Aim: This paper aims to explain the added value increasing method of reject coal which has not utilized by the company. Methodology and Results: The method to increase added value in this study used the agglomeration process of briquettes form that changing composition by adding biomass. The biomass functions to minimize bottom ash produced from burning briquettes so that the briquettes burn entirely. Stages processes in this study consist of characterization, briquetting, physical test, and chemical test. Based on the analysis, reject coal still has a high calorific value of 5,929 cal/gr. Shapes and sizes that were not following needs of coal market or consumer due to reject coal to be a waste. Briquettes have been successfully produced and meet specification requirements based on applicable regulations in Indonesia. Besides physical properties, the briquette meet density requirements which are greater than or equal to 1 gr/cm3 and shatter index value is less than 0.5%. The gas emission test shows below threshold, which is CO 0-30 ppm, H2S 0-3.6 ppm, and NOx is not detected. After evaluation, it showed that by adding 30% biomass, ignition time could be decreased and remaining unburned briquettes or bottom ash was reduced as much as 68.68%. Conclusion, significance and impact study: The bio-coal briquettes is a strategic solution to environmental problems and alternative energy sources that are environmentally friendly, because CO and H2S emissions are still below the threshold, even for NOx not detected. Making Bio-coal briquettes as a solution to the utilization of reject coal mining waste to be used as an alternative energy source has been successfully carried out.

Rice cultivation is a source of methane emissions (CH4), contributing to global warming. Efforts to reduce CH4 emissions play an important role in sustainable rice production. This study aimed to evaluate the effect of silica-enriched biochar on CH4 emissions, soil chemical properties, and the...

The Cirasea River can provide water for both the Bandung basin and agricultural irrigation. Intensive agriculture, industry, and land use changes could have an impact on water quality. The purpose of this study is to look at the origins of heavy metals in riparian water resources. Heavy metal analysis was performed on 13 groundwater and river water samples. Heavy metals in water sources were compared with sediment and soil. The samples were analyzed for heavy metals using an AAS instrument. The research method employs statistical, geographical, and heavy metal pollution index (HPI). The HPI for river water was 131, whereas groundwater was 93. River water with an HPI value of more than 100 is highly polluted, indicating that it is unsafe for human consumption and has negative health consequences. Data verification with heavy metals in sediments reveals the presence of heavy metals coming from geogenic circumstances in various locations in the upstream area. Heavy metals in downstream areas result from geological factors and anthropogenic activities in the surrounding area. The long-term effects of heavy metal pollution along the riparian zone will become apparent. More research is needed on communities that depend on groundwater supplies along the Cirasea watershed.