Scale Upflow Anaerobic Sludge Blanket Research Articles

Feasibility of semi-pilot scale up-flow anaerobic sludge blanket fixed-film reactor for fermentative bio-hydrogen production from palm oil mill effluent

The present study focuses on bio-hydrogen production using palm oil mill effluent (POME) at a semi-pilot scale of an “up-flow anaerobic sludge blanket fixed-film (UASFF) reactor”. The reactor was operated in the palm oil mill industry for over 180 days of operation at ambient temperature through dark fermentation process with different organic loading rates (OLR) of 22–36 g-COD/l.d, depending on the COD concentration of POME. By acclimatizing the sludge, the semi-pilot scale UASFF reactor achieved hydrogen content, and hydrogen production rate (HPR) of 20%–68%, and 12 L H2/d to 39 L H2/d, respectively with a maximum COD removal of 35%. Moreover, from high through pyrosequencing analysis, hydrogen fermentation was attributed to Clostridium sensu stricto, Lactobacillus, and thermoanaerobium spp. This study offers an extensive approach to developing a semi-pilot scale bio-hydrogen production and, provides further prospects for profitable exploitation which could be a promising approach for reaching sustainability and economic feasibility (using wastewater as a low-cost feedstock) in commercial applications for future studies.

Anaerobic Digested Wastewater CO2 Sequestration Using a Biophotocatalytic System with a Magnetized Photocatalyst (Fe-TiO2)

This study presents a biophotocatalytic system as a sustainable technology for the recovery of clean water and renewable energy from wastewater, thereby providing a unique opportunity to drive industrialization and global sustainable development throughputs. Herein, inhouse magnetized photocatalyst (Fe-TiO2) with surface area 62.73 m2/g synthesized via co-precipitation, was hypothesized to hasten an up-flow anaerobic sludge blanket (UASB) reactor for the treatment of local South Africa municipality wastewater with the benefit of high-quality biogas production. A lab scale UASB process with a working volume of 5 L coupled with two UV-lights (T8 blacklight-blue tube, 365 nm, 18 W) was operated batchwise under mesophilic conditions for the period of 30 days with a constant organic load charge of 2.76 kg COD/m3. d. This biophotocatalytic system performance was investigated and compared with and without the Fe-TiO2 charge (2–6 g) with respect to effluent quality, biogas production and CO2 methanation. Using chemical oxygen demand (COD) measured as the degree of degradation of the pollutants, the best efficiency of 93% COD removal was achieved by a 4 g Fe-TiO2 charge at 14 days and pH of 7.13, as compared to zero charge where only 49.6% degradation was achieved. Under the same charge, cumulative biogas and methane content of 1500 mL/g COD.d and 85% were respectively attained as compared with the control with 400 mL/g COD.d and 65% methane content. Also, the energy produced can be used to offset the energy utilized by the UV-light for the wastewater abatement and other limitations of photocatalysis. The BP system was found to be an eco-friendly and cost-effective technology to be explored in water treatment settings.

Co-digestion of municipal wastewater and microalgae biomass in an upflow anaerobic sludge blanket reactor

Upflow anaerobic sludge blanket reactors associated in series with photobioreactors offers an efficient and low cost solution for the wastewater treatment in small communities. However, there is little information about the performance of such anaerobic process fed with microalgae biomass from high rate algal ponds. This study aimed to evaluate the performance of a 3.78 m3 working volume pilot scale upflow anaerobic sludge blanket reactor during anaerobic co-digestion of municipal wastewater and microalgae biomass from high rate algal ponds (13.7 m3 each) during 365 days. To establish a basis for comparison, in the first research phase the anaerobic process was fed exclusively with municipal wastewater and, in the second phase, with a mixture of municipal wastewater and microalgae biomass. Similar organic and hydraulic loading rates were provided to the process in both research phases. The results showed a great removal of organic matter (COD) and suspended solids (TSS) in anaerobic process during the first phase (61% COD and 74% TSS) and second phase (63% COD and 74% TSS), the latter in anaerobic co-digestion. No sign of toxicity due to excess of ammoniacal, nitrogen or sulfur compounds was found. However, COD mass balance showed an increase of 54% on COD sludge retained and indicated that most of the microalgae biomass was not converted into methane. It was also observed a significant decrease in biogas production and a washout of microalgae cells to the upflow anaerobic sludge blanket reactor effluent in the second phase. The presence of intact microalgae cells retained in the sludge at all levels of this process also evidenced the incomplete anaerobic digestion of the microalgae biomass. These findings prove that an auxiliary pretreatment of the microalgae biomass is essential to improve its conversion into methane in the upflow anaerobic sludge blanket reactor.

