Up-flow Column Reactor Research Articles

E-peroxone process of a chlorinated compound: Oxidant species, degradation pathway and phytotoxicity

An electro-peroxone (EP) process was conducted in an up-flow bubble column reactor with BDD electrodes. The efficiency of the process was tested in the 4-Chlorophenol (4-CPh) mineralization and compared with that attained by single treatments like ozonation (O3) and electro-oxidation (EO). At [TOC]o= 56 mg·L−1, pHo= 7.0, T = 293 K, j = 0.06 A·cm−2, t = 120 min, the oxidation power decreased in the following order EP>EO>O3, and the TOC removed was, in the same order, 100%> 93%> 40%. The calculated synergy coefficient was 0.31, while the mineralization current efficiency percentage (MCE%) and the energy consumption (EC) were 12.24% and 11.48%, 2.84 and 2.31 kW·h−1, for EP and EO, respectively. The germination percentage of Lactuca sativa, was 100%, 30% and 20%, at the end of EP, EO and O3, respectively. This indicates that phytotoxicity, was only eliminated with EP. Based on the by-products, e.g. aromatic compounds (4-chlorocatechol, catechol, phenol, p-benzoquinone, hydroquinone) and carboxylic acids (maleic, formic, fumaric, succinic, oxalic, malonic and acetic acids) identified by UHPLC-UV/DAD and the changes of the concentration of chloride ion (Cl-), hypochlorite, chlorite, chlorate and perchlorate, a reaction pathway was proposed for the 4-CPh mineralization by the E-peroxone process. It was demonstrated that under the studied conditions both, hydrogen peroxide and ozone, are produced during EO. At the end of EO, H2O2, carboxylic acids and perhaps persulfates, are responsible for the phytotoxicity of the solution.

Up-flow anaerobic column reactor for sulfate-rich cadmium-bearing wastewater purification: system performance, removal mechanism and microbial community structure.

This study constructed an up-flow anaerobic column reactor fed with synthetic sulfate-rich cadmium (Cd(II))-bearing wastewater, for investigating its Cd(II) removal performance and mechanism. Long-term experiment results manifest that introducing Cd(II) into influent led to an enhanced sulfate removal but did not increase the effluent sulfide concentration, implying the CdS formation. When influent Cd(II) concentration was shifted from 50 to 100mg/L, the median Cd(II) removal rate was increased from 13.6 to 32.2mg/(L·d). Batch tests indicate that the uptake and sequestration function of anaerobes merely led to a small portion of Cd(II) removal. A majority of aqueous Cd(II) (86.3%) was eliminated by precipitation reactions. The generated precipitates were found to be dominantly presented in carbonate, Fe-Mn oxide, sulfide bound and residue forms, which account for 92.6-93.9% of total Cd content of sludge obtained at diverse operation phases. The crystallographic CdS (i.e., residue fraction) particles have nano-scale sizes, and the relatively high atomic ratio of S to Cd was likely due to the adsorption/deposition of other sulfides. The dominant sulfate-reducing bacteria (SRB) were recognized as Desulfurella, Desulforhabdus and Desulfovibrio, and the primary competitor with them for substrate utilization were identified to be methanogens.

Enrichment and characterization of Anammox bacteria in a non-woven membrane reactor

Abstract An upflow column reactor packed with nonwoven fabric carrier was used to enrich anaerobic ammonium oxidation (Anammox) sludge. After 101 days, the reactor Anammox sludge concentration increased from 470 to 3,118 mg·L−1. In the stable operating stage, the average total nitrogen (TN) volume loading rate was 818.3 mg·L−1, and the maximum removal efficiencies of NH4+-N, NO2−-N and TN were 65.9, 81.2 and 63.8%, respectively. Scanning electron microscopy (SEM) showed that the cultivated sludge was dominated by a mix of short rod-shaped and spherical bacteria, which accumulated to the typical cauliflower-like aggregates assumed to be the Anammox culture. Fluorescence in situ hybridization (FISH) analysis using 16S rRNA showed that the dominant population developed in the reactor when hybridized with both PLA46 and Amx820 gene probes. This indicates that the cultivated biomass may comprise Planctomycetes bacteria. The results of real-time quantitative PCR (qPCR) showed that these bacteria formed 45 to 60% of the total bacteria in the Anammox sludge. The study demonstrated successful detection and enrichment of Anammox bacteria in wastewater.

