Development of combined plant of biogas and bio solid-refuse-fuel from swine manure slurry

Journal of Material Cycles and Waste Management - An environment-friendly treatment of organic waste like swine manure and food waste is considered to be big challenge, because the residue of...     

Settling and dewatering characteristics of granulated methane-oxidizing bacteria

We evaluated the settling ability and dewaterability of granulated methane-oxidizing bacteria (GMOB) after granulation using a continuous-flow reactor. A comparative analysis on settling and dewatering characteristics due to changes in sludge retention time (SRT, 10, 15 and 20 days) during cultivation of GMOB was conducted. In assessing dewaterability, the specific resistance to filtration (SRF) of activated sludge and GMOB was found to be 8.21×1013-2.38×1014 and 4.88 × 1012-1.98×1013 m/kg, respectively. It was confirmed that as SRT decreased, SRF of GMOB increased. In the case of bound extracellular polymeric substance (EPS), activated sludge registered 147.5 mg/g-VSS while GMOB exhibited 171-177.2 mg/g-VSS. In the case of extracellular polymeric substance soluble EPS in effluent, activated sludge measured 62 mg/L and GMOB had 17.4-21.4 mg/L. The particle size analysis showed that mean particle diameters of GMOB were 402, 369, and 350 μm, respectively, at SRTs of 20, 15 and 10 days. In addition, it was found that GMOB had a larger mean particle diameter and exhibited much better settleability and dewaterability than activated sludge did.     

Structural Change of the Manufacturing Sector in Korea: Measurement of Real Energy Intensity and CO2 Emissions

In terms of energy use, it is wellknown that energy intensity in the manufacturingsector is higher than any other sector. In Korea, theenergy intensity of the manufacturing sector hasdeteriorated since the late 1980s. This phenomenonis quite unique compared with the trend of energyintensity in other countries. In this study, weclosely examine the structural composition of Korea'smanufacturing sector from 1981 to 1996, its energyintensity, and its implications for carbon dioxide(CO₂) emissions by introducing the measurement ofreal energy intensity.The conventional index of energy intensity is notappropriate for aggregate industries. Since theaggregation of industries in the manufacturing sectorincludes structural change, it would be better toseparate the effect of structural change. Hence, inthis study, we apply a decomposition methodology forenergy intensity based on the `Divisia Index'. Ateach industry level, energy intensity is a mixedmeasurement of pure energy efficiency improvement andfuel substitution. We also calculate real energyintensity at each industry level. Based on ouranalysis, we derive carbon dioxide (CO₂) intensity and analyze the factors that affect CO₂ emission in this sector.During 1988–1993, the energy intensity of themanufacturing sector in Korea deteriorated. Industrial structural change,the real energy intensity in this sector became evenworse during this period. The primary reason for thisphenomenon was that the share of energy intensiveindustries, such as steel, cement, and petro-chemicalindustries increased. Second, during the sameperiod, liquefied natural gas (LNG) rapidlypenetrated this sector, so that theCO₂ intensity improved. We find thatharmonization of economic development strategies andenvironmental consideration is crucial for sustainabledevelopment. Based on our study, we derived somepolicy implications. Integration of industrialpolicies and energy efficiency improving programs isquite important, as well as the acceleration of fuelsubstitution to less carbon (C) intensive ones. Integration of local and global environmental policiesplays an important role for mitigatingCO₂ emissions.     

Development of an empirical equation for the transverse dispersion coefficient in natural streams

In this study, a new empirical equation for the transverse dispersion coefficient has been developed based on the hydraulic and geometric parameters in natural streams using a regression technique. First, a total of 32 data sets in 16 streams were collected. Among those sets, 16 sets were used for deriving the new equation, and the other 16 sets were used for verifying the equation. Then, through dimensional analysis, it was found that the normalized transverse dispersion coefficient is associated with several parameters such as sinuosity, aspect ratio, and a friction term. The robust least square method was applied to estimate regression coefficients. The newly proposed equation was proven to be superior in explaining the dispersion characteristics of natural streams more precisely compared to the existing equations.     

Combined steam-dry reforming of toluene in syngas over CaNiRu/Al2O3 catalysts

Cracking, steam reforming, dry reforming, and combined steam and dry reforming of toluene in model syngas were performed using catalysts to simulate tar removal produced during biomass gasification. The catalysts were prepared by adding Ru, Ca, and Mn to Ni-based catalysts, and their properties were measured using BET, pulse CO chemisorption, XRD and TG. In steam and dry reforming of toluene, a high toluene conversion was observed with increasing Ca content in the catalyst and catalysts containing Ca showed a higher activity than those containing Mn. In combined steam-dry reforming with syngas, 1%CaNiRu/Al₂O₃ indicated a conversion of 93.9% at 800°C.     

Assessment of Young Dong tributary and Imgok Creek impacted by Young Dong coal mine,South Korea

An initial reclamation of the Young Dong coal mine site, located in northeastern South Korea, was completed in 1995. Despite the filling of the adit with limestone, acid rock drainage (ARD) enters Young Dong tributary and is then discharged to Imgok Creek. This ARD carries an average of 500 mg CaCO₃/l of mineral acidity, primarily as Fe(II) and Al. Before spring runoff, the flow of Imgok Creek is 3.3–4 times greater than that of the tributary and has an alkalinity of 100 mg CaCO₃/l, which is sufficient to eliminate the mineral acidity and raise the pH to about 6.5. From April through September 2008, there were at least two periods of high surface flow that affects the flow of ARD from the adit. Flow of ARD reaches 2.8 m³/min during spring runoff. This raised the concentrations of Fe and Al in the confluence with Imgok Creek. However, by 2 km downstream the pH of the Imgok Creek is 6.5 and only dissolved Fe is above the Korean drinking water criteria (0.30 mg/l). This suggests only a minor impact of Young Dong Creek water on Imgok Creek. Acid digestion of the sediments in Imgok Creek and Young Dong Tributary reveals considerable abundances of heavy metals, which could have a long-term impact on water quality. However, several water-based leaching tests, which better simulate the bioavailable metals pool, released only Al, Fe, Mn, and Zn at concentrations exceeding the criteria for drinking water or aquatic life.

     

A novel biomonitoring system using microbial fuel cells

A novel biomonitoring system using microbial fuel cells for detecting the inflow of toxic substances into water systems has been developed for the purpose of on-site and on-line monitoring. The characteristics of electric current generation by electrochemically-active bacteria were conveniently monitored using a microbial fuel cell format and a computer-controlled potentiometer. When toxic substances (an organophosphorus compound, Pb, Hg, and PCBs) were added to the microbial fuel cell, rapid decreases in the current were observed. The inhibition ratios caused by inflow of these toxic substances (1 mg l(-1)) were 61%, 46%, 28% and 38%, respectively, when compared to the control, and generally increased in proportion to the addition time and concentration of toxic substances. When real wastewater was applied from a local wastewater treatment plant, more significant current decreases and higher inhibition ratios were observed following the introduction of toxic substances than in the laboratory tests. For example, the inhibition ratio was 76% on addition of a 1 mg l(-1) Cd and 1 mg l(-1) Pb mixture. Application of the microbial fuel cell for pollutant biomonitoring is discussed.