Asia-Pacific Journal of Science and Technology

Experimental investigation and mathematical modeling of silkworm pupae drying using far-infrared radiation combined with hot air

2023-08-10T11:17:19+07:00

This study aimed to investigate the effect of far-infrared radiation (FIR) power and the position of FIR heaters on the drying kinetics, specific energy consumption (SEC), color, and hardness of silkworm pupae undergoing drying using FIR (at 0, 100, 300, and 500 W) combined with forced convection heat transfer using hot air (at 110 °C). The FIR heaters were positioned in two ways: (1) at the top of the drying chamber, and (2) both at the top and bottom of the drying chamber. The silkworm pupae were dried to a final moisture content of less than 5% on a wet basis (w.b.). Eight mathematical models were analyzed to find the best one for describing the drying behavior of silkworm pupae. Based on the experimental results, an increased FIR power led to decreased drying time and SEC, as well as an increase in product temperature and hardness of the dried silkworm pupae. Drying silkworm pupae using higher FIR power resulted in lower lightness but higher redness and yellowness compared to those dried using lower FIR power. The position of FIR heaters did not have a significant impact on the drying time, product temperature, SEC, color, and hardness of the dried silkworm pupae. The results obtained from fitting the experimental data to mathematical drying models showed that the Page model was the best for describing the drying behavior of silkworm pupae. Additionally, the effective moisture diffusivity (Deff) values of silkworm pupae ranged between 1.13×10-8 and 1.81×10-8 m2/s.

Geotechnical characteristics of peat soil in OKI area, South Sumatra, Indonesia

2023-12-28T17:03:25+07:00

Peat soil is characterized by a high-water table, significant compressibility, and low bearing capacity. Due to these characteristics, precise information about the physical, hydraulic, and mechanical properties of peat soil is required for the successful evaluation of suitability and improvement techniques in determining safe infrastructure through field and laboratory investigations. In this paper, soil properties, permeability, vane shear tests, and triaxial tests were conducted on peat soil at the locations of Kayu Agung, Pedamaran, Pedamaran Timur, and Ogan Komering Ilir (OKI), South Sumatra. Based on the samples obtained from the borings, the average thickness of peat soil was categorized as very deep, except for the location in Pedamaran, which was extremely deep. The moisture content in the OKI area ranged from 350% to 635%, with the largest in the Pedamaran Timur district. Furthermore, samples from OKI were classified as sapric peat soil, with ash content ranging from 19.71% to 39.24%, showing high ash and moderately acidic. The correlation of various geotechnical properties of peat soil was very close, and new equations were developed. Based on the results of the Vane Shear Test and Triaxial Unconsolidated Undrained test, the consistency of the soil at each location point was found to be very soft. These results provide valuable information for identifying appropriate design parameters and establishing correlations needed for evaluating peat soil.

Treatment of high strength organic wastewater by using an anaerobic membrane bioreactor

2024-02-08T08:51:00+07:00

Properly managing wastewater with high concentrations of organic compounds is essential to prevent adverse environmental impacts. This study several various values of hydraulic retention times (HRT) to determine the optimal conditions for an anaerobic membrane bioreactor (AnMBR), as well as its performance and membrane fouling. The results indicated that an optimal chemical oxygen demand (COD) removal efficiency of 81.18% was achieved for a 48-hour HRT condition. The organic removal rate (ORR) was found to be 7.90 kg COD/m3-day, with biogas productivity of 0.224 m3/kg CODremoved. The potential operation was optimal for the 48-hour HRT condition compared to the other conditions. Importantly, the study revealed that a longer HRT could mitigate membrane fouling in the AnMBR, which was attributed to the impact of the volumetric organic loading rate.