Modeling of continuous dark fermentative hydrogen production in an anaerobic up-flow column bioreactor

Dark fermentation (DF) of several types of wastes is a promising process to alleviate environmental pollution as it leads to the production of valuable hydrogen (H2) gas and high added value products, such as volatile fatty acids (VFAs). In this study a kinetic model for fermentative H2 production in an Up-flow column reactor (UFCR) is presented. Τhe model structure includes seven biochemical reactions taking place in a two-phase biofilm-liquid system. The observed difference in the overall stoichiometry of the bioconversion process for different hydraulic retention times (HRTs) is predicted by this model as it is attributed to the difference in the extent of individual bioconversion steps, each of which has a constant stoichiometry but a different rate depending on the HRT. The respective kinetic parameters were estimated through model fitting to the experimental results of the UFCR, which operated at different HRTs (12–2 h) and fed with the soluble fraction of a food industry waste (FIW). A good agreement of the experimental and predicted values of soluble metabolic products and H2 production was obtained, rendering this model as a useful tool for further investigation and prediction of the characteristics of the DF process in attached-biomass growth systems.

Adsorptive column studies for removal of Reactive Blue 4 dye using dry cells of Rhizopus oryzae (MTCC 262)

The biosorption potential of dry biomass of Rhizopus oryzae (MTCC 262) in removing a textile dye Reactive Blue 4 from dye contaminated wastewater using up-flow packed-bed column reactor has been studied. The impact of operating parameters like flow rate of dye solution, bed height of column and concentration of dye in the feed solution on the removal potential has also been studied. The Adam-Bohart Model, Yoon-Nelson Model and Thomas model are used for the analysis of experimental data. Dye removal of 71.81% is obtained using dry biomass at flow rate of 2 mL min-1of dye solution, bed height of 15 cm and influent dye concentration of 200 mg L-1. Adsorbed dye can be successfully recovered from dry R.oryzae (MTCC 262) biomass of packed bed column reactor by running 1 (N) NaOH solution. Results demonstratesignificant reduction in Reactive Blue 4 concentration after the biosorption process.

Volatile fatty acid (VFA) removal of anaerobically digested molasses wastewater (MWW) in aerobic sequencing batch reactor (SBR) and up-flow aerobic column reactor (UACR) under various hydraulic retention time (HRT)

This paper analyses the removal of volatile fatty acid (VFA) of anaerobically digested molasses wastewater (MWW) in three different phases, which are acclimatization phase, aerobic sequencing batch reactor (SBR) phase and up-flow aerobic column reactor (UACR) phase. The UACR was modified from SBR by recycling the effluent to the influent tank for circulation purpose. The effect of hydraulic retention time (HRT) was determined during the operation of UACR. The influent tank was filled with 1.0, 2.0, 3.0, 4.0 and 5.0 L of anaerobically digested MWW which corresponds to HRT 14, 7, 4.7, 3.5, and 2.8 days. The operation of SBR achieved 85.4 ± 1.8 % of VFA removal at HRT 14 days. When modified to UACR, the VFA removal efficiency reached 85.5 ± 2.3 % at HRT 14 days. The VFA removal changed from 85.5 ± 2.3, 81.0 ± 0.4, 81.3 ± 2.2, 84.6 ± 5.1 to 87.4 ± 0.7 % in the UACR when the HRT decreased from 14 to 2.8 days. The UACR achieved optimum VFA removal at HRT 2.8 days and had greater performance when compared to SBR since it required shorter aeration time to obtain similar result.

Efficient feeding strategy to enhance the start-up of anaerobic ammonium oxidation process in an anaerobic up-flow biofilm column reactor

Anaerobic ammonium oxidation (anammox) performed by bacteria that belong to the Planctomycetes phylum could potentially be applied to treat wastewater with high ammonium content. However, anammox application is hindered by the slow growth of bacteria and nitrite and free ammonia inhibition. Thus, this study aims to enrich anammox culture in a 1.0 L anaerobic up-flow biofilm column reactors equipped with a non-woven fabric material, under three different feeding modes: (i) batch, (ii) fed-batch and (iii) continuous, to enhance the start-up of anammox process. A 16S rDNA gene analysis targeting planctomycetes-anammox bacteria was performed on various sludge sources to screen the appropriate inoculum of anammox microorganisms prior to the enrichment study. A reactor with a continuous mode of feeding showed the most effective consumption of N–NH4+ and N– NO2–, with the highest nitrogen removal rate of 0.28 kg N m–3 d–1 at 0.6 d hydraulic retention time and 27°C, compared to the fed-batch and batch of 0.14 and 0.004 kg N m–3 d–1, respectively. The enriched anammox culture showed as close to the ‘Candidatus Kuenenia stuttgartiensis’ genera based on 16S rDNA analysis. Fluorescence in-situ hybridization analysis targeting the 16S rDNA gene of anammox bacteria further confirmed the existence of an anammox population in the enriched culture.

