Immersion Cleaning Research Articles

Biofouling control of reverse osmosis membrane in municipal wastewater recycling plants using urine as a cleaning agent

Biofouling is a major issue for reverse osmosis (RO) membranes during wastewater recycling, which requires significant chemical inputs for its cleaning. This study investigated the feasibility of using urine, a human waste that can be directly obtained from the community, as a novel and low-cost cleaning agent for RO membranes subjected to biofouling. Lab-scale immersion cleaning tests and cross-flow cleaning tests were performed on four fouled RO membranes collected from municipal wastewater recycling plants (MWRPs). In the immersion cleaning test, urine solutions (15–25 %) showed higher removal efficiency for ATP, proteins, and polysaccharide than the traditional alkaline solution (NaOH, pH=11), with a cleaning efficiency of 82 %, 53 %, and 79 %, respectively. In the cross-flow cleaning test, urine solutions (15 % − 25 %) also exhibited comparable or better performance than the conventional alkaline cleaning (NaOH, pH=11) in ATP, proteins and polysaccharide removals, reaching a removal rate of 79 % − 100 %, 61 % − 90 %, and 70 % − 100 %, respectively, and permeability increase by 7.8 % − 16.0 %. Urine solutions (15–25 %) demonstrated to be a promising agent for biofouling cleaning on RO membranes in MWRPs, providing a cost-effective and environmentally friendly alternative.

Causal inference and mechanism for unraveling the removal of four pesticides from lettuce (Lactuca sativa L.) via ultrasonic processing and various immersion solutions

This study explores the reduction of carbamates (CAs) and pyrethroids (PYs) − commonly used pesticides − in lettuce using various immersion solutions and ultrasonic processing. It also examines the role of machine learning and molecular docking in understanding the mechanisms of pesticide reduction. The results revealed that the highest reduction of both CAs and PYs exceeded 80 % on lettuce leaves. In most samples, the reduction increased with the power of ultrasonic processing and processing time. The results of machine learning models (XGBoost and SHAP) showed that during the immersion cleaning of CAs and PYs, as well as during both immersion cleaning and ultrasonic processing of CAs + PYs, the reduction was most influenced by the initial pesticide levels and immersion time. Gas Chromatography-Mass Spectrometry (GC–MS) analysis of lettuce’s wax layer identified 24 compounds, including fatty alcohols, fatty acids, fatty acid esters, and triterpenoids. Despite the absence of active sites, the lipophilic nature of long-chain aliphatic compounds aids in pesticide binding, while triterpenoids form strong hydrogen bonds with pesticides, indicating a robust adsorption on the lettuce surface. This study aims to offer insights into the efficient removal of chemical pesticide residues from fruits and vegetables, addressing critical concerns for food safety and human health.

Hydrogels – a desirable alternative to water paper restoring procedures: impacting paper properties

Water immersion is a common practice for treating paper media. However, this treatment could irreversibly damage paper and the information written on it – such procedures are advised if the documents do not contain water-resistant components such as inks or paints and the form is mechanically stable. Thus, polymeric materials are an attractive alternative to water immersion cleaning. Various polymers are used to produce hydrogels, but there is not much information on cleaning effects before and after aging. Due to their highly rigid properties, Kelcogel, TopVision Agarose and PhytagelTM hydrogels could be applied to clean fragile paper media instead of water immersion. The hydrogel could safely clean without any residue or change of paper properties. Selected polymers were analysed for composition, water discharge and acidity according to the corresponding requirements for restoration processes: to establish changes in chemical and physical paper properties after hydrogel cleaning, filter paper samples were analysed with SEM, TGA, FTIR and pH-meter and compared to the benchmarks of filter paper cleaned with distilled water.

Performance of Ti/Zr and silane coating pretreatments on adhesive bonding of an automotive aluminium alloy produced using the Hot Form Quench (HFQ®) process

Surface pretreatments of an automotive aluminium alloy delivered in F temper and subsequently processed using Hot Form Quench (HFQ®), a novel press forming technique combining solution heat treatment, press forming and in-die quenching to produce high-strength aluminium alloys, for adhesive bonding have been explored. The performance of two commercial pretreatments including Ti/Zr and silane coatings, with either acid spray or alkaline immersion cleaning, was investigated. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) were employed to characterize the surface chemistry and topography of the alloy after pretreatments. Adhesively bonded aluminium-aluminium single lap shear joints and double cantilever beam specimens were tested to evaluate the performance of the pretreatments on the bonding strength and fracture resistance, respectively. The FTIR and TEM techniques show that the natural oxides and near-surface deformed layer have been successfully removed, but the surface cleanliness level was sensitive to the cleaning approach adopted. New Ti/Zr oxide layers or silane films have been built upon the aluminium surfaces, which confirms that sound surface conditions for adhesive bonding can be obtained for parts produced using HFQ® from F temper input material.