A simple anaerobic and filtration combined system for domestic wastewater treatment

Anaerobic treatment of domestic wastewater can only partially treat the effluent and still contains concentration of organic matter, suspended solids, nutrients and pathogens beyond the recommended safe limit. This study aims to observe the effect of sand filter as a low cost post treatment solution. A 250 L pilot scale upflow anaerobic sludge blanket (UASB) reactor was fed septic tank effluent and operated at an average ambient temperature of 19 °C. The reactor was fed intermittently at 6 h hydraulic retention time and the performance was monitored. The UASB effluent was filtered in a 1 m3 sand filter unit. The removal efficiencies of Total Suspended Solid, Chemical Oxygen Demand and Faecal Coliform for combined system were 93%, 87% and 93%, respectively. However, the top layer of the sand in the filter needs to be replaced in every two to three months to maintain acceptable filtration capacity performance. The tested combined anaerobic and filtration system was sufficient to treat effluents from a typical Nepalese family and the result could be useful to design and develop a suitable compact, low cost onsite sanitation system in developing countries like Nepal. The result should encourage investigating on the establishment of a safe route of sand replacement and handling as well as alternative low cost filtration media in order to avoid frequent replacement of the sand.

The study of structure of anaerobic granules and methane producing pathways of pilot-scale UASB reactors treating municipal wastewater under sub-mesophilic conditions

This study was carried out to investigate the relationship between the methane producing pathways and the characteristics of anaerobic granules treating municipal wastewater. For this purpose, two pilot scale upflow anaerobic sludge blanket reactors with different granule size distribution (1–2 mm and 3–4 mm) were investigated at operating temperatures of 20 °C and 28 °C for 239 days. There was an increased and stable biogas production when temperature was elevated to 28 °C likely due to reduction in methane solubility. Larger granules had multi-layered internal microstructures with higher acetoclastic methanogenic activities (250–437 mL CH4 g−1 VS d−1) than smaller granules (150–260 mL CH4 g−1 VS d−1). The relative abundance of acetoclastic methanogens of larger granules was higher, confirming acetoclastic methane producing pathway was more prominent. However, there was no significant difference in the performance of the two reactors because they were operating below their capacities in terms of organic loading rate to volatile solids ratio.

Anaerobic technology for treatment of concentrated wastewater from estonian food industries

Anaerobic wastewater treatment technologies are used throughout the world for effective treatment of a wide variety of industrial wastewater, in particular for the wastewater from the food industry. This type of wastewater is rich in easily biodegradable carbohydrates and has a relatively low content in suspended solids. As an example, the anaerobic bio-degradation of organic matter in wastewater (cheese whey ) was studied on a laboratory - scale Upflow Anaerobic Sludge Blanket Reactor (UASB). This wastewater was found characterized by high COD concentration, from 58.000 to 72.000 mg/L. The digester efficiency duringthe treatment process of cheese wastewater at various organic loading rates (0.5 -16 kg COD/m3 • day ) was studied and its performance was assessed by monitoring the p value ( 6.8 -7.3 ) and biogas production ( up to 24 L /day ). The investigation has demonstrated that the process of anaerobic degradation wassufficiently effective for COD removal.

