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1.
Sci Total Environ ; 915: 170019, 2024 Mar 10.
Article in English | MEDLINE | ID: mdl-38224877

ABSTRACT

Most coastal cities have been experiencing unprecedented urbanization-induced flood risk, climatic events, and haphazard anthropogenic activities, jeopardizing residents' lives and building environments. Despite mounting flood-related studies, analyzing the correlation between the spatiotemporal dynamics of Built-up Expansion patterns (BE) and flood risk remains unknown and holds divergent perspectives. In this context, the coastal city of Alexandria, Egypt, characterized by multiple urban patterns and experiencing heavy rainfall annually, was selected as a testbed. Our method defined the spatiotemporal rates of BE from 1995 to 2023, quantified flood risk spatially, and finally investigated the correlation between BE and flood risk through spatial and statistical analysis. Our results show the built-up area occupied 30.32 % of the total city area till 2023, and the infilling pattern dominated the BE growth by 45.21 % of the total built-up area, followed by leapfrogging and edge expansion by 33.25 % and 21.55 %, respectively. The unplanned-infilling pattern is predominantly highly correlated with the flood-vulnerable peaks (correlation coefficient (rk) = 0.975, p-value < 0.05) and lowers dramatically towards planned-infilling regions with flood protections. Meanwhile, a spatial mismatch exists between high-risk peaks and leapfrogging and edge expansion (rk = 0.118 and 0.662, respectively, with a p-value < 0.01), indicating that controlling the built-up amount is inadequate for mitigating flood risk. Porosity-based urban configuration and spatial distribution of built-up patches in harmony with nature-based solutions are recommended for shaping flood-resilient and effective urban planning.

2.
Water Sci Technol ; 83(2): 487-500, 2021 Jan.
Article in English | MEDLINE | ID: mdl-33504710

ABSTRACT

This study evaluated the impact of hydrothermal pretreatment on thickened waste activated sludge (TWAS) for solubilization enhancement and biomethane production improvement through the mesophilic anaerobic digestion process. In order to assess the effect of temperature, retention time and severity index (SI) of the hydrothermal pretreatment, TWAS was exposed to fifteen different pretreatment conditions within a combination of 10 different pretreatment temperature range (150-240 °C), five different retention times (5-30 min) and five different severity indexes (SI = 3, 3.5, 4, 4.5 and 5). The solubilization enhancement was observed in all hydrothermally pretreated samples with the highest solubilization efficiency of 49% in pretreatment conditions of 200 °C and 10 min retention time within the corresponding SI = 4. Biomethane production was not improved in all fifteen pretreatment conditions, pretreatment with SI beyond 4 decreased the biodegradability of TWAS. The highest biomethane production was observed in the pretreatment condition of 170 °C and 10 min with a 40% increase compared to non-pretreated TWAS.


Subject(s)
Methane , Sewage , Anaerobiosis , Bioreactors , Microwaves , Temperature , Waste Disposal, Fluid
3.
Materials (Basel) ; 13(18)2020 Sep 16.
Article in English | MEDLINE | ID: mdl-32948035

ABSTRACT

Portland cement concrete is fragile in tension and it has numerous negative impacts on the environment. To deal with these issues, both fiber reinforcement and recycled materials can be utilized to manufacture sustainable and ductile concrete. In this study, the synergistic effects of high-performance mineral admixture silica fume and glass fiber reinforcement were investigated on the hardened properties of RC. For this purpose, two concrete mix families, namely, NC and RC were prepared. To understand the benefits of synergistic utilization of glass fiber and silica fume, in both NC and RC, 0.5% glass fiber was incorporated with three different levels of silica fume. i.e., 0%, 5%, and 10%. Both strength and permeability-related durability properties were investigated. Results revealed that combined incorporation of 0.5% fiber and 10% silica fume can help in the production of RC having better mechanical and durability performance compared to reference "NC". Simultaneous incorporation of silica fume and glass fiber produces a combined effect greater than their individual effects on both mechanical and permeability properties of concrete. Silica fume plays a very dominant and positive role in the development of CS, WA, and CIPR of RC, whereas glass fiber plays a vital role in upgrading STS and FS of RC and whereas, with the addition of 0.5% glass fiber, RC can yield 8-9 times higher flexural toughness than that of the plain NC.

