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Palm kernel shells (PKS), empty fruit bunches (EFB), and trunks are by-products of the palm oil industry and form approximately 50 wt % of fresh fruit bunch (FFB). In particular, EFB accounts for approximately 20 wt % of FFB. Although large amounts of EFB are generated from palm oil mills every year in Indonesia and Malaysia, EFB is treated as waste because commercial technologies for thermo-chemical conversion of EFB into renewable energy are still under development. A robust conversion method can transform EFB into an appealing renewable energy source. In order to secure this renewable energy source, Korea can import EFB as biomass. This paper investigates literature on the status of utilization of EFB, by-products from palm oil mills in order to identify the best available technological process to use EFB as bio-solid refuse fuels (SRF). Meanwhile, physico-chemical analyses (proximate, elemental, and calorific value analyses), biomass and heavy metal content were measured in order to assess whether EFB would be suitable for use as a bio-SRF, in accordance with the Korean quality standard for SRF. According to the analysis results, EFB showed applicability to use as bio-SRF; main analysis results - moisture (9.63 wt %), ash (5.94 wt %), biomass content (97.82 wt %) and calorific value (3668 kcal kg).

Sludge generated from metal smelting processes may contain a large amount of mercury with high sulfur content. A sludge roasting technology could be used to recover mercury from such sludge. Thermo-gravimetric analysis was employed to investigate the thermal decomposition properties of mercury and mass in the sludge. At elevated temperatures ranged from 200 to 650 °C at interval of 25 °C, total mass losses of sludge and mercury decomposition from the sludge containing over 2000 ppm of mercury were experimentally investigated. At temperatures of 200–325 °C, the decomposition rate of mercury from the sludge was very low and then the decomposition was taken place very rapidly from 350 to 575 °C. As the discrete mercury decomposition data at elevated temperatures were smoothened by least square method, the kinetic parameters of mercury decomposition reaction were determined for two different temperature zones. The decomposition of mercury could be correlated with thermal mass degradation of the sludge experimented. By comparing derivative thermo-gravimetric results for mercury in the sludge with high sulfur content and pure mercury compound species, HgS and Hg2SO4 were found to be the dominant form of mercury in the sludge due to high content of sulfur.

The study conducted basic component analyses including three component analyses, elementary analysis and heavy metal content and BMP test according to the mixing ratio for food waste leachate and wastewater treatment sludge(from brewery, dairy factory, bread factory, sewage sludge), and calculated biogas production speed using mathematical models. According to the elementary analysis of organic wastes, the C/N ratio, a major condition for anaerobic digestion, is 5.40–9.23, except for food waste leachate (FWL). Defined by Tchobanoglous’ mathematical biogas prediction model, methane gas and biogas productions increased, depending on the mixing rate of FWL. Furthermore, anaerobic digestion of both wastewater sludge and food waste leachate based on the correct mixing ratio, increases methane gas productions compared to digesting wastewater sludge alone. In other words, co-anaerobic digestion is more likely to realize biogasification than single anaerobic digestion. We mixed food waste leachate and wastewater treatment sludge by proportion of 1:9, 3:7, and 5:5, respectively. It turns out that they produced 118, 175, 223 CH4 mL/g VS with the dairy factory, 176, 233, 263 CH4mL/g VS with the brewery, 268, 300, 314 CH4 mL/g VS with the bread factory and 233, 298, 344 CH4-mL/g VS with the sewage sludge of methane gas. The result proposes that as the mixing rate of food waste leachate rises, the methane gas production increases as well. In the case of co-digestion of wastewater treatment sludge and food waste leachate based on the mixing ratio, more methane gas is produced compared to single digestion of wastewater treatment sludge. Modified Gompertz and exponential models describe the BMP test results that show how methane gas is produced from organic waste. According to the test, the higher the mixing rate of food waste leachate is, the higher the methane gas production is. The mixing ratio of food waste leachate which produces the largest volume of methane gas is 1:9 for the dairy and bread facilities and 3:7 for brewery and sewage sludge. Modified Gompertz and exponential models describe the test results very well. The correlation values (R 2) that show how close the results of model prediction and experiment are 0.920–0.996.

We mix food waste leachate and sewage sludge by the proportion of 1:9, 3:7 and 5:5. It turns out that they produced 233, 298 and 344 CH4⋅mL/g⋅VS of methane gas. The result suggests that as the mixing rate of food waste leachate rises, the methane gas productions increases as well. And more methane gas is made when co-digesting sewage sludge and food waste leachate based on the mixing ratio, rather than digesting only sewage sludge alone. Modified Gompertz and Exponential Model describe the BMP test results that show how methane gas are produced from organic waste. According to the test, higher the mixing rate of food waste leachate is, higher the methane gas productions is. The mixing ratio of food waste leachate that produces the largest volume of methane gas is 3:7. Modified Gompertz model and Exponential model describe the test results very well. The correlation values(R 2 ) that show how the results of model prediction and experiment are close is 0.92 to 0.98.

This study was to find out potential of methane yield on food waste and food waste leachate as biomass in Korea. The seven biogasification facilities were selected for comparison of theoretical methane yield and actual methane yield. The theoretical methane yield was calculated based on organic constituents (carbohydrate, protein, fat) and based on element analysis. The actual methane yield was investigated based on volatile solids and CODcr. Theoretical methane yields by organic constituents were 0.52 Sm3CH4/kg VS and 0.35 Sm3CH4/kg CODcr and these by element analysis were 0.53 Sm3CH4/kg VS and 0.36 Sm3CH4/kg CODcr. Actual methane yields were 0.36 Sm3CH4/kg VSin and 0.26 Sm3CH4/kg CODcrin. Considering the average removal efficiency of organic materials of seven FWL biogasification facilities, actual methane yields were 0.48 Sm3CH4/kg VSrem and 0.33 Sm3CH4/kg CODcrrem. Methane yield by organic constituents is very similar to that by element analysis and actual methane yields of volatile solids and CODcr were similar to theoretical value. The actual methane yield in this study showed approximated boundary values with previous other references which conducted in lab-scale or biochemical methane potential (BMP) tests. In conclusion, Korean food waste and food waste leachate have sufficient potential of methane yield in the ongoing biogasification facilities.

The present investigation deals with the effectiveness of hydrogen-rich water in controlling the physical and mechanical performances of cement mortar. In this study, the different concentrations of hydrogen-rich water (0.2, 0.3, 0.4, and 0.5 ppm) were used to fabricate the mortar samples. The impact of the hydrogen-rich water was evaluated analyzing the setting time, flow table value, bulk density, water absorption, apparent porosity, compressive strength and flexural strength of the cement mortar samples. Analyzing the results, the final setting time of the control, as well as 0.5 ppm hydrogen-rich water based cement, is measured to be 257 ± 3 min and 14 ± 3 min, respectively. Additionally, the compressive as well as flexural strength of 7 days cured 0.5 ppm hydrogen-rich water based cement mortar is found to be 59% and 30% higher, respectively, as compared to that of the control mortar. This could be primarily governed by the formation of the greater extent of hydrated cement product in the presence of hydrogen-rich water. Therefore, it is demonstrated that the hydrogen-rich water behaves like a cement set accelerator admixture. Finally, a model has been proposed to explain the overall performances of hydrogen water based cement mortar.