• Korean journal of food and cookery science
• /
• v.31 no.1
• /
• pp.1-8
• /
• 2015

Organic acids are known as natural sanitizers. We examined the sanitizing effects of five organic acids (acetic acid, propionic acid, citric acid, malic acid, and lactic acid) and their persistence on three pectinolytic yeast strains isolated from decayed citrus, and the persistence of their sanitizing effects was determined during storage at $4^{\circ}C$ and $16^{\circ}C$. The 7~8 log CFU/mL of the mixed three yeast mixture was exposed to various concentrations of each organic acid for 1 min. The yeast mixtures decreased under detection limit(1 log CFU/mL) in 1% of acetic acid, followed by in 3% of propionic acid with the reduction of 5 log CFU/mL. The citric acid, malic acid, and lactic acid decreased the number of yeasts under detection limit at 7.5%. When treated with deionized water and 1~5% of organic acids were treated on the surfaces of citrus contaminated by yeasts, total numbers of the yeasts decreased under detection limit(3 log CFU) at 5% of acetic acid and 4 log CFU/piece at 5% propionic acid compared with deionized water. When treated with acetic acid and propionic acid on the stem ends of the contaminated citrus, total numbers of the yeasts significantly decreased 0.5 log CFU/piece at 3% of both organic acids. During storage at $4^{\circ}C$ and $16^{\circ}C$ for 20 days, total number of yeasts significantly decreased at 2% acetic acid compared with deionized water. This study suggested that organic acids could be used to sanitize microbial contaminants from citrus for storage and transportation.

• Journal of Environmental Science International
• /
• v.15 no.2
• /
• pp.169-175
• /
• 2006

The changes of contaminants and odor corresponding to anaerobic maturation process of piggery slurry were investigated by applying the additives, such as different kinds of complex microorganism products and deodorants containing microorganism activating agents. The pHs during 20-day anaerobic maturation were operated stably without great change regardless of the additives, although they were rather lower in the case that the additives were contained than the case that they were not contained. The effects of removing CODcr, $NH_3-N$, T-N, and T-S in case that the additives were not contained, were not so great during the 20-day operation and so it would be difficult to remove the organic materials and nitrogen ingredients simply with anaerobic maturation process. However, in case of anaerobic maturation process that the additives were contained, their average removal rates were improved with the values of $49\%,\;63.5\%,\;48.5\%,\;and\;30.7\%$ for above each of items, even if the 20-day of short-term maturation period was applied. Especial1y, odor intensity with the additives was lowered continuously during the operation period and it had more than two times of lowering effect compared to that without those.

• Journal of Korean Society on Water Environment
• /
• v.22 no.1
• /
• pp.23-29
• /
• 2006

Biosorption technology was used to remove hazardous materials from wastewater, herbicide, heavy metals, and radioactive compounds, based on binding capacities of various biological materials. Biosorption process can be explained by two steps; the first step is that target contaminants is in contact with microorganisms and the second is that the adsorbed target contaminants is infiltrated with inner cell through metabolically mediated or physico-chemical pathways of uptake. Until recently, no information is available to explain the definitive mechanism of biosorption. The purpose of this study is to evaluate biosorption capabilities of organic matters using activated sludge and to investigate affecting factors upon biosorption. Over 49% of organic matter could be removed by positive biosorption reaction under anoxic condition within 10 minutes. The biosorption capacities were constant at around 50 mg-COD/mg-MLSS for all batch experiments. As starvation time increased under aerobic or anaerobic conditions, biosorption capacity increased since higher stressed microorganisms by starvation was more brisk. Starvation stress of microorganisms was higher at aerobic condition than anaerobic one. As temperature increased or easily biodegradable carbon sources were used, biosorption capacities increased. Consequently, biosorption can be estimated by biological -adsorbed capability of the bacterial cell-wall and we can achieve the cost-effective and non -residual denitrification with applying biosorption to the bio-reduction of nitrate.

