Vertical Reactor Research Articles

Thermal degradation of Scenedesmus obliquus for biofuel production

Scenedesmus obliquus is a locally available microalgae in the north-eastern region of India. Pyrolysis of Scenedesmus obliquus has been performed in a fixed-bed vertical reactor, at 350 to 550 °C temperature range with 40 °C/min heating rate. The physicochemical properties of the solid and liquid yields were investigated. The influence of temperature on the amount of product yields was analysed. The highest bio-oil yield of 20.42% and bio-char yield of 58.63% were achieved at 500 °C and 350 °C, respectively. 1H NMR and FTIR were performed for the bio-oil characterisation. The higher heating value of the bio-oil was found to be highest 32.97 MJ/kg at 550 °C. SEM-EDX, FTIR, and XRD techniques were used for the bio-char analysis and characterisation. The resulted char was found to be porous, amorphous, heterogeneous, and basic in nature. The present work suggests Scenedesmus obliquus as a potential candidate for the production of energy substituting conventional fuel sources.

Minimal medium optimization for soluble sulfate removal by tailor-made sulfate reducing bacterial consortium

Modified medium DSMZ 641 used for the growth of SRB consortium developed in the laboratory through enrichment of soil slurry from wastewater fed aquaculture pond at Kolkata India, contained various components that added to the Chemical Oxygen Demand of the solution, making large scale operations using this consortium non-viable. The minimal medium optimization study was carried out using a "one at a time" approach analyzing sulfate reducing ability of the consortium. The consortium reduced soluble sulfate concentration by 70 and 78% (starting from an initial concentration of 2000–3000 mg/L) under suspended and immobilized states, respectively, in 50 mL working volume. The process upon scaling up to 9 L in a vertical biofilm reactor under batch mode could reduce sulfate from the optimized medium by 76% in 4 h, while the same in modified DSMZ 641 was 74%. Response Surface Methodology revealed the optimum concentration of Carbon (Lactic Acid), Nitrogen (Yeast Extract, Ammonium Chloride), and Phosphorus (Potassium Phosphate) in the medium to be 6 mL/L, 500 mg/L each and 750 mg/L respectively.

Biohydrogen production using horizontal and vertical continuous stirred tank reactor- a numerical optimization

This paper illustrates the method to predict the production of biohydrogen and biogas from the horizontal and vertical continuous mixed tank reactor using a numerical approach. Utilization of computational fluid dynamics on the estimation of bioreactor performance is very crucial owing to the uncertainty in the numerical results. Since there has been little work on CFD to determine the influence of hydraulic retention time, impeller speeds, vortex growth, and pH on biohydrogen yield rate the effort had been made. A series of simulations are done with optimal boundary conditions to ensure maximum hydrogen and biogas production rate. Two types of reactors HCSTR and VCSTR are operated at different impeller speed from 40 rpm to 120 rpm. Further, the rate of HRT and organic loading are varied. As the rpm of the impeller increase the rate of hydrogen and biomass production increases not later than 80 rpm. Meanwhile, the optimal range of HRT and pH are 4–8 h and 6.0–8.0. Running the impeller at optimized rate with derived conditions leads to high hydrogen and biogas production of 6 LH2/Ld and 30 L/d. The obtained results are validated with the experimental findings to compare the uncertainty formed due to the numerical simulations. The optimum boundary condition obtained from the study is expected to provide the essential knowledge in establishing the full-scaled reactors.

Hydrogen storage using liquid organic carriers: Equilibrium simulation and dehydrogenation reactor design

Liquid organic hydrogen carriers (LOHC) are unsaturated organic compounds used for chemical hydrogen storage. Using an equilibrium model of the LOHC N-ethylcarbazole, we discuss potential efficiency increases of hydrogen storage systems based on N-ethylcarbazole by the integration of low-temperature waste heat. N-ethylcarbazole is well suited for pressure swing operation with heat exchange between hydrogenation and dehydrogenation. We present and discuss kinetic data of the dehydrogenation reaction gathered in a tubular reactor that was mounted in different orientations and flow configurations. Similar maximum values of power density are reached in vertical and in horizontal orientation. Vertical orientation allows the favorable operation with counter-flow of the liquid carrier and the evolved hydrogen gas and radial heat transfer is significantly better than in horizontal orientation. In vertical reactor configurations, catalyst efficiency and operational stability are impaired at high void fractions. This issue can be reduced by dehydrogenation at elevated pressure and intermediate gas separation from the catalyst bed.

