Multistage System Research Articles

Efficient Scalable Template-Matching Technique for Ancient Brahmi Script營mage

Analysis and recognition of ancient scripts is a challenging task as these scripts are inscribed on pillars, stones, or leaves. Optical recognition systems can help in preserving, sharing, and accelerate the study of the ancient scripts, but lack of standard dataset for such scripts is a major constraint. Although many scholars and researchers have captured and uploaded inscription images on various websites, manual searching, downloading and extraction of these images is tedious and error prone. Web search queries return a vast number of irrelevant results, and manually extracting images for a specific script is not scalable. This paper proposes a novel multistage system to identify the specific set of script images from a large set of images downloaded from web sources. The proposed system combines the two most important pattern matching techniques-Scale Invariant Feature Transform (SIFT) and Template matching, in a sequential pipeline, and by using the key strengths of each technique, the system can discard irrelevant images while retaining a specific type of images.

Measuring efficiency of the high-tech industry using uncertain multi-stage nonparametric technologies

As an important role in China’s economy, the high-tech industry should evaluate and analyze the innovation activities from a systematic perspective to obtain innovation efficiency, thus improving high-quality development. In fact, for the efficiency assessment system of the high-tech industry, the indicators information is imprecise due to the inherent randomness, measurement error, incomplete information on economic phenomena, etc. However, few studies to date have considered and described the imprecise information. Moreover, data indivisibilities and the economic scale of the high-tech industry cause nonconvex technologies. However, little research has been conducted using the nonconvex measure to estimate innovation efficiency. In this regard, this paper is the first to combine convex and nonconvex technologies with uncertainty theory in a multi-stage system to compare the efficiency of the high-tech industry. More specifically, this paper first divides the innovation activities of the high-tech industry into a technological development stage and an economic transformation stage from the perspective of the innovation value chain. Second, uncertainty theory is adopted to express imprecise information, and uncertain multi-stage nonparametric frontier techniques are constructed to measure the innovation efficiency of the high-tech industry. Third, the high-tech industrial efficiency evaluation based on two-stage nonparametric techniques is established. Empirical results indicate that efficiency in the technology development stage is higher, particularly under nonconvex. Furthermore, the inefficiency of the whole system is mainly due to the inefficiency in the economic transformation under nonconvex, while under convex, the primary reason becomes the joint inefficiency of the two stages.

Techno-Economic Analysis towards Full-Scale Pressure Retarded Osmosis Plants

Pressure retarded osmosis (PRO) is a power generation process that harnesses the salinity gradient between two water bodies of different salinities. Using high salinity water as a draw solution, this work assesses the techno-economic feasibility of the technology to generate electricity using single and multistage systems. This work utilizes a simulator built on the rigorous Q-Electrolattice equation of state and a mass transfer model that accounts for concentration polarization, combined with the Dakota optimization tool to perform sensitivity analysis and optimization studies. The economic indicator of interest is the Levelized Cost of Electricity (LCOE), which serves to compare PRO with other sources of renewable energy. An LCOE value of USD 0.1255/kWh was obtained from the use of commercial membranes at an efficiency of 100% for the mechanical components of the PRO system. This LCOE drops to USD 0.0704/kWh when an ideal membrane is used—thus showing the improvements to economics possible with improved membrane properties. With currently obtainable membrane properties and mechanical equipment, the LCOE of a single-stage process increases to USD 0.352/kWh, which is not cost-competitive with other renewable energy sources. Setting up multistage PRO systems towards minimizing the LCOE was found to be detrimental to the net power production by the plant.

Performance investigation of a novel polygeneration system based on liquid air energy storage

Energy storage systems are important in polygeneration systems, as they help them attain sustainable performance concerning technical, economic, and environmental factors. In this work, a novel polygeneration system based on liquid air energy storage (LAES) and a multi-stage flash (MSF) desalination system is designed. To provide a comprehensive understanding of the system operation and behavior, energy, exergy, economic, and exergoenvironmental assessments are conducted. The proposed polygeneration system is able to provide electrical energy, heating, cooling, sodium hypochlorite, hydrogen, and freshwater. The overall system has three main subsystems: LAES, combined cooling, heat & power (CCHP) unit, and multi-stage flash desalination system. Energy and exergy analyses are carried out and show that the round-trip efficiencies based on energy and exergy are 63.6 % and 61 %, respectively. Also, the annual production values for the hydrogen, potable water, and sodium hypochlorite are 10.2 × 105 m3, 4.8 × 103 m3, and 43.2 tones, respectively. From an economic point of view, the payback period and internal rate of return are 3.4 years and 0.32, respectively. Finally, the exergoenvironmental study shows that the factors for environmental damage effectiveness, exergoenvironmental, exergy stability, and sustainability index for the proposed system are 3.43, 1.68, 0.7, and 1.96.

