Down-flow Hanging Sponge Research Articles

Pre-treatment and post-treatment systems for enhancing natural rubber industrial wastewater treatment

A pre-treatment system, circulation tank was proposed for residual rubber removal from natural rubber (NR) wastewater. The main treatment system consisted of an anaerobic baffled reactor (ABR) and a down-flow hanging sponge (DHS) reactor. An additional DHS reactor (post-DHS) was installed after ABR-DHS system as a post-treatment for nitrogen removal. In the pre-treatment circulation tank, the contact numbers with seed rubber was considered a key factor in the coagulation of residual rubber. Furthermore, the aerobic conditions enhanced the NR wastewater biodegradability in both ABR and DHS reactors. The post-DHS achieved single-stage nitrification-denitrification, using sodium acetate solution as a carbon source, under non-aeration conditions. Finally, the water quality of the final effluent met the quality standards of NR producing countries. In the ABR, hydrogen-utilizing methane-producing archaea, as well as syntrophic VFAs degrading bacteria, were the main bacteria contributing to the organic matter degradation in NR wastewater. On the other hand, most of the residual rubber in the NR wastewater was degraded in the DHS reactor by aerobic rubber-degrading bacteria (Gordonia).

Anti-bacterial Effects of MnO2 on the Enrichment of Manganese-oxidizing Bacteria in Downflow Hanging Sponge Reactors.

We focused on the use of abiotic MnO2 to develop reactors for enriching manganese-oxidizing bacteria (MnOB), which may then be used to treat harmful heavy metal-containing wastewater and in the recovery of useful minor metals. Downflow hanging sponge (DHS) reactors were used under aerobic and open conditions to investigate the potential for MnOB enrichment. The results of an experiment that required a continuous supply of organic feed solution containing Mn(II) demonstrated that MnOB enrichment and Mn(II) removal were unsuccessful in the DHS reactor when plain sponge cubes were used. However, MnOB enrichment was successful within a very short operational period when sponge cubes initially containing abiotic MnO2 were installed. The results of a microbial community analysis and MnOB isolation revealed that MnOB belonging to Comamonadaceae or Pseudomonas played a major role in Mn(II) oxidation. Successful MnOB enrichment was attributed to several unidentified species of Chitinophagaceae and Gemmataceae, which were estimated to be intolerant of MnO2, being unable to grow on sponge cubes containing MnO2. The present results show that MnO2 exerted anti-bacterial effects and inhibited the growth of certain non-MnOB groups that were intolerant of MnO2, thereby enabling enriched MnOB to competitively consume more substrate than MnO2-intolerant bacteria.

Multiple organic substrates support Mn(II) removal with enrichment of Mn(II)-oxidizing bacteria

Three different organic substrates, K-medium, sterilized activated sludge (SAS), and methanol, were examined for utility as substrates for enriching manganese-oxidizing bacteria (MnOB) in an open bioreactor. The differences in Mn(II) oxidation performance between the substrates were investigated using three down-flow hanging sponge (DHS) reactors continuously treating artificial Mn(II)-containing water over 131 days. The results revealed that all three substrates were useful for enriching MnOB. Surprisingly, we observed only slight differences in Mn(II) removal between the substrates. The highest Mn(II) removal rate for the SAS-supplied reactor was 0.41 kg Mn⋅m−3⋅d−1, which was greater than that of K-medium, although the SAS performance was unstable. In contrast, the methanol-supplied reactor had more stable performance and the highest Mn(II) removal rate. We conclude that multiple genera of Comamonas, Pseudomonas, Mycobacterium, Nocardia and Hyphomicrobium play a role in Mn(II) oxidation and that their relative predominance was dependent on the substrate. Moreover, the initial inclusion of abiotic-MnO2 in the reactors promoted early MnOB enrichment.

