Upflow Anaerobic Reactor Research Articles

Fermentative hydrogen production in an up-flow anaerobic biofilm reactor inoculated with a co-culture of Clostridium acetobutylicum and Desulfovibrio vulgaris

Dark fermentation systems often show low H2 yields and unstable H2 production, as the result of the variability of microbial dynamics and metabolic pathways. Recent batch investigations have demonstrated that an artificial consortium of two anaerobic bacteria, Clostridium acetobutylicum and Desulfovibrio vulgaris Hildenborough, may redirect metabolic fluxes and improve H2 yields. This study aimed at evaluating the scale-up from batch to continuous H2 production in an up-flow anaerobic packed-bed reactor (APBR) continuously fed with a glucose-medium. The effects of various parameters, including void hydraulic retention time (HRTv), pH, and alkalinity, on H2 production performances and metabolic pathways were investigated. The results demonstrated that a stable H2 production was reached after 3–4days of operation. H2 production rates increased significantly with decreasing HRTv from 4 to 2h. Instead, H2 yields remained almost stable despite the change in HRTv, indicating that the decrease in HRTv did not affect the global metabolism.

Experimental and modelling study of treatment and regeneration of ferrous-nitrilotriacetate solution scrubbed with nitric oxide by an up-flow anaerobic biofilm reactor

This paper deals with an integrated biochemical process for the treatment of stationary gaseous emissions containing nitric oxide. The process involves absorption of nitric oxide in a solution of ferrous nitrilotriacetate, followed by regeneration of the solution by microbial reduction of nitrosyl adduct of ferrous nitrilotriacetate and ferric nitrilotriacetate present in the solution generated during absorption. A laboratory-scale up-flow anaerobic biofilm reactor using polyurethane foam cubes as support matrix for biofilm was employed for the treatment of 20 mM ferrous nitrilotriacetate solution scrubbed with synthetic nitric oxide gas mixture. The biofilm was developed by fed-batch operation for 30 days by using enriched bacterial culture capable of reducing nitrosyl adduct and ferric nitrilotriacetate using ethanol as organic electron donor. Under steady-state conditions, the nitrosyl adduct reduction efficiency reached >90% at a loading rate of 0.24 mML−1 h−1 while ferric nitrilotriacetate reduction efficiency was 15–20%. The average biofilm thickness was about 550 μm, decreasing the porosity of the matrix. Reactor hydrodynamics was studied by tracer (methyl orange) experiments. The analysis based on residence time distribution theory involved axial dispersion flow model and tracer diffusion with linear adsorption inside the biofilm. Peclet number value of 28 was obtained allowing the plug-flow assumption for the reactor model. The experimental profiles of the nitrosyl adduct reduction in the reactor were explained by using a kinetic model of first order reaction coupled with NO diffusion inside the biofilm.

EVALUACIÓN HIDRÁULICA DE UN REACTOR ANAEROBIO DE FLUJO ASCENDENTE (RAFA) USANDO UN MODELO DE DISPERSIÓN AXIAL

La hidraulica, junto con los procesos bioquimicos tiene una importancia esencial en la eficiencia de los sistemas de tratamiento biologico, tales como los reactores anaerobios de flujo ascendente (RAFA). En esta investigacion se evaluo el desempeno hidraulico en un RAFA de 518 L utilizando un modelo de dispersion axial. El reactor fue inoculado con 105 L de lodo (20 % v/v) y se alimento con agua residual municipal del colector C de la ciudad de Maracaibo, Venezuela. Los ensayos fueron realizados al agregar una solucion de LiCl de forma puntual en el efluente. El Li + fue cuantificado como trazador. Las muestras fueron recolectadas en el efluente y en un punto intermedio del reactor a tiempos de retencion hidraulica teoricos (t o ) de 10, 8, 5, 4 y 3 h con tres entradas alineadas en el fondo del reactor y a to de 5 h incrementando las entradas de forma impar hasta llegar a 15. El numero de dispersion obtenido en la zona de lecho y manto de lodo (punto intermedio) fue mayor que en el efluente, obteniendo valores de 1.1842 < d < 1.7550 y 0.2911 < d < 0.7285 respectivamente. El modelo de dispersion axial con inyeccion y recoleccion en flujo (IRF) e inyeccion en flujo y recoleccion en el fluido residente (IFRFR), presento buenos ajustes a los datos experimentales de concentracion del trazador. El reactor se comporto como mezcla completa en el lecho y manto de lodo y flujo disperso en el sedimentador.