Optimization of AHWR core design: neutronics and thermal-hydraulics analysis and calculations

Advanced Heavy Water Reactor(AHWR) is being designed by BARC for thorium utilisation and demonstrate all aspects of the thorium fuel cycle. The AHWR is a vertical pressure tube type thorium-based reactor cooled by boiling light water and moderated by heavy water. The equilibrium fuel cycle of AHWR is being optimised for a discharge burn-up of 40 GWd/Te with Plutonium as makeup fuel in a closed fuel cycle. The 233U content in the Uranium and fissile Plutonium content in the Plutonium have been assumed to be about 78% and 75% respectively. One of the important passive safety features of AHWR is heat removal through natural circulation which is governed by a strong neutronic and thermal hydraulic coupling. The neutronics design simulations were done for average coolant condition. In order to study the effect of natural circulation and its consequences on the coolant behaviour and the resulting power distribution, the neutronics and thermal–hydraulic coupled calculations were carried out. The neutronics calculations code (FEMFOL) and thermal–hydraulic calculations code (ARTHA) were externally coupled to estimate the coolant density distribution and the critical heat flux ratio (CHFR) for the fuel. This paper gives the details of the critical heat flux ratio estimation and the effect of density distribution on the core power distribution at some selected operating phases during core follow-up of AHWR.

Comparison between two different fixed-bed reactor configurations for nitrogen removal coupled to biogas biodesulfurization

A comparison between a mixed aerobic-anoxic horizontal fixed-bed reactor (MAAFBR) and an aerobic horizontal fixed-bed reactor coupled with an anoxic vertical fixed-bed reactor (AHFBR-AVFBR) was made in order to evaluate the nitrogen removal behavior when nitrification and sulfide-driven autotrophic denitrification occurred in a single unit or spatially separated. Both systems achieved Total-N removal efficiencies (RE) higher than 89 %. Moreover, for both reactors, the effluent pH was affected for bicarbonate alkalinities lower than 250 mg CaCO3 L−1, decreasing the biogas desulfurization from 98 to 50 % in the MAAFBR and from 100 to 61 % in the AVFBR. Hydraulic retention times (HRTs) of 6, 8, 10 and 12 h did not affect the nitrification RE on the AHFBR, maintaining values higher than 99 %. In both cases, biogas desulfurization was achieved. However, results suggested that elemental sulfur (S0) was not predominantly formed due to the interference of oxygen. Such interference was more severe for the MAAFBR, in which the results implied diffusion of O2 and H2S between the aerobic and anoxic chambers.

Computational fluid dynamics analysis of char conversion in Sandia's pressurized entrained flow reactor.

Design and analysis of practical reactors utilizing solid feedstocks rely on reaction rate parameters that are typically generated in lab-scale reactors. Evaluation of the reaction rate information often relies on assumptions of uniform temperature, velocity, and species distributions in the reactor, in lieu of detailed measurements that provide local information. This assumption might be a source of substantial error, since reactor designs can impose significant inhomogeneities, leading to data misinterpretation. Spatially resolved reactor simulations help understand the key processes within the reactor and support the identification of severe variations of temperature, velocity, and species distributions. In this work, Sandia's pressurized entrained flow reactor is modeled to identify inhomogeneities in the reaction zone. Tracer particles are tracked through the reactor to estimate the residence times and burnout ratio of introduced coal char particles in gasifying environments. The results reveal a complex mixing environment for the cool gas and particles entering the reactor along the centerline and the main high-speed hot gas reactor flow. Furthermore, the computational fluid dynamics (CFD) results show that flow asymmetries are introduced through the use of a horizontal gas pre-heating section that connects to the vertical reactor tube. Computed particle temperatures and residence times in the reactor differ substantially from the idealized plug flow conditions typically evoked in interpreting experimental measurements. Furthermore, experimental measurements and CFD analysis of heat flow through porous refractory insulation suggest that for the investigated conditions (1350 °C, <20 atm), the thermal conductivity of the insulation does not increase substantially with increasing pressure.