Metal removal, partitioning and phase distributions in the wastewater and sludge: Performance evaluation of conventional, upflow anaerobic sludge blanket and downflow hanging sponge treatment systems

Metals pollution pose a serious problem to environmental and human health, if not effectively removed from wastewater using different state-of-the-art treatment technologies. This study investigated the phase distribution of copper (Cu), lead (Pb), zinc (Zn), chromium (Cr) and cadmium (Cd) in wastewater and sludge samples collected from domestic wastewater treatment plant (DWTP), upflow anaerobic sludge blanket (UASB), and downflow hanging sponge (DHS) reactor systems. Sludge from the UASB and DHS contained predominantly reducible fractions of Zn and Cd and oxidizable fractions of Cu, Cr, and Pb. A characteristic bioavailability sequence was Zn > Cu > Cr > Pb > Cd, with significant differences in dissolved fractions among operational modes. Metal concentrations (solid fractions) were substantially high in the DWTP water, and in UASB and DHS systems (dissolved fractions). Pb, Cr and Cd were strongly associated with the solid phase in the final polishing units (FPU) of the DHS system after treatment, indicating binding and removal (∼75–90%) of metals with particulates. MINTEQA2 calculations indicated that Zn was the most readily available metal in free form in all of the systems, with a general order of ZnDWTP > ZnUASB-DHS > PbDWTP > CdUASB-DHS > PbUASB-DHS > CuDWTP > CuUASB-DHS. Overall, metals in the UASB-DHS showed higher binding potential with coexisting ions, mainly anions like carbonates, hydroxyls, and bicarbonates. Non-anion fractions were more prevalent in DWTP samples. Sorption coefficients indicated that metal bioavailability decreases during the treatment in sludge samples, but increases in case of the wastewater samples, which means the treatment process affects metal phase distribution. In general, the selection of wastewater treatment processes should not be solely based on total metal removal efficiency, but also on their potential to promote the most desirable phase distributions.

Evaluation of key factors for residual rubber coagulation in natural rubber processing wastewater

Key factors for residual rubber coagulation in natural rubber (NR) processing wastewater were evaluated via a laboratory-scale system comprising an anaerobic baffled reactor (ABR) and a downflow hanging sponge (DHS) reactor (ABR–DHS system). Hydraulic retention time (HRT), seeding of the core rubber, and existence of air are selected as key factors for rubber coagulation. In the ABR, longer HRT and seeding of the core rubber was not affected for rubber coagulation. Only biodegradable substances were consumed in the ABR. On the other hand, the DHS reactor achieved high removal efficiency of residual rubber by both coagulation and biological degradation. In addition, seeding of the core rubber to the DHS reactor enhanced rubber coagulation. The genera Gordonia, known as a rubber-degrading bacteria, were detected from the retained sludge in the DHS reactor. Therefore, the wastewater–air and wastewater–core rubber contacts are considered as key factors for residual rubber coagulation in the NR wastewater treatment. Furthermore, biodegraded residual rubber was considered as carbon source for denitrification in the DHS reactor.

Non-aerated single-stage nitrogen removal using a down-flow hanging sponge reactor as post-treatment for nitrogen-rich wastewater treatment

A laboratory-scale experiment is conducted to remove nitrogen from nitrogen-rich wastewater using a down-flow hanging sponge (DHS) reactor. Effluent from an anaerobic–aerobic system for treating synthetic natural rubber wastewater, which still contains high levels of ammonia, was used as nitrogen-rich wastewater. Experimental period was divided into four phases based whether a carbon source was fed to the DHS reactor. The highest nitrogen removal efficiency (59.5 ± 5.4%) was achieved during phase 4, when a sodium acetate solution was fed into bottom section of the DHS reactor. In the DHS reactor, the nitrification occurred in the upper and middle sections. Then, after adding the sodium acetate solution, denitrification occurred. The final chemical oxygen demand, ammonia, and total inorganic nitrogen concentrations in the DHS reactor effluent were 37 ± 24 mg/L, 34 ± 5 mgN/L, and 42 ± 8 mgN/L, respectively. These concentrations were sufficient to meet the effluent standards of the Vietnamese natural rubber industry, which are the strictest in South-East Asia. The dominant bacteria in the sludge retained by the reactor's sponge media were the nitrifying bacteria Nitrosovibrio (0.2%) and Nitrospira (0.2–0.3%), the denitrifying bacteria Hylemonella (1.0–13.7%), Pseudoxanthomonas (1.2–2.1%), and Amaricoccus (2.4–3.5%), and the anammox bacterium Candidatus Brocadia (0.1–0.2%). Significant amounts of the nitrogen-fixing bacterium Xanthobacter (11.2–14.8%) and the rubber-degrading bacterium Gordonia (11.0–28.6%) were also found in the DHS reactor. These bacteria were thus considered to be the key microbes for nitrogen removal in a DHS reactor fed with a carbon source for denitrification.

