Ammonium sulfate (ZA) and nitrogen-phosphorus-potassium compound (NPK) are nitrogen-rich fertilisers commonly used by farmers. The fertilisers have high solubility in water, decay rapidly in wet soil and decompose into ammonia. Its lead into eutrophication phenomena and its absorption by crop roots becomes less effective. A facile and scalable method is developed to adsorb nitrogen-rich compounds into fish scale based powdered hydroxyapatite for slow-release fertiliser (SRF). Hydroxyapatite (HA) is a material that contains phosphorus and is a well-binding agent of nitrogen. This study is aiming at synthesizing HA from calcium-rich fish scale biowaste using wet-chemical precipitation method and coated the HA particles with ZA and NPK fertiliser. The fertiliser in solid form were combine with HA particles with the ratio of 6:1, and dissolved in aquadest. Total nitrogen content were measured periodically by using percolation method. The nitrogen release of the hybrids was compared to obtain the best kinetics model and it was found that zero order kinetics model was suitable for ZA-HA sample and Kosmeyer-Peppas model was suitable for NPK-HA sample. Vegetative growth of mustard plants were used to measure the effectiveness of SRF, and were found that combination of NPK-HA and ZA-HA were able to enhance up to 17% of the plant growth compare with conventional fertiliser.

The crab (Portunus pelagicus) shell is a marine biowaste produced by seafood industries. Traditionally, crab shells were collected to be converted into animal feed, however many of them are disposed of as industrial waste. A conversion of crab shells into hydroxyapatite is a better option for producing high-value biomaterial. Hydroxyapatite materials can be used as slow-release fertilizer while combining them with traditional fertilizer or as a stand-alone green fertilizer with high phosphatic content. Prior to hydroxyapatite conversion, the size reduction of crab shells is required. In this study, crab shell powder is derived from dried crab shell with the water content is approximately 10% wb. The size reduction is processed by using a customized batch type ball mill. This study is aiming at determining the kinetic model of milling parameters for crab shell milling by using the ball mills. An amount of 1.5 kg of dried crabs shell was milled by using 3-size mixed metal balls. The powder was then analyzed its particle size, and the particle size is used as an input in the mathematical model. The computational study focused on the calculation of optimal rotational velocity and kinetic model during the milling process. The kinetic model was based on Population Balance Equation of the mass balance principle, and the results are compared with experimented data characterized by particle size analyzer. It is observed that there are discrepancies between the model and experimental data due to the characteristic of raw materials; however the kinetic model can be used as a prediction of particle size reduction using the ball mill without conducting the real experiment.

Rajungan (Portunus pelagicus) merupakan salah satu hewan laut yang banyak terdapat di perairan Indonesia. Limbah cangkang rajungan memiliki kadar protein (32,95%), serat kasar (10,89%), kalsium (22,93%), dan fosfor (0,78%). Kandungan kalsium yang tinggi membuat cangkang rajungan dapat diolah untuk mendapatkan senyawa hidroksiapatit, yang bisa dipergunakan untuk pupuk lepas lambat. Sebelum dikonversi menjadi senyawa hidroksiapatit, diperlukan proses pengecilan ukuran atau penepungan dari cangkang rajungan. Proses penepungan dapat dilakukan menggunakan Ball-Mill, tetapi belum ada penelitian secara khusus yang membahas tentang mekanisme penepungan cangkang rajungan menggunakan Ball-Mill. Tujuan dari penelitian ini adalah untuk menentukan parameter penggilingan dari model kinetik pada penggilingan cangkang rajungan sehingga didapatkan prediksi pengecilan ukuran partikel tepung cangkang rajungan. Dalam penelitian ini, Ball-Mill tipe batch digunakan untuk menggiling 1,5 kg cangkang rajungan kering dengan rasio diameter bola yang berbeda. Estimasi parameter pemecahan dilakukan menggunakan model algoritma penghitungan balik,  dengan estimasi parameter pemecahan secara berurutan ɑ; α; δ; γ; 𝜙 = 1,1 ; 1,9 ; 1000 ; 0,5 ; 0,6 pada perlakuan A, dan α; δ; γ; 𝜙  adalah 8,8 ; 6,4 ; 1000 ; 0,6 ; 8,8 pada perlakuan B. Dengan menggunakan parameter tersebut dapat disimulasikan antara lama waktu penggilingan dengan ukuran partikel yang dihasilkan.