Kinetics of Fe(II) Oxidation in a Verticle Tube Reactor: A Pilot Scale Study

ABSTRACT A vertical tubular reactor is used for the oxidative leaching process in the mineral processing industry, especially sphalerite. Oxygen could oxidise ferrous ions (Fe2+), and ferric ions (Fe3+) are generated as the principal oxidation agent in the reactor afterward. The partial pressure of oxygen is an instrumental parameter that could change according to reactor height. Despite the extensive studies on Fe(II) oxidation in the high-pressure reactor, there is no published work on its oxidation behaviour in the tubular reactor. Hence, the Fe3+ ion's oxidation in sulfuric acid solutions was investigated in atmospheric condition. The effects of the FeSO4, H2SO4, ZnSO4 concentration, and pressure in the reactor bottom were studied on the rate of ferrous oxidation at different temperatures, i.e. T = 70, 87 and 95°C. Sulfuric acid drops the kinetic of ferrous oxidation, whereas temperature and pressure of the reactor bottom increase this criterion. The apparent activation energy obtained was 67.22 kJ/mol, and an empirical equation for the oxidation rate of Fe2+ by air is as follows:

Inhibition of polychlorinated dibenzo-p-dioxins and dibenzofurans by phosphorus-containing compounds in model fly ash

Waste incineration is a preferred method in China to dispose the municipal solid waste, but controlling the production of highly toxic polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans effectively during incineration is both challenging and imperative. In this study, the suppression of PCDD/Fs by various phosphorus-containing compounds was explored, and the mechanisms responsible for the inhibition were studied in detail. The experiments took place in a lab-scale vertical tubular reactor at 350 °C under a simulated flue gas (12 vol% O2 in N2 flow), and both the off-gases and residues were collected for PCDD/Fs analysis. The scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to characterize the reaction residues. The experimental results revealed that NH4H2PO4 and (NH4)2·HPO4 showed the highest inhibitory effect (57.2% and 57.3%, respectively) on the PCDD/Fs formation, followed by CaHPO4 with inhibition efficiency of 39.1%. In contrast, KH2PO4 and K2HPO4 barely inhibited the generation of the PCDD/Fs. The inhibitory effect of NH4H2PO4 and (NH4)2·HPO4 was similar to that of nitrogen-based inhibitors. At the same time, it was proven that the inhibitory activity of CaHPO4 might be due to the reaction of it with Cu2+ forming stable compounds.

Denitrification performance and microbial diversity using starch-polycaprolactone blends as external solid carbon source and biofilm carriers for advanced treatment

Enhanced nitrate removal from the secondary effluent in municipal wastewater treatment plants (WWTPs) is essential for avoiding water eutrophication. To this end, a vertical baffled solid-phase denitrification reactor (VBSDR) was developed using a starch and polycaprolactone (PCL) blend plate (S-PCL) as a carbon source and biofilm carrier. In this study, we evaluated the denitrification performance and microbial diversity of the VBSDR. The results of the Fourier transform infrared spectroscopy (FTIR), carbon leaching experiment, and scanning electron microscopy (SEM) demonstrated that the S-PCL structure can be attached and degraded more rapidly. Furthermore, the denitrification performance under varied operational conditions, i.e., influent nitrate loading rate (NLR) and operating temperature, was also investigated. Herein, when treating low C/N ratio and low-strength wastewater, a high denitrification rate (DR) [0.33 gN/(L·d)] was achieved. The effect of temperature on DR can be described by the Arrhenius-type equation, which shows that low temperature has a negative influence on DR and nitrate removal efficiency. Furthermore, DR was simultaneously affected by the NLR and temperature. The microbial diversity and community structure were determined by Illumina high-throughput sequencing. The special carbon source led to Acidovorax (denitrifying bacteria) and Flavobacterium (hydrolysis acidifying bacteria) being the VBSDR biofilm’s most predominant functional bacteria at the genus level.

Torrefaction of Rubberwood Waste: The Effects of Particle Size, Temperature &amp; Residence Time

Agriculture waste has created massive challenges over the last few decades and yet also opportunities. This work aimed to produce high-quality biochar from rubberwood waste with calorific properties close to subbituminous coal. Using a tubular vertical reactor, the effects of rubberwood particle size (wood chips and shredded wood), torrefaction temperature (220, 260, and 300 °C), and residence time (30, 60, and 90 minutes) on the quality of torrefied rubberwood were studied. The results showed that the mass loss of the rubberwood increased as the temperature increased. Also, the particle size and residence time increased due to excessive devolatilization. A higher fixed-carbon content and calorific value as well as lower moisture and volatile-matter content were achieved by increasing the torrefaction temperature and residence time in comparison to the untreated sample (raw rubberwood). The highest fixed-carbon content and calorific value were found to be 56.7% and 6313 kcal/kg, respectively, for the wood chip particles that were torrefied at 300 °C for 60 minutes. Based on the Van Krevelen diagram, torrefaction of woodchip rubberwood at 300 °C with a residence time of 60 minutes demonstrated the optimum condition to generate a product with properties that are close to those of subbituminous rank coal.

