Coffee is an important export commodity for Indonesia. Coffee drying is post-harvest processing that greatly determines the coffee quality and microbiological safety. Conventional/sun drying is time-consuming, depending on the weather, and can potentially contaminate coffee beans by dust and moisture readsorption under high relative humidity. These problems could be avoided by employing artificial drying. This literature review aims to identify the current status of coffee drying technology, its advantages and limitations, to obtain coffee beans with the desired quality, duration of drying time, and energy consumption for processing. From the three types of thermal radiation dryers being reviewed, namely tray dryer, rotary dryer, and fluidized bed dryer, it was concluded that the drying air temperature and relative humidity must be selected properly to obtain the microbiological safety and the quality of the coffee brew. Efficient energy consumption requires a balance between the rate of water evaporation inside the coffee grain and the rate of water vapor removal from the solid surface by the air stream. The most efficient coffee drying is achieved at an air temperature of 50 o C, resulting in drying time and energy consumption of 65%, and 50% lower than that of 40 o C, with a good quality of the coffee brew. Fluidized bed drying combined with zeolite adsorption is potential to reduce the drying time due to an enhancement of air capacity to absorb water vapor. Application of microwave for coffee drying resulting in much shorter drying time than conventional thermal drying, but has a drawback of un-uniform grain temperature. A hybrid drying system could be implemented by using microwave and thermal oven.

Polypropylene is a widely used material for various types of equipment. As a recyclable thermoplastic polymer, polypropylene composite provides an attractive quality of thermal insulation due to its heat-retaining property. The use of rice straw for filler in thermal insulating material is based on its low thermal conductivity, renewable material, and low cost production techniques. The composite were manufactured by melt-mixing of neat polypropylene and filler of various weight fractions, pellet formation, followed by reprocessing with injection molding. The current work focused on determining the effect of filler’s weight fraction, particle size and pretreatment on the thermal conductivity and tensile strength of the composite. The result showed that an increase of filler’s weight fraction up to 30% decreased the composite’s thermal conductivity and tensile strength gradually. Composite of fine particles filler (325 mesh) gave a lower thermal conductivity and higher tensile strength than that of coarse particle (18-35 mesh). Composite with the lowest thermal conductivity of 1.39 W/mK was obtained at 30 w.% filler content and fine particles filler (325 mesh). Improvement on composite properties achieved by acetylated rice straw which enable to reduce straw’s hydophylicity and enhance adhesion between matrix and filler.

No abstract

Improving the competency of teachers at a vocational school (SMK) in Bandung carried out by lecturers in the Chemical Engineering Department of Politeknik Negeri Bandung is the main goal of this study. This also answers the hopes and proposal of the Principal of this SMK to continue cooperation in improving SMK teachers which was conducted in 2020 by lecturers in Politeknik Negeri Bandung (Polban). The activity to increase the competency of SMKN teachers in 2021 focuses on activities to increase the competency in wastewater treatment operation and matters related to the dangers of the operation. This topic has been chosen because currently the practical activities on wastewater treatment has not been carried out at this SMK. This competence improving activity could enrich the knowledge of SMK teachers related to wastewater treatment and then the knowledge could be transferred to the students and to the existing laboratory assistants at this SMK. All participants in this online training are in the competent category because they passed the post-test of the four modules and obtained a minimum score of 70 for each module. The Laboratory of Industrial Waste and Water Treatment in the Chemical Engineering Department Polban has complete industrial wastewater treatment equipment, making it possible to create a new Chemical Engineering Scheme for the Competency Test Place (TUK) possessed by this Department. Thus by conducting the training for the SMK teachers, it is not only beneficial for the teachers of SMK Bandung but also beneficial for the TUK of the Department of Chemical Engineering Polban by preparing the new Wastewater Treatment Scheme.

No abstract