• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.5
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• pp.1-11
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• 2001

In the past, abundant and clean water was available for paper mills'use. However, the growth of population and industry made water less available nowadays. Also, environmental regulation limits wastewater discharge, which affects mill operation cost. Therefore, paper mills are under pressure to use more recycled water and mill system closure. As a result, chemical and physical parameters of water are changing and new environment if being created for microorganisms in paper mill system as well. The more soluble or suspended organic materials are increased as more water is recycled and less or scarce dissolved oxygen is available, depending on the degree of recycled water usage. Microorganism flora ill paper mill system will be a1so shifted according to the environmental change of mill system. Anaerobic bacteria, including sulfate reducing bacteria (SRB), will be dominant in the system as very low or almost no oxygen available in the system. Nevertheless, it is common in domestic paper mills that employ the same and old biocides as a means of microbial control, and microbiological control is often less recognized or even neglected. The right biocide selection for increased reductive environment of mills is critical for operation and estimated loss from paper quality defects such as sheet break, holes due to microbiological cause is tremendous compared to the microbiological control cost. It is imperative to investigate and diagnosis the environmental change of mills for right control of cumbersome microorganisms. Several useful diagnosis tools, including new technology employing OFM(Optical Fouling Monitor) in situ, are illustrated.

• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.289-294
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• 2022

Oil contained in domestic and industrial wastewater or marine spilled oil gives rise to severe environmental pollution issues such as water pollution and ecosystem destruction. The membrane filtration method as one of representative oil/water separation strategies has technological challenges such as membrane fouling and low separation rate. In this work, we devise a 3D-printed microhydrocyclone for oil/water separation by utilizing a digital lighting processing-based 3D printer. We demonstrate that the 3D-printed microhydrocyclone can effectively separate oil and water phases from oil-in-water emulsion.

• Journal of Soil and Groundwater Environment
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• v.27 no.2
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• pp.61-75
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• 2022

This study evaluated the potential threat of agricultural and human activities to groundwater in the Noseong stream watershed, a typical agricultural area, through hydrogeochemical characteristics and microbial community analyses. The groundwater in the study area was Ca-SO₄ and Ca-HCO₃ types alluvial aquifer mainly used for agricultural and living purposes, and contained high levels of NO₃^- and Cl^- ions generated from anthropogenic sources such as fertilizer, livestock wastewater, and domestic sewage. Proteobacteria was most abundant in all samples with an average of 46.1% while Actinobacteria, Bacteroidetes, and Cyanobacteria were dominant on an occasional basis. The prevalence of aerobic bacteria such as the genus Mycobacterium, Flavobacterium, and Sphingomonas suggests that groundwater was well connected with the surface layer. The potential pathogen Mycobacterium was detected in most samples, and other pathogenic bacteria were also widely distributed, indicating the vulnerability to contamination. Therefore, an integrated management system is required to secure the sustainable use of groundwater in agricultural areas with high groundwater dependence.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.486-491
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• 2022

A benthic microbial fuel cell (BMFC) is an eco-friendly energy conversion device that uses electricity generated by benthic microorganisms decomposing organic matter in the mud of the sea or lake. In this study, in order to understand how domestic wastewater flowing into tidal flats affects the performance of BMFC. BMFC performance was compared and reviewed by fermenting organic substances in food and mixing them with tidal flats. Performance of the BMFC was improved by 49% by adding fermented food rich in vitamins (B₂, B₆, B₁₂, C, D, E) and soft flour. The maximum power density increased as the amount of fermented organic matter increased, and it was shown that the fermented organic matter fermented during 25~29 days was optimal for BMFC.

• Journal of Sensor Science and Technology
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• v.32 no.5
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• pp.290-294
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• 2023

