In this study, ultrasonic waves were combined with chemical cleaning to regenerate expensive membranes or solid filters. Nitric acid cleaning alone achieved a flux recovery rate of 68%, but when ultrasonic waves were applied simultaneously, the rate increased to 91%. Similarly, cleaning with HYDREX 4710, a membrane detergent, achieved a flux recovery rate of 76%, which improved to 95% when combined with ultrasonic waves. The operational lifespan of the membranes increased by 125 hours when ultrasonic waves were used in conjunction with cleaning agents compared to using an organic detergent alone. SEM and EDX analyses of unused membranes and membranes prior to chemical cleaning revealed significant adsorption of both organic and inorganic substances, such as aluminum (Al) and silicon (Si). These findings demonstrate that combining chemical cleaning with ultrasonic waves is a highly efficient method for membrane regeneration.

Toilet liquid-type cleaners utilize operating technology that employs buoyancy mechanism to inject uniform amount of cleaning solution. Flow characteristics of velocity and pressure distributions in the flow field of toilet flush cleaner injection device have been analyzed with CFD method. The flow rate decreases near the inlet of the system, where it contacts the container of the cleaning liquid bottle. It then increases near the injection device stopper and decreases again as it moves toward the system outlet The height of the cleaning solution decreases from 12 cm to 3 cm when using the spray device, the average outlet velocity decreases by approximately 73%. The solution level difference increases from 1.616 cm to 3.216 cm, the inlet velocity decreases by approximately 4.1%~5.6%. These predicted results can be widely applied as basic conceptual design data for highly efficient toilet flush cleaner injection device.

본 연구에서는 열유도상분리법으로 제조한 polyvinylidene fluoride (PVDF) 중공사막의 오염성과 화학적 세척에 대한 실험을 진행하였다. 오염수는 소 혈청 단백질(bovine serum albumin, BSA)과 카올린(kaolin)을 이용해 제조하였으며, 차아 염소산나트륨(NaOCl), 구연산(citric acid), 황산(H2SO4)으로 화학적 세척을 진행한 후 뒤 표면 전하 분석기, 주사전자현미경 (scanning electron microscope, SEM) 그리고 에너지 분산 X선 분광법(energy dispersive X-ray spectroscopy, EDX)을 통해 세 척 효율을 평가하였다. PVDF 분리막은 높은 내화학성과 열적 안정성을 가지는 분리막으로 화학적 세척을 진행한 결과 가장 좋은 효율은 차아염소산나트륨으로 세척한 것으로 그 결과 투과도는 793.2 L/(m2.h.bar)로 초기 투과량인 945.3 L/(m2.h.bar) 값과 비교하였을 때 약 84% 회복률을 보여주었다. 이는 수처리 공정에서의 막 오염 방지 및 세척의 중요성을 제시한다.

선박운항의 효율성을 감소시키는 생물부착(biofouling)을 방지하기 위해 사용되는 방오시스템(antifouling system)은 연안의 선체 수리, 해상 부착생물 제거 및 재 페인팅과정에서 해양으로 유출될 수 있다. 이에 대한 법적규제는 마련되어 있지 않아, 해양 생태계에 부정적인 영향을 초래할 할 수 있을 것으로 우려되고 있다. 선체청소배출수에 포함된 오염화학 물질과 관련된 잠재적인 독성 위험이 우려됨에도 불구하고, 이에 대한 생물의 독성영향을 보고한 사례는 매우 제한적이다. 본 연구에서는 선체청소배출수에 노출된 넙치 수정란에 대한 발생독성영향을 분석하였다. 현장에서 실제 선체를 청소한 배출수를 채집하여 원수(wastewater)와 페인트 입자를 제거한 여과한 폐수(0.45 μm Lab filter wastewater)로 나누어, 희석 배율(10배, 100배, 1000배)에 따른 치사 및 아치사 수준의 생태독성영향을 평가하였다. 선체청소배출수의 화학조성은 결과, 구리(Cu), 철(Fe), 아연(Zn)이 높은 농도로 확인되었다. 선체청소배출수에 노출된 모든 실험구의 사망률은 유의한 차이가 없었으나, 심장 부종, 척추만곡, 꼬리지느러미 기형, 발달 지연의 아치사 수준의 형태발생기형 영향이 나타난 것을 확인할 수 있었다. 노출 6시간 후 전사체분석을 통해 독성기작을 분석한 결과, 선체청소배출수에 노출된 넙치 배아에서는 Nervous system development, Cell development, Muscle development, Animal organ development pathway와 관련된 유전자들이 유의하게 차등 발현되었다. 본 연구 결과는 선체청소배출수가 연안에 서식하는 넙치의 발생에 미치는 급성독성영향을 규명하여, 연안 해양환경을 보호하기위한 선체청소배출수의 관리기준 마련에 유용한 정보로 활용될 수 있을 것으로 생각된다.

