Decentralized Wastewater Treatment Systems Research Articles

Phosphate Recovery from Urine-Equivalent Solutions for Fertilizer Production for Plant Growth.

This study presents a proof of concept for the recovery of phosphate from aqueous solutions with high phosphorus (PO4-P) initial contents to simulate the concentration of streams from decentralized wastewater systems. Solutions with ∼500 ppm phosphorus enable phosphate adsorption and recovery, in contrast to the highly diluted inlet streams (<10 ppm) from centralized wastewater treatment plants. In this work, Mg-Fe layered double hydroxide is used as a phosphate adsorbent, demonstrating its separation from aqueous streams, recovery, and use as a fertilizer following the principles of circular economy. We demonstrate that the mechanism of phosphate adsorption in this material is by a combination of surface complexation and electrostatic attraction. After the loss of crystallinity in the presence of water in the first cycle and its associated decrease in adsorption capacity, the Mg-Fe layered double hydroxide (LDH) is stable after consecutive adsorption/desorption cycles, where desorption solutions were reused to substantially increase the final phosphate concentration demonstrating the recyclability of the material in a semicontinuous process. Phosphate recovered in this way was used to complement phosphate-deficient plant growth medium, demonstrating its efficacy as a fertilizer and thereby promoting a circular and sustainable economy.

Lesson Learned from Yangon to Mandalay on Wastewater Treatment Systems

This paper presents a comparative analysis of wastewater management practices in Myanmar’s major cities, Yangon and Mandalay, with a focus on drawing valuable lessons from Yangon’s experiences and proposing recommendations for the improvement of Mandalay’s domestic wastewater management, drawing insights from a SWOT analysis. Both cities are facing challenges due to rapid urbanization, leading to untreated discharge into the environment. The study identifies common challenges in both Yangon and Mandalay, such as limited treatment capacity, environmental concerns, and funding gaps. The decentralized-centralized strategy is a successful approach for Yangon even though the capacity is not high. Results showed that 17.5% of Decentralized Wastewater Treatment Systems (DEWATS) users were highly satisfied and 45% were somewhat satisfied. Yangon’s experience with centralized systems showed that it took several years to cover the entire city for treatment, resulting in issues to cover revenue expenditures. If Mandalay adopts a similar, it will likely encounter the same issues. A recommended approach would be to implement an integrated system with DEWATS, which offers a better solution. The recommendations for sustainable wastewater management in Mandalay include active stakeholders’ involvement in decision-making, promoting community participation, and providing training. Transparency and shared responsibility are crucial for success. Addressing membrane fouling, sludge disposal, and implementing monthly fees are essential for sustainable implementation. An integrated approach along with environmental and social impact assessments are necessary to develop a cost-effective and efficient wastewater treatment system while safeguarding public health and the environment. These insights offer broader implications, guiding developing countries towards more effective and environmentally responsible wastewater management practices.

Using walnut shells as low-cost adsorbent materials in an anaerobic filter medium of a De-centralized wastewater treatment system (DEWATS)

The flow of unprocessed sewage through municipal sewers is a great source of water contamination. This study aims to observe the pollutants removal efficiencies of walnut shells as an efficient low-cost adsorbent material compared to gravel materials as an anaerobic filter medium. Two models of the De-Centralized Wastewater Treatment System (DEWATS) were constructed. The wastewater flowing from toilets and handwashing places was connected to anaerobic filters filled with walnut shells and gravel. The efficiency of both filter media in the removal of biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), total dissolved solids (TDS), nitrate (NO3), and phosphate (PO43), pH and temperature were observed at the influent of the settler tank and then at the effluent of the collection tank (CT). Temperature and pH were within the acceptable limit of wastewater discharge. The results also indicated that the walnut shells filter media was more efficient at removing organic pollutants (TSS 94%, BOD5 88%, COD 85%, Nitrate 57%, phosphate 46%, and TDS 29%) than the gravel (TSS 81%, BOD5 82%, COD 84%, Nitrate 35%, phosphate 38%, and TDS 26%) at the successive stages. The average removal efficiency of the walnut shell was 88% while in the gravel case, it was 83%. The removal efficiency of walnut shell filters was extensively better over the complete experiment compared to gravel filters for the removal of pollutants, representing the high sorption capability of the walnut shell material. The results of this study show that the walnut shells may be a very useful substitute for other conventional fillers for anaerobic treatment in the anaerobic filter of DEWATS.

