BOD Removal Rate Research Articles

Catalytic valorization of Kraft lignin into feedstock chemicals with methyltrioxorhenium (MTO) catalyst in microbial electrochemical cell

In this study, the authors investigate a novel approach to valorize Kraft lignin using the catalyst Methyltrioxorhenium (MTO) in tandem with in-situ produced H2O2 in a Microbial Electrochemical Cell (MEC). This study demonstrates the in-situ oxidation of Kraft lignin using different concentrations of MTO catalyst (2 mM to 8 mM) and H2O2 (5.24 ± 0.40 mM to 8.91 ± 0.70 mM) in three MECs. The depolymerized Kraft lignin samples were characterized using FTIR, CHNS/O, and 1H NMR analysis. The MTO/H2O2 combination showed high selectivity towards the oxidation of Kraft lignin, resulting in both aromatic ring and side chain cleavage reactions and the production of valuable feedstock chemicals. The oxidation also led to a reduction of 68.42 % to 78.18 % in Chemical Oxygen Demand (COD) of lignin. The selective oxidation favored the recovery of Guaiacyl (G) unit-derived feedstock chemicals, with Guaiacol being the most abundant compound (45.04 mg/mL) among the quantified products by HPLC. Additionally, the system demonstrated high efficiency in anodic wastewater treatment, achieving BOD and COD removal rates ranging from 67.68 % to 72.55 %. This method showcases the use of a sustainable system in combination with a selective catalyst to produce valuable products from usually discarded Kraft lignin while simultaneously treating wastewater.

Variasi Sinar Ultraviolet pada Sistem Membran Ultrafiltrasi untuk Pengolahan Air Gambut

Peat water treatment still has many obstacles, one of the alternatives that can be used to overcomethis obstacle is membrane technology and UV light variais. This study aims to determine the effect of UV rayson the flux and content of BOD, TSS, pH, Turbidity, Color and E.Coli Bacteria. This study used a combinedmethod, namely ultraviolet (UV) light poses using a UV Water Sterilizer, the filtration process using the KUF3 ultrafiltration membrane and the phytoremediation method with kiambang plants. The results of this studyshowed the highest removal rate of BOD in the filtration process with UV 6 watts at 90 minutes of filtrationtime with an efficiency of 94.71%. The color removal rate in the filtration process with UV is 6 watts at 90minutes of filtration time with an efficiency of 70.92%. Turbidity removal rate in the filtration process withUV 6 watts at 90 minutes filtration time with an efficiency of 99.97%%. The TSS removal rate in the filtrationprocess with UV is 6 watts at 90 minutes of filtration time with an efficiency of 47.77%. The pH removal ratein the filtration process with UV is 6 watts at 90 minutes of filtration time with an efficiency of 24.79%. Theelimination rate of E.coli bacteria in the filtration process with UV is 6 watts at 90 minutes of filtration timewith 100% efficiency

Remediation and characterization of emerging and environmental pollutants from residential wastewater using a nature-based system.

The nature-based systems (NBS) are nature inspired, unflagging, efficient, and budget friendly ideas that evolved as ideal technologies for wastewater treatment. The present study deals with the purification of residential wastewater through the NBS, covering three seasons. The NBS embedded with the Canna lily effectively eliminated organic matter, nutrients, and heavy metals. Nearly 57.2-75.2% COD, 69.9-83.2% BOD, 73.4-90.6% TSS, 51.1-71.6% PO43--P, 66.3-84.8% NH4+-N, 52-61.5% NO3--N, and 68-70.6% NO2--N removal were achieved. Heavy metals like Al, Cr, Mn, Fe, Ni, Cu, Zn, Mo, and Pb were removed, with a 98.25% reduction in the total bacterial count. The pollutant removal's kinetics was calculated using first-order kinetics. The mass removal rate of BOD was high in monsoon (22.3g/m2/d), and COD was high in summer (36.4g/m2/d). Organic compound removal (65.2%), including emerging pollutants, was observed by gas chromatography-mass spectrometry (GCMS) analysis of water and Canna samples. Wavelength dispersive X-ray fluorescence spectrometer (WDXRF) studied the elements and oxides retention by media and accumulation by the plant. The CHN content of the Canna and its morphological study was checked using the carbon CHNS analyzer and scanning electron microscope-energy dispersive X-ray (SEM-EDX), respectively. The performance of the NBS was validated using variance, correlation, and principal component analysis (PCA). This study shows the NBS effects on the remediation of environmental and emerging contaminants from residential wastewater and further use it for horticultural activities, thereby achieving sustainable development goals.