STUDIES ON THE WASTEWATER TREATMENT USING MODIFIED DOWN FLOW HANGING SPONGE (DHS) PILOT AND ITS APPLICATION

In this paper the Modified Down Flow Hanging Sponge (DHS) reactor will be a good water treatment technology in the near future. It was used for excellent removal of notorious heavy metals, organic pollutants and harmful microbes. The reactor has advantages like low cost, ease of use and satisfaction level. In order to achieve these objectives, treatment scheme has been investigated. It consists of mixing a chelator with wastewater in different concentrations followed by a Down flow hanging sponge (DHS) reactor. The residual values of heavy metals are (Mn)amount decreases from 1 ppm to zero ppm (100%) after 60 min.,(Fe)decreases from 0.997 ppm to zero ppm (100%) after 60 min. (Cd) decreases from 0.901 ppm to zero ppm (100%) after 60 min. (Cu)decreases from 1.1 ppm to zero ppm (100%) after 60 min. (Pb)decreases from 1.004 ppm to zero ppm (100%) after 60 min. (Ni)decreases from 0.922 ppm to 0 ppm (100%) after 60 min. The results show that removals of fecal coliforms were achieved. From the results of DHS effluent, fecal coliforms decreased from 5.2x106 to 200 and the overall removal efficiency of fecal coliforms is (99.99%) at 37Co.

Anaerobic and aerobic sewage treatment plants in Northern India: Two years intensive evaluation and perspectives

Abstract The present study investigates the long term treatment performance of seven different sewage treatment plants located in different cities of north India for over a period of two years; two treatment technologies based on intensive aerobic processes — sequencing batch reactor (SBR) and moving bed bio-film reactor (MBBR) and; three combination of Up-flow Anaerobic Sludge Bed (UASB) reactor followed by aerobic processes — Polishing Ponds (PP), Aeration + PP and Down-flow Hanging Sponge (DHS). Effluent quality was not in accordance to the surface water disposal standards, Ministry of Environment, Forest and Climate Change Govt. of India, for UASB followed by PP and by Aeration +PP. However, a high effluent quality was observed in UASB followed by DHS; SBR and MBBR systems. In the last cases, NH4-N and PO4-P removal was higher than 85 and 60%, respectively; with a final effluent concentration of 20 mg BOD5/L, 50 mg COD/L, 20 mg TSS/L, 10 mg NH4-N/L and 5 mg PO4-P/L. Although strictly intensive aerobic systems showed a better performance, UASB followed by simple aerobic systems, such as the DHS process is a promising technology, especially in India to reach required BOD level for water reuse at low costs.

Downflow Hanging Sponge (DHS) Reactor for Wastewater Treatment - A Short Review

A combination of upflow anaerobic sludge blanket (UASB) and downflow hanging sponge (DHS) reactor has emerged as an interesting alternative wastewater treatment process. The combined system not only exhibited good organic removal performance in pilot scale experiment, moreover, several studies in the last decades also showed the good efficiency and robustness of DHS reactor in full-scale operation for wastewater treatment. This paper provides a review on the basic concept, historical process development and application of the DHS reactor for wastewater treatment. Over twenty-year development of DHS technology suggests that DHS reactor had become a viable alternative not only solving the sanitation problems in developing countries but also great further potential development in the field of resources recovery technologies from wastewater.