Linking Urban Water Management, Wastewater Recycling, and Environmental Education: A Case Study on Engaging Youth in Sustainable Water Resource Management in a Public School in Casablanca City, Morocco

The management of water resources is crucial for sustainable development, necessitating innovative solutions to address the increasing demand for safe water. Alternative approaches must be adopted to effectively engage young generations in understanding the importance of water resources. This chapter reports on an experiment that aimed to promote sustainability education by linking wastewater treatment and reuse with an educational garden. In particular, an undertaking was executed to establish a decentralized wastewater treatment system wherein purified water was employed for the purpose of irrigation. The study’s primary focus is on the association between urban water management, wastewater recycling, and environmental education. The study has two distinct components. The first segment discusses three examples of projects that have employed urban wastewater treatment and reuse to generate environmental education materials using various approaches. The second component features a case study of a public high school in Casablanca, where students participated in a questionnaire and participatory workshops to design an educational garden. The study’s outcomes include a proposed educational garden design that will be presented to the relevant authorities and project partners.

A survey on constructed wetland publications in the past three decades.

Decentralised wastewater treatment systems, such as constructed wetlands, are becoming increasingly popular these days because they are more economical and cost-effective than conventional plants. The primary objective of this review paper is to determine the number of studies that have been conducted on constructed wetlands, specifically 'free water surface flow constructed wetlands', 'horizontal subsurface flow constructed wetlands', 'vertical subsurface flow constructed wetlands', and 'hybrid constructed wetlands'. In addition, the paper examines the status of research publications on constructed wetlands by country, author, and journal. Based on the review, it has been found that although constructed wetland technology is economical and cost-effective, it is still not among the top 10 effluent treatment methods. Compared to other constructed wetland systems, 'hybrid constructed wetlands' have received minimal attention. Based on the search results, 4639 documents published between 1989 and 2021 have been extracted from the online edition of SCI-EXPANDED, Web of Science. The documents associated with constructed wetlands are divided into eight main document types. Articles and proceedings papers are the most common document type, accounting for 93% of all publications, followed by reviews (4%), meeting abstracts (1.3%), corrections (0.56%), editorial materials (0.38%), news items (0.2%), letters (0.04%), and book reviews (0.02%).

Enhancement of a Decentralized Wastewater Treatment System by Applying a Bio-tower - A Project for Improving our Environmental Footprint

To investigate if decentralized wastewater treatment systems impact on the environment performance can be improved, a Field Bio-tower Tank Septic system was designed, installed on an existing 1,500-gal (5678 l) decentralized wastewater treatment system. The system was started up during a 14-day start-up phase, followed by a 130-day test phase. The system was operated at an average hydraulic retention time of 16.7 days based on a 90 gal (204.4 l) daily influent wastewater flow.&#x0D; The systems recirculation flow for the bio-tower was 22.6 l/min (6 gal/min) for the start-up phase and 40.0 l/min (10.6 gal/min) for the test period with a corresponding recirculation of the entire septic tank from 5.7 to 10.1 times a day respectively.&#x0D; During the testing period a daily average temperature of 19.3°C (66.7°F) and an average rainfall of 5 l/m² was observed. The FBST system operated at an average influent pH level and temperature of 8.6 and 22.0°C. The average effluent pH and temperature was 8.5 of 20.9°C.&#x0D; The installed system reduced on average the influent TS from 79151 mg/l to 43021 mg/l and showed an average reduction of the TDS from 36424 mg/l to 21965 mf/l. The TSS and VSS was reduced on average from 94.1 mg/l to 69.9 mg/l and 89.0 mg/l to 64.9 mg/l.&#x0D; NH3-N content was reduced from 57.5 mg/l in the influent to 53.4 mg/l in the effluent. The average BOD and COD was reduced from the average influent value of 88.2 mg/l and 318.2 mg/l to 66.8 mg/l and 256.2 mg/l respectively. However, at the end of the 130-day test period BOD and COD values were the lowest at 15.5 mg/l and 56.0 mg/l respectively, indicating bacteria cultures are well established and the system operation of the FBTS system is mostly constant.&#x0D; This research showed that the FBST system can improve operations of a DWWTS system significantly reducing the effluent load over 10 times compared to the influent load of the system.