Variasi Sinar Ultraviolet terhadap Fluks untuk Pengolahan Air Gambut Sistem Membran Ultrafiltrasi

Abstract-Peat water treatment still has many obstacles, one of the alternatives that can be used to overcome this obstacle is membrane technology and UV light variais. This study aims to determine the effect of UV rays on the flux and content of BOD, TSS, pH, Turbidity, Color and E.Coli Bacteria. This study used a combined method, namely ultraviolet (UV) light poses using a UV Water Sterilizer, the filtration process using the KUF-3 ultrafiltration membrane and the phytoremediation method with kiambang plants. The results of this study showed the highest removal rate of BOD in the filtration process with UV 6 watts at 90 minutes of filtration time with an efficiency of 94.71%. The color removal rate in the filtration process with UV is 6 watts at 90 minutes of filtration time with an efficiency of 70.92%. Turbidity removal rate in the filtration process with UV 6 watts at 90 minutes filtration time with an efficiency of 99.97%%. The TSS removal rate in the filtration process with UV is 6 watts at 90 minutes of filtration time with an efficiency of 47.77%. The pH removal rate in the filtration process with UV is 6 watts at 90 minutes of filtration time with an efficiency of 24.79%. The elimination rate of E.coli bacteria in the filtration process with UV is 6 watts at 90 minutes of filtration time with 100% efficiency

A sawdust Filter is Used to Remove Oil From The Kitchen Wastewater

Proteins, carbohydrates, detergents, oils, fats, and other dissolved and suspended compounds, as well as other concerns like clogged drainpipes, are the main contaminants in residential wastewater from the kitchen. The study’s purpose was to use sawdust as an agricultural waste which was used as absorbents in sink filters to treat the Gray water, many parameters were evaluated such as pH, electrical conductivity EC, total dissolved solid TDS, dissolved oxygen DO, biochemical oxygen demand BOD, and oil & grease O&G. from results were shown the removal rates of pH, EC, TDS, DO, BOD, and Oil & Grease are (6.2-7.41), (470- 1412 µs /cm), (357- 939 mg/L), (3.2- 4.2 mg/L), (40- 150) mg/L), and (190-1210 mg/L) respectively. however, the oil removal efficiency was high ranging from 94 to 98 %, implying that sawdust was successfully used to remove contaminants and O&G from Gray water by Kitchen filter.

Comparative analysis of biodegradation and characterization study on agal-assisted wastewater treatment in a bubble column photobioreactor

In this study, the process of phycoremediation is employed to assess the effect of nutrient degradation on the synthetic agricultural waste water by utilizing three different microalgal strains viz. Chlorella vulgaris, Scenedesmus obliquus and Desmococcous sp., in a bubble column photobioreactor (BC-PBRs). The experimental results showed higher biomass productivity in C. vulgaris than other two strains. NH4N removal rate was 96% in C. vulgaris, while S. obligus and Desmococcus sp. showed removal rate of 98% and 94% respectively. The removal rate of PO4-P in C. vulgaris, S. obligus and Desmococcus sp., was found to be 95%, 97% and 90% respectively. The removal rate of COD and BOD was also found to be high in C. vulgaris with 78% and 65% respectively followed by Desmoccous sp and S. obliquus. The experimental results also demonstrated the higher nutrient removal rate of C. vulgaris and S. obliquss when compared to Desmococcus sp. From SEM micrograph analysis the cell structure after wastewater treatment was found to be better in C. vulgaris than other two species. FTIR spectroscopy consortia showed the peaks of various functional groups in all the three algae which demonstrated the potential of lipid, carbohydrates and protein content which indirectly evaluate the biofuel potential of the three species.