4.
Molecules ; 24(8)2019 Apr 13.
Article in English | MEDLINE | ID: mdl-31013911

ABSTRACT

This study compares the effects of pre- and post-hydrothermal treatment of source- separated organics (SSO) on solubilization of particulate organics and acidogenic fermentation for volatile fatty acids (VFAs) production. The overall COD solubilization and solids removal efficiencies from both schemes were comparable. However, the pre-hydrolysis of SSO followed by acidogenic fermentation resulted in a relatively higher VFA yield of 433 mg/g VSS, which was 18% higher than that of a process scheme with a post-hydrolysis of dewatered solids from the fermentation process. Regarding the composition of VFA, the dominance of acetate and butyrate was comparable in both process schemes, while propionate concentration considerably increased in the process with pre-hydrolysis of SSO. The microbial community results showed that the relative abundance of Firmicutes increased substantially in the fermentation of pretreated SSO, indicating that there might be different metabolic pathways for production of VFAs in fermentation process operated with pre-treated SSO. The possible reason might be that the abundance of soluble organic matters due to pre-hydrolysis might stimulate the growth of more kinetically efficient fermentative bacteria as indicated by the increase in Firmicutes percentage.


Subject(s)
Acetates/metabolism , Bacteria/genetics , Bioreactors , Butyrates/metabolism
5.
Environ Sci Pollut Res Int ; 25(29): 29240-29255, 2018 Oct.
Article in English | MEDLINE | ID: mdl-30117028

ABSTRACT

Trace elements (TEs) play an indispensable role in enhancing the stability of anaerobic digestion (AD) of food waste (FW). Significant research on AD of FW with TE supplementation has been conducted with low Fe content inoculum. However, the use of Fe-rich inoculum is inevitable due to chemical phosphorous removal from wastewater in North America. We conducted comprehensive mesophilic batch tests to investigate the effect of TEs (Fe, Ni, Co, Se, and Mo) on FW digestion inoculated with Fe-rich sludge (≥ 1000 mg Fe L-1). This paper presents the impact of supplementing various concentrations of TEs on specific methanogenic activity (SMA), maximum specific methane production rate (SMPRmax), and apparent hydrolysis rate constant (Kh). The addition of TEs adversely impacted methanogenic activity by 20 to 58% in the SMA tests. The effects of individual and mixed supplementation of TEs on the SMPRmax and Kh during FW digestion were negligible; exceptions include Fe, Mo, and Co. Final soluble TE concentrations were 10-29% of the initial soluble TEs. The high Fe concentration in the inoculum reduces the bioavailable fraction of added TEs via coprecipitation. Contrary with many literature reports indicating the need to supplement TE to improve FW digestion efficiency, with Fe-rich sludges, FW digestion does not require TE supplementation.


Subject(s)
Bioreactors , Iron/analysis , Refuse Disposal/methods , Sewage/analysis , Trace Elements/analysis , Anaerobiosis , Garbage , Ontario
6.
Bioresour Technol ; 241: 152-160, 2017 Oct.
Article in English | MEDLINE | ID: mdl-28554101

ABSTRACT

The effect of co-culturing C. beijerinckii and C. saccharoperbutylacetonicum for H2 production using mono- and co-substrates of glucose, starch, and cellulose was assessed. Monod kinetic parameters (K, maximum specific substrate utilization rate; and Ks, half-saturation constant) of the C. beijerinckii, C. saccharoperbutylacetonicum, and the co-culture were determined. Co-cultures utilizing glucose competed for the substrate, but showed enhancement for utilizing starch. The maximum values for K on glucose and starch were 0.48g substrate/gVSS.h achieved by C. saccharoperbutylacetonicum mono-culture and 0.39g substrate/gVSS.h achieved by the co-culture, respectively. The average Ks for all mono- and co-culture experiments was 0.93±0.03g/L. Acetate, butyrate, and propionate were the main fermentation products for all experiments. Maximum H2 production yields on glucose (2.69mol/molglucose) and starch (1.07mol/molhexose) were achieved by C. beijerinckii and C. saccharoperbutylacetonicum mono-cultures, respectively; however, neither culture was able to degrade cellulose as a mono-substrate.