Evaluating the fire-reaction properties of building materials used in informal settlements in Dhaka, Bangladesh

2023-12-28T09:09:09+07:00

In Bangladesh, the alarming rise of fire incidents in informal settlements is becoming a growing concern for the government and citizens. Informal settlements, also known as slums, ghettos, etc., are unplanned developments often not in compliance with planning and building regulations, overcrowded, lacking basic infrastructure, and constructed of flammable materials highly vulnerable to fire outbreaks are unplanned areas illegally where housing is not in compliance with planning and building regulations. Overcrowded and lack basic infrastructure and are highly vulnerable to fire outbreaks. The lack of proper firefighting equipment and inadequate access to clean water make it difficult to control the spread of fire in these areas, further exacerbating the situation. Consequently, hundreds of families are losing their homes and livelihoods, and many lives are being lost in devastating fires. A comprehensive numerical analysis for understanding the fire-reaction properties of construction materials used in informal settlements and Cone Calorimeter simulation according to ASTM E1354: Standard Test Method for Heat and Visible Smoke Release Rates for Materials and Products were conducted. An Oxygen Consumption Calorimeter was used to characterize the fire-reaction properties of construction materials under varying heat flux values. Additionally, an advanced numerical model based on the finite volume method was developed using Fire Dynamics Simulator (FDS) and PyroSim. Wood, polyurethane foam, and cardboard were chosen for rapid fire development. Simulation results have been compared against analytical and experimental data with reasonable accuracy. This paper extends the understanding of the behavior of construction materials that are directly responsible for rapid-fire growth.

The influence of wave height and period on airflow velocity and differential pressure in L-shaped oscillating water column (L-OWC) chamber for wave energy converter (WEC)

2023-09-20T15:43:01+07:00

The Oscillating Water Column (OWC) technology is widely recognized as a highly efficient solution for harnessing wave energy and has shown significant progress. In this context, the OWC device with an L-shaped chamber, recently introduced and developed by Wave Swell Energy Australia, has garnered significant interest from researchers in the field of marine energy. This device stands apart from conventional OWCs or other models due to its utilization of an L-shaped channel for capturing wave energy. This research aims to understand the influence of wave height and wave period on airflow velocity and pressure differentials within the L-shaped OWC chamber and to obtain the efficiency value of the L-shaped OWC (L-OWC) chamber with variations in input wave generation characterized by relatively short-wave periods. The research was conducted using numerical simulations with Flow 3D software version 11, validated through 2D physical model testing at the Coastal Dynamics Laboratory - National Research and Innovation Agency (1:8 scale). The numerical study observed that wave height and wave period significantly affect the airflow velocity and differential air pressure within the L-OWC chamber. The L-OWC effectively harnesses energy optimally with wave periods longer than 2.47 seconds. The L-OWC chamber design demonstrates optimization at a Tin period of 2.47 seconds, with an average efficiency of 84.2% across various wave height scenarios. The peak power efficiency of the L-OWC device is 98.2%, achieved with a Hin variation of 0.1875 m and Tin of 2.47s.

Decolorization of Remazol Brilliant Blue R with immobilized laccase from Megasporoporia sp. onto spent coffee ground biochar

2024-02-28T14:51:06+07:00

In this study, biochar was synthesized from spent coffee grounds and subsequently treated with glutaraldehyde for the immobilization of laccase, which was used in the decolorization of an azo dye. The optimal conditions for immobilizing Megasporoporia sp. laccase onto activated biochar (10mg) were investigated by varying the times, enzyme activities, and glutaraldehyde concentrations. The maximum enzyme loading (68.80±2.89 mg/g) with a laccase activity of 16.39±1.35 U/g was achieved by using 1%(v/w) glutaraldehyde as the crosslinking agent, with an initial laccase activity of 40 U/g support after performing the incubation reaction for 2 hrs. This immobilized enzyme achieved a maximum decolorization rate of 95.00% when incubated with 100 ppm Remazol Brilliant Blue R in sodium acetate buffer (pH 5.0) at 50°C for 3 hrs. The thermal stability of immobilized laccase with spent coffee ground biochar (SCGB-laccase) after incubation at 50°C for 6 hrs was significantly higher than that of the crude enzyme with decolorization rates of 79.21% and 53.70%, respectively. Additionally, the residual activity of immobilized SCGB-laccase was 57.64% after being used for six cycles. The degradation product was tested for its phytotoxicity, and it was found that the germination index values of mung bean and sweet corn were significantly higher in the treated dye (77.66% and 64.50%, respectively) compared to those in the non-treated dye (51.88% and 34.89%, respectively). Therefore, the efficiency of immobilized laccase onto activated spent coffee ground biochar for dye decolorization was noted, and this technique could be further applied for wastewater treatment on an industrial scale.