Biogenic coal-to-methane conversion can be enhanced with small additions of algal amendment in field-relevant upflow column reactors

Subsurface coal environments, where biogenic coal-to-methane conversion occurs, are difficult to access, resulting in inherent challenges and expenses for in situ experiments. Previous batch reactor studies provided insights into specific processes, pathways, kinetics, and engineering strategies, but field-relevance is restricted due to limited substrate availability or byproduct accumulation that may influence reactions or metabolisms. In this study, continuous-flow column reactors were used to overcome some batch limitations, improve the understanding of in situ conditions, and increase field-relevance for subsurface engineering technology development. The bench-scale reactor system was constructed to investigate the addition of algal amendment for enhancing microbial coal-to-methane conversion previously developed in batch systems. Four reactor columns were packed with coal and inoculated with a microbial consortium from the same Flowers-Goodale coal bed. Two reactors were amended with 13C-labeled algal amendment on day 0, and two were unamended. On day 61, one previously amended and one previously unamended reactor were re-amended. Produced gases were captured in a gas trap, and CH4 and CO2 were quantified. The reactor amended twice produced 1712.6 µmol CH4 (4.6% as 13CH4). The reactor amended only on day 0 produced 1485.5 µmol CH4 (2.6% as 13CH4). The reactor amended only on day 61 produced 278.9 µmol CH4 (3.9% as 13CH4). The reactor with no amendment produced no measurable gases for the duration of the 172-day experiment. Amendment increased the rate of coal-to-methane conversion and total gas production; most of the produced gases were due to coal conversion with only small contributions (<7%) from amendment conversion.

Draft Genome Sequence of a Novel Marine Anaerobic Ammonium-Oxidizing Bacterium, "Candidatus Scalindua sp."

A novel anaerobic ammonium-oxidizing (anammox) bacterium was detected in an upflow column reactor treating synthetic nitrogen-rich saline solution. Here, we assembled a 4.59-Mb draft genome sequence of this bacterium, identified as a member of the genus "Candidatus Scalindua," that has 84% nucleotide-level genomic similarity with the closest related anammox bacterium ("Candidatus Scalindua rubra").

Aggregation ability of three phylogenetically distant anammox bacterial species

Anaerobic ammonium-oxidizing (anammox) bacteria are well known for their aggregation ability. However, very little is known about cell surface physicochemical properties of anammox bacteria and thus their aggregation abilities have not been quantitatively evaluated yet. Here, we investigated the aggregation abilities of three different anammox bacterial species: “Candidatus Brocadia sinica”, “Ca. Jettenia caeni” and “Ca. Brocadia sapporoensis”. Planktonic free-living enrichment cultures of these three anammox species were harvested from the membrane bioreactors (MBRs). The physicochemical properties (e.g., contact angle, zeta potential, and surface thermodynamics) were analyzed for these anammox bacterial species and used in the extended DLVO theory to understand the force-distance relationship. In addition, their extracellular polymeric substances (EPSs) were characterized by X-ray photoelectron spectroscopy and nuclear magnetic resonance. The results revealed that the “Ca. B. sinica” cells have the most hydrophobic surface and less hydrophilic functional groups in EPS than other anammox strains, suggesting better aggregation capability. Furthermore, aggregate formation and anammox bacterial populations were monitored when planktonic free-living cells were cultured in up-flow column reactors under the same conditions. Rapid development of microbial aggregates was observed with the anammox bacterial population shifts to a dominance of “Ca. B. sinica” in all three reactors. The dominance of “Ca. B. sinica” could be explained by its better aggregation ability and the superior growth kinetic properties (higher growth rate and affinity to nitrite). The superior aggregation ability of “Ca. B. sinica” indicates significant advantages (efficient and rapid start-up of anammox reactors due to better biomass retention as granules and consequently stable performance) in wastewater treatment application.