Subject(s)
Clostridium beijerinckii , Coculture Techniques , Clostridium , Fermentation , Kinetics
7.
AMB Express ; 7(1): 84, 2017 Dec.
Article in English | MEDLINE | ID: mdl-28429329

ABSTRACT

Cellulose utilization by hydrogen producers remains an issue due to the low hydrogen yields reported and the pretreatment of cellulose prior to fermentation requires complex and expensive steps. Clostridium termitidis is able to breakdown cellulose into glucose and produce hydrogen. On the other hand, Clostridium beijerinckii is not able to degrade cellulose but is adept at hydrogen production from glucose; therefore, it was chosen to potentially enhance hydrogen production when co-cultured with C. termitidis on cellulose. In this study, batch fermentation tests were conducted to investigate the direct hydrogen production enhancement of mesophilic cellulolytic bacteria C. termitidis co-cultured with mesophilic hydrogen producer C. beijerinckii on cellulose at 2 g l-1 compared to C. termitidis mono-culture. Microbial kinetics parameters were determined by modeling in MATLAB. The achieved highest hydrogen yield was 1.92 mol hydrogen mol-1 hexose equivalentadded in the co-culture compared to 1.45 mol hydrogen mol-1 hexose equivalentadded in the mono-culture. The maximum hydrogen production rate of 26 ml d-1 was achieved in the co-culture. Co-culture exhibited an overall 32 % enhancement of hydrogen yield based on hexose equivalent added and 15 % more substrate utilization. The main metabolites were acetate, ethanol, lactate, and formate in the mono-culture, with also butyrate in the co-culture. Additionally, the hydrogen yield of C. beijerinckii only in glucose was 2.54 mol hydrogen mol-1 hexose equivalent. This study has proved the viability of co-culture of C. termitidis with C. beijerinckii for hydrogen production directly from a complex substrate like cellulose under mesophilic conditions.

8.
Bioresour Technol ; 221: 598-606, 2016 Dec.
Article in English | MEDLINE | ID: mdl-27693725

ABSTRACT

This study evaluated the impact of furfural (a furan derivative) on hydrogen production rates and yields at initial substrate-to-microorganism ratios (S°/X°) of 4, 2, 1, and 0.5gCOD/gVSS and furfural concentrations of 4, 2, 1, and 0.5g/L. Fermentation studies were carried out in batches using synthetic lignocellulosic hydrolysate as substrate and mesophilic anaerobic digester sludge as seed. Contrary to other literature studies where furfural was inhibitory, this study showed that furfural concentrations of up to 1g/L enhanced hydrogen production with yields as high as 19% from the control (batch without furfural). Plots of hydrogen yields against gfurfural/gsugars and hydrogen yields versus gfurfural/gbiomass showed negative linear correlation indicating that these parameters influence biohydrogen production. Regression analysis indicated that gfurfural/gsugarsinitial exerted a greater effect on the degree of inhibition of hydrogen production than gfurfural/gVSSfinal.


Subject(s)
Biotechnology/methods , Furaldehyde , Hydrogen/metabolism , Anaerobiosis , Biological Oxygen Demand Analysis , Biomass , Fermentation , Furaldehyde/chemistry , Furaldehyde/metabolism , Hydrolysis , Lignin , Regression Analysis , Sewage/chemistry
9.
Bioresour Technol ; 198: 223-30, 2015 Dec.
Article in English | MEDLINE | ID: mdl-26398665

ABSTRACT

An integrated dark fermentation and microbial electrochemical cell (MEC) process was evaluated for hydrogen production from sugar beet juice. Different substrate to inoculum (S/X) ratios were tested for dark fermentation, and the maximum hydrogen yield was 13% of initial COD at the S/X ratio of 2 and 4 for dark fermentation. Hydrogen yield was 12% of initial COD in the MEC using fermentation liquid end products as substrate, and butyrate only accumulated in the MEC. The overall hydrogen production from the integrated biohydrogen process was 25% of initial COD (equivalent to 6 mol H2/mol hexoseadded), and the energy recovery from sugar beet juice was 57% using the combined biohydrogen.