Adsorption of colour from dye wastewater effluent of a down-flow hanging sponge reactor on purified coconut fibre

ABSTRACTThis study was carried out to evaluate the potential application of agricultural waste coconut (Cocos nucifera) fibre in its purified form for decolorization of dye-containing effluent from a down-flow hanging sponge (DHS) reactor. Batch adsorption experiments were conducted by varying adsorbent dose, solution pH, contact time and temperature. The results showed that the adsorption percentage of colour increased with increasing in adsorbent dosage from 0.1 g to 1.3 g, solution pH from 2 to 10 and contact time from 1 h to 72 h. The adsorption process was sensitive to temperature and the adsorption percentage of colour reached the highest value at 30°C but decreased when temperature increased from 30°C to 60°C. Purified coconut fibre (PCF) had a good adsorption capacity under the optimal conditions of an adsorbent dose of 0.7 g, pH 8, temperature of 30°C and 24 h contact time. The equilibrium data were well fitted to both Langmuir and Freundlich isotherms, and the best fit of equilibrium isotherms was described using the Freundlich isotherm model. The Langmuir maximum adsorption capability of the PCF was found to be 303 (Pt/Co)/g at 30°C. The results of this study indicated the applicability of PCF as post-treatment unit of DHS reactor for removal of colour in the industrial dye effluent.

Characterization of downflow hanging sponge reactors with regard to structure, process function, and microbial community compositions.

The activated sludge (AS) process has been the most widely used process for wastewater treatment despite it has several limitations for its further application and adoption worldwide, owing to unsustainable properties such as high-energy consumption and the production of large amount of excess sludge. To overcome the drawbacks of the AS process, the downflow hanging sponge (DHS) has been developed as an energy-saving and easy-to-maintain alternative. To date, six types of different sponge configurations have been developed and their performances have been evaluated in practical- to full-scale DHS reactors. A large number of studies have been carried out in order to enhance the performance and expand the application fields of the DHS. Transition of this process to the deployment and diffusion stage from the research and development phase is now ongoing in India and Egypt as well as in Japan. Under this situation, concise and state-of-the art review is important for enhancing DHS research and future applications. Herein, we summarize and present the DHS concerning the history of development, the mechanism of treatment, recent studies on its use in the field of wastewater treatment, and the features of microbial community structure.

A research on the performance of down-flow hanging sponge (DHS) reactor treating domestic wastewater

The aim of this study was to evaluate the performance of a down-flow hanging sponge (DHS) system in treating domestic wastewater. A pilot-scale of DHS system with a capacity of 60 L was designed and fabricated from polyvinyl chloride (PVC). The dimensions of DHS system are 1.5 m in height and square surface with 0.2 m in width, consists of three identical segments connected vertically in series. Each segment was filled by polyurethane sphere containing sponge. The total area of sponge and polyurethane sphere was 3,300 m2 m-3, density at 150 kg m-3, void ratio at 90%. DHS system was operated at ambient temperature within 82 days and stepwise increased of organic f rate from 0.5 to 1 and 1.5 kg COD m-3 d-1. The results showed that, this system performed well throughout the operational period and achieve the maximum removal of COD, BOD5, NH4+-N, and TN as 80%, 83%, 65% and 60%. The effluent of wastewater from DHS system achieved the requirement for National technical regulation on domestic wastewater of Vietnam type B QCVN 14:2008/BTNMT. In conclusion, the performance of DHS system indicated a high potential for application in removing organic matter and converting nitrogen ammonia to nitrogen nitrate, however it did not perform well for the removal of total nitrogen, it is necessary to study further by providing an anoxic zone in the system to enhance the treatment of nutrient in wastewater.

Effluent treatment in an aquaponics-based closed aquaculture system with single-stage nitrification–denitrification using a down-flow hanging sponge reactor

A laboratory-scale demonstration of the aquaculture effluent treatment was conducted in a system that combined a down-flow hanging sponge (DHS) reactor and a hydroponic cultivation bed (HCB). Cyprinus carpio was used as a model aquaculture fish and Cupsicum frutescens was used as a model hydroponic plant. The aquarium water was circulated through the HCB and DHS using a submerged pump. The experiment was divided into six phases in which the sodium acetate solution was supplied using different feeding patterns. The sodium acetate solution acted as a carbon source and not only eliminated nitrogen through denitrification but also increased the alkalinity through biological degradation of the acetate. Denitrification was observed to eliminate 7.7% of the total nitrogen at the inlet out of which 53.5% was converted by C. frutescens to form a fruit. The microbial community in the sludge that was retained in the DHS contained both nitrifying and denitrifying bacteria. Nitrososhaera was the dominant ammonia-oxidizing bacterium, whereas Nitrospira was the dominant nitrite-oxidizing bacterium. Further, Opitutus acted as the dominant denitrifying bacterium. No major bacterial pathogen was detected in the DHS–HCB system. The study confirmed that the DHS system provided single-stage nitrification–denitrification and that the overall DHS–HCB system provided a low-cost and high-performance aquaculture effluent treatment system that is capable of being used for safe food production.