FABRIC FILTERS FOR WASTE WATER TREATMENT IN RURAL COMMUNITIES IN EGYPT

Fabric filtration is a new trend in waste water reuse applications. In an attempt to improve the waste water quality resulting from a compact unit composed of an up-flow anaerobic reactor to obtain waste water effluent quality which is complying with the law 48/1982 for discharge in agricultural drains, and which can be used safely for unrestricted irrigation, this research study aims at testing the performance of four different fabric materials at the bench scale level at different operating conditions in order to identify the optimum operating conditions for the selected material. In this research, nonwoven fabrics and woven fabrics were tested as separation media. The effect of different water heads (pressure) and flux rates were tested to evaluate the fabric material removal performance. Two parameters were used to evaluate the removal of suspended solids and organic material namely; TSS and COD. Based on the results of this research study, nonwoven fabrics were found to be promising as separation media for the waste water and more effective than woven fabrics. Low flux rates and low water heads showed better results compared to high flux rates and pressure. The selected fabric material will be tested at the full scale real wastewater resulting from a village existing in a rural area in Egypt.

Effect of electrode position on azo dye removal in an up-flow hybrid anaerobic digestion reactor with built-in bioelectrochemical system

In this study, two modes of hybrid anaerobic digestion (AD) bioreactor with built-in BESs (electrodes installed in liquid phase (R1) and sludge phase (R2)) were tested for identifying the effect of electrodes position on azo dye wastewater treatment. Alizarin yellow R (AYR) was used as a model dye. Decolorization efficiency of R1 was 90.41 ± 6.20% at influent loading rate of 800 g-AYR/ m3·d, which was 39% higher than that of R2. The contribution of bioelectrochemical reduction to AYR decolorization (16.23 ± 1.86% for R1 versus 22.24 ± 2.14% for R2) implied that although azo dye was mainly removed in sludge zone, BES further improved the effluent quality, especially for R1 where electrodes were installed in liquid phase. The microbial communities in the electrode biofilms (dominant by Enterobacter) and sludge (dominant by Enterococcus) were well distinguished in R1, but they were similar in R2. These results suggest that electrodes installed in liquid phase in the anaerobic hybrid system are more efficient than that in sludge phase for azo dye removal, which give great inspirations for the application of AD-BES hybrid process for various refractory wastewaters treatment.

A new method of two-phase anaerobic digestion for fruit and vegetable waste treatment

A novel method of two-phase anaerobic digestion where the acid reactor is operated at low pH 4.0 was proposed and investigated. A completely stirred tank acid reactor and an up-flow anaerobic sludge bed methane reactor were operated to examine the possibility of efficient degradation of lactate and to identify their optimal operating conditions. Lactate with an average concentration of 14.8g/L was the dominant fermentative product and Lactobacillus was the predominant microorganism in the acid reactor. The effluent from the acid reactor was efficiently degraded in the methane reactor and the average methane yield was 261.4ml/gCOD removed. Organisms of Methanosaeta were the predominant methanogen in granular sludge of methane reactor, however, after acclimation hydrogenotrophic methanogens enriched, which benefited for the conversion of lactate to acetate. The two-phase AD system exhibited a low hydraulic retention time of 3.56days and high methane yield of 348.5ml/g VS removed.

