbial community analysis indicated that Nitrosomonas, Nitrospira, and Candidatus Brocadia were the main functional taxa. Anaerobic ammonia oxidizing bacteria (AnAOB) proliferated within the biofilm, inhibiting NOB growth by competing for nitrite. Endogenous denitrifying bacteria also grew, coexisting with AnAOB. Predicted abundance of genes related to fermentation correlated with those involved in denitrification, indicating the possibility of heterotrophic denitrification. These findings help further our understanding of biofilm control-based strategies for NOB management and have implications for establishing autotrophic nitrogen removal using MABRs.

The Ripple Effect of Climate Change: Assessing the Impacts on Water Quality and Hydrology in Addis Ababa City (Akaki Catchment).

This research aimed to evaluate the effects of climate change on the hydrology and water quality in the Akaki catchment, which provides water to Addis Ababa, Ethiopia. This was performed using the soil and water assessment tool (SWAT) model and an ensemble of four global climate models under two Shared Socioeconomic Pathways (SSP) emission scenarios from Coupled Model Intercomparison Project Phase 6 (CMIP6). The climate data were downscaled and bias-corrected using the CMhyd tool and calibrated and validated using the SWAT-CUP software package. Change points and patterns in annual rainfall and temperature were determined using the homogeneity test and Mann-Kendell trend test. Water quality data were obtained from Addis Ababa Water and Sewerage Authority (AAWSA), and more samples were taken and analyzed in accordance with APHA recommended procedures. The SWAT model output was then used to assess the impacts of climate change on hydrological components and water quality. Rainfall increased by 19.39 mm/year under SSP2-4.5 and 12.8 mm/year under SSP8.5. Maximum temperature increased by 0.03°C/yr for SSP2-4.5 and 0.04°C/yr for SSP5-8.5. Minimum temperature increased by 0.03°C/yr under SSP2-4.5 and 0.07°C/yr under SSP5-8.5. This warming will augment the evapotranspiration rate which in turn will have a negative impact on the freshwater availability. Streamflow will increase by 5% under SSP2-4.5 and 9.49% under SSP5-85 which may increase sporadic flooding events. Climate change is expected to contribute to the deterioration of water quality shown by 61%, 36%, 79%, 115%, and 70% increased ammonia, chlorophyll-a, nitrite, nitrate, and phosphorus loadings, respectively, from 2022. The increase in temperature results in increases in nutrient loading and a decrease in dissolved oxygen. Overall, this research demonstrated the vulnerability of the catchment to climate change. The findings of this research can offer vital knowledge to policymakers on possible strategies for the sustainable management of water.

An Analysis of Disaster Preparedness and Mitigation in Ammonia Loading Systems

PT. X has several products produced for distributors and consumers. One of the products produced is a liquid chemical product, namely ammonia which is distributed via tank trucks or containers. If the ammonia gas reaches a volume of 16-17% and flies freely in the air, an explosion may occur which will become a source of fire for the ammonia spray that comes out at high pressure. From the hazard description, it proves that the process of filling and transporting ammonia through tank trucks has many risks that can cause work accidents for workers in the loading and transporting sector of ammonia. The specific aim of this research is to determine the company’s level of preparedness in dealing with disaster failure of the ammonia loading system on tank trucks or containers and determine mitigation steps. To assess the level of disaster preparedness or readiness assessment, this research uses a checklist. The standard used in making this checklist is CAR (Capability Assessment of Readiness) Emergency Management Function. After all the checklist data is obtained, a validity test and reliability test will be carried out. The results of the readiness assessment showed that the emergency preparedness level was 47% fully capable and 53% very capable. Mitigation preparation is proposed based on the results of the readiness assessment. The non-structural mitigation provided is that management should not only provide a regular schedule for worker training, but management must also pay attention to the material that will be delivered at the training; management is advised to make a regular schedule to provide emergency response system training to the community around PT. X; provision of safety equipment during an emergency is very important to note; management should carry out equipment control efforts during the design stage.

Review: Ammonia adsorbent development for white-shrimp ponds

Ammonia is a harmful organic substance for aquaculture existence coming from high-protein foods that significantly enhances the growth of white-shrimp. The cultivation rate of artificial feed production increases the water-soluble ammonia load. Unfortunately, not all regional regulations adopt the Minister of Environment Regulation to limit ammonia levels to no more than 5 mg/L. Adsorption is an alternative solution to remove or reduce ammonia levels in liquid waste bodies. This study aims to describe the efficiency of ammonia absorption as a form of environmental management towards sustainable coastal resources, especially in hatchery of vannamei’s. The points of the discussion are the technology used in the adsorbent pre-treatment strategy, laboratory scale, and field tests for the adsorption of water-soluble ammonia. Various types of adsorption materials were compared to determine the best physical and chemical properties to be used as biosorbent. Results of the review show that applying composite technology is able to absorb more ammonia compared to a single material. An important point are finding the right adsorption material and the number of times this material which can be used to adsorb ammonia material. this has an effect on the need for provision costs for waste management in the hatchery.

