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The paper summarizes the state-of-the-art of the most recent advances in biological nitrogen removal, including process design criteria and technological innovations. Withreference to the Modified Ludzck Ettinger (MLE) process (pre-denitrification and nitrification in the activated sludge process), the most common nitrogen removal process used nowa...
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Context 1
... by the Paques company, it uses the SHARON process (Single reactor system for High Activity Ammonium Removal Over Nitrite), a stable, partial nitrification to nitrite instead of nitrate ( Hellinga et al., 1998), to convert ammonia to nitrite, followed by the anammox process (Figure 2A). This is optimized by controlling pH, DO, and by taking advantage of the higher growth rate of ammonia-oxidizing bacteria at higher temperatures (Van Loosdrecht and Jetten, 1998). ...
Context 2
... this process, nitritation and deammonification (anammox) occur in the same reactor ( Figure 2B), making process control (pH, DO, and Oxidation-Reduction Potential -ORP) essential to prevent bacterial competition for nitrite (heterotrophic denitritation, and in particular autotrophic Nitrite Oxidizing Bacteria -NOBs), while maintaining a long solid retention time (SRT) for anammox bacteria. Ammonia reduction of 95%, with over 80% total nitrogen reduction, have been reported ( Abma et al., 2010). ...
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Background
The discovery of complete ammonia oxidizer (comammox) was groundbreaking. Comammox can use ammonia as the sole nitrogen source and turn it to nitrate. Moreover, genomic data indicated that comammox contained genes which can metabolize urea and nitrite. However, the feasibility of enriching comammox with urea and nitrite in long term has...
The dairy industry is a very productive sector worldwide and known for producing great volumes of wastewater that is rich in organic matter and nutrients. Apart from fat, the organic matter in such effluents is easily degradable, demanding an external carbon source for conventional denitrification. In this manner, new configurations of reactors pro...
Citations
... High efficiency of biological nitrogen removal processes is extremely important in the context of protection of water resources. Hence, constantly developed new criteria for the design of biological reactors, which are an improvement of the existing ones, as well as the proposed new treatment technologies by denitrification, is especially valuable (Du et al., 2015;Capodaglio, Hlavínek and Raboni, 2016). The search for the answer to the question, of which biological processes can be considered as the best for removing nitrogen from sewage can be found, for example, in the paper of McCarty (2018), in which the author compares conventional and unconventional nitrogen removal techniques. ...
... The treatment of such wastewater is crucial not only for environmental preservation but also for ensuring sustainable agricultural practices in the region. The biological processes, especially nitrification and denitrification, have been widely adopted as primary methods for removing nitrogen from wastewater in various wastewater treatment facilities (Capodaglio et al., 2016;Liu et al., 2009). The process of nitrification is often considered a costly treatment process, as it requires high levels of oxygen for the conversion of ammonia into nitrate, while the denitrification process demands an additional supplementary carbon source to proceed effectively (Raper et al., 2018;Ren et al., 2014). ...
Nitrogen pollution in water bodies has become a pressing environmental and public health issue worldwide, demanding the implementation of effective nitrogen removal strategies. This research paper delves into the performance evaluation of hybrid constructed wetlands (HCWs) as a sustainable and innovative approach for nitrogen removal, employing a comprehensive year‐long dataset gathered from a practical setup. The study collected data under diverse operating conditions to investigate the effectiveness of HCWs in removing nitrogen. Results revealed that HCWs achieved nitrogen removal efficiencies ranging from 28% to 65%, influenced by temperature and hydraulic retention time. Optimal removal occurred at an average temperature of 28°C and a 4‐day hydraulic retention time. Notably, performance declined during colder periods, with temperatures below 15°C. The study also aims to predict nitrogen removal by three modeling techniques, that is, artificial neural networks (ANNs), support vector machines Pearson VII kernel function (SVM PUK), and multiple linear regression (MLR). Prediction has been done considering temperature (TEMP), hydraulic loading rate (HLR), initial concentration of chemical oxygen demand (COD) (CODin), initial concentration of total nitrogen (TN in ), initial concentration of total phosphorous (TP in ), and initial concentration of turbidity (TB in ) as input parameters, whereas reduction of total nitrogen (RED TN) is regarded as output parameter. The performance of the soft computing techniques has been compared in terms of coefficient of determination ( R ² ), root mean square error (RMSE), and mean absolute error (MAE). The analysis revealed that the performance of the SVM (PUK) model ( R ² : 0.572, RMSE: 0.0359, MAE: 0.0294) for the prediction of TN reduction is superior followed by MLR ( R ² : 0.562, RMSE: 0.0365, MAE: 0.0294) and ANN ( R ² : 0.597, RMSE: 0.0377, MAE: 0.0301). The present study concludes that the treated effluent by the HCWs, using water hyacinth and water lettuce, is of fair quality, thus having potential application for the treatment of rice mill wastewater in warmer climates. Further, machine learning approaches employed in estimating the total nitrogen reduction by HCWs technology have shown promising applicability and utilization in such studies.