Among various types of harmful gases, hydrogen sulfide is a strong toxic gas that is mainly generated during spillage and wastewater treatment at industrial sites. Hydrogen sulfide can irritate the conjunctiva even at low concentrations of less than 10 ppm, cause coughing, paralysis of smell and respiratory failure at a concentration of 100 ppm, and coma and permanent brain loss at concentrations above 1000 ppm. Therefore, rapid detection of hydrogen sulfide among harmful gases is extremely important for our safety, health, and comfortable living environment. Most hydrogen sulfide gas sensors that have been reported are electrical resistive metal oxide-based semiconductor gas sensors that are easy to manufacture and mass-produce and have the advantage of high sensitivity; however, they have low gas selectivity. In contrast, the electrochemical sensor measures the concentration of hydrogen sulfide using an electrochemical reaction between hydrogen sulfide, an electrode, and an electrolyte. Electrochemical sensors have various advantages, including sensitivity, selectivity, fast response time, and the ability to measure room temperature. However, most electrochemical hydrogen sulfide gas sensors depend on imports. Although domestic technologies and products exist, more research is required on their long-term stability and reliability. Therefore, this study includes the processes from electrode material synthesis to sensor fabrication and characteristic evaluation, and introduces the sensor structure design and material selection to improve the sensitivity and selectivity of the sensor. A sensor case was fabricated using a 3D printer, and an Ag reference electrode, and a Pt counter electrode were deposited and applied to a Polytetrafluoroethylene (PTFE) filter using PVD. The working electrode was also deposited on a PTFE filter using vacuum filtration, and an electrochemical hydrogen sulfide gas sensor capable of measuring concentrations as low as 0.6 ppm was developed.

• Journal of the Korean Institute of Rural Architecture
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• v.26 no.2
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• pp.37-46
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• 2024

The city is developing into a smart city. Smart villages and smart farms are developing in rural areas. Architectural technology needs synergy with smart cities, smart villages, and smart factories (intelligent factories) to help architectural experts understand smart farms and build facilities and equipment. Smart farms require design and construction technology with architectural structure and function. The purpose of this study was to investigate the current status and cases of smart farms in Korea and to investigate cases abroad. The conclusion is as follows. ① Smart farms are developing rapidly. The Korean government is expanding smart farms by utilizing ICT technology and infrastructure. ② 'Smart Farm Innovation Valley', which has been promoted since 2018, is a cutting-edge convergence cluster industrial complex that integrates production, education, and research functions such as start-ups and technological innovation. ③ In domestic cases, smart farms are operated in subway stations, buildings, supermarkets, and restaurants. ④ In the Japanese case, a dome-type smart farm was being operated. It utilized factory wastewater, waste heat, renewable energy, and used new materials. Otemachi Ranch raised livestock and provided a lounge on the 13th floor of the building. ⑤ In the cases of Korea and Japan, the smart farm technology is very similar. As stated earlier, since the food culture and agricultural technology of both countries are similar, we hope to promote the development of smart farms that can reduce concerns about future food by communicating and sharing mutual technologies.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.3
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• pp.203-207
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• 2009

The concern of seriousness and harmful effects of environmental pollution is rising by the various water pollutions, appearances of new micro-noxious substances and increase of sustainable pollutants. The method is suggested that can effectively increase the removal of organic substances and several pollutants using a coagulation process. The experiment for characteristics of $ZrSiO_4$ (zirconium silicate) as a coagulation-aid was carried out for application to coagulation process with domestic wastewater and lake water, and the removal rate of the organic substances depending on a dosage was evaluated by PDA (Photometric Dispersion Analyzer) in this study. Zeta-potential of zirconium silicate solution was -32.22 mv at pH 7 and the lower negative(-) charge was detected in the more acidic conditions. Absorbance on $UV_{254}$ presented higher when zirconium silicate was added than in a domestic wastewater itself. Besides, the results by PDA experiment represented that injection of zirconium silicate could promote growing of floc. Tests for coagulation process were conducted by three ways which are pre-injection, co-injection and post-injection of zirconium silicate with alum. Accordingly, removal efficiency of organic substances increased over 15% in co-injection than in using of alum as a sole reagent. When a 20 mg/L of alum was used with a 10 mg/L of zirconium silicate, the removal efficiency was high up to 90%. Removal efficiency of $COD_{Cr}$ was improved more than 15% in case of dosage of coagulant either PAC (Poly aluminium chloride) or PACS (Poly aluminium chloride Silicate) together with zirconium silicate. As a result, the removal efficiency of $COD_{Cr}$ were 5~10% higher in a co-injection of zirconium silicate with a coagulant than a pre-injection and a post-injection but it of soluble substances was lower in a co-injection.

