The Current State of Management and Disposal of Wastes Related to COVID-19 : A review

Objectives : This paper summarizes effective waste management and disposal methods for plastic and medical wastes during the prolonged COVID-19 pandemic.Methods : We reviewed the literatures reporting and identifying the current status and characteristics of wastes related to COVID-19, and the management and treatment guidelines for those wastes. We also investigated various technologies for waste treatment and disposal, and assessed the current status and future direction of the technologies in Korea.Results and Discussion : In the first half of 2020 in Korea, the amount of plastic waste produced had increased by 15.6% year-on-year, and medical waste production also increased significantly from 0.6 ton in January 2020 to 2,928 ton in August 2021. All of the infectious wastes are currently being incinerated in Korea, but there are concerns on air pollutant emissions and insufficient treatment facilities. Municipal solid waste also suffers from a lack of landfill capacity and low price competitiveness in the recycling industry.Conclusions : Policy and system need to be improved to reduce the infectious waste generation from the sources, and treatment and disposal technologies for produced wastes also need to be developed. Furthermore, hospitals and health care facilities should establish their own waste reducing systems which may include chemical treatment and sterilization units.

Review of Fluoride Removal Appropriate Technology for Securing Safe Drinking Water in Africa

Making and securing safe drinking water is considered as the most important element and human right for sustainable human life. However, many countries in Africa still have low access to safe water, and in particular, fluorosis symptoms are severe from the people of Africa where there is a lot of groundwater and surface water contaminated with fluoride due to the geological natures. Fluoride is a colorless, tasteless, and odorless element with very strong reactivity and is emitted from the cleaning process of semiconductors and the fertilizer manufacturing industries. Various technologies such as chemical coagulation/precipitation, electrochemical method, ion exchange, separation membrane technology, nanotechnology, and adsorption may be proposed as a technology for removing fluoride for securing safe drinking water. The strengths and weaknesses of each element technology and recent research cases were investigated and analyzed, and an appropriate technology application plan for the sustainable development of emerging and developing countries in Africa was presented. Efficiency of fluoride removal may be important to secure drinking water for developing countries in Africa, but it is necessary to consider the local economic situation and cultural background first for sustainability of the applied technology. Therefore, animal bone-based adsorption process is advantageous in terms of sustainability and can be proposed as a fluoride removal technology suitable for the developing countries in Africa.

Development of Inorganic Impregnated Phase Change Material(PCM) in the Pores of Activated Carbon

Objectives : Recently, energy-related research has shifted from developing alternative energy to the efficient management technology of the produced energy. As an alternative, research on phase change materials (PCMs) capable of absorbing and releasing heat as an energy medium has been conducted. This study developed a more efficient heat storage medium using activated carbon as a medium for the phase change material. At the same time, we developed a method for efficiently impregnating the phase change material into the activated carbon pores.Methods : The activated carbon used in this experiment was charcoal powder activated carbon (250-350 mesh) and granular activated carbon. The inorganic phase change materials used in the experiment was manganese nitrate hexahydrate. The method for impregnating the phase change material was pressurization method and dilution method. The heat absorption / emission capacity of the developed material was examined within the range of 10℃ to 50℃.Results and Discussion : The Scanning electron microscope (SEM) and Transmission electron microscopy energy-dispersive X-ray spectroscopy (TEM-EDX) analysis showed that the phase change material was filled in the pore of activated carbon. When the phase change material is filled by the pressurized method, the material properties of manganese nitrate hexahydrate are reflected, resulting in absorption and release of heat at each phase change temperature. As a result of experiments for the selection of the optimum solvent in the phase change material filling study using the dilution method, when ethanol was used as the solvent, the heat absorption was clearly observed even after the phase change material was loaded. As a result of selecting the optimal dilution ratio, the ratio of ethanol was determined to be 1:1 as the dilution ratio with the lowest amount of floating activated carbon. The optimal solvent removal method experimental results show that the heat absorption/release section occurred when the ethanol was removed by evaporation at 85℃ temperature.Conclusions : 1) Both the pressurization method and the dilution method are filling methods in which inorganic phase change materials can be immobilized inside activated carbon, and heat absorption and release characteristics are maintained even after loading. 2) The heat absorption release was maintained for ethanol and the optimal dilution ratio was 1:1. 3) In case of the dilute solvent removal method, the heat absorption/release capacity was maintained when the solvent was removed using only the vaporization method.

