• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.1
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• pp.35-45
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• 2017

In order to improve the anaerobic digestion efficiency of the sewage sludge, the methane potential of the hydrolysate generated from the hydro-thermal reaction at 170, 180, 190, 200, 210, $220^{\circ}C$ was analyzed and the constitutional characteristics of the organic materials were estimated by dividing organic materials of hydro-thermal hydrolysate into easily biodegradable, decomposition resistant, and non-biodegradable organic materials applying the parallel first order kinetics model. The ultimate methane potential of sewage sludge hydro-thermal hydrolysate increased to 0.39, 0.39, 0.40, 0.44, 0.45, and $0.46Nm^3/kg-VS_{added}$ as hydro-thermal reaction temperature increased from 170, 180, 190, 200, 210, $220^{\circ}C$. It has been shown that the organic matter of sewage sludge is solubilized to increase the content of biodegradable organic material($VS_B$). The easily degradable organic matter($VS_e$) content was highest at hydro-thermal reaction temperature of 200 and $210^{\circ}C$, and optimum hydro-thermal reaction temperature for organic matter solubilization of sewage sludge was in the range of $200{\sim}210^{\circ}C$. In addition, the amount of biodegradable organic material($VS_B$) and easily biodegradable organic matter ($VS_e$) in the hydrolysate of sewage sludge was the highest at hydro-thermal reaction temperature of $200^{\circ}C$.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.1
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• pp.109-119
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• 2002

This study is to estimate that food waste bags with biodegradable plastic are really decomposed by microorganism in composting with food waste and to examinate how biodegradable plastic affects composting. 6 kinds of 30%, 4 kinds of 100% and 2 kinds of none biodegradable plastics were used in d1is study. In 30% biodegradable plastics the highest Degradation rare is 6% in meso-condition and 10% in thermal-condition. Srain at auto break decreased to 150% in meso-condition and 120% in thermal-condition. Stress at max load were also reduced to $180kgf/cm^2$ in mesocondition and $200kgf/cm^2$ in thermal-condition. Usually, LLDPE decreased larger than HDPE in physical characreristics but HDPE is higher in degradation rate. 1n stain at auto break and stress ar max load 100% biodegradable plastic declined to 230% and to $380kgf/cm^2$ in meso-condition and to 440% and to $400/cm^2$ in thermal-condition respectively. 100% biodegradable plastics showed higher biodegradation and decomposition then 30%. They appeared clearly through SEM observation. As a result, it was not appropriate to use 30% biodegradable plastics as food waste bag because they were not decomposed perfectly. It is possible to use 100% biodegradable plastic as it but cost is too high. So development of technique is needed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.69 no.1
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• pp.34-48
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• 2024

The objective of this study was to evaluate the safety of biodegradable mulching films in soybean (Glycine max) cultivation by measuring their effects on crop growth and yield, film decomposition and soil chemical and physical properties. In 2022 and 2023, plant height, branch number, chlorophyll contents, yield components, and yield of soybean did not vary significantly in areas using PE films and biodegradable mulching films. The light transmission rate of the biodegradable mulching films ranged from 6.4 to 15.8% when measured 112 days after soybean transplanting, and was higher, on average, in 2023 than in 2022. In both years, degradation of the biodegradable mulching films began 20 days after soybean transplantation and increased over time. In addition, remains of biodegradable mulching films were present in fields at soybean harvest and remained until 50 days after harvest. Decomposition rates of the biodegradable mulching films at 112 days after soybean transplanting ranged from 9.8 to 26.7% in 2022 and 13 to 36% in 2023. Although soil pH and EC varied based on the year and timing of measurements, there was no significant difference between areas that used biodegradable mulching films and PE films. Soil organic matter, nitrate and exchangeable cation contents such as Ca, Mg, and K were not significantly different in areas that used both PE films and biodegradable films. However, significantly higher levels of available phosphoric acid content were measured in areas that used biodegradable mulch films E, S, and T. Regardless of which films were used, there were no significant differences in the soil's physical properties. In 2022 and 2023, there was no difference between areas that used biodegradable mulch films and PE films. However, soil temperature in mulched areas was 2℃ higher and soil moisture was 5-15% higher than in non-mulched areas. Barley growth was not affected by being planted in soil that had been used for soybean cultivation with biodegradable films. Therefore, the biodegradable mulch films used in this study can be used without negatively affecting the growth, yield, and soil environment of soybeans.