Ethanol Production from High Solid Loading of Rice Straw by Simultaneous Saccharification and Fermentation in a Non-Conventional Reactor

Simultaneous saccharification and fermentation (SSF) at high solid loading is a potential approach to improve the economic feasibility of cellulosic ethanol. In this study, SSF using high loading of rice straw was assessed using a vertical ball mill reactor. First, the conditions of temperature and number of glass spheres were optimized at 8% (w/v) initial solids (41.5 °C, 18 spheres). Then, assays were carried out at higher solid loadings (16% and 24% w/v). At 8% or 16% solids, the fermentation efficiency was similar (ηF~75%), but the ethanol volumetric productivity (QP) reduced from 1.50 to 1.14 g/L.h. By increasing the solids to 24%, the process was strongly affected (ηF = 40% and QP = 0.7 g/L.h). To overcome this drawback, three different feeding profiles of 24% pre-treated rice straw were investigated. Gradual feeding of the substrate (initial load of 16% with additions of 4% at 10 and 24 h) and an inoculum level of 3 g/L resulted in a high ethanol titer (52.3 g/L) with QP of 1.1 g/L.h and ηF of 67%. These findings demonstrated that using a suitable fed-batch feeding strategy helps to overcome the limitations of SSF in batch mode caused by the use of high solid content.

Effect of Intermittent Aeration in a Hybrid Vertical Anaerobic Biofilm Reactor (HyVAB) for Reject Water Treatment

Water from anaerobic sludge dewatering (reject water that is recycled to the inlet main process treatment) from the Knarrdalstrand municipal wastewater treatment plant in Porsgrunn, Norway, contains 2.4 g/L of total chemical oxygen demand (TCOD) and 550 mg/L NH4-N (annual average). The high concentration of ammonium causes disturbances in the mainstream physical and chemical processes, while only a small fraction of the organics is biodegradable. A pilot-scale hybrid vertical anaerobic biofilm (HyVAB) reactor combining anaerobic and aerobic treatment was tested for reject water treatment to reduce process disturbances. The pilot HyVAB was prepared for the study with continuous aeration of the aerobic part of the reactor for 200 days, while two intermittent aeration schemes were applied during the three-month test period. Ammonium removal efficiency increased from 8% during the continuous aeration period to 50% at the end of the test when a short (7 min) aeration cycle was applied. COD removal was close to 20%, which was mainly obtained in the anaerobic stage and not significantly influenced by the aerations schemes. Simultaneous partial nitrification and denitrification were established in the biofilm that alternated between aerobic and anoxic conditions. The observed high ammonium removal is explained by two alternative shortcut processes via nitrite. The lack of biodegradable organics in the aerated stage suggests that most of the nitrogen removal was via the anammox pathway (autotrophic denitrification). The HyVAB, combining an anaerobic sludge bed and an intermittently aerated biofilm, appears to be an efficient process to treat high ammonium containing reject water.

Tofu Factory Liquid Waste for Making Struvite with Canted Vertical Reactors

Struvite is a white crystal, chemically known as magnesium ammonium phosphate hexahydrate (MgNH4PO4.6H2O). Tofu factory liquid waste is waste that can be reused because of its content. Tofu factory liquid waste can potentially pollute the environment. This research aimsto analyze the manufacture of struvite by utilizing the phosphate content contained in the liquid waste of tofu factories using vertical canted column reactors which can reduce environmental pollution due to liquid waste of tofu factories. This study uses a vertical canted column reactors by mixing anequimolar 1: 1: 1 MgCl2: NH4OH: H3PO4 solution. Struvite crystallization process operates at a temperature variation of 30°C,35°C,40°C,45.50°Cand a pH of 8, 9,10,11,12 by maintaining the air rate of 0.5 liters minute-1 and a MAP (Magnesium Ammonium Phosphate)flow of 56 ml minutes-1 as a whole. The crystallization process runs until a steady state conditionis reached. Then, the struvite crystals obtained were filtered and dried at room temperature for 24 hours. After that struvite crystals were analyzed using XRF, XRD, and SEM. The results of the study obtained the best phosphate conversion of 24.935% at 30°C and pH 8.

