In a tubular photobioreactor, microalgae cells obscure one another (Self-shading), leading to the microalgae at the bottom of the tube getting less light. The objective of this research was to design and develop Tubular Photobioreactor with 93.5 liters for microalgae cultivation. The experiments had two steps. The first step was designing the solar receiver by inserting the fin into each tube wall as follows: 12-34, 1-2-3-4, 1234, and 13-24. Then, FLUENT software was used to simulate flow behavior inside the tube by Computational Fluid Dynamics by observing the pressure drop, the amount of energy consumption, and the swirling velocity to select the best fin-type. The best fin-type with the growth rate equation is introduced in the next step to simulate the microalgae's growth and movement using the user-defined function technique. The comparison of a tubular photobioreactor is investigated between fin and without fin by observing biomass production. The results showed that algae's optimum inlet velocity is 0.15 meters per second with the tubes containing fin-type 13-24. When simulating the growth behavior of microalgae, results show that the tubes without fins had lower biomass content than the 13-24 fin-type, which were 0.675 and 0.806 grams per liter, respectively, because the 13-24 fin-type will make well microalgae distribution leading to increase the light distribution too. Tubular photobioreactor fins type 13-24 had more biomass production, up to 19.4 percent.

Carrageenan is a polysaccharide compound extracted from red seaweed and is widely used by food, cosmetic, and advanced materials industries because of its good properties as an environmentally friendly stabilizer. Carrageenan extraction generally uses alkaline treatment for one full day, where the treatment is to obtain carrageenan quality with good gel characteristics. The use of cellulase enzymes is thought to accelerate the desulfuration process of seaweed, where cellulase enzymes are used to break down cellulose in seaweed cell walls. By using a rapid visco analyzer (RVA), carrageenan was tested to see the pattern and viscosity value. This study aims to determine the effect of enzymatic pretreatment on the profile of carrageenan with a shorter alkalization process compared to the alkalization commonly used by the industry. The results showed that enzymatic treatment before KOH alkalization would produce a carrageenan profile with a viscosity value of 272-360 cP, whereas the NaOH alkalization only reached 19-24 cP. The results of the test using RVA showed that the addition of an enzymatic process could change the physicochemical properties, such as viscosity and gel point of the carrageenan alkalinized with KOH. However, there was no significant difference in the properties when treated by alkalization using NaOH, which can be described from the value of the gelling point of carrageenan treated by cellulose enzyme. Adding enzymes to KOH will accelerate the gelation process, which occurs at an average temperature of 42.78oC. Meanwhile, carrageenan without enzymatic addition has an average gelation value of 37.48oC.

In a specific range of electrical conductivity, poly(lactic acid)/PLA has the potential to be developed into environmentally friendly antistatic packaging after a modification process. PLA was blended in a mini single screw extruder at 180oC with different compositions of micro-graphite (0, 0.5, 1, and 1.5 %wt.). This report discusses the degradability of PLA composite, i.e., photo-oxidative degradation and hydrolytic degradation. The weight loss, thermal properties, and cross-section morphology of the tested specimens were monitored periodically. During the degradation test, micro-graphite could be released from the composite, leaving a rough surface and reducing the weight of the composite. Differential scanning calorimetry (DSC) test exhibited that the presence of micro-graphite did not influence the melting temperature of the composition studied. However, the onset temperature of the melting point showed a slight shift of about 2-4oC. Bulk crystallinity demonstrated a considerable dependence on the micro-graphite loading (0-1.5%wt). However, there were two contradictory phenomena after both degradation tests. UV exposure could stimulate the fragmentation of PLA chains, break the crystal structure and increase the embrittlement. Thus, crystallinity tended to decrease during photo-oxidative degradation. In hydrolytic degradation, degradation firstly occurred in the amorphous regions and was ongoing within the studied range of time (0-20 weeks). Thus, the bulk crystallinity of composite tended to increase.