Over the past decade, there has been global expansion in the advancement of underwater cleaning technology for ship hulls. This methodology ensures both diver safety and operational efficiency. However, recent attention has been drawn to the harmful effects of ship hull-cleaning wastewater on marine animals. It is anticipated that this wastewater may have various impacts on a wide range of organisms, potentially leading to populationand ecosystem-relevant alterations. This concern is especially significant when the wastewater affects functionally important species, such as aquaculture animals and habitat-forming species living in coastal regions, where underwater cleaning platforms are commonly established. Despite this, information on the ecotoxicological effects of this wastewater remains limited. In this mini review, we discuss the adverse effects of wastewater from in-water cleaning processes, as well as the current challenges and limitations in regulating and mitigating its potential toxicity. Overall, recent findings underscore the detrimental effects posed by sublethal levels of wastewater to the health status of aquatic animals under both acute and chronic exposure.

Recently, separation membranes have been applied to fields such as water supply, sewage treatment, gray water reuse, and air pollution control. Chemical cleaning technology is attracting attention among the methods of reusing these expensive separation membranes. It was found that the separation membrane could be regenerated using chemical cleaning. Specifically, it was found that the use time of the separation membranes regenerated by chemical cleaning was sustainable for more than 1,700 hours. Additionally, it was found that the flux recovery ratio after chemical cleaning was maintained at least 60%. In addition, the flux recovery ratio of HYDREX 4710, an organic membrane cleaner, and 4703, an inorganic membrane cleaner, was 76% and 62%, respectively, showing the highest flux recovery ratio among the chemicals used. Considering that the target raw water of this study is biological secondary treatment water, it was suggested that chemical cleaning could be actively used to regenerate separation membranes in future water treatment.

At Pyropia farms, organic acid treatments have enhanced productivity and quality by removing pest algae (such as Ulva spp. and diatoms) and reducing the occurrence of diseases. Ulva spp. attaches to the Pyropia nets competing for inorganic nutrients & space and diminishing productivity. Additionally, the presence of attached contaminants (such as diatoms and middy particles) on the Pyropia nets negatively affects the quality of Pyropia. This study investigated the effects of removing Ulva linza and washing the Pyropia yezoensis nets using an activating treatment agent (organic acid and highly saline solution) with an air bubble device. The results of measuring the dead cell ratios after treatment under different conditions showed that the dead cell ratio of U. linza did not significantly increase when the air bubble device combined the activating treatment agent with the activating treatment agent alone. When washing the P. yezoensis nets, the air bubble device was about 19-37% more effective than the activating treatment agent alone. The findings of this study suggest that the air bubble device enhances the efficacy of the activating treatment agent, resulting in the effective cleaning of the Pyropia nets.

