• Korean Journal of Environmental Agriculture
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• v.1 no.2
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• pp.116-122
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• 1982

Investigation on the water quality of Hwangguji River and experiment on the effects of nitrogen and soil improvements were carried out in the paddy field irrigated with polluted water of the river. The obtained results are as follows: 1) Amount of COD and $NH_4-N$ in water of the river were 54 ppm, 65 ppm, during the seeding time, and were 52 ppm, 512 ppm during the transplanting time respectively. Their concentrations were over the standard levels. It seemed that the water pollution was mainly caused by organic waste matters. 2) It seemed that the effective nitrogen level was $7{\sim}8$kg/10a in the paddy field irrigated with polluted water of the river. 3) The rice yields of potassium twice quantity application plot with N.P.K. fertilizer, the calcium application plot with N.P.K. fertilizer and the combined plot with potassium, wallarstonite, calcium and fresh straw, were increased 4, 5 and 8%, respectively, than that of the N.P.K. fertilizer standard level plot.

• Journal of the Korean Institute of Gas
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• v.16 no.5
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• pp.14-20
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• 2012

Biogas can be obtained from biogenic materials through an anaerobic digestion process. Since biogas has low calorific value and its composition significantly varies, appropriate combustion strategies need to be established to obtain stable combustion in engine applications. In this study, efforts have been made to investigate the effects of inert gas composition variations on engine performance and emissions. Results show that the MBT spark timing was advanced and $NO_x$ was reduced as the inert gas in the biogas rose. Moreover, $NO_x$ emission drop in $CO_2$ diluted biogas was more significant than that of $N_2$ due to higher heat capacity of $CO_2$, while THC emissions showed the opposite tendency. Thermal efficiency was increased in $N_2$ case with elevation of $N_2$ due to the decreased heat loss and PMEP. However, there is no difference in $CO_2$ case because of deteriorated flame propagation speed.

• Journal of the Korean Institute of Gas
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• v.15 no.5
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• pp.25-30
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• 2011

Biogas obtained from the biodegradable organic wastes in an anaerobic digester consists of $CH_4$ and inert gases such as $CO_2$ and $N_2$. Since the composition of biogas varies by anaerobic digester conditions and the origin of wastes, it is necessary to respond to these variations so as to make stable combustion and accomplish high efficiency when it is used as a fuel for power generating SI engines. In this study, efforts have been made to investigate the effect of changes in the calorific values of biogas on the engine performance and exhaust characteristics. The biogas was simulated by supplying of $CH_4$ with $N_2$ dilution of various ratios, and ECM was developed to achieve accurate control of ignition and combustion. The results show that as the $CH_4$ concentration of the biogas decreases, the optimal spark timing is advanced due to the elevated thermal capacity and lowered $O_2$ concentration of the in-cylinder charge. Furthermore, since combustion temperature was reduced by increased inert gas, $NO_x$ emissions decreased, whereas THC emissions increased.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.2
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• pp.47-52
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• 2015

A microbial fuel cell (MFC) is a device that can be obtained electricity from a variety of organic through the catalytic reaction of the microorganism. The MFC can be applied to various fields, and research is required to promote the performance of the microbial fuel cell for commercialization. The lower performance of an MFC is due to oxygen reduction at the cathode and the longer time of microbial degradation at anode. The MFC amount of power is sufficient but, in consideration of many factors, as a renewable energy, now commonly power density as compared to Nafion117 it is an ion exchange membrane used is PP (Poly Propylene) from 80 to about 11 fold higher, while reducing the cost to process wastewater is changed to a microporous non-woven fabric of a low cost, it may be energy-friendly environment to generate electricity. All waste, in that it can act as a bait for microorganisms, sustainability of the microbial fuel cell is limitless. The latest research on the optimization and performance of the operating parameters are surveyed and through the SSaM-GG(Smart, Shared, and Mutual- Green Growth) or GG-SSaM(Green Growth - Smart, Shared, and Mutual) as the concept of sustainable development in MFC, the middle indices are developed in this study.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.2
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• pp.15-29
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• 2020

The aims of this study is to improve physical properties of the sewage sludge and the process sludge generated in the leachate treatment by mixing the dry fuel, to develop the neutral solidifing agents that reduce oder, and to recycle the sewage and the process sludges as landfill cover materials. The mixing ratio (W/W) of sludges and dry fuel was appropriate at about 1:1, and the mixed materials were shown to be homogeneous at that ratio. We could know that when the sludges were mixed with dry fuel, moisture contents and viscosities are reduced, and air passages are formed between particles and particles. The various mixing tests and odor tests showed that the neutral solidifing agent was effective for the odor reduction. The main ingredient of the solidifing agent is the ash of sewage sludge, enabling it competitive in waste recycling and production costs. The landfill cover, using developed neutral solidification agent, improved physical properties to satisfy the quality standards and to increase the compressive strength. It also proved to reduce the value of complex oder and the usage of solidification agent to 1/3 (3,000 to 1,000) and to 1/8 (50% to 6%), respectively, from the comparative study with alkaline solidified landfill cover. Further research is under way to prove that this can be mixed with general soil to be used as a soil improvement agent for plant cultivation.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.1
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• pp.65-72
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• 2020

The aims of this study were to compare the biomethanation of CO₂ through specific methanogenic activity (SMA) test which was inoculated with four different types of mixed microbial culture obtained from full-scale anaerobic digestion (AD) plants. The experimental results showed that CH₄ conversion was the highest in the samples inoculated by seed sludge taken from ADs of food waste and brewery; under this condition, the produced biomethane contains 89.3-91.9% of CH₄. Meanwhile, the lowest level was obtained in the sample from sewage sludge. The measured ratio of CH₄ production rate to CO₂ consumption rate in all reactors was higher than the theoretical value (1) in the middle of the period and soon dropped to 0.7-0.8. It might be due to changed metabolic pathways in the reactor by the degradation of residual organic matter and the increased activity of homoacetogenic bacteria.