Mixing in a co‐current upflow bubble column reactors with and without internals

AbstractLiquid phase mixing is a phenomenon that results mainly due to convective and turbulent flow fields, which are generated by hydrodynamic interactions between the gas and liquid phases within a continuous co‐current upflow bubble column reactor. The extent of liquid phase mixing is usually quantified through the mixing time, or the axial dispersion coefficient. In the present work, the computational fluid dynamics (CFD) simulations for mixing and RTD in a continuous bubble column (with and without internals) are performed by using OpenFOAM 2.3.1. The superficial gas velocities were 0.014, 0.088, and 0.221 m/s and the superficial liquid velocities were 0.005 and 0.014 m/s. The simulations have been performed for three different configurations of the bubble column, that is, (a) an open bubble column, (b) a column with one vertical central rod of 36 mm diameter, (c) a column with the same central rod and four vertical additional rods of 12 mm diameter. The effects of superficial gas and liquid velocities and column internals were investigated on liquid phase mixing and the axial dispersion coefficient. Comparisons have been made between the experimental measurements and the CFD simulations.

Impact of temperature and hydraulic retention time on pathogen and nutrient removal in woodchip bioreactors

Woodchip denitrification bioreactors are an important edge-of-field practice for treating agricultural drainage; however, their ability to filter microbial pollutants has primarily been explored in the context of wastewater treatment. Upflow column reactors were constructed and tested for E. coli, Salmonella, NO3-N, and dissolved reactive phosphorus (DRP) at hydraulic retention times (HRTs) of 12 and 24 h and at controlled temperatures of 10 and 21.5 °C. Influent solution was spiked to 30 mg L−1 NO3-N, 2–8 × 105E. coli and Salmonella, and 0.1 mg L−1 DRP. Microbial removal was consistently observed with removal ranging from 75 to 78% reduction at 10 °C and 90–96% at 21.5 °C. The concentration reduction ranged from 2.75 to 9.03 × 104 for both organisms. HRT had less impact on microbial removal than temperature and thus further investigation of removal under lower HRTs is warranted. Nitrate concentrations averaged 96% reduction (with load removal of 14.6 g N m−3 d−1) from 21.5 °C columns at 24 HRT and 29% reduction (with load removal of 8.8 g N m−3 d−1) from 10 °C columns at 12 HRT. DRP removal was likely temporary due to microbial uptake. While potential for removal of E. coli and Salmonella by woodchip bioreactors is demonstrated, system design will need to be considered. High concentrations of these microbial contaminants are likely to occur during peak flows, when bypass flow may be occurring. The results of this study show that woodchip bioreactors operated for nitrate removal have a secondary benefit through the removal of enteric bacteria.

Nitrogen Removal by Anammox Biofilm Column Reactor at Moderately Low Temperature

The anaerobic ammonium oxidation (anammox) as a new biological approach for nitrogen removal has been considered to be more cost-effective compared with the combination of nitrification and denitrification process. However, the anammox bioreactors are mostly explored at high temperature (&gt;300C) in which temperature controlling system is fully required. This research was intended to develop and to apply anammox process for high nitrogen concentration removal at ambient temperature used for treating wastewater in tropical countries. An up-flow biofilm column reactor, which the upper part constructed with a porous polyester non-woven fabric material as a carrier to attach the anammox bacteria was operated without heating system. A maximum nitrogen removal rate (NRR) of 1.05 kg-N m3 d-1 was reached in the operation days of 178 with a Total Nitrogen (TN) removal efficiency of 74%. This showed the biofilm column anammox reactor was successfully applied to moderate high nitrogen removal from synthetic wastewater at moderately low temperature. Keywords: Anammox, biofilm column reactor, ambient temperature, nitrogen removal

Rapid cultivation of free-living planktonic anammox cells

Despite that anaerobic ammonium oxidizing (anammox) bacteria are key players in the global nitrogen cycle, no pure cultures are still available. Planktonic cell culture with high purity is, therefore, essential for physiological and biochemical studies of anammox bacteria. However, development of such planktonic cell cultures requires an enormous amount of time and effort. Here we developed a novel rapid method for cultivating free-living planktonic anammox cells. First, anammox granules were physically dispersed, immobilized in 6% polyvinyl alcohol–4% sodium alginate (PVA-SA) gel beads, and then pre-cultured in an up-flow column reactor. Anammox bacteria grew rapidly as loosely flocculated micro-clusters in the gel beads. After 18 days of pre-cultivation, mature gel beads were harvested, physically dispersed by vortex and inoculated into a membrane bioreactor (MBR). The MBR was then continuously operated at a low nitrogen loading rate (<0.9 kg-TN m−3 d−1). After 17 days of operation, active free-living planktonic anammox cells with purity >95% were successfully developed in the MBR. Total culture time (gel beads and MBR) to accomplish free-living planktonic anammox cells was only 35 days, which was significantly shorter than the previous reports. This new cultivation technique could greatly facilitate various microbial, physiological and biochemical studies of anammox bacteria.