Population Changes of Eubacteria, Sulfate-Reducing Bacteria and Methanogenic Archaea in an Anaerobic Reactor Processing Ethanol Distillery Vinasse

Abstract The microbiological characterization by molecular techniques (DGGE and quantitative PCR) of Archaea, Bacteria domain and sulfate-reducing bacteria (SRB) from a laboratory scale Up-flow Anaerobic Sludge Blanket (UASB) processing sugar cane vinasse was performed during the operational phase with increasing organic loads. The organic load removal efficiency was between 97% and 75% for volumetric organic loads (VOL) in the range of 0.6 to 15.4 kgCOD.m-3.d−1 and for higher VOL (until 27.0 kgCOD.m-3 .d−1) the removal efficiency decreased to 48%. Archaea represented the majority of the estimated population (107 copies of 16S RNA ribosomal gene. mL-1) followed by bacteria (106 copies of 16S RNA ribosomal gene. mL-1) and sulfate-reducing bacteria (SRB) (105 copies of dsrB gene. mL-1). There was a significant difference between the populations of Archaea and SRB with increasing VOL. DGGE profiles show differences among populations with increasing VOL, especially with respect to sulfate-reducing bacteria. The presence of SRB together with a high sulfate removal percentage (97%) of about 15 kgCOD.m-3d-1h, indicates the establishment of a sulfidogenic process.

Hydraulic and organic rates applied to pilot scale UASB reactor for sugar cane vinasse degradation and biogas generation

A pilot-scale upflow anaerobic sludge blanket (UASB) reactor (120 L) was operated for biogas production by vinasse degradation. The reactor was operated for 700 days using a recirculation rate of 1:3 with organic loading rates (OLR) ranging from 0.5 to 32.4 kgCOD.m−3.d−1, upflow velocities ranged from 0.008 to 0.292 m h−1(feed added with recirculation) and the hydraulic retention time ranged from 33.33 to 0.86 days. The reactor demonstrated a stable performance at OLR at all applied loads. The COD removal efficiencies throughout the experiment were 87.5 ± 5.3 and 90.5 ± 3.6% for raw and soluble COD, respectively. Total volatile acids ranged from 59 mg L−1 to 585 mg L−1. The concentration of acetic and propionic acids at the reactor effluent reached 28 mg L−1 on OLR 20 kgCOD.m−3.d−1. The methane content in the biogas was 68.8 ± 7.14%.The methane yield of 0.299 ± 0.066 LCH4.g−1COD corresponds to about 76.4% of the theoretical methane yield. The methane productivity reached the highest value of 8.059 LCH4.L−1.d−1 at 32.27 kgCOD.m−3.d−1., corresponding to 83.9% of the theoretical value (9.611 LCH4.L−1.d−1). This result is very promising for power generation in the sugar and ethanol industry, complementing the energy balance of sugarcane, as shown by an energy balance evaluation.

Effect of Organic Loading Rate on Anaerobic Digestion Performance of Mesophilic (UASB) Reactor Using Cattle Slaughterhouse Wastewater as Substrate.

In this study, the performance of a laboratory scale upflow anaerobic sludge blanket (UASB) reactor operating at mesophilic temperature (35 °C) was examined. Cattle slaughterhouse wastewater (CSWW) was used as the main substrate. The total and effective volumes of the reactor were 8 L and 6 L, respectively. Twelve different organic loading rates (OLR) were applied and the performance was evaluated. The chemical oxygen demand (COD) removal efficiency was more than 90% during batch study. In the continuous study, COD removal was also approximately 90% at OLR 0.4 g/L d−1 which subsequently dropped to below 50% when the loading rate increased to 15 g/L d−1. Approximately 5 L/d of biogas was obtained with high methane concentration at stages VI and XI corresponding to OLR of 2 and 10 g/L d−1, respectively. It was observed that the concentration of volatile fatty acids was low and that the alkalinity of the wastewater was sufficient to avoid acidification. Specific methane yields of 0.36 and 0.38 LCH4/g COD added were achieved at OLR 7 and 10 g/L d−1. A hydraulic retention time (HRT) of 1 day was sufficient to remove greater than 70% of COD which correspond to 89% methane concentration. Parameters like soluble COD, NH3-N, pH, alkalinity, total suspended solid (TSS), fats, oil, and grease were also investigated. The results show that the UASB reactor could serve as a good alternative for anaerobic treatment of CSWW and methane production.