A portable RGB color sensor for detecting free fatty acid (FFA) in palm oil samples

2024-04-02T14:31:33+07:00

A colorimetric sensor based on red, green, blue (RGB) measurement using an OV2640 camera module and ESP32 microcontroller was developed for measuring free fatty acid (FFA) in crude palm oil samples. The proposed method is based on measuring the color of liquid samples and convert it to RGB and Grayscale intensity. The RGB sensor’s performance was evaluated for application in analysing FFA in crude palm oil samples. The FFA analysis was based on the application of the limiting reagent concept in an acid-base (palmitic acid-Na2CO3) reaction with phenolphthalein as an indicator. The RGB sensor could detect FFA with a linear relationship in the range of 0.0 - 0.1 % w/w and the linear regression equation was y = 1,125x - 2.8056, r = 0.9923, with limit of detection (LOD) and limit of quantification (LOQ) having values of 0.017 and 0.057 % w/w, respectively. The analysis of FFA in crude palm oil samples showed good agreement with results obtained from the proposed RGB sensor and the titration method (AOCS; Ca5a-40). This simple, rapid, and economical analysis method for assessing FFA holds promise for application in the quality control of crude palm oil samples.

Development of ISSR-Derived SCAR marker for rapid and accurate authentication of West Indian arrowroot (Maranta arundinacea L.)

2024-05-02T15:29:42+07:00

Arrowroot, or West Indian arrowroot (Maranta arundinacea L.), native to the Antilles, Mexico, and other Central American countries, has the potential to become a flour source. Species are primarily identified based on morphological characteristics, which are influenced by the environmental factors. Currently, the most accurate authentication method is through DNA markers or molecular fingerprinting. Arrowroot accessions from various provinces were distinguished from their related species using Inter-Simple Sequence Repeat (ISSR)-derived Sequence-Characterized Amplified Region (SCAR) markers. DNA profiling was conducted based on the results of DNA amplification using ISSR primers. The polymorphism data identified a fragment, UBC825Ma-924, which was generated by primer UBC825 and was only present in arrowroot genotypes. The specific band was sequenced, and SCAR primers (SC-UBC825Ma-630) were designed and synthesized to amplify the 630 bp band. Using the primer pair and total DNAs of M. arundinacea and related species, diagnostic PCRs produced specific amplification only in M. arundinacea genotypes. This approach is quick, reliable, simple, viable for authentication, and helpful for cultivar development and conservation.

Effect of vitamin B6 on GABA accumulation and growth stimulation in germinated mung beans

2024-06-04T09:14:51+07:00

γ-aminobutyric acid (GABA) is an inhibitory neurotransmitter in animals and humans. It has several health advantages involving relief of anxiety and depression, as well as memory and immunity enhancement. GABA is also found in seeds as a reserve protein for plant growth. It is synthesized from glutamic acid by the glutamic acid decarboxylase (GAD) enzyme using vitamin B6 as a co-enzyme. To enhance the GABA content in bean sprouts, the effect of vitamin B6, in the form of pyridoxine hydrochloride (PN), on GABA accumulation in mung beans was examined. Supplementation of PN at various concentrations (1, 10, and 50 mg/L) was carried out in soaked and germinating mung beans. The results demonstrated a negative effect of PN on GABA accumulation. GABA was dramatically reduced with increased PN concentrations during soaking and germination. The highest GABA content was found in the control sample with no PN addition. Interestingly, PN showed an unexpected effect on promoting the growth of mung bean sprouts. The stem lengths of mung bean sprouts were significantly extended by increased PN concentrations. At 50 mg/L, PN induced a 35.6% elongation of stem length over that of a control. GABA content was negatively affected by PN in soaked seeds and germinated bean sprouts. However, it promotes mung bean growth during germination. PN is an effective growth stimulant for mung beans during germination.