Subject(s)
Beta vulgaris/metabolism , Fermentation/physiology , Hydrogen/metabolism , Electrolysis/methods
10.
J Clin Psychiatry ; 76(10): 1359-65, 2015 Oct.
Article in English | MEDLINE | ID: mdl-26302441

ABSTRACT

OBJECTIVE: Alcohol use disorders worsen the course of schizophrenia. Although the atypical antipsychotic clozapine appears to decrease alcohol use in schizophrenia, risperidone does not. We have proposed that risperidone's relatively potent dopamine D2 receptor blockade may partly underlie its lack of effect on alcohol use. Since long-acting injectable (LAI) risperidone both results in lower average steady-state plasma concentrations than oral risperidone (with lower D2 receptor occupancy) and encourages adherence, it may be more likely to decrease heavy alcohol use (days per week of drinking 5 or more drinks per day) than oral risperidone. METHOD: Ninety-five patients with DSM-IV-TR diagnoses of schizophrenia and alcohol use disorder were randomized to 6 months of oral or LAI risperidone between 2005 and 2008. Explanatory (efficacy) analyses were carried out to evaluate the potential benefits of LAI under suitably controlled conditions (in contrast to real-world settings), with intent-to-treat analyses being secondary. RESULTS: Explanatory analyses showed that heavy drinking in the oral group worsened over time (P = .024) and that there was a statistical trend toward significance in the difference between the changes in heavy drinking days in the oral and LAI groups (P = .054). Furthermore, the 2 groups differed in the mean number of drinking days per week (P = .035). The intent-to-treat analyses showed no difference in heavy drinking but did show a difference in average drinking days per week similar to that obtained from the explanatory analyses (P = .018). Neither explanatory nor intent-to-treat analyses showed any between-group differences in alcohol use as measured by intensity or the Alcohol Use Scale. The plasma concentrations of the active metabolite 9-hydroxyrisperidone were significantly lower in patients taking LAI (P < .05), despite their significantly (overall) better treatment adherence (P < .005). CONCLUSION: For the population considered here, schizophrenia patients with alcohol use disorder appear to continue drinking some alcohol while taking either form of risperidone. Nonetheless, our data suggest that injectable risperidone may be a better choice than the oral form for these dual diagnosis patients. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00130923.


Subject(s)
Alcoholism/drug therapy , Antipsychotic Agents/therapeutic use , Risperidone/therapeutic use , Schizophrenia/drug therapy , Administration, Oral , Adult , Alcoholism/complications , Antipsychotic Agents/administration & dosage , Delayed-Action Preparations , Female , Humans , Interview, Psychological , Male , Psychiatric Status Rating Scales , Risperidone/administration & dosage , Schizophrenia/complications
11.
Bioresour Technol ; 193: 449-55, 2015 Oct.
Article in English | MEDLINE | ID: mdl-26159302

ABSTRACT

This study investigated the performance of microbial electrolysis cells (MECs) fed with three common fermentation products: acetate, butyrate, and propionate. Each substrate was fed to the reactor for three consecutive-batch cycles. The results showed high current densities for acetate, but low current densities for butyrate and propionate (maximum values were 6.0 ± 0.28, 2.5 ± 0.06, 1.6 ± 0.14 A/m(2), respectively). Acetate also showed a higher coulombic efficiency of 87 ± 5.7% compared to 72 ± 2.0 and 51 ± 6.4% for butyrate and propionate, respectively. This paper also revealed that acetate could be easily oxidized by anode respiring bacteria in MEC, while butyrate and propionate could not be oxidized to the same degree. The utilization rate of the substrates in MEC followed the order: acetate > butyrate > propionate. The ratio of suspended biomass to attached biomass was approximately 1:4 for all the three substrates.