Plant Growth Promoting Microorganism Selection and Activity Test for Reforestation of Topsoil Restoration Site

Objectives : This study was conducted to investigate the applicability of plant growth promoting microorganisms during restoration through re-vegetation of damaged topsoil.Methods : As the vegetation to be applied to the restoration site, Weigela subsessilis, Spiraea prunifolia, Pine densiflora, Pennisetum alopecuroides were selected. An attempt was made to isolate plant growth promoting microorganisms from the root zone of plants of the same species inhabiting domestic park sites and hiking trails. Plant growth promoting activities such as phosphate solubilization ability, siderophore production ability, IAA production ability, and ACC deaminase production ability were examined, and the species to be finally applied was selected and then identified. Among the strains whose plant growth promoting activity was confirmed, Arthrobacter sp. 1B2 and Paraburkholderia terrae 1P2 were applied to the genitalia and pine, respectively, and a pot experiment was conducted to confirm the activity.Results and Discussion : Forty-five strains were isolated from Weigela subsessilis, Spiraea prunifolia, Pine densiflora, Pennisetum alopecuroides and the IAA-producing ability and ACC deaminase-producing ability were confirmed for 16 strains whose phosphate solubilizing ability and siderophore-producing ability were confirmed. After selecting and identifying strains with excellent plant growth promoting ability, strains such as Cupriavidus sp, Arthrobacter sp., Pseudomonas fluorescens, Pseudomonas sp., Paraburkholderia terrae were obtained. Among them, Arthrobacter sp. 1B2 and Paraburkholderia terrae 1P2 strains were applied to genitalia and pine, respectively, and it was confirmed that plant growth was promoted.Conclusions : Bioassay experiments and field applications using plant growth promoting microorganisms have been mainly studied for herbaceous species (Grandaceae, corn, oats, etc.). However, in this study, the applied plants are shrubs class, which do not significantly grow in length, targeting damaged areas with high subsoil content, which are poor in environment and insufficient in organic and inorganic matter. Therefore, it is meaningful in that the activity of plant growth promoting microorganisms focused on absorption of inorganic substances, such as phosphate solubilization activity and siderophore ability, was investigated and the activity was confirmed by performing a bioassay.

Characteristics of Cesium Adsorption by Alginate Bead Adsorbent with Layer-by-Layer Synthesis of Prussian Blue

Objectives : The purpose of this study was to develop an adsorbent to which Prussian blue (PB) is stably immobilized to remove radioactive cesium (Cs).Methods : Prussian blue-Alginate (PA) bead and Prussian blue-Alginate with Layer-by-layer synthesis (PAL) bead were synthesized by immobilizing PB respectively.Results and Discussion : As a results of XRD and FT-IR analysis, PB was successfuuly immobilized in alginate bead and PA, PAL bead. SEM (EDS) and TG analysis data were confirmed that the PB content of the PAL bead to which the LBL synthesis method was applied was improved by 6.31%. It was confirmed that the Cs adsorption capacity was improved through the LBL assembly process. The maximum adsorption amount (qm) of PA bead was 25.783 mg/g, and PAL bead was mg/g. In addition, as a result of UV-vis analysis of washing water after synthesis of PA bead and PAL bead, it was confirmed that the PB desorption of the PAL bead was lower indicating that the stability was also improved by LBL synthesis.Conclusions : We developed an adsorbent which prussianblue immobilized on alginate bead for selective removal cesium in aqueous solution. PB was immobilized by LBL synthesis method qm of PAL beads was 28.294 mg/g. It was expected to applied effectively and stably to radioactive cesium contaminated water.

