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The high productivity of mangosteen and its utilization in various industries produce the mangosteen peel as a waste of the process. Mangosteen peel as a lignocellulose‐based material has great potential to be utilized as a biosorbent, especially in the separation process of wastewater pollutants. Previous studies on mangosteen peel biosorbent are limited to the adsorption of heavy metal ions, dyes, and CO2 separation process. These studies show that the separation efficiency can reach above 90%, which indicates the potential to be expanded for the usage of other compounds as the adsorbate. The gradual diffusion process of adsorbate molecules into biosorbent pores depends specifically on the suitability of the materials and the operating conditions of the adsorption process. Materials suitability can be modified by the biosorbent pretreatment process to enhance its adsorption capacity. The mangosteen peel biosorbent, which still performs well in the adsorption process even after being regenerated for a few cycles, is an added value for its potential to be utilized as a biosorbent in various applications because it can reduce costs and process waste; also expand the possibility to reuse the desorbed adsorbate compound. [ABSTRACT FROM AUTHOR]

Microbial fuel cells (MFCs) can potentially be used to overcome issues with battery powered light buoys and their frequent maintenance. In this study, a phototrophic sediment microbial fuel cell (PSMFC) was chosen, as the microalgae provide oxygen to be reduced on the cathode and to release the necessary nutrients for the bacteria on the anode. To achieve this, we studied the effect of illumination, the period of the illumination, and the distance between 9-cm2 stainless steel mesh electrodes on the performance of the MFC. The illuminated cells were able to produce higher OCP (max. 205.2 mV) and higher power density (max. 0.68 mW/m²). However, the highest current was achieved during the unilluminated variation (max. 5.3 μA unilluminated and 3.3 μA illuminated). Prolonged illumination produced a higher OCP, current, and power density. A longer electrode distance produced a higher OCP, power density, and current. SEM analysis showed that biofilm formation tended to be scattered at lower electrode distance and more clumped (filling the anode area) at higher electrode distance. Through FTIR analysis, it was found that all MFC variations had the same organic matter, but a more concentrated organic content was found in the MFC at longer electrode distances. [ABSTRACT FROM AUTHOR]

Aerobic granular sludge (AGS) as recent biological wastewater treatment has been developed in a modified sequencing batch reactor (SBR) using real textile wastewater. This experiment focused on comparing the effects of different nutrient sources, i.e. fine chemicals and fertilizer, on the characteristics of the AGS. The development of AGS conducted in a reactor that called as aerobic up-flow fluidized bed (AUFB) reactor. AUFB reactor allows the three-steps SBR operation namely filling-and-discharging, reaction, and settling. The developed AGS was characterized through some parameters i.e. physical characteristics (morphology, size distribution, settling velocity, specific gravity), granulation profile (MLSS and SVI), and removal performances (removal of COD and colour). The results showed that the developed AGS has a slight morphological difference as the effect of each nutrient source. Interestingly, metal ions contained in the nutrient sources affect the granulation profile and removal performances. Higher metal ions in the sources tent towards better profile (higher MLSS and lower SVI) but decreased removal performance (lower colour removal). In conclusions, this experiment suggests that the use of fertilizers as the nutrient source in developing AGS is comparable to the use of fine chemicals.

Biodiesel come into being used as an alternative source of energy as the diminishing of petroleum reserves. This fuel is typically stored in tanks that are commonly made from carbon steel, which is easily corroded by microorganisms. Recent studies have shown that bacteria aside from SRB may also be involved in corrosion. Therefore, this research was aimed to evaluate the effect of biodiesel concentration (15%, 20% and 30% v/v) mixed in diesel oil on the corrosion of carbon steel by S. marcescens that dominate biocorrosion on hydrocarbon products. In this study, the corrosion process was investigated by evaluation of biofilm morphology and composition, the rate of corrosion and the corrosion product of carbon steel which was exposed in the mixture of hydrocarbons and the presence of S. marcescens. It can be concluded that higher concentration of biodiesel in diesel oil leads to higher growth of bacteria in the biofilm and higher corrosion rate.

Palm Fatty Acid Distillate (PFAD), a by-product of CPO industry, contains approx. 82%-wt of free fatty acids, which can be utilized as raw material for Magnesium Salts of Fatty Acids (Mg-PFAD). The objectives of the experiment were to produce Mg-PFAD salts through saponification-fusion reaction of PFAD at low temperature and ambient pressure and investigate the effect of MgO to fatty acid molar ratio on reaction conversion and yield. Next, washing Mg-PFAD salts with ethanol was able to facilitate the recovery of vitamin E (tocopherol and tocotrienol) from PFAD. Composition of Mg-PFAD were determined by AAS and GC analysis. Based on the data, yield of Mg-PFAD was increased by the increased of MgO to PFAD molar ratio. Mg-content of the product was within the standard according to FAO reference (4-5%-wt). Reaction was completed within 5-7 min after the addition of H2O (as catalyst).