Многоуровневые алгоритмы оценки и принятия решений по оптимальному управлению комплексной системой переработки мелкодисперсного рудного сырья

The results of studies aimed at developing multi-level decision-making algorithms for management of energy and resource efficiency, technogenic and environmental safety of a complex multi-stage system for processing fine ore raw materials are presented (MSPFORM). A distinctive feature of such a system is its multidimensionality and multiscale, which manifests itself in the presence of two options for implementing technological processes for processing finely dispersed ore raw materials, the need to take into account the interaction of the aggregates included in the system, as well as the hierarchy of describing the processes occurring in them - mechanical, thermophysical, hydrodynamic, physical and chemical. Such a variety of processes characterizes the interdisciplinarity of research and the complexity of obtaining analytical, interconnected mathematical models. This situation inspired the analyze use of artificial intelligence methods, such as deep machine learning and fuzzy logic, to describe and analyze processes. The scientific component of the research results consists in the developed generalized structure of the MSPFORM, the conceptual basis of multilevel algorithms for evaluating and making decisions on the optimal control of this system, the proposed composition of the parameters and the form of the optimization criterion. The task of the study was to analyze possible options for the processing of ore raw materials, to develop a concept for the construction of the MSPFORM allowing the possibility of optimizing its functioning according to the criterion of energy and resource efficiency while meeting the requirements of environmental safety. The application of evolutionary algorithms for solving the problem of optimizing the MSPFORM according to the criterion of minimum energy consumption is announced and its stages are specified. The structure of the block of neuro-fuzzy analysis of information about the parameters of processes in MSPFORM is presented, which is based on the use of deep recurrent and convolutional neural networks, as well as a fuzzy inference system. The results of a simulation experiment on approbation of the software implementation of this block in the MatLab environment are presented.

Organizational aspects of the system of medical support for employees of large industrial companies

The development and implementation of a set of measures to preserve and strengthen the health of the working population in our country is carried out within the framework of the national projects «Health» and «Demography», the federal project «Strengthening public Health» and others. In order to determine the features of medical provision of professional health of employees of domestic industrial companies, a special study was carried out. The analysis of current regulatory legal documents regulating the system of medical provision of professional health of employees of various enterprises was carried out. The objectives, structure, medical management of industrial healthcare, as well as its main organizational and socio-economic models, both based on the departmental healthcare system and outsourcing, are considered. The advantages and limitations of using these models and possible risks were identified, while it turned out that at present the system of medical support for employees of large industrial companies is not unified and combines its own medical organizations (divisions) and health centers with elements of outsourcing and public-private partnership. However, it has been revealed that at present, in the domestic outsourcing market, the risks of transferring the medical support system of employees to the management of third-party medical organizations exceed the potential benefits. In addition, the results of studying the market of medical services for the minimum necessary types of medical work defined by the requirements of the legislation per employee showed that outsourcing of medical services does not provide economic advantages. Therefore, the most rational is the further development of a multi-stage system of providing medical care to employees of enterprises, including using public-private partnerships and innovative medical technologies, primarily high-tech and telemedicine. Along with this, it is necessary to develop a legislative and regulatory legal framework justifying the organization of medical support systems for employees of enterprises of various forms of ownership, as well as to develop motivational and economic approaches aimed at increasing the investment interest of industrial companies in this socially determined activity.