• Korean Chemical Engineering Research
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• v.47 no.2
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• pp.230-236
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• 2009

Sewage sludge cake(SSC) is seriously concerned because ocean dumping, which is the cheapest treatment method now, will be banned in 2012. On the basis of this reason, recycling of SSC is emphasized to convert the treatment method. One of the method to recycling SSC could be carbonization process which also can be reduced greenhouse gas effectively. And carbonization residue of SSC produced by carbonization process can become a renewable energy source. However, carbonization process has not been evaluated by considering basic operating data such as heating value, yield and fuel ratio. In this study, the basic characteristics of SSC such as proximate analysis, elementary analysis and heating value are analyzed. In carbonization process, the effect of carbonization temperature and time on the residue of SSC are estimated. And the analysis is carried out to obtain basic properties of the residue of SSC. From the result of chemical composition of SSC residue, there is 27% of phosphate in SSC. Phosphate will take a role of reductant to convert from hazardous substance to non-hazardous material. As increased carbonization temperature and time, heating value and yield are decreased but fuel ratio(fixed carbon/volatile combustible) of the residue is increased. In the carbonization process, the optimum temperature and time in carbonization test for SSC can be decided by $250^{\circ}C$ and 15 min, respectively. However, the carbonization residue of SSC can not be deserved to use one of renewable energy sources because the heating value at the optimum condition is relatively low. Hence, it is desirable that SSC can be mixed with other organic waste to carbonize.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.148-154
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• 2009

Composting is a biological process converting solid organic waste into valuable materials such as fertilizer. The change of bacterial populations in a composting reactor of food waste was investigated for 2 months. Based on shifts in temperature profile, the composting process could be divided into the first phase ($2^{\circ}C\sim55^{\circ}C$), the second phase ($55^{\circ}C\sim97^{\circ}C$), and the third phase ($50^{\circ}C\sim89^{\circ}C$). The number of total bacteria was $1.66\times10^{11}$ cell/g, $0.29\times10^{11}$ cell/g, and $0.28\times10^{11}$ cell/g in the first, second, and third stages, respectively. The proportions of thermophiles increased from 33% to 89% in the second stage. T-RFLP analysis and nucleotide sequencing of 16S rRNA gene demonstrated that the change of bacterial community structure was coupled with shifts in composting stages. The structure of bacterial community in the ultra-thermophilic second stage reflected that of seeding starter. The major decomposers driving the ultra-thermophilic composting were identified as phylotypes related to Bacillus and Pseudomonas.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.9
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• pp.870-878
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• 2010

We investigated the concentration and the sources of ubiquitous persistent organic pollutants [i.e., 17 toxic polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), 12 coplanar polychlorinated biphenyls (Co-PCBs), and 16 priority polycyclic aromatic hydrocarbons (PAHs)] in waste papers and lumbers from industrial complexes. The total concentrations in waste papers and lumbers ranged from 9.69~176.77 pg/g-dry and 0.14~0.25 pg/g-dry for 17 PCDD/Fs, 109.95~4097.25 pg/g-dry and 28.23~59.88 pg/g-dry for 12 Co-PCBs and 9.30~52.18 ng/g-dry and 0.82~1.82 ng/g-dry for 16 PAHs respectively. Generally, the concentration of these pollutants in waste papers was higher than those in waste lumbers. OCDD was dominant in waste papers and lumbers and the PCDD/F patterns of these samples were similar with that of stack gas. The distribution patterns of Co-PCBs in wastes were related with commercial PCB products, indicating the effect of commercial PCB products on ubiquitous environment. The diagnostic ratios of several PAH compounds in waste paper showed that they were related with pyrogenic sources.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.1
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• pp.65-72
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• 2013

This study was carried out to understand the long-term effects of organic waste treatments on the fate of heavy metals in soils originated from the organic wastes and consequent uptake of heavy metals by plant, together with examination of changes in soil properties and plant growth performance. In this study, the soils treated with three different organic wastes (municipal sewage sludge, alcohol fermentation processing sludge, pig manure compost) at three different rates (12.5, 25.0, 50.0 ton $ha^{-1}yr^{-1}$) for 7 years (1994 - 2000) were used. To see the long-term effect, plant growth study and soil examination were conducted twice in 2000 and 2010, respectively. There was no additional treatments of organic wastes for 10 years after the organic waste treatment for 7 years. Compared to plant growth examination conducted in 2000 using radish (Raphanus sativus cv. sodamaltari), it appeared that height, root length and diameter, fresh weight of radish grown in 2010 decreased in the plots treated with municipal sewage sludge and alcohol fermentation processing sludge and that the extent of decrease was higher with increase of sludge application rates. On the other hand, pig compost treatment increased plant height, root length and diameter, fresh weight with increasing application rates. Cu and Pb concentrations in radish root and leaves increased in 2010 compared to those in 2000 while Ni concentrations in root and leaves decreased. Zn concentration was increased only in the soils treated with pig manure compost. Multiple regression analysis among heavy metal species fractions in soils, soil pH, and metal concentrations in radish root and leaves indicated that the metal uptake by radish was governed mainly by the soil pH and subsequent increase of available heavy metal fractions in soils with organic waste treatments.