Water treatment and reclamation by implementing electrochemical systems with constructed wetlands

Seasonal or permanent water scarcity in off-grid communities can be alleviated by recycling water in decentralized wastewater treatment systems. Nature-based solutions, such as constructed wetlands (CWs), have become popular solutions for sanitation in remote locations. Although typical CWs can efficiently remove solids and organics to meet water reuse standards, polishing remains necessary for other parameters, such as pathogens, nutrients, and recalcitrant pollutants. Different CW designs and CWs coupled with electrochemical technologies have been proposed to improve treatment efficiency. Electrochemical systems (ECs) have been either implemented within the CW bed (ECin-CW) or as a stage in a sequential treatment (CW + EC). A large body of literature has focused on ECin-CW, and multiple scaled-up systems have recently been successfully implemented, primarily to remove recalcitrant organics. Conversely, only a few reports have explored the opportunity to polish CW effluents in a downstream electrochemical module for the electro-oxidation of micropollutants or electro-disinfection of pathogens to meet more stringent water reuse standards. This paper aims to critically review the opportunities, challenges, and future research directions of the different couplings of CW with EC as a decentralized technology for water treatment and recovery.

Stakeholder evaluation of sustainability in a community-led wastewater treatment facility in Jakarta, Indonesia

Indonesia’s severely flawed centralized wastewater treatment system has caused economic and socioeconomic losses for decades. An alternative system has been called for under a national-scale program called Sanimas or Community-Led Total Sanitation (CLTS), which would cater to 50–100 urban families in every intervention with urgent needs through the operation of a decentralized wastewater treatment system. Through household participation, this program features a co-production system wherein the national-level government initiates and provides initial funding until construction, after which a community-appointed social organization takes over. This study implemented a multicriteria approach to assess sustainability in Sanimas communities in Jakarta: 67 in Menteng (Central Jakarta) and At-Taubah in Koja (North Jakarta). Connected households and facility-operating committees were questioned separately for their opinions on six aspects that explained the survival of the establishment of a facility: technical, management, community participation, financial, institutional, and environmental. We found that although the facility’s excellence and overall satisfaction with the program were unanimous, Koja and Menteng showed substantial differences in management, institutional, and financial aspects, largely due to administrative policies, payment contributions, and committee commitments. Interviews revealed that periodic testing of the treated water was neglected, against the provided guidance. In conclusion, communities have come to focus more on the technical functionalities of the installation, regardless of the state of the management, which is indisputable not only in Menteng but also in Koja. Finally, we argue that although decentralized systems can substitute centralized systems, they still require stringent and adequate support in quality control and troubleshooting.

Life Cycle Assessment of Black and Greywater Treatment Solutions for Remote and Sensitive Areas

Sensitive and remote areas have come under pressure from growing populations and tourism, often resulting in improper wastewater management. Efficiency, durability, the use of renewable construction materials, and the minimization of environmental impacts must be conformed to a sustainable paradigm. A life cycle assessment (LCA) was applied to compare three different decentralized wastewater treatment systems built at tourist facilities: a source separation sanitation system with a hybrid constructed wetland (S1), a sequential batch reactor (SBR) with a hybrid constructed wetland (S2), and a solar-powered composting toilet (S3). Benchmarking showed that S1 was preferred over S2. The differences were up to a factor of two, except for eutrophication, which was significantly higher for S2 (10×). S3 had the lowest environmental impact, but S3 treated only the blackwater fraction, i.e., urine, faeces, and toilet paper, and excluded greywater treatment, i.e., handwashing and/or kitchen wastewater. The scenario analysis showed that the environmental performance could be improved by installing solar panels, but this would increase the impact on the abiotic depletion of elements by 83% for S2. The LCA indicated the advantages, disadvantages, flexibility, and potential for design improvements to meet the environmental sustainability and market demands for system diversity.

