© 2017 Semarang State University  Corresponding author: Jurusan Teknik Mesin, Politeknik Negeri Bali, Bukit Jimbaran Badung Bali 80364 E-mail: bagusputusukadana@pnb.ac.id ISSN 2303-0623 e-ISSN 2407-2370 Jurnal Bahan Alam Terbarukan http://journal .unnes.ac.id/nju/index.php/jbat Performance Analysis of 4-Outlets Spray Aerator for Processing of Indigofera Leaves (Indigofera Tinctoria Linn) Becomes Natural Dye Substances Ida Bagus Putu Sukadana  , I Made Rajendra, Ida Ayu Anom Arsani, I Wayan Suastawa DOI 10.15294/jbat.v6i2.8045 Jurusan Teknik Mesin, Politeknik Negeri Bali, Bukit Jimbaran Badung Bali 80364 Article Info Abstract Article history: Received November 2016 Accepted September 2017 Published December 2017 The commonly known natural dye substance processing for traditional clothes, such as batik and tenun (woven cloth) is fermentation. The fermentation process can specifically be continued with extraction to produce indigo paste. The process can be done mechanically, i.e. by stirring process, and chemically. In order to accelerate the production, manual process of aeration can be substituted with jet-spray aerator. The aerator prototype which has been developed is acrylic aerator tube with diameter of 240 mm and thickness of 5 mm. The tube was made 1 m long to provide with a sufficient space for indigo foam. Its bottom part is completed with spiral air hose having five small holes of 0.2, 0.4, and 0.6 mm diameter uniformly located along the height of solution in the tube. The aerator was designed for the 10 litters of fermentation solution of 1 kilogram indigofera leaves. Based on the mass of indigo paste produced, the optimum working condition of the aerator is achieved on 3.8 m/sec air velocity and supply pressure of 2 bar with duration of 60 minutes. The aeration test indicated operational characteristic was quite good, i.e. Oxygen Transfer Rate (OTR) of 3.6 kg/hour, Aeration Efficiency (AE) of 4.8 kg/kWh and factual Oxygen Transfer Efficiency (OTE) of 44%. Keywords : Aerator; Extraction; Natural dye; Indigofera INTRODUCTION Natural dye substances for textile are obtained from extracts of plant parts, such as leaves and twigs. Indigo blue dye substance is usually obtained from extracts of indigofera plants (Indigofera Tinctiora). Due to its limitations, the use of natural indigo dye had undergone a shift and was almost entirely taken over by synthetic indigofera. With the consideration of environmental pollution caused by synthetic materials, nowadays the natural ingredients of indigo dyes are in demand even though its development encounters several obstacles, such as limited source of raw materials due to lack of serious cultivation of indigofera crops (Departemen Pertanian, 2009). Indigofera actually grows wild in nature and is easy to cultivate (Suheryanto, 2012) so that if the cultivation is planned carefully it will become a renewable natural resource in a sustainable manner. The known method of extraction has actually been developed for a long time in Indonesia. One of them is the result of previous research on the extraction of indigofera leaves, which has been carried out by BPPI research team (Suwadji et al., 1981) to obtain optimum parameters in the extraction process. The team used a diffusion type aerator with air supplied from a pressurized vessel with a pressure of 20 psig where an air stone attached on the tip of the air hose. Variables studied were the pH of the solution, the soaking time, and the ratio of the water mass to the indigofera material as well as the alkali type. In the study of the effect of fermentation time on the weight of the resulting precipitate, it was concluded that 12 hour fermentation gave the best result.