Performance evaluation of the pilot scale upflow anaerobic sludge blanket – Downflow hanging sponge system for natural rubber processing wastewater treatment in South Vietnam

A pilot-scale upflow anaerobic sludge blanket (UASB)–downflow hanging sponge system (DHS) combined with an anaerobic baffled reactor (ABR) and a settling tank (ST) was installed in a natural rubber processing factory in South Vietnam and its process performance was evaluated for 267days. The UASB reactor achieved a total removal efficiency of 55.6±16.6% for chemical oxygen demand (COD) and 77.8±10.3% for biochemical oxygen demand (BOD) with an organic loading rate of 1.7±0.6kg-COD·m−3·day−1. The final effluent of the proposed system had 140±64mg·L−1 of total COD, 31±12mg·L−1 of total BOD, and 58±24mg-N·L−1 of total nitrogen. The system could significantly reduce 92% of greenhouse gas emissions and 80% of hydraulic retention times compared with current treatment systems.

Bacillus sp. strains to produce bio-hydrogen from the organic fraction of municipal solid waste

Bio-hydrogen, obtained by fermentation of organic residues, is considered a promising source of renewable energy. However, the industrial scale H2 production from organic waste is far to be realized as technical and economical limitations have still to be solved. Low H2 yields and lack of industrially robust microbes are the major limiting factors.To look for bacteria with both interesting hydrogen fermentative traits and proper robustness, granular sludge from a brewery full scale Upflow Anaerobic Sludge Blanket (UASB) digester was selected as trove of microbes processing complex substrates. One hundred and twenty bacterial strains, previously isolated from heat-treated granular sludge and genetically identified by 16S rDNA sequencing, were screened for extracellular hydrolytic enzymes on cellulose, hemicellulose, starch, pectin, lipids, protein. The most interesting hydrolytic strains were assessed for their H2 production from glucose and soluble starch. Two Bacillus sp. strains, namely F2.5 and F2.8, exhibited high H2 yields and were used as pure culture to convert Organic Fraction of Municipal Solid Waste (OFMSW) into hydrogen. The strains produced up to 61mL of H2 per grams of volatile solids and could be considered as good candidates towards the development of industrially relevant H2-producing inoculants. This is the first successful application of pure microbial cultures in bio-hydrogen production from OFMSW.

Treatment of Copper Contaminated Municipal Wastewater by Using UASB Reactor and Sand-Chemically Carbonized Rubber Wood Sawdust Column.

The performance of a laboratory scale upflow anaerobic sludge blanket (UASB) reactor and its posttreatment unit of sand-chemically carbonized rubber wood sawdust (CCRWSD) column system for the treatment of a metal contaminated municipal wastewater was investigated. Copper ion contaminated municipal wastewater was introduced to a laboratory scale UASB reactor and the effluent from UASB reactor was then followed by treatment with sand-CCRWSD column system. The laboratory scale UASB reactor and column system were observed for a period of 121 days. After the posttreatment column the average removal of monitoring parameters such as copper ion concentration (91.37%), biochemical oxygen demand (BODT) (93.98%), chemical oxygen demand (COD) (95.59%), total suspended solid (TSS) (95.98%), ammonia (80.68%), nitrite (79.71%), nitrate (71.16%), phosphorous (44.77%), total coliform (TC) (99.9%), and fecal coliform (FC) (99.9%) was measured. The characterization of the chemically carbonized rubber wood sawdust was done by scanning electron microscope (SEM), X-ray fluorescence spectrum (XRF), and Fourier transforms infrared spectroscopy (FTIR). Overall the system was found to be an efficient and economical process for the treatment of copper contaminated municipal wastewater.