The potential of decentralised wastewater treatment in urban and rural sanitation in South Africa: lessons learnt from a demonstration-scale DEWATS within the eThekwini Municipality

The design principles of decentralised wastewater treatment systems (DEWATS) make them a practical sanitation option for municipalities to adopt in fast-growing cities in South Africa. Since 2014, a demonstration-scale DEWATS with a modular design consisting of a settler, anaerobic baffled reactor (ABR), anaerobic filter (AF), vertical down-flow constructed wetland (VFCW) and horizontal flow constructed wetland (HFCW) has been in operation in eThekwini. A performance evaluation after the long-term operation was undertaken in 2019 by comparing the final effluent with national regulatory requirements. Despite limitations in characterising the raw wastewater, a comparison of the settler and final effluent quality indicated high (≥ 85%) removal efficiencies of total chemical oxygen demand (CODt), ammonium-N (NH4-N) and orthophosphate-P (PO4-P), 75% removal of total suspended solids (TSS) and 83.3% log10 removal of Escherichia coli. Lack of exogenous and endogenous carbon and high dissolved oxygen (DO) concentrations (&gt; 0.5 mg‧L−1) inhibited denitrification in the HFCW, resulting in 12.5% of the effluent samples achieving compliance for nitrate-N (NO3-N). Moreover, mixed aggregate media and low residence times in the HFCW may have also contributed to poor NO3-N removal. During the COVID-19 lockdown, an unexpected shutdown and subsequent resumption of flow to the DEWATS indicated a 16-week recovery time based on achieving full nitrification in the HFCW. Although design modifications are necessary for the HFCW, the installation of urine diversion flushing toilets at the household will reduce the nutrient loading to the DEWATS and potentially achieve fully compliant effluent. Alternatively, the application of two-stage vertical flow constructed wetlands to improve denitrification should also be explored in the South African context. With an improved design, DEWATS has the potential to fill the gap in both urban and rural sanitation in South Africa, where waterborne sanitation is still desired but connections to conventional wastewater treatment works (WWTWs) are not possible.

Feasibility Study of Anaerobic Baffled Reactor Coupled with Anaerobic Filter Followed by Membrane Filtration for Wastewater Treatment.

The performance of a Decentralized Wastewater Treatment System (DWTS) comprising an Anaerobic Baffled Reactor (ABR) and an Anaerobic Filter (AF) and Membrane Filtration (MF) module was studied for domestic wastewater treatment. The efficiency of the system was evaluated by running ABR at four different HRTs (14, 12, 10, and 8 h) resulting in COD removal efficiencies of 74, 72, 69, and 65%, respectively. The performance of AF using four different filtration media, i.e., PVC pipe (25 mm), PVC pipe (20 mm), PVC pipe (15 mm), and Kaldnes K3, was determined at optimized HRT (12 h). Among all the filtration media tested, the highest performance efficiency of the system was found with the PVC pipe (20 mm), which showed COD, TP, and TKN removal of 79, 32, and 63%, respectively. The efficacy of the system was proven via significant COD and turbidity removal of 94.6 and 87.2%, respectively, by the combined system.

Environmental Performance Assessment of Decentralized Wastewater Treatment System in Jordan Using Life Cycle Analysis

This research utilized Life Cycle Analysis (LCA) within SimaPro 9 software to evaluate the potential environmental burdens: global warming, eutrophication, acidification, and ozone layer depletion of three Decentralized Wastewater Treatment Systems (DWWTS) in Jordan over the entire period of its life cycle of construction and operation phases. The obtained laboratory test results showed that Feynan (M1) has the best performance regarding treatment efficiency, where the treated effluent parameters TN, TP, COD, and BOD were the lowest compared to Jerash (M2) and SMART (M3). On the other hand, the overall outcomes show that M3 and M2 are approximately 25% and 50%, respectively, compared to M1 contribution in burdens. Construction of wetlands has the highest contribution to most of the environmental burdens of the three plants. It was found that cement production is the key factor causing environmental burdens resulting from the construction of these plants. Whereas concrete blocks, reinforcing steel, and PVC pipes have less contribution. LCA is approved as a supportive investigation of the environmental burdens of such plants that guide decision-makers in developing new strategies to achieve sustainability.