Practitioner Points
Hybrid constructed wetlands (HCWs) are effective in removing nitrogen from wastewater.
The performance of HCWs in nitrogen removal can vary due to physical, chemical, and biological processes.
The performance of the HCWs highly depends on temperature and hydraulic retention time.
Artificial neural networks (ANNs) and support vector machines (SVMs) provided better predictions of nitrogen removal with high accuracy and low root mean square error.
... The removal of ammonia from various wastewaters has attracted much attention because ammonia is harmful to aquatic species due to its significant impact on eutrophication and reducing dissolved oxygen (Qing et al., 2021;Rahimi et al., 2020). There are several methods for removing ammonia from wastewater, including air stripping (Folino et al., 2020;Kim et al., 2021), adsorption and ion exchange (Capodaglio et al., 2015), reverse osmosis (Obotey Ezugbe and Rathilal, 2020), chemical precipitation (Capodaglio et al., 2015), and biological treatment (Capodaglio et al., 2016;Eddy et al., 2013). However, these processes have limitations, including complex operations, a large investment in capital construction, sensitivity to environmental conditions, and their inability to reduce ammonia to low levels (Liu et al., 2009;Zhang et al., 2018). ...
... However, these methods either cause secondary pollution or incur additional costs. Biological nitrification oxidizes ammonia nitrogen by bacteria, but this microbial activity is susceptible to environmental influences and the reaction speed is slow [16]. In addition to the above methods, freeze concentration, as an environment-friendly, cost-effective, and efficient method, has been developed recently [17][18][19][20][21][22]. ...
Ammonium wastewater is a serious and common water pollutant that can have harmful effects on the environment. Freeze concentration, as an energy-efficient and environmentally friendly method, is used to treat ammonium wastewater by ice-water phase transition. The simulation results show that most of the ions are retained in the water phase, and it is reported for the first time that the probability of NH4+ (90%) remaining in the water is significantly higher than that of Cl− (67%). We analyzed the influence of ions on ice/water phase structure from the perspective of structure and energy, and explained the reason for the difference in the probability of NH4+ and Cl− remaining in water. We found that the coordination number (CN) of NH4+ decreased from 6 to 4 when one NH4+ permeated the ice layer, indicating that the first hydration layer of ammonium ions underwent significant reorganization during this period. In contrast, a similar reduction in CN was not observed during the entry of Cl− into the ice layer. Moreover, the hydration energy shows that NH4+ prefers to stay in liquid phase than in ice phase because of the higher hydration energy difference compared with that of Cl−. The results of this work indicate that freeze concentration can efficiently remove NH4+ by ice-water phase transition, which greatly reduces the discharge of ammonium wastewater and pave the way for further study of the freezing process for wastewater treatment.
... In aqueous solutions, NH 3-N generally exists as ammonium ions [NH 4 + ] at pH below 8, whereas NH 3 is the predominant form when the pH is above 9.75 (Zhang et al., 2018). These two species of NH 3 -N are the most common source of nitrogen contamination in drinking water and the primary cause of eutrophication, which is harmful to fish and other aquatic organisms (Capodaglio et al., 2016;Liu et al., 2018). In response to these issues, research on wastewater treatment technologies has increased significantly in recent years owing to stringent environmental regulatory requirements for the disposal of nitrogencontaining compounds into receiving water systems. ...
