Jun-Wei Lim

Recent progress on biomass co-pyrolysis conversion into high-quality bio-oil

Co-pyrolysis of biomass with abundantly available materials could be an economical method for production of bio-fuels. However, elimination of oxygenated compounds poses a considerable challenge. Catalytic co-pyrolysis is another potential technique for upgrading bio-oils for application as liquid fuels in standard engines. This technique promotes the production of high-quality bio-oil through acid catalyzed reduction of oxygenated compounds and mutagenic polyaromatic hydrocarbons. This work aims to review and summarize research progress on co-pyrolysis and catalytic co-pyrolysis, as well as their benefits on enhancement of bio-oils derived from biomass. This review focuses on the potential of plastic wastes and coal materials as co-feed in co-pyrolysis to produce valuable liquid fuel. This paper also proposes future directions for using this technique to obtain high yields of bio-oils.

Nitrogen removal in moving bed sequencing batch reactor using polyurethane foam cubes of various sizes as carrier materials

The performance of moving bed sequencing batch reactors (MBSBRs) added with 8 % (v/v) of polyurethane (PU) foam cubes as carrier media in nitrogen removal was investigated in treating low COD/N wastewater. The results indicate that MBSBR with 8-mL cubes achieved the highest total nitrogen (TN) removal efficiency of 37% during the aeration period, followed by 31%, 24% and 19 % for MBSBRs with 27-, 64- and 125-mL cubes, respectively. The increased TN removal in MBSBRs was mainly due to simultaneous nitrification and denitrification (SND) process which was verified by batch studies. The relatively lower TN removal in MBSBR with larger PU foam cubes was attributed to the observation that larger PU foam cubes were not fully attached by biomass. Higher concentrations of 8-mL PU foam cubes in batch reactors yielded higher TN removal.

Comparison of harvesting methods for microalgae Chlorella sp. and its potential use as a biodiesel feedstock

Three methods for harvesting Chlorella sp. biomass were analysed in this paper – centrifugation, membrane microfiltration and coagulation: there was no significant difference between the total amount of biomass obtained by centrifugation and membrane microfiltration, i.e. 0.1174±0.0308 and 0.1145±0.0268 g, respectively. Almost the same total lipid content was obtained using both methods, i.e. 27.96±0.77 and 26.43±0.67% for centrifugation and microfiltration, respectively. However, harvesting by coagulation resulted in the lowest biomass and lipid content. Similar fatty acid profiles were obtained for all of the harvesting methods, indicating that the main components were palmitic acid (C16:0), oleic acid (C18:1) and linoleic acid (C18:2). However, the amounts of the individual fatty acids were higher for microfiltration than for centrifugation and coagulation; coagulation performed the most poorly in this regard by producing the smallest amount of fatty acids (41.61±6.49 mg/g dw). The harvesting method should also be selected based on the cost benefit and energy requirements. The membrane filtration method offers the advantages of currently decreasing capital costs, a high efficiency and low maintenance and energy requirements and is thus the most efficient method for microalgae harvesting.

Simultaneous 4-chlorophenol and nitrogen removal in moving bed sequencing batch reactors packed with polyurethane foam cubes of various sizes.

Moving bed sequencing batch reactors (MBSBRs) packed with 8% (v/v) of 8-, 27- and 64-mL polyurethane (PU) foam cubes, respectively, were investigated for simultaneous 4-chlorophenol (4-CP) and nitrogen removal at increasing 4-CP concentration. When the 4-CP concentration exceeded 300 mg L(-1), the MBSBR with 27-mL foam cubes was observed to outperform the other MBSBRs in removing 4-CP and nitrogen. The reasons were: (1) there were more biomass in inner layer of the 27-mL cubes, compared to that of the 8-mL cubes, which was more shielded from the inhibitory effect of 4-CP and (2) the 27-mL cubes were more mobile than the 64-mL cubes. Although increasing 4-CP concentration to 600 mg L(-1) resulted in incomplete removal of 4-CP in the MBSBRs, results of the batch reactor with 27-mL foam cubes showed that complete 4-CP removal within the REACT period could be achieved by increasing the packing volume to 20%.

Electrophoretic interactions between nitrocellulose membranes and proteins: Biointerface analysis and protein adhesion properties.

Protein adsorption onto membrane surfaces is important in fields related to separation science and biomedical research. This study explored the molecular interactions between protein, bovine serum albumin (BSA), and nitrocellulose films (NC) using electrokinetic phenomena and the effects of these interactions on the streaming potential measurements for different membrane pore morphologies and pH conditions. The data were used to calculate the streaming ratios of membranes-to-proteins and to compare these values to the electrostatic or hydrophobic attachment of the protein molecules onto the NC membranes. The results showed that different pH and membrane pore morphologies contributes to different protein adsorption mechanisms. The protein adsorption was significantly reduced under conditions where the membrane and protein have like-charges due to electrostatic repulsion. At the isoelectric point (IEP) of the protein, the repulsion between the BSA and the NC membrane was at the lowest; thus, the BSA could be easily attached onto the membrane/solution interface. In this case, the protein was considered to be in a compact layer without intermolecular protein repulsions.