• Korean Journal of Ecology and Environment
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• v.36 no.1 s.102
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• pp.38-47
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• 2003

The water quality of the Pyeongtaek Reservoir and its main streams has been eval uated far water pollution state in March, June, September and December,2000. The following are the findings: $NH_4$ accounts for the majority of TN in the inflow streams. In the reservoir, TN and $NH_4$ are the more present in the winter season and less in the summer season, with $1.6{\sim}2.4$ times of $NO_3$ and $5.3{\sim}11.4$ times of $NO_2$ found in December and June compared with other seasons. The concentration of each component is different between streams: $NH_4$ among inorganic nitrogen has the highest concentration in the upstream, and $NO_3$ is more prevalent in the downstream. SRP accounts for $25{\sim}69%$ of TP in the stream. Unlike N component, P component in the reservoir rapidly decreases from upstream toward downstream, except in the summer. Average SRSi slightly increases in the fall, i.e., immediately after rainfall. In the streams, the average concentration of chlorophyll-a ranges from 9 to $33{\mu}g/l$, and is relatively high in the downstream. In contrast, in the reservoir, it is the highest in the upstream where $NH_4$ and SRP are frequently found. In particular, diatom and cryptomonad algae are bloomed in March, and blue-green algae in September; their maximum values are $108{\mu}g/l$ and $130{\mu}g/l$, respectively. Considering the concentration of N and P nutrients, pollution loads can affect the Pyeongtaek Reservoir in the downstream in this order: Ansong Stream

• Journal of Korean Society of Environmental Engineers
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• v.34 no.7
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• pp.495-503
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• 2012

The water quality of Gul-po Stream, the subject of this study, has been deteriorating because of the inflow of domestic sewage and the industrial wastewater due to industrialization and the problems relating to the structure of river including slow flow rate and the covering of river. In particular, the domestic sewage from small-medium sized factories by the river and large-scale industrial complex by the upper and middle streams of the river, and the domestic sewage from increasing population due to the regional development are the main pollution sources. Thus, this study aims to survey the water quality and the sediment affecting Gul-po Stream; monitor the state of pollution in water body; assess the yield of sediment and investigate the water quality of river and the problems arising from sediment; and then suggest reasonable ways to improve the situation. The findings from surveying pollution load shows the discharge increases up to average 72.8 times from the upper stream to the downstream of Gul-po Stream, and pollution load increases up to: SS 111 times, BOD 150 times, COD 145 times, the nutrient T-N 222 times and T-P 312 times on an average basis. As for the pollution concentration range, ignition loss is 1.29~12.43%; COD is 4,015~37,547 kg/day; T-N and T-P 94.8~352.5 kg/day and 81.8~372.3 kg/day, respectively. As for the releasing rate of sediment, T-N is -14.46~$156.61mg/m^2/day$; T-P is -11.53~$26.10mg/m^2/day$, indicating the likelihood of internal contamination due to the elution of sediment. This study is expected to be used as basic data to manage Gul-po Stream basin.

• Journal of the Korean earth science society
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• v.41 no.6
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• pp.630-646
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• 2020

In rural areas, nitrate-nitrogen (NO3-N) pollution caused by agricultural activities is a major obstacle to the use of shallow groundwater as domestic water or drinking water. In this study, the water quality characteristics of shallow groundwater in Hyogyo-ri agricultural area of Yesan-gun, Chungcheongnam-do province was studied in connection with land use and chemical composition of soil layer. The average NO3-N concentration in groundwater exceeds the domestic and agricultural standard water qualities of Korea and is caused by anthropogenic sources such as fertilizer, livestock wastewater, and domestic sewage. The groundwater type mainly belongs to Ca(Na)-Cl type, unlike Ca-HCO3 type, a general type of shallow groundwater. The average NO3-N concentration (7.7 mg L-1) in groundwater in rice paddy/other (upstream, ranch, and residential) area is lower than the average concentration (22.8 mg L-1) in farm field area, due to a lower permeability in paddy area than that in farm field area. According to the trend analysis by the Mann-Kendall and Sen tests, the NO3-N concentration in the shallow groundwater shows a very weak decreasing trend with ~0.011 mg L-1yr-1 with indicating almost equilibrium state. Meanwhile, SO42- and HCO3- concentrations display annual decreasing trend by 15.48 and 13.15%, respectively. At a zone of 0 to 5 m below the surface, the average hydraulic conductivity is 1.86×10-5 cm s-1, with a greater value (1.03×10-4cm s-1) in sand layer and a smaller value (2.50×10-8 cm s-1) in silt layer.