Peanut is a well-known food allergen that causes adverse reactions ranging from mild urticaria to life-threatening anaphylaxis. Consumers suffering from peanut allergies should thus avoid consuming undeclared peanuts in processed foods. Therefore, effective cleaning methods are needed to remove food allergens from manufacturing facilities. To address this, wet cleaning methods with washing water at different temperatures, abstergents (peracetic acid, sodium bicarbonate, dilute sodium hypochlorite, detergent), and cleaning tools (brush, sponge, paper towel, and cotton) were investigated to remove peanuts from materials used in food manufacture, including plastics, wood, glass, and stainless steel. Peanut butter was coated on the surface of the glass, wood, stainless steel, and plastic for 30 min and cleaned using wet cleaning. The peanut residue on the cleaned surfaces was swabbed and determined using an optimized enzyme-linked immunosorbent assay (ELISA). Cleaning using a brush and hot water above 50oC showed an effective reduction of peanut residue from the surface. However, removing peanuts from wooden surfaces was complicated. These results provide information for selecting appropriate materials in food manufacturing facilities and cleaning methods to remove food allergens. Additionally, the cleaning methods developed in this study can be applied to further research on removing other food allergens.

In this study, we compared the microbial reduction effects of drying, hot water, and microwave sterilization in scourers and dishcloths to suggest a most suitable sterilization method. Three scourer types (silver, copper, and mesh) were used, and three dishcloth types (silver, bamboo, and cotton) were used. Drying time dependent reduction in Escherichia coli was high in silver and copper scourers, but minimal bacterial reduction was obtained against Bacillus cereus in all scourers and dishcloths. In scourers, E. coli was not detected after ≥30 s of hot water sterilization at 77oC, and B. cereus was not detected after ≥60 s of hot water sterilization at 100oC. In dishcloths, E. coli was not detected after hot water sterilization at 77oC for ≥30 s, but B. cereus was detected after hot water sterilization at 100oC for ≥60 s. In scourers, E. coli was not detected after microwave sterilization at 700 W for 3 min, but B. cereus was detected. In dishcloths, E. coli was not detected after microwave sterilization with 700 W for ≥1 min, but B. cereus was detected in the cotton dishcloth even after sterilization for 3 min. In conclusion, the use of antimicrobial scourers (silver and copper) and dishcloths (silver and bamboo) are not sufficient to reduce the microbial contamination. The guideline provided by the Ministry of Food and Drug Safety suggesting dishcloth sterilization via hot water at 100oC for 30 s was also found to be insufficient. Based on our research, we suggest that the most effective methods of microbial management are submerging scourers in hot water at 100oC for ≥1 min, and sterilizing dishcloths for ≥3 min using a 700 W microwave.

In this study, a two-stage electrostatic precipitator (ESP) was developed using a novel automatic dry cleaning device to reduce the ultrafine particles in subway stations. Collection efficiency was evaluated with a pilot scale ESP (1.2m× 1.2m) and the scale of the test duct was half of the subway air handling unit. The maximum collection efficiency for 0.3 μm particles was 96.9%. In addition, we studied a method of automatic dry cleaning for maintenance of the ESP. The cleaning efficiency was analyzed according to the cleaning flow rate for each particle loading amount to achieve a recovery rate over 90%. In addition, we derived the equation to estimate the reduction in collection efficiency according to the particle loading amount. It was confirmed that the performance of the contaminated ESP was restored to the initial state by the automatic dry cleaning in this study and that the electrical energy consumption was 5 times lower compared to utilizing conventional water cleaning.

In this study, chemically enhanced steam cleaning(CESC) was applied as a novel and efficient method for the control of organic and inorganic fouling in ceramic membrane filtration. The constant filtration regression model and the resistance in series model(RISM) were used to investigate the membrane fouling mechanisms. For total filtration, the coefficient of determination(R2) with an approximate value of 1 was obtained in the intermediate blocking model which is considered as the dominant contamination mechanism. In addition, most of the coefficient values showed similar values and this means that the complex fouling was formed during the filtration period. In the RISM, Rc/Rf increased about 4.37 times in chemically enhanced steam cleaning compared to physical backwashing, which implies that the internal fouling resistance was converted to cake layer resistance, so that the membrane fouling hardly to be removed by physical backwashing could be efficiently removed by chemically enhanced steam cleaning. The results of flux recovery rate showed that high-temperature steam may loosen the structure of the membrane cake layer due to the increase in diffusivity and solubility of chemicals and finally enhance the cleaning effect. As a consequence, it is expected that chemically enhanced steam cleaning can drastically improve the efficiency of membrane filtration process when the characteristics of the foulant are identified.