Nitrogen Removal by Anammox Biofilm Column Reactor at Moderately Low Temperature

The anaerobic ammonium oxidation (anammox) as a new biological approach for nitrogen removal has been considered to be more cost-effective compared with the combination of nitrification and denitrification process. However, the anammox bioreactors are mostly explored at high temperature (>300C) in which temperature controlling system is fully required. This research was intended to develop and to apply anammox process for high nitrogen concentration removal at ambient temperature used for treating wastewater in tropical countries. An up-flow biofilm column reactor, which the upper part constructed with a porous polyester non-woven fabric material as a carrier to attach the anammox bacteria was operated without heating system. A maximum nitrogen removal rate (NRR) of 1.05 kg-N m3 d-1 was reached in the operation days of 178 with a Total Nitrogen (TN) removal efficiency of 74%. This showed the biofilm column anammox reactor was successfully applied to moderate high nitrogen removal from synthetic wastewater at moderately low temperature. Keywords: Anammox, biofilm column reactor, ambient temperature, nitrogen removal

Maximum specific growth rate of anammox bacteria revisited

Anammox bacteria have long been considered to be slow-growing bacteria. However, it has recently been reported that they could grow much faster than previously thought when they were cultivated in a membrane bioreactor (MBR) with a step-wise decrease in the solid retention time (SRT). Here, we reevaluated the maximum specific growth rates (μmax) of three phylogenetically distant anammox bacterial species (i.e. “Ca. Brocadia sinica”, “Ca. Jettenia caeni” and “Ca. Scalindua sp.”) by directly measuring 16S rRNA gene copy numbers using newly developed quantitative polymerase chain reaction (qPCR) assays. When free-living planktonic “Ca. B. sinica” and “Ca. J. caeni” cells were immobilized in polyvinyl alcohol (PVA) and sodium alginate (SA) gel beads and cultivated in an up-flow column reactor with high substrate loading rates at 37 °C, the μmax were determined to be 0.33 ± 0.02 d−1 and 0.18 d−1 (corresponding doubling time of 2.1 day and 3.9 day) from the exponential increases in 16S rRNA genes copy numbers, respectively. These values were faster than the fastest growth rates reported for these species so far. The cultivation of anammox bacteria in gel beads was achieved less than one month without special cultivation method and selection pressure, and the exponential increase in 16S rRNA gene numbers was directly measured by qPCR with high reproducibility; therefore, the resulting μmax values were considered accurate. Taken together, the fast growth is, therefore, considered to be an intrinsic kinetic property of anammox bacteria.

Improvement of start-up and nitrogen removal of the anammox process in reactors inoculated with conventional activated sludge using biofilm carrier materials

ABSTRACTThe start-up of the anaerobic ammonium oxidation (anammox) process in three up-flow column reactors seeded with common mixed activated sludge and added with three materials, sponge (R1), sponge + volcanic rock (R2) and sponge + charcoal (R3), as carriers for biofilm formation were comparatively investigated in this study. The supplement of volcanic rock and charcoal could significantly shorten the start-up time of the anammox process, which primarily occurred in the activity-enhanced phase, with ammonium and nitrite removal efficiencies stabilized above 92.5% and 93.4% after an operation period of 145, 105 and 121 d for R1, R2 and R3, respectively. After the successful anammox start-up, R2 performed significantly better in TN removal (p < .05), achieving an average rate of 91.0% and 191.5 g N m−3 d−1 compared to R1 of 88.4% and 172.1 g N m−3 d−1, and R3 of 89.9% and 180.1 g N m−3 d−1 in the steady running phase. The ratios of consumed and generated /consumed after anammox start-up were lower than the theoretical values, probably suggesting the simultaneous existences of anammox, denitrification as well as nitrification processes in the reactors. A reddish brown biofilm was wrapped on the carriers and morphological detection of biofilm displayed the presentations of thick and compact floc aggregates and some filamentous bacteria on the sponge, and spherical-, ovoid- and shortrod-shaped microorganisms on the volcanic rock and charcoal. Using porous material as carrier for biofilm development is an effective strategy for practical application of the anammox reactor.