Constructed Wetland for Sustainable and Low-Cost Wastewater Treatment: Review Article

There is a growing need for more sustainable wastewater treatment technologies to provide non-conventional water sources. Constructed Wetland systems (CW) are viewed as a low-cost treatment technology with proven treatment efficiency. CWS can treat a variety of contaminants using low energy and natural systems by altering various design parameters. There are two configuration types of constructed wetlands: vertical (VF) and horizontal flow CW (HF). Both configurations have been widely adopted in both large and pilot scale studies with proven records of reasonable wastewater treatment efficiency. The current article reviews the recent development of CW technology and highlights the main achievements and successful applications for wastewater treatment at various locations. The review has indicated that a considerable removal efficiency is attained while using engineered CW systems with variable treatment rates for various pollutants. The treatment efficiency is a function of various parameters including wastewater type, scale dimensions, applied plant and the retention time. The review compared the treatment efficiency for both VF and HF and has revealed that various removal rates of BOD, COD, TSS, TN, TP and NH₄ was attained using both configurations. Yet, the removal efficiency in the case of VF was slightly higher compared with the HF with an average treatment level of 77% and 68% was achieved in both systems, respectively. The review revealed that the CW is an effective and sustainable technology for wastewater treatment with the initial influent level, microbial biofilm, detention time, plant species and configuration among the most dominating parameters that are directly controlling the removal rates.

Enhancement Effects of Water Magnetization and/or Disinfection by Sodium Hypochlorite on Secondary Slaughterhouse Wastewater Effluent Quality and Disinfection By-Products

Wastewater disinfection is one of the most critical issues in protecting human health against exposure to waterborne pathogenies. Chlorine is among the most commonly used disinfectants in many wastewaters’ treatment plants. Nevertheless, disquiets regarding chlorine’s disinfection by-products (DBPs) have grown recently. One of the most effective ways to reduce DBPs generation is to reduce chlorine dosage by increasing disinfectant efficiency. Using magnetic field (MF) in wastewater treatment is one of the promising research topics with significant progression. This study aimed to evaluate the efficiency of using a magnetic field and/or sodium hypochlorite (NaClO) disinfection on secondary slaughterhouse wastewater effluent quality and by-products. Three groups of secondary slaughterhouse wastewater effluents were used: G1 was treated with NaClO only at 0, 2, 4, and 6 mg/L; G2 was treated with exposure to MF at 14,500 gausses, and G3 was pretreated with MF, then NaClO at the exact chlorine dosages and MF strength. The results showed an augmented effect when using a magnetic field as a pre-treatment step before NaClO treatment in the remediation of slaughterhouse wastewater over the use of any of them solely. The removal rate of COD and BOD increased by up to 26 and 20%, respectively, when pre-treatment with MF was employed as a mean percentage at all chlorine dosages, while TSS, TDS, and EC increased by 23.5 and 5.5%, respectively. Over and above, the removal rate for each TN and TP increased by 12 and 6.5% as a mean percentage at all chlorine dosages when using a combination of the two. In addition, pre-treatment by MF reduced the required concentration of NaClO from 6 to 4 mg/L, resulting in an 11% increase in the reduction rate of total coliform count, 8% increase in the reduction rate of fecal coliforms, and 10% increase in the reduction rate of E. coli and 5% in Salmonella via increasing the disinfection efficiency of NaClO. Finally, it decreased the concentration of Chloroform produced by more than 77.2% by using the higher concentration of NaClO (6 mg/L). The issue that approved the promising approach of using MF as a pre-treatment step in the treatment of slaughterhouse wastewater provides the advantage of using smaller dosages of disinfection, lowering the cost of the procedure process, and reducing the harmful concentration of DBPs.

The Study Based on Intelligent Big Data Technology for Water Resources Audit

The fast progress of science and technology has given immense ease to our lives, but it is also steadily destroying the environment in which we live. Environmental auditing was developed to safeguard the Earth we rely on for our existence, and subsequently, sustainable development was introduced to protect the planet we rely on for survival. Even though the quality of the natural environment is continuously increasing, it should not be taken for granted at this time. Therefore, in this paper, we study water resources auditing and sustainable development technologies based on AI-based big data. Specifically, we use an AI-based big data approach to construct the audit indicators of water resources and summarize the sustainable development technology of water resources. Finally, the proposed approach is used for case implementation. The experimental result shows that the BOD removal rate is about 95%, and the removal process is basically the same as removing COD.