A novel biological sulfate reduction method using hydrogenogenic carboxydotrophic mesophilic bacteria

Sulfate reduction by carbon monoxide (CO) utilizing anaerobic biomass from a large scale upflow anaerobic sludge blanket reactor was studied. Anaerobic mixed microbial consortia from five different sources were initially examined for their biological CO conversion potential. Among the different biomass, the biomass from an upflow anaerobic sludge blanket reactor treating domestic wastewater, located in Kavoor, Karnataka, India, showed a maximum CO conversion efficiency. The effect of three main culture parameters, i.e. inoculum volume, initial CO concentration and temperature on simultaneous CO conversion and sulfate reduction was assessed employing the Taguchi experimental design technique. A maximum CO conversion of 85.62% and a maximum sulfate reduction of 50.65% were achieved. Furthermore, the experimental data was fitted to substrate inhibition models reported in the literature. Among the different models, Monods and Haldane kinetic models were found most suitable to describe the kinetics of biomass growth and CO removal by the anaerobic biomass.

Biogas production from brewery spent grain enhanced by bioaugmentation with hydrolytic anaerobic bacteria

Lignocellulosic substrates are widely available but not easily applied in biogas production due to their poor anaerobic degradation. The effect of bioaugmentation by anaerobic hydrolytic bacteria on biogas production was determined by the biochemical methane potential assay. Microbial biomass from full scale upflow anaerobic sludge blanket reactor treating brewery wastewater was a source of active microorganisms and brewery spent grain a model lignocellulosic substrate. Ruminococcus flavefaciens 007C, Pseudobutyrivibrio xylanivorans Mz5T, Fibrobacter succinogenes S85 and Clostridium cellulovorans as pure and mixed cultures were used to enhance the lignocellulose degradation and elevate the biogas production. P. xylanivorans Mz5T was the most successful in elevating methane production (+17.8%), followed by the coculture of P. xylanivorans Mz5T and F. succinogenes S85 (+6.9%) and the coculture of C. cellulovorans and F. succinogenes S85 (+4.9%). Changes in microbial community structure were detected by fingerprinting techniques.

Performance of an UASB Reactor at Lab-Scale Treating Domestic Wastewater with Low Concentrations of Copper

Aims: The objective was to investigate the effect of copper at low concentrations in an Upflow Anaerobic Sludge Blanket (UASB) reactor performance under continuous conditions and its geochemical distribution in anaerobic sludge through sequential extraction. Study Design: Continuous operation. Original Research Article Barcelo-Quintal et al.; BJAST, 7(5): 456-466, 2015; Article no.BJAST.2015.164 457 Place and Duration of Study: Department of Basic Science, Universidad Autonoma Metropolitana -Azcapotzalco, between July 2013 and December 2013. Methodology: A lab scale UASB reactor was inoculated with sludge from a full-scale UASB reactor treating brewery wastewater and it was allowed to acclimate during two months. After acclimation period, three different copper concentrations were added to UASB influent: 0.25, 0.65 and 1.35 mg l -1 , during one month each one. At the end of the experiment, freeze-dried samples of inoculum and UASB reactor sludge were treated with a series of solvents to perform sequential extractions. pH, temperature, oxidation reduction potential (ORP), total chemical oxygen demand (COD), the ratio between partial and total alkalinity, total suspended solids and volatile suspended solids were measured in UASB reactor influent and effluent. Results: Sequential extractions showed that the fraction with the major affinity with copper was organic/sulfide bound, with a percentage distribution of 96%. Regarding UASB performance, copper caused a total alkalinity diminution in the effluent; however, the system buffer capacity was enough to overcome such instability, as partial alkalinity/total alkalinity ratio results confirmed. COD removal decreased 15% when 1.35 mg l Cu was added in comparison to acclimation period. Conclusion: Copper addition in UASB reactor influent at low concentrations affected adversely its performance; though, did not cause complete inhibition to anaerobic microorganisms. Metal speciation results in the inoculum and the UASB reactor evidenced that the fraction which had the major affinity with copper was the organically/sulfide bound fraction, however, further studies are needed to establish which is the weight of organic matter and sulfide in copper binding.