Modeling granule development and reactor performance on anaerobic granular sludge reactors

In this study, a dynamic model for up-flow anaerobic granular sludge reactors capable of simultaneously predicting the granule development (size and composition) and the reactor performance was developed, implemented and validated. The model couples the anaerobic digestion model No.1 (ADM1), slightly adapted, with the reactor hydrodynamics and the mass transfer processes within the granule for soluble and particulate components. Granular development prediction was achieved by considering the kinetic processes and the advective flux for particulate components inside the granular matrix and particulate detachment in the granule surface. The model was implemented in Matlab software. Simulations accurately predicted the methane production rate and the granular size distribution of a bench-scale expanded granular sludge bed (EGSB) reactor treating synthetic sucrose based wastewater. Additionally, the model was successfully implemented, not only considering a mean granule size, but also including a granule size distribution. Results showed that considering the granule size distribution only affected the particulate concentration in the reactor outlet stream at the expense of highly increasing the computational cost for simulation.

High-rate hydrogen production from galactose in an upflow anaerobic sludge blanket reactor (UASBr)

High-rate hydrogen production from galactose and rapid granule formation were achieved in a mesophilic (37 °C) upflow anaerobic sludge blank reactor (UASBr).

Cathode material as an influencing factor on beer wastewater treatment and methane production in a novel integrated upflow microbial electrolysis cell (Upflow-MEC)

As a reliable source for methane production, the major goal of our research was to design and testify a novel microbial electrolysis assisted upflow anaerobic (Upflow-MEC) reactor for beer wastewater treatment and simultaneous methane production. Three reactors with different cathode materials were constructed and the reactor with Ni cathode had a maximum COD removal of 85%, methane yield of 142.8 mL/gCOD, TOC removal of 83%, Carbohydrate removal of 97%, Protein removal of 62% and current production of 8.6 mA, under 0.8 V applied voltage at HRT of 24 h. It was an application-oriented, membrane-free, continuous reactor and shortening the reaction time and increasing organic content conversion to methane were the key developing targets.

Inoculation of paperboard mill sludge versus mixed culture bacteria for hydrogen production from paperboard mill wastewater.

A comparative evaluation of paperboard mill sludge (PMS) versus mixed culture bacteria (MCB) as inoculum for hydrogen production from paperboard mill wastewater (PMW) was investigated. The experiments were conducted at different initial cultivation pHs, inoculums to substrate ratios (ISRs gVS/gCOD), and hydraulic retention times (HRTs). The peak hydrogen yield (HY) of 5.29 ± 0.16 and 1.22 ± 0.11 mmol/gCODinitial was occurred at pH = 5 for MCB and PMS, respectively. At pH of 5, the HY and COD removal achieved the highest values of 2.26 ± 0.14 mmol/gCODinitial and 86 ± 1.6% at ISR = 6 for MCB, and 2.38 ± 0.25 mmol/gCODinitial and 60.4 ± 2.5% at ISRs = 3 for PMS. The maximum hydrogen production rate was 93.75 ± 8.9 mmol/day at HRT = 9.6 h from continuous upflow anaerobic reactor inoculated with MCB. Meanwhile, the 16S ribosomal RNA (rRNA) gene fragments indicated a dominance of a novel hydrogen-producing bacterium of Stenotrophomonas maltophilia for PMS microbial community. On the other hand, Escherichia fergusonii and Enterobacter hormaechei were the predominant species for MCB.

Effect of the chemical nature of fixed-bed reactor support materials on bioreactor performance and biomass accumulation

ABS TRACT: This study investigated the effect, on reactor performance and biomass retention inside the bed, of the material used to make the supports of anaerobic fixed-bed reactors. Three inert supports of similar shape but made of three different materials polyvinyl chloride, polypropylene, high-density polyethylene were manufactured and used. All three supports had the same specific surface area but different relative densities. Three identical 10 L lab-scale upflow anaerobic fixed-bed reactors were filled (80% of the working volume) each respectively with polyvinyl chloride, polypropylene and polyethylene support, and fed with vinasse (44 g total COD/L) for 140 days at 35 °C. The organic loading rates were increased from 0.5 g/L.d. to the maximum acceptable by each reactor. Fairly similar maximum organic loading rates were reached for each type of support, with values above 20 g of COD/L.d. and more than 80 % soluble chemical oxygen demand removal efficiency. A very large amount of biomass was entrapped and attached in all the supports and represented more than 95% of the total biomass inside the reactors. In terms of performance and biomass accumulation, this study demonstrated quite similar behavior for anaerobic fixed-bed reactors with supports made of different materials, which suggests that the nature of the material used to make the supports has no major influence. The chemical nature of the support material clearly has negligible effect and thus the size, shape, and porosity of the support must be more influential.