Effects of coal and biomass types towards the quality of hybrid coal produced via co-torrefaction

Coal is an abundant source of energy in Indonesia, but the reserves are dominated by low-rank coal, which is less favorable to be utilized. Indonesia also has various biomass that has potential to be used as an alternative energy source. Combining low-rank coal and biomass in a co-torrefaction process resulted in hybrid coal: an upgraded solid fuel that has higher calorific value than its original coal. The aims of this research are to analyze the effect of different biomass and coal blends on hybrid coal yield, calorific value, energy yield, and non-neutral CO2 emission reduction. This study utilized two types of coal that are X and Y, and three different types of biomass: (a) sugarcane bagasse, (b) rubberwood, and (c) empty palm fruit bunch that are being most widely found in Indonesia. The blends consist of 30%wt biomass were co-torrefied in a vertical tubular furnace reactor for 60 minutes with temperature 300°C in an inert environment and ambient pressure. Solid yields of hybrid coal founded in the range of 57.0 to 63.8% which different types of biomass gave significant effect. Calorific value was increased 37.6-44.1% to 5681-6288 kcal/kg from its original coal. The energy yield ranges from 77.0 to 89.0%. The product reduced non-neutral CO2 emission within the range of 18.1-22.2%.

Design of small-scale electrocoagulation reactor for non-sugar removal of sugarcane juice

The most common sugarcane juice purification method practiced in Java is liming and sulphitation. In this research, electrocoagulation method was used to purify the sugarcane juice. This research purpose is to design an electrocoagulation reactor for the non-sugar removal of sugarcane juice. The design method of the reactor is based on IR-Drop and surface area per volume ratio (S/V) optimization. Electrode type and configuration was chosen considering the characteristic of sugarcane juice. A circulated vertical flow reactor type was built to conduct the electrocoagulation. The dimension of the reactor was 10 × 10 × 24 cm and had 8 electrodes installed with 1 cm inter electrode distance. The electrode was aluminium plate and arranged in bipolar configuration. The experiment used 35, 45, and 55 volt, flow rate of 40 L/min, and 30 minutes reaction time with 5 minutes interval. The result showed that an increase in voltage and reaction time increases the non-sugar removal efficiency. The mixed juice treated by electrocoagulation with 55 volt for 5 minutes could remove the non-sugar up to 21.47% and 33.49% for 30 minutes reaction time. The average of non-sugar removal by sulphitation in Java is 11.50% and 29.00% by carbonation. This study shows that electrocoagulation is more effective than the conventional method in removing the non- sugar. With the right scaling up method, electrocoagulation is possible to be practiced in a large scale sugar industry. Future studies are needed to evaluate the performance of electrocoagulation in terms of the clear juice quality and process efficiency.

Phase tailoring and wafer-scale uniform hetero-epitaxy of metastable-phased corundum α-Ga2O3 on sapphire

Heteroepitaxy of corundum-structured α-Ga2O3 is proven as an alternative strategy to solve current challenges in heat dissipation and large scale productivity for Ga2O3-based power electronic devices. In this work, we demonstrate low thermal budget and highly uniform epitaxy of α-Ga2O3 single-crystalline films on 2-inch sapphire substrate by mist-chemical vapor deposition technique. Phase tailoring is performed by tuning the growth temperature and pure phase α-Ga2O3 single-crystalline epilayers are achieved with atomically smooth surface and a reduced dislocation density. High-resolution transmission electron microscopic results indicate α-Ga2O3 growth on sapphire is semi-coherent without any impurity phases, dominated by the multiple domain matching epitaxial mode. Relaxation of strain induced by lattice misfits result in the propagation of edge dislocations along the c-axis. The wafer-scaled epilayers exhibit high crystallographic and thickness uniformity with deviations less than 3%, which stems from the formation of laminar flow on the growing front surface. The herein developed wafer-scale epitaxy in a designed vertical reactor configuration is a straightforward and economic productive scale-up approach to deliver high-quality low-cost wide-bandgap oxide semiconductors towards practical applications in power devices and solar-blind optoelectronics.