Pressure-driven membrane nutrient preconcentration for down-stream electrochemical struvite recovery

Nutrient recovery from wastewater is a sustainable solution to combat the harmful release of nutrients to the environment. Here, we investigate nutrient recovery from wastewater by pre-concentration of wastewater nutrients using pressure-driven membranes prior to downstream electrochemical nutrient precipitation. When using electrochemical struvite precipitation, a higher nutrient concentration leads to a higher precipitation efficiency. Therefore, we investigate the performance of commercial nanofiltration (NF) and reverse osmosis (RO) membranes with different polymer chemistry and molecular weight cut-offs (MWCO) and discuss the membrane selection based on design goals and wastewater compositions for maximum nutrient recovery efficiency. Our results indicated that the Alfa membrane, a polyamide thin film composite (PA-TFC) NF membrane with 300 Da MWCO has the highest concentration factor in phosphorus (P) preconcentration among all the membranes studied due to the high flux and removal efficiency. BW30LE (PA-TFC, 100 Da), Synder (PA-TFC, 100–250 Da) and NF90 (PA-TFC, 200–400 Da) achieved a high concentration factor for nitrogen (N) recovery. NF90 and Synder NF membranes are able to achieve a nitrogen concentration factor similar to BW30LE RO membrane at much lower energy consumption. A multistage membrane system design is suggested using the selected membranes for effective nutrient recovery. Life cycle assessment (LCA) was conducted to characterize the environmental impact of the multistage membrane nutrient recovery system. Among the different process configurations of the selected membranes, key trends included: 1) environmental impacts across most categories increased as the number of membranes increased, and 2) as the amount of fertilizer substitute that could be produced in a given configuration increased, total environmental impacts decreased with some exceptions.

Research on the effect of tooth root defects on the motor-multistage gear transmission system

In this paper, a coupled dynamic model is proposed for a motor and a multistage gears system of a coal mining machine with tooth root defects. The model effectively simulates the influence of the tooth root cracks on the vibration signals in a multistage gears system when the cracks occur in the planetary subsystem and fixed-shaft gear train subsystem. Comparing the Kurtosis and Crest factor indicators of planetary gear dynamic force and vibration velocity signals, the former is more sensitive to tooth root faults and more suitable as a dynamic indicator for evaluating the effect of tooth root defects on the planetary gear system. The electromechanical system is simulated by coupling the dynamic model of three-phase asynchronous motor and gear system, and the effect of gear tooth faults with different crack depths on the dynamic characteristics of motor-multistage gear system is explored. The results show that the motor current signature analysis (MCSA) can be applied to the detection of gear tooth faults in the transmission system. This method greatly reduces the workload of signal acquisition and spectrum analysis, and can be used as an effective supplement to the traditional vibration signal detection technology.

Minimum power consumption of multistage irreversible Carnot heat pumps with heat transfer law of q ∝ (ΔT) m

Abstract For the given initial finite high-temperature heat reservoir temperature, continuous Hamilton–Jacobi–Bellman equations are established to obtain optimal finite high-temperature heat reservoir temperature for minimum power consumption of multistage Carnot heat pumping system with generalized convective heat transfer law [q ∝ (ΔT) m ]. Analytical expression of optimal heat reservoir temperature with Newtonian heat transfer law (m = 1) is obtained based on generalized optimization results for minimum power consumption. For other heat transfer laws (m ≠ 1), numerical solutions for minimum power consumption are provided. Optimization results for multistage Carnot heat pumps are compared with maximum power output solutions of multistage irreversible Carnot heat engines.

Modelling and Simulation of 1 MW Grid-Connected PV System Regulated by Sliding Mode Control, Model Predictive Control and PI Control

The design and modeling of a 1 MW grid-connected multistage PV system consisting of four equal power rated PV arrays are presented. Two nonlinear control methods, namely sliding mode control and discrete time model predictive control with finite switching states are adopted as the current control scheme of the inverter together with the parameter update for the LCL filter for each control mode. The proposed controllers are based on coordinate transformation of the variables and use decoupling to improve control performance. The dynamic and steady-state performances of these controllers have been thoroughly evaluated and compared with the conventional decoupled PI current control scheme in Matlab Simulink environment under fixed and changing weather conditions. It is observed that the performances of the controller schemes are satisfactory and they give almost similar steady-state performances under given test conditions, although there are little changes observed during system starting.

