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The first part of this study investigated chitosan characteristics, i. e. degree of deacetylation (DD) and molecular weight that allowed high sludge flocculation with minimum dosage under the defined environmental conditions. Chitosan... more
The first part of this study investigated chitosan characteristics, i. e. degree of deacetylation (DD) and molecular weight that allowed high sludge flocculation with minimum dosage under the defined environmental conditions. Chitosan with 85% DD was more effective than that with 70% DD as the former required lower dose to obtain 90% flocculation at all studied pH and ionic strength. In addition, low molecular weight chitosan (MW = 2.5x10 5 dalton) enhanced the flocculation better than high molecular weight chitosan (MW = 1.4x10 6 dalton). The chitosan was able to function either in acidic or neutral conditions, and very small amounts of chitosan (< 4 mg/ g suspended solids) were required. The second part of this study investigated the effect of adding chitosan with 85%DD and MW of 2.5x10 5 dalton on the performance of a UASB reactor. Only small amounts of chitosan were applied (two injections with 2 mg chitosan/g suspended solids at each injection). The UASB performances were st...
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The formation of microbial granules and reduction of microorganism losses at the outflow are important for optimal performances of Upflow Anaerobic Sludge Blanket systems (UASB). In a conventional UASB, continuous selection of sludge... more
The formation of microbial granules and reduction of microorganism losses at the outflow are important for optimal performances of Upflow Anaerobic Sludge Blanket systems (UASB). In a conventional UASB, continuous selection of sludge particles, generally created by upflow pattern, results in losses of light and dispersed sludge but maintenance of heavy sludge. The objective of this study was to investigate the performance of a 30 liter UASB with a modified three-phase separator giving a spiral flow pattern. A UASB with a conventional threephase separator was also set-up and operated in parallel for performance comparison. Wastewater, with COD between 2,000-9,000 mg l and pH 5-6, was accommodated from a canned fruit factory. The initial seed for microbial granules with volatile suspending solid around 23.37 g l was from an anaerobic digester system. The UASB operation was started up under the atmospheric temperature with the hydraulic retention time (HRT) at 85 h, corresponding to an...
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The objective of this work is to study the behaviour during sheet thermoforming process of a Tapioca starch-biodegradable polyester (EnpolTM) blend with the mixing ratio of 50:50 by weight. The mechanical behavior of the material extruded... more
The objective of this work is to study the behaviour during sheet thermoforming process of a Tapioca starch-biodegradable polyester (EnpolTM) blend with the mixing ratio of 50:50 by weight. The mechanical behavior of the material extruded in the form of thin sheet was studied by means of compression tests with varying strain rates at temperatures ranging from between 363 K to 393 K. The Elastic–Perfectly Plastic material model was used to capture the compressive deformation behavior of the material. It was found that the model described reasonably well the behavior of the material and the 2D Finite element simulation with Elastic–Plastic material model gave good representation of the real thermoforming process.
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The magnetic induction assisted technique is an alternative heating method for hydrothermal zeolite synthesis with a higher heat-transfer rate than that of the conventional convection oil bath technique. The research demonstrates, for the... more
The magnetic induction assisted technique is an alternative heating method for hydrothermal zeolite synthesis with a higher heat-transfer rate than that of the conventional convection oil bath technique. The research demonstrates, for the first time, the application of the magnetic induction heating technique with direct surface contact for zeolite synthesis. The magnetic induction enables direct contact between the heat source and the reactor, thereby bypassing the resistance of the heating medium layer. A comparative heat-transfer analysis between the two methods shows the higher heat-transfer rate by the magnetic induction heating technique is due to (1) eight-time higher overall heat-transfer coefficient, attributed to the absence of the resistance of the heating medium layer and (2) the higher temperature difference between the heating source and the zeolite gel. Thereby, this heating technique shows promise for application in the large-scale synthesis of zeolites due to its as...
