Coffee wastes are by-products after extracting liquid from ground coffee beans. The coffee wastes were classified as household wastes, but they can be used as bio-solid fuels. Coffee wastes have almost no elements of heavy metal, and low heating values are more than 10% higher than wood pellets which is expected to be used as renewable energy. The purpose of this study is to design and manufacture a 20-horsepower Pelletizer to make coffee wastes as pellet-type solid fuels, and to analyze the possibility of use them as renewable energy through experiment. As results, it is found that if the compression ratio of dice used in ordinary wood Pelletizer is increased by about 50%, it was able to make coffee waste pellets with high strength and excellent heating value without additives for pelletizing.

The development of nanostructured functional materials derived from biomass and/or waste is of growing importance for creating sustainable energy-storage systems. In this study, nanoporous carbonaceous materials containing numerous heteroatoms were fabricated from waste coffee grounds using a top-down process via simple heating with KOH. The nanoporous carbon nanosheets exhibited notable material properties such as high specific surface area (1960.1 m2 g–1), numerous redox-active heteroatoms (16.1 at% oxygen, 2.7 at% nitrogen, and 1.6 at% sulfur), and high aspect ratios (>100). These unique properties led to good electrochemical performance as supercapacitor electrodes. A specific capacitance of ~438.5 F g–1 was achieved at a scan rate of 2 mV s–1, and a capacitance of 176 F g–1 was maintained at a fast scan rate of 100 mV s–1. Furthermore, cyclic stability was achieved for over 2000 cycles.

In this study, coffee waste was extracted with different solvents such as ethyl acetate, methylene chloride and methanol to investigate the total polyphenol contents, electron donating ability and the inhibitory effect on glutathione S-transferase. The total polyphenol contents were 3,060.61±357.12 μg GAE/mL in ethyl acetate, 909.09±35.71 μg GAE/mL in methylene chloride, and 1,602.27±30.36 μg GAE/mL in methanol. The total polyphenol contents showed a significant difference (p<0.05) between the solvents. The electron donating ability was 80.20±1.45% for ethyl acetate, 81.94±0.45% for methylene chloride, and 85.14±1.53% for methanol. The electron donating abilities were significantly different (p<0.05) between the solvents. The inhibitory effect of the various extracts on glutathione S-transferase (% inhibition) was 92.12±0.56%, 88.48±0245% with methylene chloride extract, and 90.85±0.14% with methanol extract. These too were significant different (p<0.05) between the solvents. The two portions of coffee waste extracts obtained from ethyl acetate and methanol showed meaningful results on the total polyphenol contents, and the inhibition effects on glutathione S-transferase. Therefore, they can be utilized to develop health care foods and can be applied as antioxidants for cosmeceuticals.

H2S adsorption characteristics of adsorbent made by coffee waste were investigated. For analyses of the manufactured adsorbent, various methods such as scanning electron microscope(SEM), measurements of BET(Brunauer Emmett Teller) surface area, pH, and Iodide adsorption were adopted. As major adsorption characteristics, adsorption equilibrium capacity was measured by using a batch type experimental apparatus for operating variables such as adsorption temperature(25～45℃), adsorbent types. The experimental result showed that the H2S adsorption equilibrium capacity of adsorbent made by coffee waste much more increases with steam activation for the coffee waste.

This study performed a basic test to evaluate the energy value of food waste and ground coffee residue, and measured the calorific value of mixtures of food waste and ground coffee in the mass ratios of 1 : 1, 1 : 2, and 2 : 1. According to the results of this study, food waste, ground coffee, and their mixtures are technically viable as energy resources because they all meet Korea’s quality criteria for Bio-SRF. The proximate analysis results for food waste and ground coffee mixture showed 51.6% moisture, 46.2% combustibles, and 2.2% ash content. The high calorific value and low calorific value measured by the SE-C5500 Bomb Calorimeter were 4,602 kcal/kg and 3,927 kcal/kg, respectively. Heavy metal analysis showed the absence of mercury (Hg) and arsenic (As). Therefore, food waste, ground coffee residue, and their mixture sample met Korea’s quality criteria for Bio-SRF, which are technically and economically viable for use as bio-solid fuel (Bio-SRF).

Korea belongs to a very fast growing market for coffee consumption and at the same time the amount of coffee waste has also been proportionally increased, But until now on only a small amount of coffee waste is utilized as a fertilizer, even it contains many kinds of valuable substances for agricultural purpose. With several treatment-technology of coffee waste a higher productivity can be established in combination with additional supplements. In this study the roasting effect of coffee waste was compared in combination with other substances in terms of mushroom cultivation. Roasted coffee waste contains many kinds of bio-active compounds and minerals and such components are very useful for plants, fungi and mushroom cultivation. We tried to develop a more effective and efficient medium for mushroom. Mushroom belong to typical health food and the consuming amount is also increasing. Pleurotus ostreatus is one of the most popular mushroom. The growing market and fast cultivation has been demanding. A qualified media with reasonable price is an important factor, because why coffee waste has a good value for mushroom production. In this study Pleurotus ostreatus spores were cultivated in roasted coffee waste with addition of variable substances, for example, bentonite and hydrogel. By the counting number of spores the effect of these added substances were compared.

H2S adsorption characteristics of adsorbent made by coffee waste were investigated. The manufacturing method of adsorbent is to activate the coffee waste with steam after carbonization of dried coffee waste. For analyses of the manufactured adsorbent, various methods such as scanning electron microscope (SEM), measurements of BET(Brunauer Emmett Teller) surface area, pH, and Iodide adsorption were adopted. As major adsorption characteristics, adsorption equilibrium capacity was measured by using a batch type experimental apparatus for operating variables such as adsorption temperature (25~45℃), adsorbent types. The experimental result showed that the H2S adsorption equilibrium capacity of adsorbent made by coffee waste much more increases with steam activation for the coffee waste.