Subject(s)
Bioelectric Energy Sources/microbiology , Electrolysis/methods , Fatty Acids, Volatile/pharmacology , Biological Oxygen Demand Analysis , Biomass , Bioreactors/microbiology , Electricity , Electrodes , Hydrogen/metabolism , Ion Exchange Resins/chemistry , Thermodynamics
12.
Bioresour Technol ; 192: 741-7, 2015 Sep.
Article in English | MEDLINE | ID: mdl-26101964

ABSTRACT

In this study, batch tests were conducted to investigate the performance of mesophilic anaerobic digester sludge (ADS) at thermophilic conditions and estimate kinetic parameters for co-substrate fermentation. Starch and cellulose were used as mono-substrate and in combination as co-substrates (1:1 mass ratio) to conduct a comparative assessment between mesophilic (37 °C) and thermophilic (60 °C) biohydrogen production. Unacclimatized mesophilic ADS responded well to the temperature change. The highest hydrogen yield of 1.13 mol H2/mol hexose was observed in starch-only batches at thermophilic conditions. The thermophilic cellulose-only yield (0.42 mol H2/mol hexose) was three times the mesophilic yield (0.13 mol H2/mol hexose). Interestingly, co-fermentation of starch-cellulose at mesophilic conditions enhanced the hydrogen yield by 26% with respect to estimated mono-substrate yields, while under thermophilic conditions no enhancement in the overall yield was observed. Interestingly, the estimated overall Monod kinetic parameters showed higher rates at mesophilic than thermophilic conditions.


Subject(s)
Biofuels/microbiology , Bioreactors/microbiology , Carbohydrate Metabolism/physiology , Hydrogen/metabolism , Models, Biological , Starch/metabolism , Coculture Techniques/methods , Computer Simulation , Hydrogen/isolation & purification , Temperature
13.
Biotechnol Lett ; 37(10): 1965-71, 2015 Oct.
Article in English | MEDLINE | ID: mdl-26093605

ABSTRACT

OBJECTIVE: To determine Monod kinetics parameters (µmax, Ks, kd and YX/S) of the mesophilic H2 producer Clostridium termitidis grown on glucose and cellobiose by modeling in MATLAB. RESULTS: Maximum specific growth rates (µmax) were 0.22 and 0.24 h(-1) for glucose and cellobiose respectively; saturation constants (Ks) were 0.17 and 0.38 g l(-1) respectively and the biomass yields (YX/S) were 0.26 and 0.257 g dry wt g(-1) substrate. H2 yields of 1.99 and 1.11 mol H2 mol(-1) hexose equivalent were also determined for glucose and cellobiose respectively. CONCLUSION: The microbial kinetics of this model microorganism will enhance engineering biofuel production applications.


Subject(s)
Cellobiose/metabolism , Clostridium/growth & development , Clostridium/metabolism , Glucose/metabolism , Hydrogen/metabolism , Biofuels , Clostridiales , Computer Simulation
14.
Bioresour Technol ; 190: 315-20, 2015 Aug.
Article in English | MEDLINE | ID: mdl-25965257

ABSTRACT

This study investigates the potential of using a novel integrated biohydrogen reactor clarifier system (IBRCS) for acetone-butanol-ethanol (ABE) production using a mixed culture at different organic loading rates (OLRs). The results of this study showed that using a setting tank after the fermenter and recycle the settled biomass to the fermenter is a practical option to achieve high biomass concentration in the fermenter and thus sustainable ABE fermentation in continuous mode. The average ABE concentrations of 2.3, 7.0, and 14.6gABE/L which were corresponding to ABE production rates of 0.4, 1.4, and 2.8gABE/Lreactorh were achieved at OLRs of 21, 64, and 128gCOD/Lreactord, respectively. The main volatile fatty acids components in the effluent were acetic, propionic, and butyric acids. Acetic acid was the predominant component in the OLR-1, while butyric acid was the predominant acid in OLRs 2 and 3.