• Journal of environmental and Sanitary engineering
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• v.16 no.4
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• pp.47-54
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• 2001

흡착된 유기물들의 생물막상에서 오존효과(오존에 의한 생물학적 분해능)를 관찰하기 위해 파 일롯 실험이 수행되었다. 유입원수 내 용존유기물들 중에는 THM전구물질이 존재하고 염소화 정 수과정에서 생성된 THM은 원수내 염소의 양이 2배에서 5배로 증가될수록 THM중 클로로포름은 5배에서 10배 가량 증가되고 디브로모클로라이드는 5배 가량 증가된다. 이러한 THM은 활성탄에 흡착되고 생물학적 분해에 의해 제거된다는 사실이 발견되었다. 특히 암모니아성 질소는 활성탄 에서보다 생물활성탄에서 40% 가량 생물학적 제거능이 증가된다는 활성탄내부의 생분해성이 발 견되었다. 또한 본 연구의 대상인 THb7에서도 활성탄에서 보다 생물활성탄에서 미생물분해효과에 의해 제거효율이 20% 이상 증가하는 것으로 나타났다.

• Journal of the Korea Organic Resources Recycling Association
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• v.32 no.1
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• pp.49-59
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• 2024

Biodegradable coating urea plays an important role in reducing the non-pollutants in agroecosystems, maximizing the plant nutrient utilization efficiency and slow-releasing nitrogen. Herein, the objective of this study was to investigate the nitrogen-releasing patterns and greenhouse gas emissions on different biodegradable coating urea. The treatments consisted of the control as an application of chemical fertilizers, NBCF as the non-biodegradable coating urea, NB60, and MDS as biodegradable coating urea. As a result of this study, the maximum accumulated total nitrogen (TN) concentration in the NBCF was higher at 33% than one in the NB60 during the precipitation periods. Its leaching period in the NCBF was prolonged for day 10 compared to the NB60. TN and NO₃-N releasing patterns in the NBCF and NB60 were fitted well on linear types(R²≥0.991), but their control and MDS were fitted well on Sigmoid curves(R²≥0.994) with high releasing concentration in the MDS compared to the control during leaching periods. For the greenhouse gas emissions, CH₄ emissions in the NBCF, NB60, and MDS were increased at 0.38%, 11.36%, and 5.91%, and N₂O emissions were also increased at 50.5%, 32.4%, 58.8% as compared to the control, respectively. Therefore, application of biodegradable polymer coating urea might mitigate the non-point pollutants in agro-ecosystem.

• Korean Journal of Ecology and Environment
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• v.52 no.3
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• pp.192-201
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• 2019

While a fairly large amount of organic matter is produced daily via phytoplankton photosynthesis in Lake Paldang, South Korea, knowledge of the role of algal-derived organic matter (OM) as a refractory OM source is not adequate. To understand the contribution of algal-derived OM to the refractory pool, biodegradation experiment and $KMnO_4$ oxidation experiment were conducted for 60 days using $^{13}C$ and $^{15}N$ labeled natural phytoplankton assemblage. The assemblage was collected from Lake Paldang on May 20, 2010. The photosynthetically produced total organic carbon ($TO^{13}C$), particulate organic carbon ($PO^{13}C$), and particulate nitrogen ($P^{15}N$) remained at 26%, 20%, and 17% of the initial concentrations, respectively, in the form of non-biodegradable organic matter. In addition, 12% and 38% of $PO^{13}C$ remained after $KMnO_4$ treatment on Day 0 and 60, respectively. These results indicate that photosynthetic products could be an important source of refractory organic matter after microbial degradation. Moreover, the microbially transformed algal-derived OM could contribute to the oxidation rate of the chemical oxygen demand.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.3
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• pp.119-126
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• 2001

A process for the production of bioplastics from wastewater with an open microbial culture was developed and evaluated. The process consists of a selection reactor to select bacteria in feast/famine regime and an accumulation reactor to produce PHA using selected bacteria. Polyhydroxyalkanoate(PHAs) accumulating bacteria could be efficiently grown in a sequencing batch reactor(SBR) without any growth limitation. For the high production of PHA limitation such as oxygen and nutrients seemed to be needed. Accumulation experiments were performed to evaluate the level of accumulation of PHA. Limited aeration had no effect, but nutrients limitation showed high accumulation. Bacteria which were selected in the SBR could accumulate PHA till 60% of cellular dry weight in accumulation experiments under nitrogen limitation. PHA accumulation rate decreased with increasing PHA content in the cells. Clearly, PHA accumulation rate has a strong correlation with the PHA content of the cells.