Study of Treating Wastewater with a Laboratory Benchtop Septic Systems

Efficient wastewater treatment technologies are needed to curb water scarcities and prevent the spread of diseases and contamination of water sheds. Decentralized wastewater treatment systems or respectively septic systems are easy to afford and handle – especially in rural areas. In this research a developed 19.9 l (5 gal.) laboratory septic system containing 15 l (3.96 gal.) of liquid was operated at a temperature of 18°C (64.4°F) with wastewater collected from a primary clarifier of a local wastewater treatment plant. The laboratory study included a hydraulic retention time of 30-, 10- and 5-day with and without addition of bacteria from an anaerobic sludge blanket reactor and commercially available bacteria for enhancement of septic systems.&#x0D; Operating the laboratory septic system at a 10-day HRT showed the best performance for all system operations with and without enhancement bacteria in comparison n to 30- and 5-day HRT.&#x0D; The developed laboratory septic system proved to be a valuable way to investigate septic systems performance on a laboratory scale.

Investigation of mechanisms of an upflow-downflow siliceous sand filtration system for surfactants bathroom grey water treatment.

Sustainable decentralized wastewater treatment systems (DEWATS) at the local level are considered as a smart alternative for small communities particularly in arid areas. The present study examines the mechanisms of an upflow-downflow Siliceous Sand (SS) filtration system involved in surfactants bathroom grey water treatment. In order to get a better understanding of the mechanisms involved in surfactants removal, particle size distribution and Fourier transform infrared (FTIR) spectroscopy of the SS particles were performed. Optimization of the upflow-downflow SS filtration system, operated following operational conditions of hydraulic load rate (HLR) and SS amounts, results indicates an average removal efficiency (ARE) of 93.7% reached with respect to surfactants removal. Results showed also that the resulting silicate materials react with surfactants in a cooperative assembly process involving the interaction of SS particles with surfactants aggregates. Brunauer, Emmett and Teller (BET) surface area, pore volume (Vp), and pore size were found to be significantly reduced post-filtration with respectively 3.39%, 24.31%, and 21.86% reduction. From FTIR spectroscopy analysis of the Sulfonates, Silanol and Silane functional groups appear to be involved in mesoporous constructed micelle organization for surfactants removal. Such geo-materials could be green and sustainable for various applications in water and environmental engineering.

Renewable Electricity and Hydrogen Production via Decentralized Wastewater Treatment Systems

Urban wastewater could be converted into energy if microbial electrochemical technologies (METs) like microbial dual-chamber electrolysis cells (MDEC) or microbial fuel cells (MFC) are applied as a treatment method. Mathematical modelling of MFC and MDEC for wastewater treatment and energy recovery has been developed in this study. The Radaue method has been used to solve ordinary differential equations (ODEs), and the model outputs were successfully validated with previous experimental and modelling data. A case study in Montreal, Canada, has also been considered for testing the application of METs on an urban scale with a total daily wastewater flow of 75,000 L/day. The results show that from 1 m3 of wastewater, MDEC and MFC can generate 0.077 kg H2 and 0.033 kWh, respectively.

Decentralized wastewater system practices in developing countries: A systematic review

Decentralized wastewater systems (DWWSs) are an alternative to the ever-expanding sanitation problems in developing countries. This systematic review aims to identify the decentralized wastewater management system practices in developing countries. The PRISMA methodology and the archival research methods were used to identify papers published in the last 20 years through Scopus and Google Scholar. The results showed that about 45% of the studies conducted performance analyses of different types of decentralized wastewater systems, indicating a relatively average rate of practice and implementation of decentralization in various developing countries, even though there are constraints that hinder the adoption of the systems.

Design of Photocatalytic Materials for Hydrogen Peroxide Production

Hydrogen peroxide (H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt;) has been widely utilized as an oxidant in diverse industries such as pulp and paper bleaching, chemical synthesis, wastewater treatment, fuel, etc., which has been supplied by anthraquinone process. However, this method needs explosive hydrogen and oxygen gases, high temperature/pressure, massive organic solvent, and noble metal catalysts. The photocatalytic production of H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; is cost-effective and environmentally-benign process since only oxygen, water, and light are required. In this review, titanium dioxide (TiO&lt;sub&gt;2&lt;/sub&gt;) and graphitic carbon nitride (g-C&lt;sub&gt;3&lt;/sub&gt;N&lt;sub&gt;4&lt;/sub&gt;) as a representative UVand visible-light-active photocatalyst, respectively, are discussed with overviewing various structure and surface modification techniques in order to improve the photocatalytic H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; production. Furthermore, recent studies based on the photoelectrochemical(PEC) H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; production are briefly mentioned to understand how the separation of redox-reaction is important to obtain a high apparent quantum yield. Finally, the review proposes the outlook and perspective on the photocatalytic H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; production to build-up decentralized wastewater treatment system.