A novel approach for toluene gas treatment using a downflow hanging sponge reactor.

A novel gas-scrubbing bioreactor based on a downflow hanging sponge (DHS) reactor was developed as a new volatile organic compound (VOC) treatment system. In this study, the effects of varying the space velocity and gas/liquid ratio were investigated to assess the effectiveness of using toluene gas as a model VOC. Under optimal conditions, the toluene removal rate was greater than 80%, and the maximum elimination capacity was observed at approximately 13g-Cm-3h-1. The DHS reactor demonstrated slight pressure loss (20Pa) and a high concentration of suspended solids (up to 30,000mg/L-sponge). Cloning analysis of the 16S rRNA and functional genes of toluene degradation pathways (tmoA, todC, tbmD, xylA, and bssA) revealed that the clones belonging to the toluene-degrading bacterium Pseudomonas putida constituted the predominant species detected at the bottom of the DHS reactor. The toluene-degrading bacteria Pseudoxanthomonas spadix and Pseudomonas sp. were also detected by tmoA- and todC-targeted cloning analyses, respectively. These results demonstrate the potential for the industrial application of this novel DHS reactor for toluene gas treatment.

High-rate anaerobic treatment system for solid/lipid-rich wastewater using anaerobic baffled reactor with scum recovery

A laboratory scale experiment was conducted to investigate the treatment of solid/lipid-rich wastewater with an anaerobic baffled reactor (ABR) and a down-flow hanging sponge (DHS) reactor. In this study, experimental periods were divided into three phases to explore efficient treatment of solids and lipids in wastewater. In ABR, >90% of the influent chemical oxygen demand (COD) was removed and >70% of the removed COD was converted to methane under steady-state conditions during each phase. During this period, >4.5 kg COD m−3 d−1 was achieved on an average in Phases 1 and 3. Biogas contributed to scum formation, and the scum was categorized into lipid-rich and sludge-containing types, which have energy potentials of 53.4 and 212 kcal/kg-wet weight, respectively. Therefore, by recovering solids and lipids, which formed persistent scum, ABR can be applied as a high-rate treatment for solid/lipid-rich wastewater.

Assessment of UASB–DHS technology for sewage treatment: a comparative study from a sustainability perspective

ABSTRACTThis paper assesses the technical and economic sustainability of a combined system of an up-flow anaerobic sludge blanket (UASB)–down-flow hanging sponge (DHS) for sewage treatment. Additionally, this study compares UASB–DHS with current technologies in India like trickling filters (TF), sequencing batch reactor (SBR), moving bed biofilm reactor (MBBR), and other combinations of UASB with post-treatment systems such as final polishing ponds (FPU) and extended aeration sludge process (EASP). The sustainability of the sewage treatment plants (STPs) was evaluated using a composite indicator, which incorporated environmental, societal, and economic dimensions. In case of the individual sustainability indicator study, the results showed that UASB-FPU was the most economically sustainable system with a score of 0.512 and aeration systems such as MBBR, EASP, and SBR were environmentally sustainable, whereas UASB–DHS system was socially sustainable. However, the overall comparative analysis indicated that the UASB–DHS system scored the highest value of 2.619 on the global sustainability indicator followed by EASP and MBBR with scores of 2.322 and 2.279, respectively. The highlight of this study was that the most environmentally sustainable treatment plants were not economically and socially sustainable. Moreover, sensitivity analysis showed that five out of the seven scenarios tested, the UASB–DHS system showed good results amongst the treatment system.

Defining microbial community composition and seasonal variation in a sewage treatment plant in India using a down-flow hanging sponge reactor.