Implementation of outdoor photobioreactors has been challenged by an extremely oversaturated daily peak of solar irradiance. This study aims to understand the role of column size and paranet shading as well as to investigate the most convenient light control in outdoor cyanobacterial culture. The photobioreactor (PBR) consisted of plastic columns with a diameter of 12.74 cm (PBRd-20) and 31.85 cm (PBRd-50) laid outdoors and inclined at 158.22° upwards against solar radiation, while paranet shading was provided at 0%, 50%, 70%, and 90% shading capacity. A semi-continuous culture of cyanobacterium Arthrospira (Spirulina) platensis was conducted for 6 weeks with weekly monitoring of the growth parameter as well as the proximate and pigments content, while the daily irradiance and culture maximum temperature were recorded. The result shows that the column diameter of 12.74 cm had a lethal risk of 44.7% and this decreased to 10.5% by widening the column diameter to 31.85 cm. This lethal risk can be eliminated by the application of a paranet at a 50% reduction level for the column diameter of 31.85 cm and a 70% reduction level for the column diameter of 12.74 cm. The highest culture productivity of 149.03 mg/(L·day) was achieved with a PBRd-20 with 50% shading treatment, but a PBRd-50 with 90% shading treatment led to an increase in the protein and phycocyanin content by 66.7% and 14.91%, respectively. [ABSTRACT FROM AUTHOR]

This study explored the applicability of chemical cleaning and air-backwash to alleviate biofouling on seawater membrane distillation (SWMD). Membrane performance and wettability properties maintained at optimum duration and frequency of the treatments, as indicated by low permeate conductivity throughout the tests. The cleaning of the membrane using 2% NaOH by immersing the membrane for 30 min after 240 min operation removed the biofouling layer, indicated by low permeate conductivity of 370 µScm−1 after cleaning. However, more frequent membrane cleaning led to membrane damage, more severe wetting, and membrane hydrophobicity reduction. Ten-second air-backwash after 240 min of operation was also effective in controlling the biofouling, particularly when conducted at air pressure of 1 bar. More frequent air-backwash resulted in more aggravated inorganic fouling and accelerated biofouling formation due to the recurring introduction of air, leading to rapid membrane wetting. [ABSTRACT FROM AUTHOR]

This research studied how the type of organic solvent and the number of extraction stages affect the vitamin E cumulative extraction yield and recovery rate from Mg-PFAD. First, PFAD was saponified to produce Mg-PFAD, then vitamin E was extracted from the Mg-PFAD using ethanol, isopropanol, or hexane, followed by evaporation to produce vitamin E concentrate. Three-stage hexane extraction with a solvent to Mg-PFAD mass ratio of 3 kg solvent/kg MgPFAD produced the highest vitamin E recovery rate. Organic solvent with a lower polarity gave a higher extraction yield and recovery rate of vitamin E from MgPFAD. In general, an increase of the number of extraction stages led to an increase of the vitamin E extraction yield and recovery rate from Mg-PFAD. [ABSTRACT FROM AUTHOR]

Palm fatty acid distillate (PFAD) was used as raw material to produce solid lubricant, or anti-adherent, for confectionery or pharmaceutical products. To improve the degree of saturation, the PFAD was hydrogenated by using two methods: gaseous hydrogenation (GH) and catalytic transfer hydrogenation (CTH) using ammonium formate to produce hydrogenated PFAD (HPFAD). The HPFAD was saponified with MgO to produce magnesium salts of hydrogenated PFAD (Mg-HPFAD). The objective of this research was to investigate the effect of hydrogen concentration and reaction temperature on the iodine value of HPFAD, and to investigate the characteristics of paracetamol tablets when using Mg-HPFAD as lubricant compared to commercial Mg-stearate. The HPFAD produced by CTH had a lower iodine value than the HPFAD produced by GH. The lowest iodine value was obtained after CTH using 3.6 M ammonium formate at 90ï,°C. Paracetamol tablets with Mg-PFAD or Mg-HPFAD lubricant showed higher dissolution of active compounds with similar friability, frictiability, and hardness compared to paracetamol tablets with Mg-stearate. [ABSTRACT FROM AUTHOR]

Biodiesel can act as carbon source for bacterial metabolisms, leading to corrosion of carbon steel. In this study, the corrosion of carbon steel by biodiesel blends (B15, B20, B30) was observed in the presence of Bacillus megaterium. The effect of biodiesel concentration on microorganism-induced corrosion was investigated by electrochemical impedance spectroscope (EIS), scanning electron microscope (SEM) and digital microscope. The results showed that under various biodiesel concentrations, Bacillus megaterium can grow and form biofilm on carbon steel. Based on the impedance analysis, their presence can increase the corrosion rate and cause pitting corrosion because the biofilm can change the electrochemical reactions in the metal or the interface solution and the kinetics of the anodic cathodic reactions. Also, Bacillus megaterium produces acid metabolites and can oxidize iron. Besides being influenced by Bacillus megaterium activities, the pitting formed on carbon steel depends on the biodiesel concentration. The results showed a great deal of shallow pit formation in B30, exacerbating the severity of metal roughness. [ABSTRACT FROM AUTHOR]