• Journal of Soil and Groundwater Environment
• /
• v.12 no.1
• /
• pp.1-35
• /
• 2007

In the last decades, the decrease in biological or chemical availability of sorbed contaminants as contact time passed, is generally accepted. This phenomenon so called as "aging" or "sequestration" is known to directly affect risk of the contaminats. This was observed for mainly for hydrophobic organic contaminants (HOCs), but also reported for heavy metals. Aging is known to be directly related to sorption-desorption hysteresis, irreversible sorption, desorption-resistance, nonequilibrium sorption, etc. The decrease in bioavailability due to aging or sequestration indicates realistic decrease in risk potential. Recently a risk-based management concept by scientific evidences but not the simple measurement of contaminant concentration has been attempted to determine environmentally acceptable remedial endpoint. This is because selection of remedial endpoint based on not total concentration but the bioavailability and toxicity of contaminants can reduce both the treatment cost and remedial activities of the contaminated sites. The bioavailability and toxicity of the residual contaminants are highly affected by the fate and transport and also directly affect the exposure pathways and bioaccumulation of contaminants in the living biota. In this paper, scientific feasibility on the risk-based clean-up and management of contaminated sites is reviewed.

• Journal of Food Hygiene and Safety
• /
• v.29 no.4
• /
• pp.312-315
• /
• 2014

The present study demonstrated the development and validation of the method for the quantification of phenol in food using gas chromatography coupled with mass spectrometry (GC-MS). After spiking of internal standard (Phenol-$d_5$) to food, those samples were extracted with organic solvent mixture (acetone : dichloromethane = 1 : 1, v/v) using ultra sonic extractor and cleaned by gel permeation chromatography (GPC) technique. The amount of phenol was determined by GC/MS. To validate the developed method, we evaluated parameters were the selectivity, linearity, accuracy, precision, and recovery. To demonstrate the selectivity of the method, blank samples of rice, corn, and fish(mackerel) were prepared and subjected to GC-MS analysis. To verify the linearity of the method, six different standard concentrations of phenol at 0.01, 0.05, 0.1, 0.5, 1 and 2.5 mg/kg were evaluated. The correlation coefficient ($r^2$) of calibration curve was 0.9999. The recovery rate for phenol standard calculated by internal standard method were 82.2~101.5% for samples fortified with 0.25, 0.50, and 1.0 mg/kg, respectively. Also the repeatability and reproducibility for validation of precision were 0.2~5.5%. According to the result of the validation, this established method was suitable for AOAC guideline. The limit of detection (LOD) for phenol analysis were 0.03~0.1 mg/kg, and the limit of quantification (LOQ) were 0.1~0.3 mg/kg. Therefore, we established the optimal analysis method for determination of phenol in food using GPC and GC/MS.

• Korean Journal of Agricultural Science
• /
• v.46 no.4
• /
• pp.869-883
• /
• 2019

China is currently facing great challenges in protecting its arable soil from contamination by heavy metals, especially Cd in paddy soil. China enacted the first soil environmental quality standards (SEQS) for ten pollutants in 1995, and the Ministry of Ecology and Environment released the results of the first nationwide soil survey in 2014. The soil survey showed that as much as 16% of China's soil and 19% of the agricultural soils were contaminated mainly with heavy metals and metalloids beyond the environmental quality limits. The exceeded rate of the contaminant limits in food crops was widespread in China, and the most severe regions were East and Southwest China. Heavy metals and metalloids accounted for 82.4% of the contaminants in soils while organic pollutants accounted for 17% of the contaminants in the soil. Among the heavy metals and metalloids exceeding the Ministry of Environmental Protection (MEP) limit, cadmium (Cd) was highest at 7.0%, followed by nickel (4.8%), arsenic (2.7%), cobalt (2.1%), mercury (1.6%) and lead (1.5%). However, all the average concentrations of the pollutants were lower than the recommended values for the contaminants except for Cd for three levels of pH (< 6.5, 6.5 - 7.5, and > 7.5). According to the Action Plan on Prevention and Control of Soil Pollution released by the State Council in 2016, 90% of contaminated farmland will be made safe by 2020 with an increase to 95% by 2030. Therefore, it is necessary to improve the soil quality to meet the environmental quality standard for soils and heavy metal standards for food safety.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.20 no.1
• /
• pp.63-69
• /
• 2010