• Journal of the Korean Geotechnical Society
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• v.36 no.5
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• pp.17-24
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• 2020

In order to analyze the effect of applying the bioreactor landfills on the waste landfill for acceleration of waste biocompression, a settlement experiment was performed. The secondary compression indices (C_α) were analyzed, and compared with the results of experimental studies conducted in other countries. Analyses of C_α from the experiment showed that the recirculation method of mixing leachate and FWL could accelerate the waste settlement as much as 2.9 times and 2 times more than the leachate recirculation and the sanitary landfills due to additional biocompression generated by the organic matter in FWL. The C_α in this study was smaller than the C_α of the other studies due to the low organic content of the waste in accordance with domestic waste policies to reduce food waste. The relation between biodegradable waste content and C_α was analyzed. The C_α of the waste was shown to be sensitive to biodegradable waste content, and become higher as the content of the biodegradable waste increases.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.4
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• pp.55-65
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• 2021

This study investigated methane productions and a degradation rate of organic matters by German standard method, VDI4630 test. In this study, 11 waste biomasses from agricultural fields were selected for the investigation. The objective of this study was to estimate a distribution of organic matters by using the Double first-order kinetics model in order to calculate the rate of biodegradable organic matters which degrade rapidly in the initial stage and the persistently biodegradable organic matters which degrade slowly later. As a result, all the biomasses applied in this study showed rapid decomposition in the initial stage. Then the decomposition rate began to slow down for a certain period and the rate became 10 times slower than the initial decomposition rate. This trend of decomposition rate changes is typical conditions of biomass decompositions. The easily degradable factors (k₁) were raged between 0.097~0.152 day^-1 from vegetable crops and persistent degradable factor (k₂) were 0.002~0.024 day^-1. Among these results, greater organic matter decomposition rates from VDI4630 had greater k₁ values (0.152, 0.144day^-1) and smaller k₁ values (0.002, 0.005day^-1) from cucumbers and paprika. In a meanwhile, radishes and tangerine rinds which had low decomposition rates showed 0.097 and 0.094 day^-1 of k₁ values and decomposition rates seems to affect k₁ values.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.62-62
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• 2021

산업 고도화로 인하여 복잡하고 다양한 유기물의 사용량이 증가하였으며, 공공수역 내 새로운 오염물질이 유입됨에 따라 생화학적 산소요구량(BOD) 중심의 수질평가에 한계를 나타내었다. 이후 난분해성 물질을 고려한 유기물관리 정책과 총량관리의 필요성이 제기되었고 국내 하천과 호소에서는 총 유기탄소(TOC)를 유기물 관리지표로 설정하였다. 그러나 부영양 하천과 호소에서 TOC는 외부 부하뿐만아니라 식물플랑크톤의 과잉성장에 의해 증가할 수 있는 항목이므로 TOC 관리정책 추진을 위해서는 유기물의 기원에 대한 파악이 필요하다. 특히, 국내 하천에서 나타나고 있는 난분해성 유기물 오염도의 증가 추세에 대응한 실효성 있는 유기물 오염관리 정책을 수립하기 위해서는 다양한 유기물의 근원을 정확하게 파악하는 것이 매우 중요하다. 본 연구의 목적은 금강 수계 최대 상수원인 대청호를 대상으로 3차원 수리-수질 모델을 적용하여 유기탄소 성분 별 유입과 유출, 내부생성 및 소멸량을 평가하고 저수지시스템에서의 유기탄소 물질수지를 해석하는 데 있다. 유기탄소 물질수지 해석을 위해 AEM3D 모델을 사용하였으며 2017년을 대상으로 입력자료를 구축한 후 보정을 수행하였고 2018년을 대상으로 모델을 검정하였다. 모델은 유기탄소를 입자성, 용존성, 그리고 난분해성과 생분해성으로 구분하여 모의하며 유기물질 성상별 실험결과를 이용하여 입력자료를 구축하였다. 유기탄소 물질수지 해석을 위해 4가지의 탄소성분과 조류 세포 내 탄소의 질량 변화율을 계산하였다. 이를 위해 외부 유입·유출부하율, 수체 내 생성(일차생산, 재부상, 퇴적물과 수체 간 확산) 및 소멸률(POC 및 조류 침강, DOC 무기화, 탈질)을 고려하였다. 모델은 2017년과 2018년의 물수지를 적절히 재현하였으며 저수지의 성층구조를 잘 재현해내면서 전반적인 수온, 수질을 적절하게 모의하였다. 연간 TOC 부하량 중 내부기원 부하량은 2017년 68.4 %, 2018년은 높은 강우량의 영향으로 55.0%로 산정되었다. 내부 소멸 기작 중 침전으로 인한 손실이 가장 높은 것으로 나타났으며, 2017년과 2018년 각각 31.3%, 29.0%로 나타났다. TOC의 공간분포는 Chl-a 농도 분포와 유사하게 나타났으며, 댐 설치로 형성된 정체수역은 유역의 유기물 순환에 많은 영향을 미치는 것으로 평가되었다. TOC 관리 정책 기초자료 확보를 위해서는 향후 유역-저수지 시스템을 연계한 유기물 물질순환 심층 연구가 필요하다.