Rotating Biological Contactor Wastewater Treatment using Geotextiles, Sugarcane Straw and Steel Cylinder for green areas irrigation

Due to the recent climatic and economic developments in the Middle East, the region has become on the verge of water poverty. It has become imperative to reconsider the policy of water spending and rationalization of consumption and to consider recycling all types of water, thus in this study, two identical stages of the RBCs system were used to treat wastewater after its primary treatment at Zenin wastewater treatment plant in Giza, Egypt. Different materials were used in the treatment process such as geotextile, (in two different forms), circular discs and discs in the form of gear, with 15 discs per RBC stage, a steel cylinder, in addition to a plastic bottle with holes with sugarcane straw inside. The rotation speeds were varied between 5, 8 and 10 RPM, with 40% submergence for the geotextile discs of the normal circular shape and for the rest of the materials a rotation speed of 5 RPM were used, where it was found later that it gave the best results. The hydraulic retention time ranged between one, two, and three up to seven days. It was found that the best results obtained at HRT of 3 days. Results showed that the removal rates of BOD, COD and TSS were almost 82%, 86.7% and 81.5% at 5RPM for normal circular discs shape respectively, while for gear shaped discs removal rates were almost 83.7%, 91% and 81.3% respectively. For sugarcane straw plastic bottle, BOD, COD and TSS removal rates were almost 64.86%, 69.49 and 68.18% at 5RPM respectively, noting that sugarcane straws removal rates were the lowest among the rest of materials. Removal rates were almost 86.9%, 94.4 and 82.14% for BOD, COD and TSS respectively at 5RPM for steel cylinder. Steel cylinder showed the highest removal rates among all other materials.

Equilibrium strategy based waste load allocation using simulated annealing optimization algorithm.

This study focuses on development of equilibrium strategy based on simulated annealing (SA) algorithm for balancing economic and environmental concerns in waste load allocation (WLA) problem. To resolve conflicts among various stakeholders, including Iran Department of Environment (DoE) as governmental authority and industrial and municipal dischargers, Stackelberg and Nash bargaining games have been applied in this WLA problem and the results have been compared. SA algorithm has been coupled to QUAL2Kw model to derive optimal WLA program and the environmental penalty tariff (EPT) in Nash bargaining and Stackelberg games. The proposed tools and methodologies were illustrated in a case study of multi-stakeholders WLA problem in Gheshlagh River, Sanandaj, Kordestan, Iran. The results indicate that lower BOD removal rates are allocated to the pollutant dischargers in the Stackelberg game compared to the Nash bargaining game. Furthermore, the EPT assigned by Iran DoE in Stackelberg and Nash bargaining games are 11.25 and 3.6 Rials/(gr/month), respectively. The estimated EPT in the Stackelberg game is close to the current tariff (10 Rials/(gr/month)) specified by Iran DoE on impermissible BOD discharges.

Biogas Production from Biodegradable Kitchen Waste Generated on University of Science and Technology Campus, Ghana

The alarming potential environmental problems (low investment, operation cost, technical requirements, air, water and land pollutions, improper waste management practices) linked to organic fraction of municipal solid waste which is mostly landfilled in many parts of the world have fostered the need for a biological treatment using anaerobic digestion. This is an attractive technology for waste stabilization with potential mass and volume reduction and significantly the generation of valuable by-products such as biogas and compost material.This research work focused on the biogas production from kitchen waste generated on the Kwame Nkrumah University of Science and Technology campus, Ghana. The experiment was carried out in a multi-stage anaerobic digestion system operated under mesophilic temperature. Various process parameters were measured including temperature, pH, conductivity, total solids, moisture content, BOD, percentage BOD removal, biogas production and biogas production rate. The waste degraded at a rate of 36.1±2.2% / day, with average biogas production of 8.9±3.15 litres per day. Maximum biogas production rate per kilogram of total solids (TS) was 4.5±1.6 L/kg TS of biogas per day. Key w ords: Biogas production; biodegradable waste; kitchen waste; methanogenic reactor; hydrolysis reactor; buffer system; KNUST; Ritter TG05/5 Drum-type Gas Meter; gas analyser, MSW DOI: 10.7176/JEES/10-7-04 Publication date: July 31 st 2020

Study on the treatment of livestock farm wastewater by falling water aeration constructed wetland

The livestock farms produce wastewater with high concentration of nitrogen and phosphorus through water rinsing, which is treated by building constructed wetlands. In order to improve the removal efficiency of nitrogen, the author set up a water tank, through falling water aeration to obtain a higher concentration of oxygen to promote nitrification and denitrification reaction. Experiments showed that the removal rates of BOD, NH3-N, TN and TP were 88%, 79.9%, 90.8% and 91.1% respectively. The results show that the experimental removal effect is good, and the results have practical significance for the treatment of aquaculture wastewater.