Modelling of experimental drying kinetics of Codiaeum Variegatum Brilliantissima-Zanzibar used as a corrosion inhibitor

2023-12-28T16:23:11+07:00

The drying kinetics of Codiaeum Variegatum Brilliantissima-Zanzibar (Wire Croton) in the open air were modelled in this research. Daily temperature and the humidity of the environment were monitored every 12 hrs during the experiment. Wire Croton drying results obtained every 12 hrs were plotted against drying time to study the drying properties of the sample at 12 and 24-hr intervals. The results obtained were fitted into Lewis, Page, Modified Page, Handerson-Pabis and Ademiluyi’s model for the determination of the Root Mean Square Error (RMSE), which gave values of 0.277, 0.115, 0.173, 0.163 and 0.170, respectively and the coefficient of regression (R2) values of 0.539, 0.525, 0.954, 0.539 and 0.954, respectively for 12 hourly test. The 24-hour interval test gave RMSE values of 0.218, 0.113, 0.101, 0.162 and 0.097, corresponding R2 values of 0.801, 0.448, 0.448, 0.801 and 0.851. The Izionworu & Ojong model was developed and tested. When compared with existing models, Izionworu & Ojong’s thin-layer model gives the least RMSE value of 0.104 and 0.029 at 12 and 24-hour intervals respectively, compared to the other models and an R2 of 0.988 and 0.918 correspondingly for both the 12 and 24 hrs drying intervals. A 50% error deviation was achieved when the Izionworu & Ojong model was compared with the other two-term models confirming that the drying characteristics of wire croton in the open air are best described by the Izionworu & Ojong model.

Isolation and nitrogen removal efficiency of halophilic heterotrophic nitrifying bacteria, Alcaligenes strains SRNB23 and SRNB35

2024-03-11T15:46:22+07:00

The halophilic heterotrophic nitrifying bacteria play a significant role in mitigating the toxicity of inorganic nitrogen compounds, namely ammonia, nitrite, and nitrate in shrimp production systems. Two strains of heterotrophic nitrifying bacteria, namely strain SRNB23 and strain SRNB35, were obtained from sediment samples collected from a pacific white shrimp farm. The microorganisms were classified as Alcaligenes faecalis, with a similarity value ranging from 91% to 98%. The findings indicated that the ammonium removal effectiveness of SRNB23 and SRNB35 was 91.75% and 91.21%, respectively. The optimal proportion of the SRNB23 and SRNB35 mixture was determined to be 30% SRNB23 and 70% SRNB35. The observed ratio exhibited an ammonium removal effectiveness of 59.72%. As a result, sodium citrate has been identified as the preferred carbon source for SRNB23, whereas sucrose has been found to be the best carbon source for SRNB35. Ammonium sulfate was shown to be the most effective nitrogen source for both strains. The C/N ratio of SRNB23 and SRNB35 was found to be 16 and 2, respectively, indicating their respective ideal conditions. Subsequently, an analysis was conducted on both individual bacterial strains and bacterial mixtures in order to assess their efficacy in the treatment of wastewater originating from a shrimp farm, characterized by an ammonium concentration ranging from 461 to 467 mg-N/L. The findings indicated that the combination of SRNB23 and SRNB35 exhibited the most notable efficacy in removing ammonium, with an efficiency rate of 63.07%.