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Summary Bacteriocin-like activity (BLA) was screened in 133 strains of lactic acid bacteria (LAB) isolated from traditional Thai fermented sausages. The inhibition assay against the test organisms showed that eight out of 133 isolates... more
Summary Bacteriocin-like activity (BLA) was screened in 133 strains of lactic acid bacteria (LAB) isolated from traditional Thai fermented sausages. The inhibition assay against the test organisms showed that eight out of 133 isolates (CP1-15, CP2-11, CP3-1, CP7-3, CP10-3, CP11-6, CP14-1 and CP14-4) suppressed the growth of Bacillus cereus and four (CP1-15, CP7-3, CP14-2 and CP14-3) suppressed the growth of Staphylococcus aureus but none could suppress the growth of Escherichia coli and Salmonella sp. The isolates with the highest activity against the two Gram positive test strains (CP3-1 for B. cereus and CP7-3 for S. aureus) were further investigated for the effect of heat treatment at different pH values and for combined effects of dual mixtures. The increase in heating temperature (between 65 and 100 o C) and time (between 5 and 60 min) significantly decreased BLA, while the changes in pH (between 4 and 6) had little effect. When the filtrates of the two isolates were mixed, BLA...
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The efficiency of electrocoagulation in treating textile wastewater was investigated in this study. The textile wastewater was originated from dyeing and finishing activities which involved mostly direct and disperse dyes. Five different... more
The efficiency of electrocoagulation in treating textile wastewater was investigated in this study. The textile wastewater was originated from dyeing and finishing activities which involved mostly direct and disperse dyes. Five different current densities were applied (10, 20, 30, 40 and 50 A·m -2 ) and for each current density, electrocoagulation time of 5, 10, 15 and 20 min were tried. The electrochemical technique showed satisfactory efficiency for turbidity removal of 85-95% and 95% for direct dyes and disperse dyes, respectively. Even though the visual appearance of water became desirable, the total dissolved solids (TDS), conductivity and chemical oxygen demand (COD) were not significantly reduced by the electrocoagulation process.
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As an alternative to applying the hydrothermal treatment to the raw algal feedstock before the anaerobic digestion (i.e. pre-treatment), one considered a post-treatment scenario where anaerobic digestion is directly used as the primary... more
As an alternative to applying the hydrothermal treatment to the raw algal feedstock before the anaerobic digestion (i.e. pre-treatment), one considered a post-treatment scenario where anaerobic digestion is directly used as the primary treatment while the hydrothermal treatment is thereafter applied to the digestate. Hydrothermal treatments such as wet oxidation (WetOx) and hydrothermal carbonization (HTC) were compared at a temperature of 200°C, for initial pressure of 0.1 and 0.82MPa, and no holding time after the process had reached the temperature setpoint. Both WetOx and HTC resulted in a substantial solids conversion (47-62% with HTC, 64-83% with WetOx, both at 0.82MPa) into soluble products, while some total chemical oxygen demand-based carbon loss from the solid-liquid phases was observed (20-39%). This generated high soluble products concentrations (from 6.2 to 10.9g soluble chemical oxygen demand/L). Biomethane potential tests showed that these hydrothermal treatments allo...
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Palm oil mill effluent (POME) is wastewater with a relatively high temperature (80 – 90 °C) that is generated from the extraction of oil from palm fruit and palm kernels. Owing to its high discharge temperatures, the thermophilic... more
Palm oil mill effluent (POME) is wastewater with a relatively high temperature (80 – 90 °C) that is generated from the extraction of oil from palm fruit and palm kernels. Owing to its high discharge temperatures, the thermophilic anaerobic digestion (AD) of POME could be advantageous as treatment at thermophilic temperatures can reduce loads for cooling the wastewater. In this study, the effects of stepwise temperature increments of 5 °C from 55 °C to 70 °C on the AD of POME were investigated in a continuous stirred tank reactor (CSTR) operated under high organic loading rates (OLRs). The process performance and microbial community structure at each temperature interval were evaluated. It was observed that the methane production rates of the CSTR increased with increasing OLRs up to values of 13.7 g/L d, 25.7 g/L d, and 26.5 g/L d at operating temperatures of 55 °C, 60 °C, and 65 °C, respectively. As a result of the increasing OLRs, the maximum rate of methane production increased f...
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Adoption of the circular economy concept to utilize wastes and by-products from the cassava starch industry for biogas production has been considered a viable option. The annual generation of wastewater and cassava pulp in Thailand is... more
Adoption of the circular economy concept to utilize wastes and by-products from the cassava starch industry for biogas production has been considered a viable option. The annual generation of wastewater and cassava pulp in Thailand is reported to be approximately 21 million m3 and 9.5 Mt, respectively. This research therefore aimed to analyze the key drivers and challenges in implementing the circular economy concept in the cassava starch industry in order to generate higher demand for biogas systems, increase the energy security and resource efficiency, and combat the environmental problems associated with cassava wastes. The following three scenarios were analyzed in this study: (1) a factory without integrated biogas system, (2) a factory with integrated biogas installation using wastewater as a raw material, and (3) a factory with biogas system using both wastewater and cassava pulp as raw materials. The assessment of economic feasibility, resource efficiency, water recovery, la...
