Chicken meat agroindustry is one of the industries that contribute to environmental impacts. The environmental impacts are due to the use of resources, energy, and waste along the chicken meat chain. This study aimed to evaluate the environmental impacts along the life cycle of the chicken meat chain from cradle-to-grave using a life cycle assessment (LCA) approach. The data inventory consisted of inputs and outputs from five sub-systems: feed production, broiler production on the farm, carcass production at the slaughterhouse, supplier distribution, and consumer use. The impact categories included global warming, acidification, and eutrophication. The process of impact calculation used the CML-IA (Centre of Environmental Science of Leiden University Impact Assessment) baseline method on the SimaPro software. The results showed that consuming 1 kg of fried chicken resulted in a global warming impact of 5.86 kg CO 2 eq, acidification of 38.3 g SO 2 eq, and eutrophication of 24.1 g PO 4 3eq. Feed production, litter, and energy usage were the most significant contributors to the environmental impacts. Improvement scenarios in reducing environmental impacts included reducing crude protein in feed, composting litter, installing inverters on refrigeration compressors, and electrical energy efficiency. The present study indicated the importance of environmental impact assessment on the entire chicken meat chain to improve environmental performance in the Indonesian chicken agroindustry.

The synthesis of matrix silica-potassium-humic acid gel (Si-K-HAs) has been performed successfully by gradual extraction and acidification method. The extraction was carried out in two stages: 1) extraction of humic substances from peat prepared by potassium hydroxide to produce potassium humate (K-HAS) solution, 2) extraction silica from geothermal sludge using K-HAs solution to produce Si-K-HAs solution. Acidification of Si-K-HAs solution prepared by citric acid (1-3N) to produce matrix gel of Si-K-HAs. The Si-K-HAs matrix gel products are characterized by Fourier Transform InfraRed (FTIR), X-ray fluroscence (XRF), and Brunauer–Emmett–Teller (BET) analysis. The acidification process was carried out in neutral to acid (pH 3-7) conditions and the results showed that at neutral pH no Si-K-HAs gel formed. IR spectra confirmed the presence of humic acid in the gel product, whereas XRF analysis confirmed the presence of potassium (K) and silica (SiO2) in the gel product. The molar ratio of SiO2:K2O in the product is 0.9 - 0.3 in the pH range of 3-5. Si-K-HAs powder can be used as soil fertilizer especially for soils that lack silica, humic, and potassium nutrients or for future application development. Keywords: gradual extraction; geothermal sludge; matrix gel; humic substance

Abstract. Precipitated silica from silica and carbon dioxide gas has been studied successfully. The source of silica was obtained from pumice stone while precipitation process was carried out with carbon dioxide gas (CO 2 ). The sodium silicate solution was obtained by extracting the silica from pumice stone with sodium hydroxide (NaOH) solution and heated to 100 °C for 1 h. The carbon dioxide gas is injected into the aqueous solution of sodium silicate in a bubble column reactor to form precipitated silica. m 2 /g. The results indicate that the products obtained are precipitate silica have surface area in the range of 100 -227 m 2 /g, silica concentration more than 80%, white in appearance, and silica concentration reached 90% at pH 7.

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