... This process is commercially known under the proprietary name NEREDA [114]. Granular sludge is also at the basis of the ANAMMOX ® process, a highly energy efficient denitrification process [115]. Both NEREDA and ANAMMOX substantially reduce the structural and mechanical design complexity and the environmental footprint of WWTPs, both as land occupancy and energy requirements, improving plant efficiency. ...
Current wastewater management paradigms favor centralized solutions, as taught in traditional engineering schools, which imply high capital costs, long-range water transfer, long and disruptive construction and highly trained operators. On the other hand, small decentralized systems are seldom considered even though they require lower capital costs, less disruptive infrastructure construction and allow for the maintenance of a closer, more sustainable water cycle. This manuscript starts with an extensive review of the long history of wastewater systems, from the Greek antiquity to the modern era. The use of natural and physical systems in history and their evolution into modern technology is also analyzed. Finally, future trends are considered with emphasis on technological adaptation and sustainability of decentralized systems, with a view that lessons that can be learned from history and past practices. The manuscript aims to provide a critical overview of water and wastewater management in view of the oncoming challenges of this sector.
... The mean EEITN rem value achieved by Zylka [11] was over threefold higher than that reported by Panepinto et al. [6], which amounted to 14.66 kWh/kgTN rem and was computed for an entire wastewater treatment plant with a capacity of 615,000 m 3 /day. They were also much higher than the values reported by Henze et al. [17] (who stated that, in activated sludge processes with nitrificationdenitrification, energy consumption was 2.3 kWh/kg N removed) and by Capodaglio et al. [18]. The latter studies presented data concerning ANITA TM MOX (MBBR system) technology energy requirements of 1.6-1.9 ...
An attempt was undertaken to determine indicators of energy consumption in bio-electro reactors (BERs) i.e., an aerobic rotating electrobiological disc contactor (REBDC) and an anaerobic sequencing batch biofilm reactor (SBBR), during contaminant removal from soilless tomato cultivation wastewater having a specific composition, i.e., high nitrate and phosphorus concentrations and low COD. Because of this specificity, the energy consumption during the treatment process was characterized by a cumulative indicator for simultaneous removal of phosphorus and nitrates—EEINUTRIENTSrem (electric energy consumption per unit of removed nutrient load, expressed as kWh/kgNUTRIENTSrem). Four values of direct current density were tested: 0.63, 1.25, 2.5, and 5.0 A/m2. The indicator values were compared at a hydraulic retention time (HRT) of 24 h. The study demonstrated that the values of electric energy consumption per unit of removed nutrient load determined in the anaerobic SBBR ranged from 30 to 464 kWh/kg NUTRIENTSrem and were lower than the values obtained in the aerobic REBCD, i.e., 80–1380 kWh/kg NUTRIENTSrem.
... The amount of biodegradable COD used per unit of nitrogen in nitrate form is based on biomass conversion yield. As a general rule, it takes about 4 gBOD 5 /g NO 3 2 reduced (Capodaglio et al., 2016). ...
The activated sludge is a traditional biological treatment, using microorganisms mixed with suspended solids in the mixture to treat domestic and industrial wastewater. It can achieve high treatment efficiencies with a wide variety of emerging organic pollutants present in the wastewater. This chapter aims to provide (1) the fundamentals of the activated sludge process, including microbial community characteristics, microbial growth kinetics, and environmental factors; (2) advanced technologies with activated sludge such as sequencing batch reactor, UNITANK system, and intermittent cycle extended aeration system; and (3) applications of activated sludge processes to remove emerging pollutants in wastewater. Also, the energy and cost required to treat wastewater by activated sludge were highlighted. Finally, this chapter provides a comprehensive review of the activated sludge process, leading to its application for wastewater treatment in further research.