Qualitative Evaluation of Factors Inducing Environmental Pollution of the Sandy Beaches of Jeju Island Using Styrene Oligomers

Objectives : Plastic pollution is a very important environmental issue in Korea as well as abroad. The objective of this study is to evaluate the internal and external factors that cause pollution of the coastal environment of Jeju Island using styrene oligomers (SOs) originated from polystyrene (PS) plastic.Methods : In order to achieve the above objective, this study is conducted to quantitatively measure the concentration of 12 individual SOs chemicals, through gas chromatography/mass spectroscopy (GC/MS) analyzing seawater and beach sand samples around sandy beaches in Jeju Island. This study evaluates the degree of environmental pollution according to internal or external factors of the sandy beach by using the physicochemical characteristic that SOs species are adsorbed on the surface of sand particles.Results and Discussion : The average concentration of SOs in the beach sand of Jeju Island ranges from a minimum of 9.80 ng/g to a maximum of 13.62 ng/g, and the average concentration of SOs in seawater is relatively low with a constant 0.05 to 0.11 µg/L. Although the concentration distribution of SOs species differs considerably depending on the sample collected, the concentration of SOs decreases in the order of styrene trimers (7 isomers) > styrene dimers (4 isomers) > styrene monomer. As a result of monitoring, the concentration of SOs at the sandy beaches of Jeju Island is much higher in the beach sand than in the seawater. This result means that the major beaches of Jeju Island can be polluted mainly by internal factors (e.g. population density, number of travelers according to population movement, and so on), because SOs species are adsorbed on the surface of the sand particles and their mobility is limited.Conclusions : This study shows that the sandy beaches of Jeju Island are mainly polluted by internal factors. It is thought that the pollution degree of the sandy beaches is the highest in the order of Gwakji Beach < Samyang Beach, Hamdeok Beach, Pyoseon Beach < Ihoteho Beach, Sagye Beach < Seopjikoji Beach, Gimnyeong Beach, and Hyeopjae Beach. This study is expected to contribute to the evaluation of the causes of plastic pollution in the coastal environment of Jeju Island.

Influence of the Smoking and Spitting Behaviors in Public Smoking Areas on the Microbial Contamination and Spread

Objectives : The purpose of this study was to investigate the effect of spitting behavior on microbial public health in smoking areas. Through this investigation, bacterial concentration and spread of bacteria from the smoking areas were evaluated for the prospective public health and environment.Methods : The number of spitting and the spitting location in the smoking areas were measured visually by observers. For the microbial analysis, filter papers (5 × 5 cm) as sample collectors had been attached to the surface of the smoking areas for a given time. Using the collected filter paper, ATP bioluminescence measurement (RLU), colony forming unit (CFU) were measured. For the estimation of spitting behaviors in the smoking area on the spread microorganisms, saliva containing filters were selected from the areas, and fluorescent powder (0.01 g/cm2) was added to the papers. After 4 hours, the papers around the smoking areas were collected and the fluorescence activity was measured.Results and Discussion : The results showed that there was a clear relationship between the spitting behavior and the microbial activity in the smoking areas. In the case of sampling area A, the highest number of spitting was observed at the lunch hour (102 ± 16 times), and the RLU from the sample collected near the smoking area showed about 5,139 ± 1,267 RLU. When the RLU around the smoking area was measured, the lowest values were found at distance of 11 and 17 m from the cigarette bin (1,329 ± 148 and 1,204 ± 203 RLU), and it was confirmed that smoking and spitting did not occur at this sampling points. In the case of sampling area B, the highest number of spitting (45 ± 6 times) was observed at evening hour, and the RLU from the sample collected near the smoking area showed about 5,274 ± 1,297 RLU. The lowest value was in the sampling area B shown at 11 and 18 m (1,181 ± 243 RLU and 1,148 ± 168 RLU) from the cigarette bin, and it was also confirmed that smoking and spitting did not occur at this sampling points. The results indicate that the spitting during the smoking induced the increases of the microbial contamination of the public environment. The fluorescence powder diffusion analysis indicated that the saliva on the ground surface would enhance the spread of the microorganisms from the smoking area.Conclusions : Spitting in smoking areas can pose a high risk of microbial infection for smokers and non-smokers in smoking areas. Thus extensive and systematic attention related to the smoking manner must be paid to protect our public health.