Subject(s)
Acetone/metabolism , Bioreactors/microbiology , Butanols/metabolism , Ethanol/metabolism , Fatty Acids, Volatile/metabolism , Glucose/metabolism , Acetone/isolation & purification , Butanols/isolation & purification , Ethanol/isolation & purification , Rheology/methods
15.
World Psychiatry ; 14(1): 64-73, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25655160

ABSTRACT

Major depressive disorder (MDD) is a prevalent and disabling condition, and many patients do not respond to available treatments. Deep transcranial magnetic stimulation (dTMS) is a new technology allowing non-surgical stimulation of relatively deep brain areas. This is the first double-blind randomized controlled multicenter study evaluating the efficacy and safety of dTMS in MDD. We recruited 212 MDD outpatients, aged 22-68 years, who had either failed one to four antidepressant trials or not tolerated at least two antidepressant treatments during the current episode. They were randomly assigned to monotherapy with active or sham dTMS. Twenty sessions of dTMS (18 Hz over the prefrontal cortex) were applied during 4 weeks acutely, and then biweekly for 12 weeks. Primary and secondary efficacy endpoints were the change in the Hamilton Depression Rating Scale (HDRS-21) score and response/remission rates at week 5, respectively. dTMS induced a 6.39 point improvement in HDRS-21 scores, while a 3.28 point improvement was observed in the sham group (p=0.008), resulting in a 0.76 effect size. Response and remission rates were higher in the dTMS than in the sham group (response: 38.4 vs. 21.4%, p=0.013; remission: 32.6 vs. 14.6%, p=0.005). These differences between active and sham treatment were stable during the 12-week maintenance phase. dTMS was associated with few and minor side effects apart from one seizure in a patient where a protocol violation occurred. These results suggest that dTMS constitutes a novel intervention in MDD, which is efficacious and safe in patients not responding to antidepressant medications, and whose effect remains stable over 3 months of maintenance treatment.

16.
Bioresour Technol ; 164: 371-9, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24865326

ABSTRACT

This study assesses the impact of organic loading rate on biohydrogen production from glucose in an up-flow anaerobic packed bed reactor (UAnPBR). Two mesophilic UAPBRs (UAnPBR1 and 2) were tested at organic loading rates (OLRs) ranging from 6.5 to 51.4 g COD L(-1)d(-1). To overcome biomass washout, design modifications were made in the UAnPBR2 to include a settling zone to capture the detached biomass. The design modifications in UAnPBR2 increased the average hydrogen yield from 0.98 to 2.0 mol-H2 mol(-1)-glucose at an OLR of 25.7 g COD L(-1)d(-1). Although, a maximum hydrogen production rate of 23.4 ± 0.9 L H2 L(-1)d(-1) was achieved in the UAnPBR2 at an OLR of 51.4 g COD L(-1)d(-1), the hydrogen yield dropped by 50% to around 1 mol-H2 mol(-1)-glucose. The microbiological analysis (PCR/DGGE) showed that the biohydrogen production was due to the presence of the hydrogen and volatile acid producers such as Clostridium beijerinckii, Clostridium butyricum, Megasphaera elsdenii and Propionispira arboris.


Subject(s)
Biofuels , Bioreactors , Biotechnology/instrumentation , Biotechnology/methods , Hydrogen/metabolism , Organic Chemicals/pharmacology , Rheology , Anaerobiosis/drug effects , Bacteria/genetics , Biological Oxygen Demand Analysis , Biomass , Bioreactors/microbiology , Denaturing Gradient Gel Electrophoresis , Fermentation/drug effects , Molecular Sequence Data , Phylogeny , RNA, Ribosomal, 16S/genetics , Solubility , Time Factors , Volatilization/drug effects
17.
Bioresour Technol ; 121: 411-8, 2012 Oct.
Article in English | MEDLINE | ID: mdl-22864177

ABSTRACT

The primary objective of this work was to investigate the treatability of thin stillage as a by-product of bioethanol production plants using an anaerobic fluidized bed bioreactor (AFBR) employing zeolite with average diameter of (d(m)) of 425-610 µm and specific surface area (SSA) of 26.5m(2)/g as the carrier media. Despite the very high strength of thin stillage with chemical oxygen demand of 130,000 mg TCOD/L and suspended solids of 47,000 mg TSS/L, the AFBR showed up to 88% TCOD and 78% TSS removal at very high organic and solids loading rates (OLR and SLR) of 29 kg COD/m(3)d and 10.5 kg TSS/m(3)d respectively and hydraulic retention time (HRT) of 3.5 days. Methane production rates of up to 160 L/d at the steady state equivalent to 40 L(CH4)/L(thin stillage)d and biogas production rate per reactor volume of 15.8L(gas)/L(reactor)d were achieved.