Numerical Simulation and Experimental Study of a Multistage Multiphase Separation System

Nowadays, most oilfields have entered the high water cut stage of waterflood development. The importance of oil–water separation technology becomes more obvious. Gravity separation is one of the most commonly used treatment techniques for produced fluid. The gravitational separator has a large processing capacity and a wide application range, but its structure is relatively simple and the separation efficiency gradually falls behind to meet current production needs. The key difficulties to improve the separation efficiency are to analyze the flow field and coalescing components inside the separator. Aiming at these difficulties, this paper reports an innovatively designed series-parallel multistage multiphase separation system (MMSS). A horizontal separator is connected in series with a vertical separator, and the vertical separator consists of five discrete pipes connected in parallel. Different coalescing components are then set inside the vertical separator. The separation effect of the MMSS is studied by numerical simulation and laboratory experiments. The oil phase volume distribution cloud diagrams of coalescing components are analyzed by numerical simulation, including semicircle baffle, spiral track plate, four-hole plate and seven-hole plate. Laboratory experiments show that MMSS has a high separation efficiency, and the water content at the oil outlet is 3.0% less than that of the horizontal separator. By observing the shape of oil droplets at the outlet and measuring the oil cut and water cut at the sampling outlet, the separation effect of four coalescent plates is obtained. According to the statistics, when the volumetric flow at the inlet of the separator is 1.5 m3/h, the average particle size of oil drops in the blank pipe, semicircular baffle, four-hole plate, spiral track and seven-hole plate increases in turn. A continuous oil layer appears at the outlet of the vertical separator in the fully open state. The water content at the oil outlet of the semicircular baffle coalescing component is always at a high level under different flow rates. When the inlet volumetric flow rate is less than 1.6 m3/h, the performance of the spiral track coalescing component is better. With the increase of the inlet volumetric flow rate, the separation efficiency of the spiral track is lower than that of the orifice. The results show that the semicircular coalescing component has the worst performance, the spiral track coalescing component is superior at small volumetric flow rates, and the orifice coalescing component is superior at large volumetric flow rates.

Analysis of low emission characteristics of NH3/H2/air mixtures under low temperature combustion conditions

The complex dynamics of NH3/H2/air mixtures have been numerically investigated in an idealized reactor environment of fast fuel/air mixing represented by perfectly stirred reactors (PSR). The complete steady state “S-curve” solutions are obtained with eigenvalue analysis for quantifying the stable/unstable characteristics of different branches. With four different chemical mechanisms, stable cool flame branches are observed for NH3/H2/air mixtures. The reactions involving species NH2, H2NO and NNH are found important for both fuel consumption and NOx formation on the cool flame branch. The parametric study further shows that with less than 5 % hydrogen addition in ammonia (in volume), stable cool flames exist over a wide range of inlet temperature, equivalence ratio and pressure. For the states in the cool flame branch, although hydrogen is almost consumed completely, only portion of the ammonia is consumed resulting in low NOx emission due to the reduction effects of remaining ammonia and high N2O emission resulting from low temperature. Inspired by the observed stable cool flame characteristics, a multi-staged low-temperature model system is formulated for low NOx emission of NH3/H2/air combustion, in which small amount of hydrogen is sequentially injected to homogeneous reactors of lean NH3/H2/air mixture. With the representative high inlet temperature of 850 K, pressure of 20 atm, fuel lean of ϕ=0.7 and critical fuel efficiency of 99.7 %, results with the 28-species Li reduced mechanism show that less than 75 ppm of NOx and 98 ppm of N2O can be achieved with two-staged homogenous combustion operating at low temperature of 1300 K and 2 % H2 addition in each stage. With three-staged homogenous combustion, less than 70 ppm of NOx and 10 ppm of N2O can be achieved at 1300 K. NOx emission is lower than those of direct NH3/H2/air combustion without aftertreatment, demonstrating the opportunity of utilizing low temperature combustion to achieve high fuel conversion, low NOx and N2O formation for lean NH3/H2/air mixtures.

Approaching theoretical maximum energy performance for desiccant dehumidification using staged and optimized metal-organic frameworks

Dehumidification systems including desiccant wheels are widely used in commercial and a few residential air conditioning systems to remove latent loads. These wheels require high-temperature heat to regenerate and are often quite inefficient, with a typical single-pass efficiency of around 20%. In this work we propose a novel desiccant wheel system that takes advantage of the unique behavior of metal-organic frameworks (MOF) sorbents. We show that for any given entering air condition, there exists an optimal MOF that if included in the dehumidification systems will result in maximum efficiency. Based on this idea, we develop a multi-stage dehumidification system in which each stage uses the optimal MOF. To do so, we first mathematically model and validate a MOF-based desiccant wheel system and use it to systematically identify the optimal MOF isotherm shape as a function of inlet air conditions. Then we extend the model to different multi-stage MOF-based desiccant wheel systems and optimize them to achieve energy performance far exceeding a single-desiccant wheel. We use our validated discretized dynamic model to compare the energy needed for operation of these systems with other possible configurations. Finally, we show that an optimized staged MOF system can approach the theoretical maximum energy performance for desiccant dehumidification, using nearly 100% of regeneration energy for desorption of water and wasting very little. The results also show that a multi-stage MOF-based dehumidification system can have a regeneration efficiency 2 to 5 times greater than a single-stage system. Adding adsorption heat removal stages between the desiccant wheel stages can increase the regeneration efficiency by 5–20%, and the dehumidification effectiveness of the system 20–40%.