ABSTRAKCabai rawit merupakan komoditas unggulan yang banyak dibutuhkan masyarakat Indonesia. Komoditas ini mudah mengalami kerusakan seperti susut bobot, turunnya kandungan vitamin C, warna memudar, dan pembusukkan sehingga menyebabkan umur simpannya berkurang. Proses penyimpanan yang tidak tepat menyumbang sekitar 30% kerusakan cabai rawit. Tujuan penelitian ini adalah merancang alat hypobaric storage yang dapat menurunkan tingkat respirasi produk hortikultura dan kadar gas etilen sehingga memperpanjang umur simpan cabai rawit. Alat ini terdiri dari beberapa komponen yaitu storage room, reservoir tank, vacuum pump, control penel, dan meja penyangga. Metode penelitian yang dilakukan adalah perancangan dan pengujian alat serta uji kualitas cabai. Hypobaric storage menggunakan tekanan -60 sampai (-55) kPa dan suhu 22,9 °C. Hasil penelitian meliputi rancang bangun hypobaric storage, otomatisasi instrumen berjalan baik, dan cabai rawit yang disimpan dengan hypobaric storage memiliki susut bobot, kadar air, dan vitamin C sebesar 3,28%; 1,05%; dan 12,91%. Perubahan parameter susut bobot, kadar air, dan vitamin C pada refrigerator adalah 6,66%; 6,8%; dan 48,61%, sedangkan pada suhu ruang memiliki hasil 9,7%; 15,98%; dan 52,17%. Hal ini menunjukkan bahwa Hypobaric storage for Chili mampu menjaga kualitas cabai rawit dibanding dengan penyimpanan suhu ruang dan refrigerator.Kata kunci: Cabai rawit; hypobaric storage; rancang bangun penyimpanan, kualitas mutu ABSTRACT Chili is a superior commodity that is much needed by Indonesian people. This commodity is susceptible to damages such as weight loss, decreased vitamin C content, color fades, and decay, which causes reduced shelf life. An improper storage process accounts for about 30% damage to chili. The objective of the research was designing a chili storage tool based on the hypobaric system which can decrease the respiration rate and ethylene gas, thus expending the shelf life. This tool consisted of several components, namely storage room, reservoir tank, vacuum pump, control panel, and a table. The research method included design and instrument, also pepper quality testing. Hypobaric storage used a pressure of -60 (-55) kPa, and a temperature of 22.9 °C. The results showed that the hypobaric storage design, instrument automation ran well, and the chili with hypobaric storage had minimal weight loss, water content, and vitamin C degradation, at 3.28%, 1.05%, and 12.91%. Parameters alteration based on entitlement with refrigerator were 6.66%, 6.8%, and 48.61%, whereas with room temperature the results were 9.7%, 15.98%, and 52.17%. Hypobaric storage for Chili was able to keep the chili quality better than room temperature and refrigerator.

Mixed matrix membrane combines the ability of polymer matrix to separate liquid subtances by using size exclusion approach and functionalized fillers which able to enhance the separation processes. Activated carbon might potentially used as fillers in mixed matrix membranes as this porous solid has ability on absorbing fluid phase subtances. Two indigenous locally produced biowaste were examined in this study for production of biomass derived activated carbon, i.e. candlenut and pangium shells. Chemically based activation process utilizing 10% of ZnCl 2 , CaCl 2 and CH 3 COOH, respectively. While carbonization temperature fixed at 400 °C and 600 °C, respectively. Based on the evaluation, activated carbon derived from candlenut shell can absorp iodine up to 629.905 mg/g and surface area of 694.661 m 2 /g, by using CH 3 COOH activator agent. The pangium shell derived activated carbon has the average iodine absorption value of 693.564 mg/g and surface area up to 764.864 m 2 /g, using CaCl 2 activator agent. It is concluded that these biowaste have potential application of activated carbon as a separator for many industrial processes, including the utilization as absorber filling in mixed matrix membranes.