Characterization of a halotolerant acetoclastic methanogen highly enriched from marine sediment and its application in removal of acetate

A marine sediment collected from Hiroshima Bay was cultured in artificial seawater, containing 0.51M NaCl and 60mM acetate and was found to exhibit active methane production at 37°C. Following four successive serial dilutions of cultures in medium containing 0.51M NaCl, 60mM acetate, and antibiotics, the well-acclimated methanogen was found to exhibit growth over a range of NaCl concentration (between 0M and 2.06M). The specific growth rates of the highly enriched methanogen, termed strain HA, in the absence of NaCl and in the presence of 1.54M NaCl were estimated to be 0.037h(-1) and 0.027h(-1), respectively. The pH and temperature for optimum growth were determined to be 7.0-8.8 and 37°C, respectively. Although cells that had morphology similar to Methanosaeta sp. became dominant in the culture, methane production was still detected in the medium containing 0.51M NaCl and other substrates such as methanol, formate, and methylamine, indicating contamination with other methanogens. The phylogenetic tree based on 16S rRNA gene sequences revealed that the strain HA was closely related to Methanosaeta harundinacea 6Ac and 8Ac(T), with sequence similarity of 98% and 97%, respectively. The continuous removal of acetate with upflow anaerobic filter reactor for industrial use of strain HA determined a methane production rate of 70mM/d under condition of 0.51M NaCl and successful methane production even under 1.54M NaCl.

Sulfate reduction and mixotrophic sulfide-utilization denitrification integrated biofilm process for sulfate-laden wastewater treatment and sulfur recovery.

A novel and integrated biofilm process--the sulfate reduction (SR) and mixotrophic (MR) sulfide-utilization denitrification process (SMSD)--was recently proposed for sulfate treatment and sulfur recovery. The process consisted of two bioreactors: a 5.1 L anaerobic upflow reactor for SR, and a 3.5 L anaerobic upflow reactor for MR desulfurization-denitrification. The experiment was conducted for 370 days to evaluate the performance of SMSD at various sulfate concentrations and hydraulic retention times. The process successfully achieved sulfate, organics and nitrogen compound removal efficiencies of 94.1, 97.7 and 99.1%, respectively. Sulfate was predominantly converted to element sulfur, while nitrate and nitrite were finally converted to nitrogen gas. In SR, with the help of high pH and sponge cubes with various bacteria, 97.5% of sulfide conversion efficiency and 540 mgS/L of sulfide were obtained. In MR, sulfide was removed up to 100% and was partially oxidized to sulfur. The extent of heterotrophic denitrification, which ranged from 35.8 to 59.8%, depended on the categories of electron acceptors.

High organic loading rate on thermophilic hydrogen production and metagenomic study at an anaerobic packed-bed reactor treating a residual liquid stream of a Brazilian biorefinery

This study evaluated the influence of a high organic loading rate (OLR) on thermophilic hydrogen production at an up-flow anaerobic packed-bed reactor (APBR) treating a residual liquid stream of a Brazilian biorefinery. The APBR, filled with low-density polyethylene, was operated at an OLR of 84.2kg-CODm−3d−1. This value was determined in a previous study. The maximum values of hydrogen production and yield were 5,252.6mL-H2d−1 and 3.7mol-H2mol−1total carbohydrates, respectively. However, whereas the OLR remained constant, the specific organic load rate (sOLR) decreased throughout operation from 1.38 to 0.72g-Total carbohydratesg-VS−1h−1, this decrease negatively affected hydrogen production. A sOLR of 0.98g-Total carbohydratesg-VS−1h−1 was optimal for hydrogen production. The microbial community was studied using 454-pyrosequencing analysis. Organisms belonging to the genera Caloramator, Clostridium, Megasphaera, Oxobacter, Thermoanaerobacterium, and Thermohydrogenium were detected in samples taken from the reactor at operation days 30 and 60, suggesting that these organisms contribute to hydrogen production.