Organic dyes used in the food and textile industries are the primary sources of environmental contamination due to their high toxicity and nonbiodegradability. This paper describes the synthesis of cellulose nanocrystals/zinc oxide (CNC/ZnO) nanocomposite via the sol-gel method. Various characterization techniques such as FTIR spectroscopy, UV-Vis spectroscopy, and FESEM-EDX analysis were done. FTIR and UV-Vis analyses initially confirmed the formation of CNC/ZnO nanocomposites. FESEM-EDX showed a fiber-like structure with agglomerated particles on the CNC-ZnO image, suggesting the functionalization of ZnO nanoparticles onto the CNC. The photocatalytic potential of the CNC/ZnO nanocomposite was then evaluated by degrading 10 ppm thiazine dye (methylene blue) solution. The solution was irradiated with UV and visible light at an ambient temperature. The degradation was monitored at different time intervals using a UV spectrophotometer to measure the absorbance value intermittently. Results on the photocatalytic activity indicated that the synthesized CNC/ZnO nanocomposite showed faster degradation under UV light irradiation than the visible light, with an efficiency of 96.11% and 85.60%, respectively, after 180 mins of light irradiation. Further, the results suggest that the synthesized CNC/ZnO nanocomposite showed great promise as a sustainable material for the degradation of organic contaminants in an aqueous solution.

The amount of biomass products generated globally increases year after year. Nature produces lignocellulose, which is largely constituted of three components in the following order: cellulose (34–50%), hemicellulose (15–35%), and lignin (5–30%). A promising conversion method known as biomass conversion employs a liquid media-based process to address the issue of an abundance of biomass as waste. Converting biomass with ionic liquid (IL) can address not only environmental issues caused by the abundance of biomass waste but also generate new energy sources or new products with economical selling value. IL can be employed as a green catalyst, solvent, or electrolyte, as well as in a number of conversion processes. In general, 1-alkyl-3-methyl-imidazolium-based cations are the most commonly used IL types for biomass conversion. The conversion conditions are relatively mild, consisting of a low temperature of around 95-220 °C, 1 atm, for 10–240 minutes. This paper review is expected to be a significant reference in the future for the development of other biomass conversion processes.

The drying technique of Antiozonant Wax (AOW) using drying air in the spray drying tower has a considerable effect on the produced AOW powder. In this study, the drying air flow rate was measured in such a way that AOW can transform into a powder with a size of 800 mesh. The diameter and height of the spray drying tower are 1 and 6 m, respectively. Meanwhile, the AOW flow rate to the spray drying tower varies from 100 kg/hour to 500 kg/hour. The intake AOW temperature was 70 °C and at the outlet was 40 °C, while the drying air temperatures in and out of the spray drying tower were 30 and 55 °C, respectively. From the calculation results, the flow rate of the drying air is directly proportional to the flow rate of the AOW into the spray drying tower but inversely proportional to the speed of the AOW powder down the spray drying tower. In the meantime, the drying period for AOW to become a powder is between 1.033 – 1.279 s, not significantly different. It gives insight into the need to dry air in the spray drying tower configuration so that the findings will conform to the predetermined requirements.

Cockspur coral (Erythrina crista-galli L) petals are flowers that contain anthocyanins and active compounds of flavonoids and tannins. This study aims to determine the optimum conditions for the anthocyanin extraction process of cockspur coral petals using Microwave-Assisted Extraction (MAE), analyzed through the Response Surface Method (RSM). This process uses ethanol-hydrochloric acid solvents and a Box-Behnken experimental design involving three factors, namely the solvent ratios (w/v) (1:5, 1:15, and 1:25), microwave powers (300, 450, and 600 watts), and extraction times (3, 9, and 15 minutes). As a result, the second-order polynomial model was enhanced and sufficient to explain the variation of the data that denoted the significant correlation with the independent variables and the response. Derringer's desired function methodology was used for optimizing studies and generated ideal conditions for each or combined an independent variable. The optimum anthocyanin extract of 5.82 mg/L was obtained at a power condition of 325,5 Watts, an extraction time of 3.05 minutes, and a solvent ratio of 20.5. Meanwhile, the operating conditions at a power of 310.8 Watts, a time of 14.94 minutes, and a solvent ratio of 24.96 resulted in the optimum color intensity (IC) of 1040.26. In the meantime, the optimum antioxidant activity was obtained at a power of 585.97 Watts, a time of 4.93 minutes, and a solvent ratio of 5.43 with IC50 of 0.115.