Study on the Effect of Porous Subsurface Flow Constructed Wetland on Sewage Purification

In this paper, a new porous subsurface flow constructed wetland was developed to remove BOD, TN and TP from sewage. A water inlet is arranged at the front of the wetland 0.25m and 0.45m from the ground. The design has the characteristics of simple structure and uniform water distribution, which makes the wetland easy to construct and improve the removal effect of pollutants. The results showed that the average removal rates of BOD, TN and TP in the wetland system were 85.63%, 80.29% and 89.07%, respectively, when the average temperature was 26°C and the hydraulic retention time was 1.3d. The removal effect is good, which can play a certain ecological and social benefits.

On Site Evaluation of a Tubular Microbial Fuel Cell Using an Anion Exchange Membrane for Sewage Water Treatment

This study evaluated the performance of a tubular microbial fuel cell (MFC) having a core of air-chamber wrapped with an anion exchange membrane in sewage wastewater treatment. Three MFCs were vertically assembled into one module and floated in sewage water channels before and after the treatment in primary sedimentation tank. The two MFC-modules showed almost similar electricity production in the range of 1.3–5.7 Wh·m-3-MFC, while the bottom MFCs (60–90 cm) showed a decrease in electricity than the top MFC (0–30 cm) and the middle MFC (30–60 cm). One of the MFC modules was then evaluated for the COD removal rate with two external resistances of 27 and 3, in a chemostat reactor (MFC:reactor = 1:5, v/v) under three hydraulic retention times (HRTs), 3 h, 6 h, and 12 h. The best COD removal rate of the MFC (COD-RTMFC), 54 ± 14% and BOD removal rate, 37 ± 17%, were observed with 3 of resistance and 12 h of HRT, resulting in 3.8 ± 2.0 A·m-3 of current recovery and 15 ± 7.5 % of Coulombic efficiency. Electricity generation efficiency (EGEMFC) was the best with 27 of resistance and 12 h of HRT and accounted for 0.18 ± 0.11 kWh·kg-COD-1 with 17 ± 6.4 % of COD-RTMFC and 0.65 ± 0.10 Wh·m-3 electricity production. Based on the calculation using the COD-RTMFC and EGEMFC, wastewater treatment can reduce electricity consumption by 55% via integration of the MFC treatment prior to the aeration.

Removal of organic matter in stormwater ponds: a plug-flow model generalisation from waste stabilisation ponds to shallow rivers

ABSTRACTThis study investigates the effect of flow conditions on the organic matter concentration, removal efficiency, and reaction kinetics in a stormwater pond in Fortaleza, Brazil. As a result of unauthorized sewage discharges, BOD and COD concentrations were similar to those of combined sewer systems. The concentrations remained roughly the same during the rainy season, which was attributed to sewage network overflow. Removal efficiencies ranged from 70–90%, similar to primary facultative ponds. Fitting different hydraulic models to the field data, it was possible to obtain BOD and COD removal rates that could be described as functions of the Reynolds number. The best fit was achieved considering the plug-flow assumption, and a general BOD model including data reported in the literature for waste stabilisation ponds, stormwater ponds and shallow rivers was derived. Lastly, simulations with this general model were performed to assess the impact of remediation measures on the studied pond.

Membrane Bioreactor Technology for Wastewater Reclamation

Responding to the water shortage in Egypt, the use of submerged membrane bioreactor (SMBR) for wastewater reclamation has been studied. The impact of hydraulic retention time (HRT), as the most influential operational parameter has been investigated. A bench-scale module was operated at three HRT: 6, 10 &15hs. The results demonstrated that total COD and BOD removal rates were not affected by changing the HRT or by variations in raw wastewater strength. Average residual COD values in the membrane permeate ranged from 14 to 20.3 mg O2 L-1. Corresponding residual BOD was below 3.0 mgL-1. Nitrification capacity of the SMBR was high. HRT was found to be a key parameter for fouling. Decreasing the HRT enhances membrane fouling. At HRT of 6h, fouling happened after 6 days. Corresponding values for HRTs 10 and 15 were 13 day and more than 42 days, respectively. Total coliform bacteria counts in most of the MBR permeate samples were below the detection limit of 10 CFU/100 mL. All protozoan parasitic stages detected in raw wastewater were removed by the SMBR. At HRT of 15h, both human rotaviruses and adenoviruses genome copies were reduced by 2 to 3 log10. This ratio was reduced by decreasing the HRT.