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This paper presents a study of the startup and operation of a high-rate upflow anaerobic sludge blanket (UASB) treating diluted decanted palm oil mill effluent (POME) under thermophilic conditions. The operating temperature was increased... more
This paper presents a study of the startup and operation of a high-rate upflow anaerobic sludge blanket (UASB) treating diluted decanted palm oil mill effluent (POME) under thermophilic conditions. The operating temperature was increased in one-step from 25 to 55 °C. The organic loading rate (OLR) of POME was increased stepwise from 2 g/L day of COD to 23.8 g/L day. High-rate anaerobic digestion with methane (CH 4) productivity of 8 L/L day was achieved. The development of microbial populations in the sludge involved an increase in both H 2 producers, specifically the genus Clostridium, and H 2 consumers, specifically the order Methanobacteriales. A gene quantification based on real-time polymerase chain reaction (PCR) showed that the archaeal rRNA gene concentration increased from 3.48 × 10 7 copies/mL in the original digested sludge to 1.89 × 10 9 copies/mL in the acclimated sludge. The increase in archaeal rRNA gene concentration was accompanied by a 3700 times increase in Methanobacteriales gene concentration. However, the Methanobacteriales was found to be vulnerable to substrate overloading with its gene concentration decreasing 35 fold from that in the original digested sludge at an OLR of 23.8 g/L day.
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In this study, we investigated the effectiveness of microbial enrichment in enhancing the anaerobic digestion of lignocellulosic biomass of anaerobically digested sewage sludge in a complex substrate under both mesophilic (305 K) and... more
In this study, we investigated the effectiveness of microbial enrichment in enhancing the anaerobic digestion of lignocellulosic biomass of anaerobically digested sewage sludge in a complex substrate under both mesophilic (305 K) and thermophilic (328 K) conditions. Palm oil mill effluent (POME) was used as the enrichment culture, and Brachiaria mutica (paragrass) as a representative of a lignocellulosic biomass with relatively low lignin content (ca. 10 wt%). The microbial enrichment was found to increase the hydrolytic activities of the sludge more than twofold, and to increase the bacterial diversity, especially under the mesophilic condition. The microbial enrichment was also found to increase the diversity of methanogenic archaea and the methanogenic activities of the sludge. When compared with the original sludge, the enriched microbial culture under the mesophilic condition increased the methane yield from 275 to 312 cm3 STP/g VS added. However, despite increased hydrolytic, acetogenic and methanogenic activities, the enriched microbial culture under the thermophilic condition failed to enhance methane production in a long-term anaerobic digestion of paragrass.
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The objective of this study was to investigate the influence of a three-phase separator configuration on the performance of an upflow anaerobic sludge bed (USAB) treating wastewater from a fruit canning factory. The performances of two... more
The objective of this study was to investigate the influence of a three-phase separator configuration on the performance of an upflow anaerobic sludge bed (USAB) treating wastewater from a fruit canning factory. The performances of two 30-L UASB reactors--one with a modified three-phase separator giving a spiral flow pattern and the other with a conventional configuration-were investigated in parallel. Wastewater, with a chemical oxygen demand (COD) concentration between 2000 and 7000 mg/L, was obtained from a fruit-canning factory. Based on the effluent data of the first 100 operation days, the UASB with the three-phase separator giving spiral flow patterns yielded up to 25% lower biomass washout. It also showed better efficiencies in treating wastewater--up to 60% lower effluent COD, up to 20% higher COD percent removal, and up to 29% higher biogas production. This work presents evidence of an improvement on the conventional physical design of a UASB.