The characteristics of the microbial community in a practical-scale down-flow hanging sponge (DHS) reactor, high in organic matter and sulfate ion concentration, and the seasonal variation of the microbial community composition were investigated. Microorganisms related to sulfur oxidation and reduction (2-27%), as well as Leucobacter (7.50%), were abundant in the reactor. Anaerobic bacteria (27-38% in the first layer) were also in abundance and were found to contribute to the removal of organic matter from the sewage in the reactor. By comparing the Simpson index, the abundance-based coverage estimator (ACE) index, and the species composition of the microbial community across seasons (summer/dry, summer/rainy, autumn/dry, and winter/dry), the microbial community was found to change in composition only during the winter season. In addition to the estimation of seasonal variation, the difference in the microbial community composition along the axes of the DHS reactor was investigated for the first time. Although the abundance of each bacterial species differed along both axes of the reactor, the change of the community composition in the reactor was found to be greater along the vertical axis than the horizontal axis of the DHS reactor.

KAJIAN PENDAHULUAN KELAYAKAN PENERAPAN INSTALASI PENGOLAHAN AIR LIMBAH DOMESTIK SECARA KOMUNAL DI PERMUKIMAN KOTA BOGOR

A preliminary assessment of an application of sewerage system with Upflow Anaerobic Sludge Blanket (UASB) and Down flow Hanging Sponge (DHS) technology was conducted inNorth Bogor. The Problem which often emerge in management of domestic wastewater is the limited land area and fund to built and operate a wastewater treatment facility. To overcome such problem, it is needed to develop a cheap wastewater treatment technology with high efficiency, easy to operate and also should be compact. The combination technology of UASB and DHS is proposed as an economic wastewater treatment which easy to handling. Therefore, to make sure that the technology is feasible or not to be built inNorth Bogor, there is need the preliminary assessment. The assessment was conducted through a survey of technical and social economic aspect. The results show that sewerage system using UASB and DHS technology is feasible. Key word: domestic wastewater, upflow anaerobik sludge blanket, downflow hanging sponge, preliminary assessment.

A Low-Tech Bioreactor System for the Enrichment and Production of Ureolytic Microbes.

Ureolysis-driven microbially induced carbonate precipitation (MICP) has recently received attention for its potential biotechnological applications. However, information on the enrichment and production of ureolytic microbes by using bioreactor systems is limited. Here, we report a low-tech down-flow hanging sponge (DHS) bioreactor system for the enrichment and production of ureolytic microbes. Using this bioreactor system and a yeast extract-based medium containing 0.17 M urea, ureolytic microbes with high potential urease activity (> 10 μmol urea hydrolyzed per min per ml of enrichment culture) were repeatedly enriched under non-sterile conditions. In addition, the ureolytic enrichment obtained in this study showed in vitro calcium carbonate precipitation. Fluorescence in situ hybridization analysis showed the existence of bacteria of the phylum Firmicutes in the bioreactor system. Our data demonstrate that this DHS bioreactor system is a useful system for the enrichment and production of ureolytic microbes for MICP applications.

Evaluación de una planta piloto para el tratamiento de aguas residuales ordinarias por medio de un filtro percolador con relleno de esponjas colgantes de flujo descendente (DHS) como postratamiento de un efluente de sedimentador primario

La investigación consistió en evaluar un filtro percolador con material de relleno de espuma de poliuretano para el postratamiento de un efluente de sedimentador primario. A esta tecnología se le conoce como DHS por sus siglas en inglés para Downflow Hanging Sponge. El tren de tratamiento se completó con un sedimentador secundario (SS) a la salida del DHS. El sistema DHS + SS se monitoreó por más de un año (entrada al DHS y salida del SS), haciendo variar el tiempo de retención hidráulica y revisando las eficiencias de remoción de materia orgánica en términos de la DBO, DQO y los SST. El sistema presentó su mejor desempeño para un tiempo de retención hidráulica de 2,8 horas, equivalente a una carga orgánica volumétrica de entre 0,60 a 0,80 kgDBO/m3-d. Para esa condición se cumplió con los límites de DBO y DQO del DE-33601-S-MINAE en el 100% de los casos, aunque se incumplió en un 25% del tiempo para el parámetro de SST. Se presume que el sistema presentó problemas a nivel del sedimentador secundario, generando un arrastre de lodos que afectó el resultado de SST en el efluente final. Se recomienda ampliar la escala de la prueba con el reactor DHS, usando una planta de tratamiento de escala real y mejorando sustancialmente el sistema de distribución de agua a la entrada y el sedimentador secundario.