Hybrid multi-stage flash (MSF) and membrane distillation (MD) desalination system for energy saving and brine minimization

A hybrid multi-stage flash and multi-stage membrane distillation system for freshwater recovery from the rejected MSF brine is studied. The proposed system reduces environmental impact through reducing the rate of rejected brine, desalination energy and product cost. This is achieved by utilizing the energy rejected from the brine heater to heat a portion of MSF reject that is fed into the MD system since MD systems operate at relatively low temperature and are tolerant to high salinity input. The system includes a multi-stage MD system with a capacity ranging from 75 to 200 m3/day that help in reducing brine volume as model novelty. MD energy is supplied from the condensate leaving MSF brine heater. The effect of MD feed inlet temperature on the performance of stand-alone MD and hybrid MSF-MD systems is investigated for various layouts of the integrated system. Performance of the proposed system is quantified in terms of productivity, MD gained output ratio (GOR), specific electric energy consumption (SEEC), freshwater recovery rate (RR) and water cost. The hybrid MSF-MD system can be used for rejected brine reduction. Parallel feed – parallel coolant integrated arrangement provides the best performance among other configurations, with a productivity, RR, GOR, and SEEC of 218.3 m3/day, 3.544 %, 0.921 and 1.107 kWh/m3, respectively for the MD system. Additionally, the hybrid MSF-MD system yielded about 30,098m3/day, 57.544 %, and 8.583 in productivity, RR and GOR, respectively. MD freshwater cost is reduced by 70 % - 90 % compared to the conventional MD system with an independent energy supply.

Performance Assessment of a Novel Solar and Biomass-Based Multi-Generation System Equipped with Nanofluid-Based Compound Parabolic Collectors

The current paper proposes a novel multi-generation system, integrated with compound parabolic collectors and a biomass combustor. In addition to analyzing the comprehensive system in a steady state, the feasibility of using nanofluids as heat transfer fluids in the solar cycle and their effect on the overall performance of the system was studied. The multi-generation system is generally designed for generating electricity, cooling, freshwater, drying, hot water, and hydrogen, with the help of six subsystems. These include a double stage refrigeration system, an organic Rankine cycle, a steam Rankine cycle, a dryer, a proton exchange membrane electrolyzer, and a multistage flash distillation system. Two types of nanoparticles (graphene, silver), which have various high-quality properties when used within ethylene glycol, were chosen as absorbing fluids in the solar cycle. The performance parameters of the base case thermodynamic analysis and some of the variable parameters were calculated, and their effect on system performance was determined. According to the results, a spike in solar irradiation, ambient temperature, output temperature of biomass combustor and nanofluids’ concentration positively affected the overall system performance. The results also clearly showed an improvement in system performance when using nanofluids as working fluids in solar collectors.

On error reduction by the symmetric rejection method in multi-stage biometric verification systems

On error reduction by the symmetric rejection method in multi-stage biometric verification systems

Educational Reforms and Blended Learning

Indian education system has deep ancestries and have seen many transformations. History denote many records, how education in this diversified, multicultural region has changed from informal to formal edification, from Gurukulas, Madarsas to School and University Education. Formal education is still rebellious; ever ready to update and upgrade itself. So the education society always has to keep its learning switch mode on to get transfigured according to the needs of the society. Education infact has no single motive towards the society. It has to fulfil the multiple wants and desires and so as its transformations occur according to the needs of the society. Today, no doubt, education system worldwide has flourished and developed formally with numerous education bodies and societies. Various education policies & recommendations has been shouldering the responsibility to sharpen the edges followed by various legal enactments time to time. Like India, many countries has upgraded its education into formal multi-staged education system. Efforts of NCERT, MHRD, UGC, AICTE, NCTE, NAAC, NIRF, NIEPA etc. should always need to be appreciated. The present paper overviews the role and functions of various contributing apex bodies to bring periodical transformations in the education system. It further endeavor to review the pros and cons of existing system and attempts to evaluate its efficacy in emergent pandemic situations. The paper concludes with recommendations to reform and ameliorate in the light of recommendations of NEP, 2020. It also recommends to adopt blending learning and teaching method for impending era.