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Electrocoagulation Water treatment Color removal Gas separation a b s t r a c t In this paper, a technique of hydrogen recovery from an electrocoagulation process treating dye-containing wastewater is presented. The electrocoagulation... more
Electrocoagulation Water treatment Color removal Gas separation a b s t r a c t In this paper, a technique of hydrogen recovery from an electrocoagulation process treating dye-containing wastewater is presented. The electrocoagulation system used consists of a continuous-mode electrocoagulator connected with a gas separation tank and two sedimenters. It is shown that a significant amount of hydrogen can be harvested using the gas separation tank whose configuration follows that of a conventional upflow anaerobic sludge bed. The experimental hydrogen yields obtained were comparable with those calculated from theory. The electrical energy demand of the electrocoagulation process for treating Reactive Blue 140 and Direct Red 23 was 1.42 and 0.69 kWh e m À3 , respectively, while the energy yield of harvested hydrogen was 0.2 kWh m À3. The quality of water treated by the electrocoagulation system was satisfactory, i.e., the color, COD and TS removal were 99%, 93% and 89%, respectively.
ABSTRACT A batch electrocoagulator was developed for optimal removal of reactive blue 21 from wastewater. The data from the batch reactor were then used to develop a continuous-flow reactor with similar performance for reduction of... more
ABSTRACT A batch electrocoagulator was developed for optimal removal of reactive blue 21 from wastewater. The data from the batch reactor were then used to develop a continuous-flow reactor with similar performance for reduction of chemical oxygen demand (COD) and color removal. In the 1.8-L batch system, COD removal of 90% and color removal of 95% were achieved using a current density of 30 A/m2, electrode area of 0.10 m2, and electrocoagulation time of 7 min. The continuous-flow electrocoagulator consisted of two hollow iron tubes put together in a concentric configuration with a working volume of 1.5 L and an effective electrode area of 0.15 m2. By keeping the current density and the applied electric charge the same in both the batch and the continuous-flow systems, the COD and color removals and energy consumption of both systems were the same within 10%. However, the color and COD removals by the batch reactor were higher than those of the continuous-flow electrocoagulator because the distribution of electroactive species in the batch reactor was more effective than that in the tube-in-tube electrocoagulator.
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Effects of the freeze-thaw process on physical properties, cell viability, microbial activities and population structures of anaerobic sludge were investigated. It was found that the sludge volume index was greatly reduced from 16.4 mL/g... more
Effects of the freeze-thaw process on physical properties, cell viability, microbial activities and population structures of anaerobic sludge were investigated. It was found that the sludge volume index was greatly reduced from 16.4 mL/g in the original sludge to 4.0 mL/g in the solid fraction of the frozen-thawed sludge. Even though the freeze-thaw process decreased cell viability in the solid fraction of the frozen-thawed sludge, microbial activity tests showed that the freeze-thaw process enhanced acidogenic activity approximately 20%. The enhanced acidogenic activity of the solid fraction was in good agreement with the enrichment of Clostridiaceae, Porphyromonadaceae and Propionibacteriaceae found in the solid fraction. The relative abundances of Proteobacteria families Oxalobacteraceae, Moraxellaceae, and Pseudomonadaceae were found to be highest in the liquid fraction where they form a substantial proportion of the bacterial community (a total of 59%).
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This study presents an investigation of electrochemical variables in the operation of a continuous upflow electrocoagulation process in treating textile wastewater. Reactive Blue 140, which is porphyrin-based, was used as a representative... more
This study presents an investigation of electrochemical variables in the operation of a continuous upflow electrocoagulation process in treating textile wastewater. Reactive Blue 140, which is porphyrin-based, was used as a representative dye in the experiments. The optimal values of the design and operating parameters were found, from a batch mode, to be the following: iron anode, distance between electrodes of 8 mm, current density of at least 30 A/m2, and contact time of at least 5 minutes. These optimal values were used to design a continuous upflow electrocoagulation reactor. The pattern of liquid flow within the upflow reactor was studied using a computational fluid dynamics (CFD) program, which simulated the flow behavior inside the reactor using the finite volume method. For optimal parameter values, the water passing the electrode plates had a uniform distribution, and the reactor performance was satisfactory, with &amp;amp;amp;amp;amp;amp;gt;90% color removal and energy consumption of approximately 1.4 kWh/m3.
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The formation of microbial granules and reduction of granule losses at the outflow are important for optimal performances of Upflow Anaerobic Sludge Blanket systems (UASB). To study the effects of chitosan on the reduction of granule... more
The formation of microbial granules and reduction of granule losses at the outflow are important for optimal performances of Upflow Anaerobic Sludge Blanket systems (UASB). To study the effects of chitosan on the reduction of granule losses and the efficiency of UASB, chitosan with degree of deacetylation of 85% was added to UASB reactors treating wastewater from a fruit-canning factory.