Piyungan landfill is the biggest landfill in the Special Region of Yogyakarta, Indonesia, which receives municipal solid waste (MSW) from two districts and a city, while its designed service time has been over and faces operational obstacles. Meanwhile, the volume of the MSW grows rapidly and exceeds the reduction rate in their sources. The difficulty in finding a new landfill area is the reason why appropriate technological alternatives in the MSW management are strongly needed. Therefore, the study aimed to evaluate the social and economic aspects and formulate appropriate technology based on the waste entrepreneurship (wastepreneurship) concept. The methods of this study were conducting calculation of waste characteristics and composition, social evaluation, and economic evaluation of the combination of composting, incinerator, and sanitary landfill. Waste characteristics and composition were taken using direct field measurement following Indonesia's National Standard Guideline about retrieving and measuring examples of urban waste emergence and composition. Characteristics of waste are used for the calculation of calorific value and energy. The social evaluation was conducted using an in-depth interview with the rag pickers. The economic evaluation was conducted using net present value, internal rate of return, and payback period. The result of the study shows that Piyungan Landfill with total combustion waste reach 82.22% has the potential of incinerator implementation. In social evaluation, the implementation of composting and incinerator technologies would open employment for the surrounding community and rag pickers. The economic evaluation shows the combination of composting and incinerator technologies was economically feasible with an average profit margin of 12.97% in the operational period of 18 years. In conclusion, the concept of wastepreneurship is relevant in Piyungan Landfill by adjusting the MSW management paradigm from previously cost-center into business-center.

Kedondong is an underutilized fruit cultivated in a small scale in Malaysia and it contains nutrients that can be preserved through drying. The dried product can be sold as a premium fruit snack that could generate revenue for the producer. We studied the drying of peeled and unpeeled kedondong fruits using hot air (60-80°C). This study aims to investigate the drying kinetics (drying rates and effective diffusivities) of kedondong fruits and model the drying curves using thin layer models. Ten thin layer models were employed and solved using non-linear regression. Drying kinetics showed that only falling rate periods were observed, which implied that internal diffusion was the dominant mechanism for moisture release. Mathematical models showed that Modified Hii et al. (I) and (II) models were able to predict the drying curve well with the highest R2 (0.9992-0.9999), the lowest RMSE (8.0 x 10-4 - 2.5 x 10-3) and the lowest χ2 (4.0 ×10-5 - 2.0 x 10-4). Peeled samples showed higher effective diffusivities (average 3.2 x 10-11 m2/s) than unpeeled samples (average 2.7 x 10-11 m2/s). The activation energy was lower in peeled samples (25.8 kJ/mol) as moisture diffusion could occur more easily than unpeeled samples (32.1 kJ/mol). Results from this study provide kinetic information that can be used in scaling up of dryer and optimizing dryer performances.

Empty palm oil fruit bunches (EPOFB) are lignocellulose which is abundantly available in Indonesia. EPOFB has big potential as raw materials to substitute wood in nanocellulose manufacture. The production of nanocellulose from EOPFB consists of various stages, such as preparation by grinding and sizing, α-cellulose isolation, acid hydrolysis, and freeze-drying. α-cellulose isolate from POEFB through delignification using 17.5% NaOH (w / v) at 80oC for 30 minutes and bleaching using 10% H2O2 (v / v) at 70oC for 15 minutes. The bleached cellulose was then hydrolyzed by acid hydrolysis process using 64% H2SO4 for 45 minutes with temperature variations to determine the effect of temperature on the size of nanocellulose. Obtained nanocellulose then dried with the freeze-drying method at a temperature of 50oC for 6 hours. The nanocellulose morphology was characterized using SEM analysis, and FTIR analysis was done to determine the presence of cellulose and lignin. The smallest average diameter obtained at 50oC temperature is 86.8 nm with a 51.5 – 66.5 nm distribution range.