EFEKTIVITAS INSTALASI PENGOLAHAN AIR LIMBAH (IPAL) RUMAH SAKIT UMUM ROEMANI MUHAMMADIYAH SEMARANG

The waste management at the Roemani Muhammadiyah General Hospital Semarang uses anaerobic technology with the DEWATS (Decentralized Wastewater Treatment System) system whose outlet test results for COD, BOD and Coliform bacteria are still above the specified quality standards. This study aimed to evaluate aspects of fluid waste management and management, whether it follows existing liquid waste management regulations, and determine the effectiveness of wastewater treatment at Roemani Muhammadiyah General Hospital Semarang. This type of research was a mixed-method with a concurrent triangulation strategy; the research was supported by quantitative data carried out descriptively. The results of the management aspect of the Roemani Muhammadiyah Hospital Semarang is following the regulation of the Minister of Health No. 7 of 2019 concerning Hospital Environmental Health. While liquid waste management is still not following existing laws. Roemani Muhammadiyah Hospital Semarang has been efficient in reducing TSS, BOD, COD and NH3 while for the parameters of Colifom bacteria, WWTP Roemani Muhammadiyah Hospital Semarang is still not efficient in reducing the parameters of Colifom bacteria. Therefore, it is hoped that the hospital will pay more attention to waste water quality, especially that produced by each health service agency.

Electro-oxidation treatment of sewage water using mixed metal oxide anodes for microbial decontamination

Electrochemical technologies provide an alluring decentralized wastewater treatment system to remove microbial load from contaminated water. The mixed metal oxide (MMO) anodes used for this electrooxidation (EO) technology are stable due to the presence of titanium, ruthenium, iridium, and platinum oxides. This EO technology works by passing current in the presence of minimum electrolyte concentration, sufficient to kill the bacteria present in sewage and simulated water. This technology can be used in sewage pre-treatment plants so that the microbes present in sewage water will not come into the environment, thus, preventing the spread of an epidemic. The lab-scale electrochemical disinfection experiments were performed under batch conditions to see the inactivation efficacy of the EO system with eight different bacteria (Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Salmonella enterica, Acinetobacter calcoacetius, Serratia marcescens, Listeria sp., Enterococcus faecalis). The results showed that at an optimized condition of current density (2.38 mA/cm2), NaCl concentration (1 g/300 mL), treatment time (2 min), 100% inactivation of all the eight bacteria in simulated water was achieved. Under the same optimized conditions, 100% inactivation was achieved with actual sewage water with a treatment time of 8 min. Further, potassium ion leakage and vital staining tests were performed to confirm the complete inactivation of bacteria. The electrodes used in this study were durable even after 80 cycles, as demonstrated through FE-SEM/EDS, XRD, and Raman spectra. Thus, this developed EO system with inexpensive MMO electrodes would open up new channels in treating waterborne epidemics, especially in healthcare facilities.

Effects of effluent recycle on treatment performance in a vertical flow constructed wetland

As part of the effort to improve design and operation schemes of decentralized wastewater systems, the Danish EPA funded a research initiative, to re-evaluate the Danish guidelines for VFCW with an aim to improve its design. Therefore, the aim of this study is to assess the effect of recycling water from the effluent of the VFCW to the pump chamber at several recycle ratios and to compare the effects of recycle to the sedimentation tank in lieu of the pump chamber. In addition, water quality changes within the depth of the bed were assessed in order to make recommendations on an appropriate depth for effective treatment. The results showed overall the system performed very well regardless of the recycle ratio with removal rates of TSS, TOC, BOD5, NH4-N and TP around 99% and thus easily exceeding the national discharge requirements. Despite that, the better results for TN effluent concentrations, below 45 mg/L, were achieved for recycling water from the effluent of VFCW to pump chamber at recirculation rates of 50% to 100%. The changes in concentrations of measured parameters with depth suggest that almost all transformations occurred with the top 20 cm of the 1.0 m thick effective bed depth, thus, the results show that the VFCW dimensions given in the Danish guidelines may be overdesigned from the perspective of meeting current discharge limits.