Subject(s)
Bacteria, Anaerobic/metabolism , Biofuels , Bioreactors , Methane/biosynthesis , Waste Products/analysis , Zea mays/chemistry , Biological Oxygen Demand Analysis , Particle Size , Time Factors , Zeolites
18.
Bioresour Technol ; 111: 122-6, 2012 May.
Article in English | MEDLINE | ID: mdl-22366605

ABSTRACT

A comparative evaluation of single-stage and two-stage anaerobic digestion processes for biomethane and biohydrogen production using thin stillage was performed to assess the impact of separating the acidogenic and methanogenic stages on anaerobic digestion. Thin stillage, the main by-product from ethanol production, was characterized by high total chemical oxygen demand (TCOD) of 122 g/L and total volatile fatty acids (TVFAs) of 12 g/L. A maximum methane yield of 0.33 L CH(4)/gCOD(added) (STP) was achieved in the two-stage process while a single-stage process achieved a maximum yield of only 0.26 L CH(4)/gCOD(added) (STP). The separation of acidification stage increased the TVFAs to TCOD ratio from 10% in the raw thin stillage to 54% due to the conversion of carbohydrates into hydrogen and VFAs. Comparison of the two processes based on energy outcome revealed that an increase of 18.5% in the total energy yield was achieved using two-stage anaerobic digestion.


Subject(s)
Anaerobiosis , Crops, Agricultural/metabolism , Biofuels , Fatty Acids/metabolism , Hydrogen/metabolism , Methane/metabolism , Volatile Organic Compounds/metabolism
19.
Bioresour Technol ; 110: 18-25, 2012 Apr.
Article in English | MEDLINE | ID: mdl-22342042

ABSTRACT

Biochemical methane potential tests were conducted to evaluate the effect of using a blank versus a pre-incubated inoculum in digestion of primary sludge at different waste to inoculum ratios (S/X). In addition, this study explored the influence of using two different anaerobic inoculum sources on the digestion of food waste: digested sludge from a municipal wastewater treatment plant and from a digester treating the organic fraction of municipal solid wastes. The results revealed that although there was no significant difference in methane yield (on average 114mLCH(4)/g TCOD(sub)) or biodegradability (on average 28.3%) of primary sludge using pre-incubated or non-incubated inocula, the maximum methane production rates using non-incubated inoculum were higher than those using pre-incubated inoculum at all S/X ratios. Moreover, interestingly the inoculum from an anaerobic digester treating municipal wastewater sludge was superior over the inoculum from anaerobic digester treating food waste in digesting food waste.


Subject(s)
Food , Methane/metabolism , Sewage , Anaerobiosis , Biodegradation, Environmental
20.
J Hazard Mater ; 187(1-3): 140-9, 2011 Mar 15.
Article in English | MEDLINE | ID: mdl-21255923

ABSTRACT

Steady state operational data from a pilot scale circulating fluidized bed bioreactor (CFBBR) during biological treatment of landfill leachate, at empty bed contact times (EBCTs) of 0.49, and 0.41 d and volumetric nutrients loading rates of 2.2-2.6 kg COD/(m(3)d), 0.7-0.8 kg N/(m(3)d), and 0.014-0.016 kg P/(m(3)d), was used to calibrate and compare developed process models in BioWin(®) and AQUIFAS(®). BioWin(®) and AQUIFAS(®) were both capable of predicting most of the performance parameters such as effluent TKN, NH(4)-N, NO(3)-N, TP, PO(4)-P, TSS, and VSS with an average percentage error (APE) of 0-20%. BioWin(®) underpredicted the effluent BOD and SBOD values for various runs by 80% while AQUIFAS(®) predicted effluent BOD and SBOD with an APE of 50%. Although both calibrated models, confirmed the advantages of the CFBBR technology in treating the leachate of high volumetric loading and low biomass yields due to the long solid retention time (SRT), both BioWin(®) and AQUIFAS(®) predicted the total biomass and SRT of CFBBR based on active biomass only, whereas in the CFBBR runs both active as well as inactive biomass accumulated.


Subject(s)
Bioreactors , Models, Theoretical , Refuse Disposal
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