Adsorption of zinc by biogenic elemental selenium nanoparticles

Abstract The adsorption of Zn 2+ ions onto biogenic elemental selenium nanoparticles (BioSeNPs) was investigated. BioSeNPs were produced by reduction of selenite (SeO 3 2− ) in the presence of anaerobic granules from a full scale upflow anaerobic sludge blanket (UASB) reactor treating paper mill wastewater. The BioSeNPs have an iso-electric point at pH 3.8 at 5 mM background electrolyte concentration. X-ray photoelectron spectroscopy showed the presence of a layer of extracellular polymeric substances on the surface of BioSeNPs providing colloidal stability. Batch adsorption experiments showed that the uptake of Zn 2+ ions by BioSeNPs was fast and occurred at a pH as low as 3.9. The maximum adsorption capacity observed was 60 mg of zinc adsorbed per g of BioSeNPs. The Zn 2+ ions adsorption on the BioSeNPs was largely unaffected by the presence of Na + and Mg 2+ , but was impacted by the presence of Ca 2+ and Fe 2+ ions. The colloidal stability of BioSeNPs decreased with the increasing Zn 2+ ions loading on BioSeNPs (increase in mg of zinc adsorbed per g of BioSeNPs), corresponding to the neutralization of the negative surface charge of the BioSeNPs, suggesting gravity settling as a technique for solid–liquid separation after adsorption. This study proposes a novel technology for removal of divalent cationic heavy metals by their adsorption on the BioSeNPs present in the effluent of an UASB reactor treating selenium oxyanions containing wastewaters.

Sequential treatment of diluted olive pomace leachate by digestion in a pilot scale UASB reactor and BDD electrochemical oxidation

The efficiency of the anaerobic treatment of olive pomace leachate (OPL) at mesophilic conditions was investigated. Daily and cumulative biogas production was measured during the operational period. The maximum biogas flowrate was 65 L/d, of which 50% was methane. In addition, the applicability of electrochemical oxidation as an advanced post-treatment method for the complete removal of chemical oxygen demand (COD) from the anaerobically treated OPL was evaluated. The diluted OPL, having a pH of 6.5 and a total COD of 5 g/L, was first treated in a 600 L, pilot-scale up-flow anaerobic sludge blanket (UASB) reactor. The UASB reactor was operated for 71 days at mesophilic conditions (32 ± 2 °C) in a temperature-controlled environment at a hydraulic retention time of 3 days, and organic loading rates (OLR) between 0.33 and 1.67 g COD/(L.d). The UASB process led to a COD removal efficiency between 35 and 70%, while the particulate matter of the wastewater was effectively removed by entrapment in the sludge blanket of the reactor. When the anaerobic reactor effluent was post-treated over a boron-doped diamond (BDD) anode at 18 A and in the presence of 0.17% NaCl as the supporting electrolyte, complete removal of COD was attained after 7 h of treatment predominantly through total oxidation reactions. During electrochemical experiments, three groups of organo-chlorinated compounds, namely trihalomethanes (THMs), haloacetonitriles (HANs) and haloketons (HKs), as well as 1,2-dichloroethane (DCA) and chloropicrin were identified as by-products of the process; these, along with the residual chlorine are thought to increase the matrix ecotoxicity to Artemia salina.