Development of a high-speed bioaerosol elimination system for treatment of indoor air

We developed a high-speed filterless airflow multistage photocatalytic elbow aerosol removal system for the treatment of bioaerosols such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Human-generated bioaerosols that diffuse into indoor spaces are 1–10 μm in size, and their selective and rapid treatment can reduce the risk of SARS-CoV-2 infection. A high-speed airflow is necessary to treat large volumes of indoor air over a short period. The proposed system can be used to eliminate viruses in aerosols by forcibly depositing aerosols in a high-speed airflow onto a photocatalyst placed inside the system through inertial force and turbulent diffusion. Because the main component of the deposited bioaerosol is water, it evaporates after colliding with the photocatalyst, and the nonvolatile virus remains on the photocatalytic channel wall. The residual virus on the photocatalytic channel wall is mineralized via photocatalytic oxidation with UVA-LED irradiation in the channel. When this system was operated in a 4.5 m3 aerosol chamber, over 99.8% aerosols in the size range of 1–10 μm were removed within 15 min. The system continued delivering such performance with the continuous introduction of aerosols. Because this system exhibits excellent aerosol removal ability at a flow velocity of 5 m/s or higher, it is more suitable than other reactive air purification systems for treating large-volume spaces.

Toward automated interpretable AAST grading for blunt splenic injury.

The American Association for the Surgery of Trauma (AAST) splenic organ injury scale (OIS) is the most frequently used CT-based grading system for blunt splenic trauma. However, reported inter-rater agreement is modest, and an algorithm that objectively automates grading based on transparent and verifiable criteria could serve as a high-trust diagnostic aid. To pilot the development of an automated interpretable multi-stage deep learning-based system to predict AAST grade from admission trauma CT. Our pipeline includes 4 parts: (1) automated splenic localization, (2) Faster R-CNN-based detection of pseudoaneurysms (PSA) and active bleeds (AB), (3) nnU-Net segmentation and quantification of splenic parenchymal disruption (SPD), and (4) a directed graph that infers AAST grades from detection and segmentation results. Training and validation is performed on a dataset of adult patients (age ≥ 18) with voxelwise labeling, consensus AAST grading, and hemorrhage-related outcome data (n = 174). AAST classification agreement (weighted κ) between automated and consensus AAST grades was substantial (0.79). High-grade (IV and V) injuries were predicted with accuracy, positive predictive value, and negative predictive value of 92%, 95%, and 89%. The area under the curve for predicting hemorrhage control intervention was comparable between expert consensus and automated AAST grading (0.83 vs 0.88). The mean combined inference time for the pipeline was 96.9s. The results of our method were rapid and verifiable, with high agreement between automated and expert consensus grades. Diagnosis of high-grade lesions and prediction of hemorrhage control intervention produced accurate results in adult patients.

Performance and sustainability of a multi-stage free water surface constructed wetland under seasonal change and shock loading

Multi-stage constructed wetlands (CWs) are widely used for water quality improvement, especially in the treatment of wastewater. Many studies focus on their treatment efficiency under steady loading, but fewer studies consider their sustainability under variable conditions. This study examines the multi-stage CWs in the Hong Kong Wetland Park for their long-term performance and sustainability in terms of water quality under seasonal changes, storm events, and shock loadings of pollutants. The results show that the multistage design performs well and is stable under these changing conditions. In such multistage CWs, the type of units and some changing conditions (e.g., inflow concentrations, seasonal changes of vegetation, and water levels) also affect the performance of the whole system. Compared to individual CW, a multi-stage CW system could recover more quickly on dissolved oxygen (DO), and ammonia nitrogen (NH4), but slowly on biochemical oxygen demand (BOD) and total phosphorus (TP). A pre-processing and buffering area is necessary to handle the shock loadings of BOD and TP in such a multistage CW system. Although water levels recover quickly in both, it is difficult to return to original water levels in multi-stage CWs compared to single ones. Besides, for sustainable operation, attention should be paid to the DO of the inlet, and aeration measures might be taken.