Role of UASBs in River Water Quality Conservation in India

Appropriate low-cost treatment technologies are a prerequisite for sound management of natural water resources against pollution in developing countries. Among the existing technologies available, UASB is found to be economically viable for India when considering all factors including operation and maintenance cost and treatment efficiency. However, this technology suffers setbacks in meeting the effluent guidelines prescribed by the government of India. Post treatment is supplemental to this process to meet the effluent standards in terms of removal of organic matter, suspended solids, pathogens and nutrients. Recent stringent effluent guidelines notified by the Ministry of Environment, Forests and Climate Change, Government of India has further reduced the limits of BOD by 3 times, COD and TSS by 5 times, NH4-N and total Nitrogen by 10 times as compared to the previous guidelines. Fecal Coliforms has been specified as <100MPN/100mL. In this paper, the present scenario of UASB based STPs and their role in river conservation is reviewed against the backdrop of stringent effluent guidelines. The minimum removal rates of BOD, COD and TSS in these plants are around 42 – 44% and the average removal rates are reported to be 66%, 61% and 65% respectively. The enhanced removal of BOD (97%), COD (98%) and TSS has been reported in STPs in conjunction with post treatment facilities such as facultative aerated lagoons, aeration tanks and polishing ponds.

Comparison of Performance of an Intermittent Aeration Membrane Bioreactor and a Conventional Activated–sludge System in the Treatment of Palm Oil Mill Effluent

The main objective was to compare the performances and the removal efficiencies of two biological treatment systems, a submerged membrane bioreactor (SMBR) and a simultaneous activated sludge (AS), for treating Palm Oil Mill Effluent (POME). Two lab scale units of SMBR and AS with a working volume of 24 L were operated under favorable biological conditions and minimized membrane fouling intensity. To achieve both carbonaceous and nitrogen removal, the cyclic air intermittent and dissolved oxygen control were performed into SMBR and AS with the influent flow rate about 16 L/d respectively. In terms of organic removal and membrane performance, the SMBR showed good removal efficiency to treat high strength wastewater with organic loading variation of POME. The average removal rates of TCOD, BOD, Turbidity, Color, Oil and Grease, NH3–N, TKN were 69±2, 76±2, 100±1, 37±21, 92±6, 67±4 and 75±10% respectively. Results pointed out the benefit of membranes retained totally the active compositions of biomass in each stage of development. The AS showed the limitation of sedimentation phase for sludge and oil separation. The characteristics of sludge in SMBR showed healthy floc formations and good settling after 240 h. The concentrations of COD and BOD in permeate were around 870±53 and 37±13 mg/L.

Evaluation of the process performance of a down-flow hanging sponge reactor for direct treatment of domestic wastewater in Bangkok, Thailand

ABSTRACTThis study assesses the performance of an aerobic trickling filter, down-flow hanging sponge (DHS) reactor, as a decentralized domestic wastewater treatment technology. Also, the characteristic eukaryotic community structure in DHS reactor was investigated. Long-term operation of a DHS reactor for direct treatment of domestic wastewater (COD = 150–170 mg/L and BOD = 60–90 mg/L) was performed under the average ambient temperature ranged from 28°C to 31°C in Bangkok, Thailand. Throughout the evaluation period of 550 days, the DHS reactor at a hydraulic retention time of 3 h showed better performance than the existing oxidation ditch process in the removal of organic carbon (COD removal rate = 80–83% and BOD removal rate = 91%), nitrogen compounds (total nitrogen removal rate = 45–51% and NH4+–N removal rate = 95–98%), and low excess sludge production (0.04 gTS/gCOD removed). The clone library based on the 18S ribosomal ribonucleic acid gene sequence revealed that phylogenetic diversity of 18S rRNA gene in the DHS reactor was higher than that of the present oxidation ditch process. Furthermore, the DHS reactor also demonstrated sufficient COD and NH4+–N removal efficiency under flow rate fluctuation conditions that simulates a small-scale treatment facility. The results show that a DHS reactor could be applied as a decentralized domestic wastewater treatment technology in tropical regions such as Bangkok, Thailand.