Interannual variability of atmospheric ammonia over the Sichuan Basin, southwestern China: Trend, sources, and implications on particle matter control

Atmospheric ammonia (NH3) is an important constituent of biogeochemical cycle and excessive NH3 in the environment results in detrimental effects on ecosystems, air quality, and human health. However, interannual variability and emission changes of NH3 remain highly uncertain, particularly for NH3 hotspot areas. Here, we identify the emission hotspots of NH3 and reveal the trend of NH3 emissions over the Sichuan Basin (SCB) based on a high-resolution map from infrared Atmospheric Sounding Interferometer (IASI) satellite observations in combination with the MEIC inventory from 2008 to 2019. IASI observations indicate that NH3 columns persistent increase over time while MEIC inventory suggests that the past increase in NH3 emissions has indeed ended in 2017 and exhibit decreasing trend afterwards. The NH3 hotspots derived from IASI mainly concentrate in the Chengdu Plain and southern SCB city cluster, which mostly agrees with MEIC emission inventory. CMAQ model simulations well reproduce PM2.5 and ammonia loading and capture observed patterns of NH3. We find that ammonium makes up 15–35% of inorganic fine PM2.5 mass in winter over the SCB. Regulation efforts focused on joint reducing 30% of NOx, SO2, and NH3 emissions could lead to basin-wide wintertime PM2.5 reduce by 10.0 μg/m3, while cutting 30% emissions of NH3 or NOx alone only yield PM2.5 reduced by 0.8 and 5.0 μg/m3, respectively. This work contributes insights on the trend and spatial pattern of NH3 source over the SCB and reveals the critical role of regulating NH3 emissions in mitigating PM2.5 pollution, shedding insights on nitrogen management strategies

A decadal atmospheric ammonia reanalysis product in China

Atmospheric ammonia has great environmental implications due to its important role in ecosystem and nitrogen cycle, as well as contribution to formation of secondary particles. China is recognized as a hotspot of NH3 pollution owing to agricultural and livestock intensification. In the quest to achieve a comprehensive understanding of atmospheric ammonia load and to quantify its environmental impacts in China, relying solely either on existing measurements or on model simulations falls short. Their limitations, either in spatial coverage and integrity or in data quality, fails to meet the needs. Available reanalysis products exhibit a marked deficiency in ammonia data. We therefore aim to propose an integrated ammonia reanalysis product in China, adeptly melding satellite observations from the Infrared Atmospheric Sounding Interferometer (IASI) NH3 retrievals with chemical transport model simulation, capitalizing on the robust Ensemble Kalman Filter (EnKF) data assimilation methodology. The product is validated in high quality via the comparison against independent measurements from ground monitoring stations. Spanning a decade from 2013 to 2022, our reanalysis uncovers not just the spatial intricacies of NH3 concentrations but also their temporal dynamics. Our findings pinpointed the spatial disparities in atmospheric ammonia intensities, highlighting regional hotspots in the NCP, SCB, and Northeast China, and identified annual and seasonal patterns. Our research provides crucial insights for shaping future NH3 pollution prevention and control strategies in China.

The effects of ammonium loading rates and salinity on ammonium treatment of wastewater from super-intensive shrimp farming

Treatment of wastewater from super-intensive shrimp farming (SISF) for discharge or recirculation purposes is currently attracting the attention of managers and researchers. The fixed bed biofilm reactor (FBBR) has been successfully used for biological treatment of drinking water as well as for wastewater treatment in aquaculture farm. Ammonium and salinity are important factors affecting the efficiency of pollutants treatment. This paper presents the results of research on ammonium treatment in super-intensive shrimp wastewater by aerobic microbiological process using FBBRs. The results showed that at ammonium loading rates of 0.014; 0.028; 0.049 and 0.070 kg/m3/d, at salinity of 10‰, the ammonium removal efficiencies were 98 - 99; 97.7 - 98.8; 96.8 – 98.7 and 95.7 – 98.0 percent respectively (ammonium concentrations in effluent were 0.05 – 0.1; 0.12 – 0.23; 0.23 – 0.56 and 0.51 – 1.07 mgN/l, respectively), at salinity of 15‰, the ammonium removal efficiencies were 95.8-96.0, 94.5-92.0, 93.1-92.3 and 66.8-68.8 percent respectively (ammonium in effluent were 0.20 – 0.21; 0.55 – 0.8; 1.20 – 1.35 and 7.8 – 8.3 mgN/l, respectively), at salinity of 20‰, the ammonium removal efficiencies were 92.0-96.0, 87.0-89.0, 69.1-70.9 and 59.6-66.0 percent respectively (ammonium in effluent were 0.2 – 0.4; 1.1 – 1.3; 5.1 – 5.4 and 8.5 – 10.1 mgN/l, respectively). This result showed that the influence of ammonium loading and salinity on ammonium treatment efficiency was very significant.

Heterotrophic nitrifying bacteria from activated sludge in DHS reactor for ammonium removal of natural rubber processing wastewater treatment

Two heterotrophic nitrifying bacterial strains, D2 and D7 were isolated from an activated sludge of sponges in a laboratory-scale downflow hanging sponge reactor. Both strains exhibited efficient ammonium removal ability over a wide range of ammonium loads. At the initial concentration of 100 mg/L, NH4+-N was completely degraded within 20 h by both strains. When the initial concentration was increased to 200 mg/L, the NH4+-N removal efficiency was 99.6 % within 20 h by the strain D2 and 61.3 % by the strain D7. In natural rubber processing wastewater, the ammonium removal efficiencies of strain D2 and D7 were 38 % and 99 % with the initial N-NH4+ concentration of 280 and 380 mg/L after 88 h, respectively. The 16S rRNA gene sequence of D2 and D7 showed the highest similarity to the Pseudomonas aeruginosa and Glutamicibacter nicotianae, respectively. This is the first report to demonstrate the ability to remove ammonium in NRPW by ​heterotrophic nitrifying bacteria isolated from activated sludge in DHS reactor.