Forecasting continuous carbon nanotube production in the floating catalyst environment

We present validated statistical models and univariate correlations of carbon nanotube (CNT) textile properties (specific electrical conductivity, Raman G:D ratio and mass yield rate) extracted continuously from floating catalyst chemical vapour deposition (FC-CVD) reactors over a uniquely wide multivariate experimental space. This includes directly controlled reactor settings (e.g. precursor concentrations, gas flow rates, furnace temperatures and winding speeds), indirect parameters (e.g. ambient temperature and pressure), and time-dependent reactor influences such as reactor tube age. Two vertical FC-CVD reactors, with different precursor delivery architectures, were considered: 1) in which precursors were pre-mixed together as a liquid solution that was directly injected into reactor; 2) in which vaporised precursors were independently injected in the gas phase using Coriolis-based microfluidic mass flow controllers with concentrations monitored in-line using FTIR spectroscopy. Factors favouring highest electrical conductivity fibres include: lower hydrogen flows, lean fuel-to-gas mixtures, higher winding rates, higher argon flows, with many thiophene concentration interactions with other parameters; for highest Raman G:D ratios: leaner fuel-to-gas mixtures, lower thiophene concentrations, higher hydrogen flows, and greater external laboratory pressure; but for yield rate, systematic trends were harder to discern. This study demonstrates the degree of predictability in FC-CVD reactors, quantitatively ranks impact of FC-CVD parameters, and identifies regions of fibre “spinnability” which correspond well with a recent meta-analysis of experimental results in the literature.

A cost-effective production of hydrogen peroxide via improved mass transfer of oxygen for electro-Fenton process using the vertical flow reactor

This study has investigated a novel jet-type reactor (vertical flow reactor) in order to improve the oxygen utilization for enhanced production of hydrogen peroxide (H2O2). In vertical flow electro-Fenton (EF) system, the effects of current density, water flow rate, Fe2+ concentration and initial pH were investigated for the removal of tetracycline hydrochloride. The efficient removal of tetracycline hydrochloride could reach 100% within 60 min under the current density of 24 mA cm−2, water flow rate of 10 L h−1 and pH of 3. The vertical flow reactor was relatively stable and reusable for the removal of pollutants. The removal rates of tetracycline hydrochloride and total organic carbon (TOC) were maintained at about 95% and 80%, respectively in a 5-time continuous runs. Moreover, the vertical flow reactor could efficiently remove a wide type of organic pollutants, and the TOC removals of acid magenta, rhodamine B, alizarin yellow R, orange Ⅳ and diclofenacdium were 75.96, 77.90, 61.27, 72.11 and 82.89%, respectively after 3 h of reaction time. Cathodic adsorption, anodization, and H2O2 oxidation played minor roles in the removal of tetracycline hydrochloride, while the OH radicals are the most pivotal oxidizing substance in the system. As compared with the traditional aeration, the vertical flow reactor has a high-speed jet flow state, which makes the liquid-gas mixture homogeneous, and renders it high oxygen absorption rate, cost effectiveness and high power efficiency for the degradation of pollutants.

Environmental impacts and cost-effectiveness of Thailand’s centralized municipal wastewater treatment plants with different nutrient removal processes

This research investigates the organic and nutrient removal efficiency of eight centralized municipal wastewater treatment plants (WWTP) in Thailand’s capital Bangkok, under five treatment schemes. The environmental impacts were assessed using life cycle assessment, and the cost-effectiveness was determined by life cycle cost assessment. The five treatment schemes were contact stabilization (scheme A/base case), activated-sludge with nutrient removal (scheme B), cyclic activated-sludge (scheme C), two-stage activated-sludge (scheme D), and vertical loop reactor activated-sludge (scheme E). The results showed that scheme A achieved the highest organic removal efficiency (93.01% on average), with all other treatment schemes achieving more than 83% removal efficiency. Scheme E achieved the highest total phosphorus and total nitrogen removal efficiencies (69.12% and 59.74% on average), and scheme C was effective in removing total Kjeldahl nitrogen and ammonia (82.84% and 89.12% on average). The environmental impact assessment indicated that electricity use was the major contributor of almost all environmental impact categories except aquatic eutrophication. Scheme E had the lowest environmental impacts in almost all categories except aquatic eutrophication. Total costs (including operation, maintenance, and environmental costs) of WWTPs with nutrient removal were lower than without nutrient removal. Scheme E had the lowest total cost (2.754 THB2017 per m3) and lowest compounds removal costs, in addition to highest nutrient removal efficiency. Scheme E is the most cost-effective scheme with lowest environmental impacts (i.e., the most eco-efficiency scheme).