The anaerobic treatment of pharmaceutical industry wastewater in an anaerobic batch and upflow packed-bed reactor

The pharmaceutical industry constitutes an important place in terms of health and environment, both in our country and throughout the world. Various complex organic chemicals are present in the wastewater generated by pharmaceutical industries. The accumulation of toxic and persistent organic substances in wastewater is a serious problem for the environment. Therefore, it is important that pharmaceutical industry wastewater is treated before being discharged into receiving waters. Today, anaerobic treatment systems are commonly used for wastewater-containing high organic matter. The first stage of this study statistically investigates the optimization of anaerobic treatment conditions of pharmaceutical industry wastewater in a batch study. In the second stage, continuous treatment processes were planned using data obtained as a result of the batch study. For processing, an upflow anaerobic packed-bed reactor was used for treating substrate mixtures containing 10–100% pharmaceutical industry wastewater. The effects of operating parameters on the chemical oxygen demand (COD) removal efficiency and the methane production rate were evaluated. COD removal efficiencies of 93–97% were obtained for the pharmaceutical industry wastewater using a 2.5–4 d hydraulic retention time and a 0.6–2.2g COD d−1 organic loading rate. The overall results suggested that the mixed bacterial and archaeal biomass was able to efficiently treat pharmaceutical industry wastewater under determined anaerobic conditions.

A comprehensive review on utilization of wastewater from coffee processing.

The coffee processing industry is one of the major agro-based industries contributing significantly in international and national growth. Coffee fruits are processed by two methods, wet and dry process. In wet processing, coffee fruits generate enormous quantities of high strength wastewater requiring systematic treatment prior to disposal. Different method approach is used to treat the wastewater. Many researchers have attempted to assess the efficiency of batch aeration as posttreatment of coffee processing wastewater from an upflow anaerobic hybrid reactor (UAHR)-continuous and intermittent aeration system. However, wet coffee processing requires a high degree of processing know-how and produces large amounts of effluents which have the potential to damage the environment. Characteristics of wastewater from coffee processing has a biological oxygen demand (BOD) of up to 20,000 mg/l and a chemical oxygen demand (COD) of up to 50,000 mg/l as well as the acidity of pH below 4. In this review paper, various methods are discussed to treat coffee processing wastewaters; the constitution of wastewater is presented and the technical solutions for wastewater treatment are discussed.

Biofilm formation by designed co-cultures of Caldicellulosiruptor species as a means to improve hydrogen productivity.

BackgroundCaldicellulosiruptor species have gained a reputation as being among the best microorganisms to produce hydrogen (H2) due to possession of a combination of appropriate features. However, due to their low volumetric H2 productivities (QH2), Caldicellulosiruptor species cannot be considered for any viable biohydrogen production process yet. In this study, we evaluate biofilm forming potential of pure and co-cultures of Caldicellulosiruptor saccharolyticus and Caldicellulosiruptor owensensis in continuously stirred tank reactors (CSTR) and up-flow anaerobic (UA) reactors. We also evaluate biofilms as a means to retain biomass in the reactor and its influence on QH2. Moreover, we explore the factors influencing the formation of biofilm.ResultsCo-cultures of C. saccharolyticus and C. owensensis form substantially more biofilm than formed by C. owensensis alone. Biofilms improved substrate conversion in both of the reactor systems, but improved the QH2 only in the UA reactor. When grown in the presence of each other’s culture supernatant, both C. saccharolyticus and C. owensensis were positively influenced on their individual growth and H2 production. Unlike the CSTR, UA reactors allowed retention of C. saccharolyticus and C. owensensis when subjected to very high substrate loading rates. In the UA reactor, maximum QH2 (approximately 20 mmol · L−1 · h−1) was obtained only with granular sludge as the carrier material. In the CSTR, stirring negatively affected biofilm formation. Whereas, a clear correlation was observed between elevated (>40 μM) intracellular levels of the secondary messenger bis-(3′-5′)-cyclic dimeric guanosine monophosphate (c-di-GMP) and biofilm formation.ConclusionsIn co-cultures C. saccharolyticus fortified the trade of biofilm formation by C. owensensis, which was mediated by elevated levels of c-di-GMP in C. owensensis. These biofilms were effective in retaining biomass of both species in the reactor and improving QH2 in a UA reactor using granular sludge as the carrier material. This concept forms a basis for further optimizing the QH2 at laboratory scale and beyond.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0201-7) contains supplementary material, which is available to authorized users.