The microbial fuel cell (MFC) is an alternative technology that can be used to simultaneously solve problems related to wastewater production and energy demand. This study investigates the influence of electrode distance on power density in a microbial fuel cell using tapioca wastewater. A graphite sheet without metal catalyst was used for both electrodes, separated by a Nafion membrane. Four variations of electrode distance were used. The MFC with the longest electrode distance achieved the highest equilibrium OCV (676 mV), while the MFC with the shortest electrode distance achieved the highest power density (7.74 mW/m2). Electrochemical impedance spectroscopy (EIS) measurement suggested that the charge transfer resistance was dominant in all MFC configurations. The wastewater COD removal was in the range of 35-46%, which is in accordance with the power density of MFCs. [ABSTRACT FROM AUTHOR]

Dried biosorbent was prepared from Aphanothece sp. cyanobacteria harvested from a photobioreactor system fed with atmospheric carbon dioxide. Cadmium-ion biosorption of the prepared biosorbent from aqueous solution was characterized by non-linear (Langmuir, Freundlich and Dubinin-Radushkevich) isotherms, non-linear kinetics (pseudo first-order and pseudo second-order) and thermodynamic analysis. The optimum conditions were pH 8.0, 30°C, 0.1 g/L biomass, and 60 min contact time. The biosorption efficiencies exceeded 90%. The low-range data (initial Cd concentration C0 = 1.09-6.23 mg/L) and highrange data (C0 = 5.41-83.07 mg/L) were best fitted to the Langmuir model, with maximum uptake capacities of 12.01 and 187.5 mg/g (R2 = 0.995 and 0.996). In the Dubinin-Radushkevich isotherm model, the mean biosorption energy was 12.91 kJ/mol, suggesting that ion exchange was the working mechanism. The biosorption apparently followed pseudo second-order kinetics (R2 = 0.994- 0.999; k2 = 2.04 E-03 to 3.86 E-02 g/mg min). The biosorption process was energetically feasible (ΔG0 = −13.47-−8.88 kJ/mol), exothermic (ΔH0 = −74.82 kJ/mol) and tended to become more ordered (ΔS0 = −0.204 kJ/mol K) towards the end of the process. The biosorbent was reusable through three adsorption/desorption cycles in 1 M HCl. [ABSTRACT FROM AUTHOR]

The conventional method for cadmium removal in aqueous solutions (1–100 mg/L) is ineffective and inefficient. Therefore, a batch biosorption reactor using a local freshwater microalga (originating from an urban lake, namely, Situ Rawa Kalong-Depok) as dried biosorbent was tested. Biosorbent made from three kinds of cyanobacterium Aphanothece sp. cultivars (A0, A8, and A15) were used to eliminate cadmium (Cd2+) ions in aqueous solution (1–7 mg/L). The biosorbents were harvested from a photobioreactor system enriched with carbon dioxide gas of 0.04% (atmospheric), 8%, and 15% under continuous light illumination of about 5700–6000 lux for 14 d of cultivation. Produced dried biosorbents had Brunauer–Emmet–Teller (BET) surface area ranges of 0.571–1.846 m2/g. Biosorption of Cd2+ was pH and concentration dependent. Sorption was spontaneous (ΔG = −8.39 to −10.88 kJ/mol), exothermic (ΔH = −41.85 to −49.16 kJ/mol), and decreased randomness (ΔS = −0.102 to −0.126 kJ/mol·K) on the interface between solid and liquid phases when the process was completed. The kinetic sorption data fitted best to the pseudo-second-order model (k2 = 2.79 × 10−2, 3.96 × 10−2, and 4.54 × 10−2 g/mg·min). The dried biosorbents of A0, A8, and A15, after modeling with the Langmuir and Dubinin–Radushkevich isotherm models, indicated that cadmium binding occurred through chemisorption (qmax, D-R = 9.74 × 10−4, 4.79 × 10−3, and 9.12 × 10−3 mol/g and mean free energy of 8.45, 11.18, and 11.18 kJ/mol) on the monolayer and homogenous surface (qmax, Langmuir of 12.24, 36.90, and 60.24 mg/g). In addition, the results of SEM, EDX, and FTIR showed that there were at least nine functional groups that interacted with Cd2+ (led to bond formation) after biosorption through cation exchange mechanisms, and morphologically the surfaces changed after biosorption. Biosorbent A15 indicated the best resilient features over three cycles of sorption–desorption using 1 M HCl as the desorbing eluent. These biosorbents can be a potent and eco-friendly material for treating aqueous wastewater. [ABSTRACT FROM AUTHOR]