Statistical Analysis and Review of Event Mean Concentrations in Stormwater Runoff from Agricultural Nonpoint Source Pollution among Different Land Use Types

Objectives : In this study, the characteristics of stormwater runoff from agricultural nonpoint pollution sources investigated under various experimental conditions were evaluated among different land use types (e.g., paddy, field, field (alpine), and vinyl house), and event mean concentrations (EMCs) for each water quality parameter were statistically analyzed. These results can be used in calculating the contribution of stormwater runoff to water quality of receiving water body by performing quantitative and qualitative analysis. The unit loads calculated were compared with Ministry of Environment TMDL (2019) to secure the reliability of the calculated unit loads.Methods : EMCs and unit loads investigated in various studies were classified in terms of paddy, field, field (alpine), and vinyl house. Among various land use types, EMCs and unit loads were statistically analyzed quantitatively and qualitatively. For EMCs, a null hypothesis is that ‘EMCs of water quality parameters among different land use types are not different at a statistically significant level (α=0.05)’. Based on the results of statistical analysis, heteroscedasticity (p<0.05) and Welch-test method were consequently applied, and post hoc test was performed using the Games-Howell method. Finally, unit loads was compared and reviewed against the TMDL (2019) unit loads of the Ministry of Environment.Results and Discussion : Various EMCs in all water quality parameters were found among different land use types (i.e., paddy, field, field (alpine) and vinyl house). For most water quality parameters, EMCs tended to decrease in the order of field (alpine) > field > vinyl house > paddy. The coefficient of variance (CV) values of all water q uality parameters were 0.5 or greater. Based on these results, EMCs in agricultural nonpoint source pollution are very diverse and deviated due to the combination of natural and artificial factors. Post hoc test results indicated different statistical significance among all water quality parameters. In addition to the land use types, both natural factors (i.e., season, rainfall, antecedent rainfall day, and, rainfall runoff rate) and artificial factors (i.e., cultivator manipulation, emission route, type of crop, and amount of compost) affect the characteristics of stormwater runoff. In particular, in the case of field (alpine) with prominent topographical feature of slope, and EMCs were statistically greater than those from other land use types in all water quality categories (p<0.05).Conclusions : Countermeasures for field (alpine)with greater EMCs than paddy, field and vinyl house, should be performed priority. EMCs were affected by a complex interaction between natural factors (i.e., season, rainfall, antecedent rainfall day, and, rainfall runoff rate) and artificial factors (i.e., cultivator manipulation, emission route, type of crop, and amount of compost), and additional data and research are required for further study to elucidate these complex interactions.

Recent Trends and Prospects of Microbial Fuel Cell Technology for Energy Positive Wastewater Treatment Plants Treating Organic Waste Resources

Microbial fuel cell (MFC) technology is receiving a lot of attention recently as a promising technology for generating electricity by treating organic waste resources. Over the past 20 years, the MFC technology has made rapid progress: various research on system architectures, electrochemistry, materials, and microbiology has been conducted for developing practical ideas and fundamental principles. Recently, a lot of research on scaled-up systems for practical application is being conducted in the MFC field. In this review, materials, electrochemistry, system development and scale-up systems of MFCs studied so far are reviewed, and future prospects and directions of MFC technology are presented.

Analysis of Boron Removal for Reverse Osmosis, Ion Exchange, and Capacitive Deionization

Objectives : This article provides a comparative analysis of boron removal for brackish water reverse osmosis (BWRO), boron selective ion exchange (IX), or capacitive deionization (CDI) processes. Permeate of 1st-Pass RO process has to be post-treated for additional boron removal. Hence, we experimentally analyzed the performance of boron removal and specific energy consumption (SEC) of three aforementioned processes and investigated whether the processes are suitable for 2nd pass process of RO desalination.Methods : Raw feed water was prepared using NaCl and B(OH)3. Semi-pilot scale RO and IX systems (over 1 m3/hr capacity) and bench scale CDI system (over 2.5 L/min) were tested for performance comparison. Boron concentration was measured using Azomethine-H method for feed and product water. Energy consumption was monitored by using power quality analyzer.Results and Discussion : Each process has its own operating conditions. The RO process required high pH of feed water for high boron removal rate, the IX process was operated below breakthrough point considering adsorption capacity of boron selective resin, and the CDI process didn’t remove boron because chloride ion has higher ion selectivity for carbon electrode than boron. In terms of SEC, the pressure-driven RO process showed the highest SEC among three processes. The CDI process based on electrical adsorption of carbon electrode showed a considerable energy consumption as well. On the other hand, the IX process was operated at low energy consumption because its removal is just based on adsorption-desorption mechanism.Conclusions : The RO and CDI processes have received a lot of attention as leading and emerging technology while the IX process was regarded as a stubborn process because of regeneration of resin and its several segmentalized steps. However, we found that the IX process has a better performance for boron removal and energy consumption.