Packed-bed column biosorption of chromium(VI) and nickel(II) onto Fenton modified Hydrilla verticillata dried biomass

The present study represents the first attempt to investigate the biosorption potential of Fenton modified Hydrilla verticillata dried biomass (FMB) in removing chromium(VI) and nickel(II) ions from wastewater using up-flow packed-bed column reactor. Effects of different packed-bed column parameters such as bed height, flow rate, influent metal ion concentration and particle size were examined. The outcome of the column experiments illustrated that highest bed height (25cm); lowest flow rate (10mLmin−1), lowest influent metal concentration (5mgL−1) and smallest particle size range (0.25–0.50mm) are favourable for biosorption. The maximum biosorption capacity of FMB for chromium(VI) and nickel(II) removal were estimated to be 89.32 and 87.18mgg−1 respectively. The breakthrough curves were analyzed using Bed Depth Service Time (BDST) and Thomas models. The experimental results obtained agree to both the models. Column regeneration experiments were also carried out using 0.1M HNO3. Results revealed good reusability of FMB during ten cycles of sorption and desorption. Performance of FMB-packed column in treating secondary effluent was also tested under identical experimental conditions. Results demonstrated significant reduction in chromium(VI) and nickel(II) ions concentration after the biosorption process.

Effects of organic matter in livestock manure digester liquid on microbial community structure and in situ activity of anammox granules

Anaerobic ammonium oxidation (anammox) is a promising process for NH4+-rich wastewaters such as anaerobic digester liquids. In the present study, we investigated various properties of an up-flow column reactor containing anammox granules and fed with a real digester liquid at four different concentrations (Phases 1 to 4). The efficiencies of NH4+ and NO2− removal decreased by up to 32% and 42%, respectively, in the digester-liquid-fed reactor (reactor-DL). When the performance of reactor-DL deteriorated, the community structure, spatial distribution, and in situ anammox activity in the two reactors were further investigated using 16S rRNA gene-based phylogenetic analysis, fluorescence in situ hybridization (FISH), and microelectrode measurements. The phylogenetic analysis and FISH results showed that non-anammox bacteria were predominant in the granule outer layers in reactor-DL, whereas anammox bacteria still dominated the granule interiors. Microelectrode measurements showed clear evidence of NH4+ oxidation activity in the interiors of granules from reactor-DL. Batch experiments using anammox granules at different acetate concentrations indicated that concentrations up to 50 mM had no effects on the anammox activity, whereas inorganic carbon uptake decreased in the presence of acetate. The present study clearly shows that the anammox activity and anammox bacterial density in the granules were maintained after feeding the digester liquid to the reactor for 140 days.

Food Industry Waste’s Exploitation via Anaerobic Digestion and Fermentative Hydrogen Production in an Up-Flow Column Reactor

The present study focuses on the exploitation of food industry waste for hydrogen and methane production, via biological processes. Fermentative hydrogen production in an anaerobic up-flow column reactor (AUFCR), using indigenous microbial species and fed with the soluble fraction of the waste coming after an extraction procedure, was investigated at different Hydraulic Retention Times (HRTs) in the range of 12–2 h. The highest hydrogen production rate (2.94 ± 0.37 L H2/L/d) was obtained at the HRT of 2 h, while the highest yield of hydrogen produced per mol of consumed carbohydrates, expressed in glucose equivalents was achieved at the HRT of 12 h (0.14 ± 0.01 mol/mol). Methane production via anaerobic digestion (AD) in a CSTR—type reactor was also assessed, using the whole diluted food industry waste (without extraction). The HRTs tested were 20, 15 and 10 days, while when the reactor operated at the HRT of 10 days, the feeding medium was also thermally treated, in order to assess the effect of pretreatment in AD. The maximum methane production rate (0.24 ± 0.02 L CH4/L/d) was observed for the HRT of 10 days and thermally treated substrate, while the maximum methane yield was obtained at the HRT of 15 days (247.9 ± 0.15 L CH4/kg waste). The IWA ADM1 model was finally used to predict the anaerobic digesters’ behavior through the operational period, resulting to a quite satisfactory simulation for a wide range of operational conditions.