Colour removal and its mechanisms in textile wastewater treatment by UASB reactor system with anaerobic granular sludge

Textile wastewaters generated from different stages of textile processing contain various toxicants orpollutants that are seriously harmful to natural aquatic environment when released without propertreatment. Although there are different methods, which can be adopted for the treatment of textilewastewater. biological approaches are considered as environmentally friendly, low cost and effectivemethods over other physico-chemical methods. In the present study, simulated textile wastewater(STW) prepared by mixing of three popular acid dyes (Acid blue 204, Acid red 131 and Acid yellow79) in synthetic wastewater was studied for the decolourization and removal of degradable organic inthe laboratory scale Upflow Anaerobic Sludge Blanket Reactor system with anaerobic granular sludgefor about five months at different organic and dye loading rates. The colour removal mechanismsunder .maerobic treatment were also examined since microbial colour removal occurs basically in twoways namely biological degradation, which is more important in textile wastewater treatment, andadsorption of dye molecules onto microbial biomass. Chemical oxygen demand (COD) removal ofacid red 131 (AR 131) containing STW was about 80% at 300 mg/l dye concentration and it was over89% in acid yellow 79 (AY79) dye containing STW under studied conditions. Although acid blue 204(AB204) showed a little inhibition over rnethanogenic consortia, about 93% of COD removal wasobserved at 100 mg/l dye concentration. Colour removal of AR 131 dye containing STW was 95% and.it was credited to biodegradation. Treatment of STW prepared using AY79 showed 95% colourremoval owing to biodegradation while AB204 was quite resistant to biodegradation by anaerobicrn icroorgan isms. Observed colour removal was merely due to the adsorption of dyes onto microbialgranules. Even though a little accumulation of volatile fatty acid (YFA) was observed in increaseddye concentrations, the detected values ofYFA, alkalinity and pH showed that those values were inthe range of desirable limits of anaerobic process. It seems that AR 131 and AY79 can be decolourizedalmost completely by UASB reactor system while AB204 cannot be decolourised since all colourremoval attributed to adsorption of dye onto microbial granules. It can be concluded that anaerobictechnology can be used for the treatment of textile wastewater containing different dyes as an alternativemethod over other methods. However, further study ofUASB reactor for the treatment of real textilewastewater is suggested to find out matrix effect of other chemicals present in real textile wastewaterbefore application to the real world situations.

Effect of upflow velocity on the effluent membrane fouling potential in membrane coupled upflow anaerobic sludge blanket reactors

This study investigated the effect of upflow velocity (Vup) on biological removal efficiency and effluent filterability in a laboratory scale upflow anaerobic sludge blanket (UASB) reactor. Upflow velocities of 1.2, 0.6 and 1.2m/h were applied in three successive stages over a total operation period of 116 days. Filterability tests were carried out during each stage in order to assess the effect of Vup on subsequent membrane performance. Results indicated a significant impact of Vup on both biological performance and physicochemical effluent characteristics. The observed differences in protein/carbohydrate ratio and particle size distribution (PSD), which play important roles in membrane fouling, lead to the hypothesis that Vup is a critical parameter for effluent filterability in membrane coupled UASB reactors. Results showed that filterability of the effluent during the operation at 0.6m/h was better than that during the operation at 1.2m/h.

Dedicated Observer Scheme for Fault Diagnosis and Isolation in Instruments of an Anaerobic Reactor

This paper proposes a dedicated observer scheme for fault diagnosis and isolation in instruments of an anaerobic reactor. An asymptotic observer is proposed for the estimation of the concentration of Chemical Oxygen Demand (COD), the concentration of anaerobic biomass and the produced biogas flow rate for an anaerobic reactor. The proposed observer is based on the ADM1 for applications in continuous UASB reactors and its main feature is that allows the monitoring of a dynamic balance between anabolic (biological synthesis) and catabolic (methane production) fluxes without biomass measurements in the reactor. Experimental results are shown using the ADM1 for the treatment of wastewater with high organic matter content from a brewery. Validation is carried out using real data obtained from a 2.1 L laboratory scale Up-flow Anaerobic Sludge Blanket (UASB) reactor.