... The selected site situated in the center region of the Great Plain, Hungary, has an average capacity of 4700 m 3 /d and receives a peak hourly flow of 1.8, resulting in a hourly maximum flow of 353 m 3 /h without equalization capacity. The plant is capable of biological nutrient removal, consisting of a mechanical treatment with screening, grit removal, and Energies 2022, 15, 6113 4 of 13 a primary treatment, followed by an activated sludge system using a modified Ludzack-Ettinger (MLE) reactor layout [31]. The volume of the biological reactor is 2500 m 3 , of which 40% is the anoxic zone and 60% is the aerobic zone. ...
... The selected site situated in the center region of the Great Plain, Hungary, has an average capacity of 4700 m 3 /d and receives a peak hourly flow of 1.8, resulting in a hourly maximum flow of 353 m 3 /h without equalization capacity. The plant is capable of biological nutrient removal, consisting of a mechanical treatment with screening, grit removal, and a primary treatment, followed by an activated sludge system using a modified Ludzack-Ettinger (MLE) reactor layout [31]. The volume of the biological reactor is 2500 m 3 , of which 40% is the anoxic zone and 60% is the aerobic zone. ...
Wastewater treatment is an energy-intensive process for treating liquid-phase pollutants in urban settlements. The aerobic processes of the biological treatment involve a significant air demand. An optimal control strategy could be used to minimize the amount of excess air entering the system due to safety factors applied in the design procedures. A plant-wide mechanistic modeling approach including an activated sludge model and one-dimensional settler model was proposed as an effective tool for predicting the actual air demand and for selecting the optimal aeration strategy. In this study, a sewage treatment plant receiving strong influent flow was investigated. At the sludge ages of 14–18 days, the plant was capable of achieving a 90% organic matter reduction and 85% nutrient reduction. By applying a constant dissolved oxygen concentration of 1.5 mg/L, the air demand decreased by 25%, which could be further increased by 10% if the cascade ammonium control approach was applied at peak periods. The dependence of the aeration energy demand on the temperature and dissolved oxygen was formulated, meaning the operators could select the optimal setpoint and minimize the energy consumption while the effluent quality requirements were met
... Microbial nitrate reduction is coupled to the anaerobic oxidation of an organic substrate, and use NO 3 − or NO 2 − as a terminal electron acceptor (mediated by heterotrophic bacteria) (Rivett et al., 2008;Capodaglio et al., 2016). Heterotrophic denitrification, on which most denitrificationbased treatments are based, can be described by the general Reaction 2 sequence (Jørgensen et al., 2004), as follows: ...
The occurrence of nitrate is the most significant type of pollution affecting groundwater globally, being a major contributor to the poor condition of water bodies. This pollution is related to livestock-agricultural and urban activities, and the nitrate presence in drinking water has a clear impact on human health. For example, it causes the blue child syndrome. Moreover, the high nitrate content in aquifers and surface waters significantly affects aquatic ecosystems since it is responsible for the eutrophication of surface water bodies. A treatability test was performed in the laboratory to study the decrease of nitrate in the capture zone of water supply wells. For this purpose, two boreholes were drilled from which groundwater and sediments were collected to conduct the test. The goal was to demonstrate that nitrate in groundwater can be decreased much more efficiently using combined abiotic and biotic methods with micro-zero valent iron and biostimulation with lactic acid, respectively, than when both strategies are used separately. The broader implications of this goal derive from the fact that the separate use of these reagents decreases the efficiency of nitrate removal. Thus, while nitrate is removed using micro-valent iron, high concentrations of harmful ammonium are also generated. Furthermore, biostimulation alone leads to overgrowth of other microorganisms that do not result in denitrification, therefore complete denitrification requires more time to occur. In contrast, the combined strategy couples abiotic denitrification of nitrate with biostimulation of microorganisms capable of biotically transforming the abiotically generated harmful ammonium. The treatability test shows that the remediation strategy combining in situ chemical reduction using micro-zero valent iron and biostimulation with lactic acid could be a viable strategy for the creation of a reactive zone around supply wells located in regions where groundwater and porewater in low permeability layers are affected by diffuse nitrate contamination.