This study was conducted to compare the concentration of various air contaminants in nine different laboratories during routine activities. Volatile organic compounds (VOC) were sampled and analyzed using NIOSH Method 1500 and asbestos fibers were sampled and analyzed using NIOSH Method 9002 and 7400. Detectable levels of acetone, toluene and ethanol were found in all the laboratories and xylene and n-hexane were detected in eight of the nine laboratories. All the VOC concentrations were well below the Korean Ministry of Labor's Exposure Limit and American Conference of Governmental Industrial Hygienists' (ACGIH) Threshold Limit Values (TLVs). Total VOC concentrations at the university laboratories were significantly higher than those at governmental agency laboratories. Airborne fiber concentrations were below 0.01 fibers/cc, while the concentration of chrysotile was 2% in insulation materials sprayed on the ceiling of one laboratory. While all the governmental agency laboratories (n=4) had fume hoods, two out of the five university laboratories did not have fume hoods. The capture velocity of half of the fume hoods were below the maintenance standard(0.4 m/sec). In conclusion, the study suggests that the current controls in place at both university and government agency laboratories are not sufficient in limiting exposure to harmful chemicals to non-detectable levels, though they appear to be adequate in protecting workers to levels below applicable occupational exposure limits. The study also suggests that researchers working in university laboratories may be exposed to greater levels of contaminant than those working in government agency laboratories.

• Journal of Korean Society on Water Environment
• /
• v.37 no.6
• /
• pp.501-509
• /
• 2021

In 2018, total 263 micro and emerging contaminants were selected as target substances by the Ministry of Environment, and 80 of them were first-class substance including endocrine disruptors, residual Pharmaceuticals and Personal Care Products (PPCPs), residual organic pollutants, pesticides and heavy metals. In this study, in order to evaluate the Hazard Quotient (HQ) of the 80 types in the domestic water environment the concentration of discharged effluent and nearby water environment reported by Korean institutes since 2010 was investigated. There were 45 substances reported to be detected, and Measurement Environment Concentration (MEC) were obtained by collectively converting them into water environment concentration. For biotoxicity, half maximal Effective Dose (EC50) to Daphnia magna, a water fleas species widely adopted in Material Safety Data Sheet (MSDS) was applied. As for the biotoxicity level, the Predicted No-Effect Concentration (PNEC) was obtained by applying the Assessment Factor (AF) and the HQ was derived by dividing it from the MEC. As a result of calculating the HQ, more than 1 substances were Cabamazepine, Mefenamic acid, Acetaminophen, Ibuprofen, Nonylphenol, Nickel, Erythromycin, Acetylslic acid, etc. Meanwhile, perfluorinated compounds were identified as hazardous substances in the water env ironment, with 5 out of 14 species included in the 20 ranks of first-class substance.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2003.09a
• /
• pp.330-333
• /
• 2003

Recently electrokinetic process is known to be a promising remediation technology for the contaminated soils with heavy metals, radionuclides, organic matters, and so on. The contaminants in electrokinetic technology are removed mainly by three mechanisms; electroosmosis, electromigration, and electrophoresis. When direct current is introduced between two electrodes planted in soil, a large amount of hydrogen ions is formed and moves from anode to cathode with the other cations contained in electrolyte. The water flow caused by tile movement of cations is called as electroosmosis. Especially for non-ionic pollutants, the electroosmotic flow(EOF) is the most important removal mechanism among them and transports contaminants from anode to cathode along the water flow. In this study, characteristics of electroosmotic flow was investigated according to the resistance state of soil. The decrease, maintenance, and increase of soil resistance could be obtained by controlling ions in soil. When the resistance of soil was decreasing or maintained, the EOF is proportional to electric current and voltage, respectively and when the resistance was increasing, the EOF is proportional to only electric current not voltage.

• Journal of Korea Soil Environment Society
• /
• v.2 no.2
• /
• pp.95-103
• /
• 1997

Solvent extraction using aqueous solutions is presumed as one of the most effective methods applicable to in situ conditions without excavation of contaminated soils. Laboratory permeameter soil flushing test is performed to describe the process of solvent extraction of contaminants absorbed on soil particles. When the permeameter tests conducted, diffusion of contaminants through the permeameter flexible-wall was considered for adjusting the remediation percentage. Input and output balance for concentration was well matched in the permeameter tests. Nitrobenzene diffused so excessively (approximately 75%) that it was not suitable for the permeameter desorption tests. No biodegradation was detected in the soil samples.