Opciones de tratamiento para aguas residuales de tres granjas porcícolas

For the treatment of wastewater there are low-cost technologies such as stabilization ponds and anaerobic processes. Both technologies have been used to treat high load wastewater such as swine farm wastewater. The aim of this paper was to present treatment options for different types of swine wastewater, conducting an analysis of area requirements. We present the characterization of wastewater from three different swine farms (technified, low sophisticated and backyard) is presented, besides a description of the treatment system for each case, calibration of the design for the backyard farm. The proposed treatment configurations allow reducing 31 % the area requirements (m2•m 3), for the low sophisticated farm by including an anaerobic digester; and 35 % in the area requirements (m2•m 3) for the technified farm by including an anaerobic digester and an upflow anaerobic reactor in the treatment train.

Effect of physical property of supporting media and variable hydraulic loading on hydraulic characteristics of advanced onsite wastewater treatment system

A laboratory-scale study was carried out to investigate the effects of physical properties of the supporting media and variable hydraulic shock loads on the hydraulic characteristics of an advanced onsite wastewater treatment system. The system consisted of two upflow anaerobic reactors (a septic tank and an anaerobic filter) accommodated within a single unit. The study was divided into three phases on the basis of three different supporting media (Aqwise carriers, corrugated ring and baked clay) used in the anaerobic filter. Hydraulic loadings were based on peak flow factor (PFF), varying from one to six, to simulate the actual conditions during onsite wastewater treatment. Hydraulic characteristics of the system were identified on the basis of residence time distribution analyses. The system showed a very good hydraulic efficiency, between 0.86 and 0.93, with the media of highest porosity at the hydraulic loading of PFF ≤ 4. At the higher hydraulic loading of PFF 6 also, an appreciable hydraulic efficiency of 0.74 was observed. The system also showed good chemical oxygen demand and total suspended solids removal efficiency of 80.5% and 82.3%, respectively at the higher hydraulic loading of PFF 6. Plug-flow dispersion model was found to be the most appropriate one to describe the mixing pattern of the system, with different supporting media at variable loading, during the tracer study.

The use of the carbon/nitrogen ratio and specific organic loading rate as tools for improving biohydrogen production in fixed-bed reactors

This study assessed the effect of the carbon/nitrogen (C/N) ratio on the hydrogen production from sucrose-based synthetic wastewater in upflow fixed-bed anaerobic reactors. C/N ratios of 40, 90, 140, and 190 (gC/gN) were studied using sucrose and urea as the carbon and nitrogen sources, respectively. An optimum hydrogen yield of 3.5molH2mol−1 sucrose was obtained for a C/N ratio of 137 by means of mathematical adjustment. For all C/N ratios, the sucrose removal efficiency reached values greater than 80% and was stable after the transient stage. However, biogas production was not stable at all C/N ratios as a consequence of the continuous decreasing of the specific organic loading rate (SOLR) when the biomass accumulated in the fixed-bed, causing the proliferation of H2-consuming microorganisms. It was found that the application of a constant SOLR of 6.0gsucroseg−1VSSd−1 stabilized the system.