An insight into the remediation of highly contaminated landfill leachate using sea mango based activated bio-char: optimization, isothermal and kinetic studies

AbstractThe feasibility of converting sea mango to activated bio-char that can be used to remove organic and inorganic pollutants such as chemical oxygen demand (COD), color, and ammoniacal nitrogen (NH3-N) from landfill leachate was investigated in the present study. The preparation conditions, temperature (400–800°C), bio-char impregnation ratio with KOH (0.5–3), and retention time (1–3 h), were optimized using response surface methodology and subsequently analyzed with analysis of variance. Equilibrium data were best dealt with the pseudo-second-order kinetic model, while the adsorptive removal of organic and inorganic pollutants onto sea mango-derived activated bio-char (SMAB) was thoroughly explained by the Langmuir isotherm model. The treatment conditions such as shaking speed, contact time, adsorbent dosage, and pH were also fine-tuned in order to optimize the overall treatment process. The highest adsorptive removal for color (95.1%), COD (84.94), and NH3-N (95.77) was achieved, respectively. The ...

Kinetic studies and thermodynamics of oil extraction and transesterification of Chlorella sp. for biodiesel production

In this work, a mixture of chloroform and methanol (1:1, v/v) was applied to oil extraction from Chlorella sp. at 30, 40, 50 and 60°C for 150 min extraction times. Kinetic studies revealed that the values of n and the rate constants were found to depend strongly on temperature. The activation energy was Ea=38.893 kJ/mol, and the activation thermodynamic parameters at 60°C were Δ S≠=−180.190 J/mol K, Δ H≠=36.124 kJ/mol and Δ G≠=96.128 kJ/mol. Both Δ H and Δ S yielded positive values, whereas Δ G was negative at 60°C, indicating that this process is endothermic, irreversible and spontaneous. The acidic transesterification process was also investigated by gas chromatographic analysis of the microalgae fatty acid methyl esters (biodiesel) at different temperatures and reaction times. The fatty acid profile indicated that the main components were palmitic, linoleic and linolenic acids. The concentration of linolenic acid increased and oleic acid decreased as the temperature increased. Two-hour transesterification is the best reaction time for biodiesel production because it produces the highest percentage of unsaturated fatty acids (74%). These results indicate the potential of Chlorella sp. to produce biodiesel of good quality.

Evaluation of aeration strategy in moving bed sequencing batch reactor performing simultaneous 4-chlorophenol and nitrogen removal.

The aeration strategy ranging from intermittent to continuous aeration in the REACT period of moving bed sequencing batch reactor (MBSBR) was evaluated for simultaneous removal of 4-chlorophenol (4-CP) and nitrogen. The results show that the removal rates of 4-CP and ammonium nitrogen (NH4+–N) increased with the increase of continuous aeration period. In the presence of 4-CP, NH4+–N removal was mainly by the assimilation process. The removal of NH4+–N to oxidized nitrogen via oxidation was only observed after 4-CP was completely degraded with sufficient aeration period provided indicating the inhibitory effect of 4-CP on nitrification. As the intermittent aeration strategy would lead to slower 4-CP degradation resulting in the delay of nitrification process, continuous aeration would be the preferred strategy in the simultaneous removal of 4-CP and nitrogen in the MBSBR system.

Inhibitory effect of 2,4-dichlorophenol on nitrogen removal in a sequencing batch reactor

We examined the inhibitory effect of 2,4-dichlorophenol (2,4-DCP) on nitrogen removal in the sequencing batch reactor (SBR) system. The reactor was operated with FILL, REACT (nitrification: denitrification), SETTLE, DRAW and IDLE phases in the duration ratio of 2: 12 (9: 3): 1: 1: 8 for a 24 h cycle time. The deterioration of 2,4-DCP removal efficiency from 100 to 41% was observed when the influent concentration of 2,4-DCP was increased to 30mg/L. The residual 2,4-DCP remaining in the mixed liquor was found to inhibit the nitrification process, resulting in the decrease of nitrogen removal efficiency to 25 %. For kinetic study, the result showed that the experimental data of ammoniacal nitrogen (AN) removal at every stage fitted well to the first-order kinetics equation with high R2 values. The rate constant of AN removal, kAN, decreased with increasing influent concentration of 2,4-DCP, from 0.053 to 0.0006/min when 2,4-DCP concentration increased from 0 to 30 mg/L, respectively. However, the observed gradual recovering of AN removal with respect to the removal efficiency and kinetics during the recovery stage indicated that the inhibitory effect of 2,4-DCP on the nitrification process was reversible.

Bioremediation of wastewaters containing various phenolic compounds by phenol-acclimated activated sludge

AbstractThis study was conducted to investigate the potential of activated sludge which had been acclimated to phenol in biodegrading different concentrations of various phenolic compounds in the batch reactors. The phenol-acclimated activated sludge was capable to completely remove the initial phenol concentration of 280 mg/L, which was twice the concentration it had been acclimated. In the presence of o-cresol and m-cresol at the initial concentration of 280 mg/L each in the separated batch reactors, more than 95% of cresols could be removed by the phenol-acclimated activated sludge. However, the phenol-acclimated activated sludge was only able to achieve 38% of 4-chlorophenol removal efficiency at this initial concentration. The presence of 2-chlorophenol and 3-chlorophenol in the separated batch reactors at initial concentrations of, as low as, 35 mg/L was adequate to inhibit the phenol-acclimated activated sludge from removing them. The kinetic data for the phenolic compounds and their respective che...