Fenton cleaning strategy for ceramic membrane fouling in wastewater treatment

Membrane fouling is an obstacle impeding the wide applications of ceramic membranes and organics are responsible for most of the membrane fouling issues in wastewater treatment. In this study, Fenton cleaning strategy was firstly proposed to clean ceramic membrane fouling in wastewater treatment. Fe2+ efficiently catalyzed fouling cleaning with H2O2 (1.5%) to recover the filterability of ceramic membrane. The maximum ∆TMP recovery (over 99%) was achieved at an optimal Fe2+ dosage of 124 mg/L after 6 hr of immersion cleaning. The total residual membrane fouling resistance decreased gradually from this optimum value as the Fe2+ dosage increased above 124 mg/L. The residual hydraulically reversible fouling resistance accounted for most of the membrane fouling and was basically removed (≤3.0 × 109 m−1) when Fe2+ dosages higher than 124 mg/L were used. The foulants responsible for the formation of a residual hydraulically reversible fouling layer (DOC (dissolved organic carbon), proteins, polysaccharides, EEM (fluorescence excitation-emission matrix spectra), SS (suspended solids), and VSS (volatile suspended solids)) were gradually removed as the Fe2+ dosage increased. These residual organic foulants were degraded from biopolymers (10–200 kDa) to low molecular weight substances (0.1–1 kDa), and the particle size of these residual foulants decreased significantly as a result. The strong oxidation power of hydrogen peroxide/hydroxy radicals towards organic foulants was enhanced by Fe2+. Fe2+ played a significant role in the removal of hydraulically reversible fouling and irreversible fouling from the ceramic membrane. However, Fe2+ (≥124 mg/L) increased the likelihood of forming secondary iron-organics aggregates.

Manual Cleaning and Immersion Cleaning ; A Comparative Study in Medical Device Precleaning

Manual Cleaning and Immersion Cleaning ; A Comparative Study in Medical Device Precleaning

A comparison of ultrasonically activated water stream and ultrasonic bath immersion cleaning of railhead leaf-film contaminant

Leaf-film adhered to the railway track is a major issue during the autumn/fall season, as leaves fall onto the track and are entrained into the wheel-rail interface. This results in the development of a smooth, black layer. Presently, pressure washers must be used to clean the residue to prevent loss of traction, which can cause crashes or delays by forcing a reduced speed. These pressure washers consume large amounts of water and energy. In this study, use of an ultrasonic cleaning apparatus equipped with a 100 W transducer is investigated, using a low volume of water in the order of 1 l min−1. This was applied to leaf-film samples generated in the laboratory, whose surface properties and thickness were confirmed with optical and stylus profilometry methods. Cleaning achieved by an ultrasonically activated water stream was compared to (a) non-activated water and (b) an ultrasonic bath with comparable power consumption. Cleaning efficacy was found to be much greater than that afforded by the ultrasonic bath; a rate of 14.3 mm2 s−1 compared to 0.37 mm2 s−1, and the ultrasonic bath only cleaned off around 20% of the leaf-film coverage even after 3 min of exposure.

1916 マイクロパズルの表面電位などの特性が油の浸漬洗浄に及ぼす影響(OS7-4 流れの計測と制御IV,OS7 流れの計測と制御)

1916 マイクロパズルの表面電位などの特性が油の浸漬洗浄に及ぼす影響(OS7-4 流れの計測と制御IV,OS7 流れの計測と制御)

Post-etch residue removal using choline chloride–malonic acid deep eutectic solvent (DES)

Eutectic mixture of choline chloride (CC) and malonic acid (MA) in a molar ratio of 1:1 has been evaluated as a potential chemical system for the removal of residues produced by CF4/O2 plasma etching of copper coated with DUV photoresist. Immersion cleaning was performed in the liquid at the eutectic composition at 40 and 70 °C. Residue removal rate was screened using scanning electron microscopy and verified using X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy measurements. The results presented in this paper show that choline chloride–malonic acid eutectic is effective in removing post-etch residues and has the potential to function as a back end of line cleaning formulation.

Non-invasive measurement of membrane scaling and cleaning in spiral-wound reverse osmosis modules by ultrasonic time-domain reflectometry with sound intensity calculation

This study describes the ultrasonic time-domain reflectometry (UTDR) with a sound intensity calculation for monitoring membrane scaling and cleaning in a 4-inch spiral-wound reverse osmosis module. Three focused transducers with the frequency of 2.25 MHz were located equidistantly along the feed flow direction. The scaling experiments were carried out with 2.0 g/L calcium sulfate for 90 h fouling and the cleaning processes consisted of three phases: pure water flushing, immersion cleaning and acid-washing. According to this study, the ultrasonic response signals and the corresponding sound intensity gradually decreased to minimum with the fouling and deposition of the foulants on the membrane and then increased with the formation of fouling layer. The initial induction time in the change of sound intensity became shorter and the sound intensity became lower along the fluid direction during the fouling process. It was found that the CaSO 4 scaling first precipitated near the downstream owing to the increased concentration polarization. Furthermore, the permeate flux and the sound intensity all recovered step by step with the cleaning processes. The results obtained by independent methods such as SEM and weight measurements were in good agreement with the observations by ultrasonic technology. Overall, this study confirms that the UTDR technique with a sound intensity calculation and modeling is capable to evaluate the membrane scaling and cleaning in spiral-wound modules.

Use of Urea-Choline Chloride Eutectic Solvent for Back End of Line Cleaning Applications

A liquid mixture formed from two benign chemicals, urea and choline chloride, in the molar ratio of 2:1 has been evaluated for post etch residue (PER) removal from copper surface. Residue films were prepared by etching DUV photoresist films coated on copper in CF4/O2 plasma. Film removal was evaluated under immersion cleaning conditions using X-ray photoelectron spectroscopy and scanning electron microscopy and verified using electrochemical impedance spectroscopy measurements. The residue film was effectively removed in the temperature range of 40–70°C. The results of this study show that choline chloride and urea based DES system has the potential to function as a back end of line cleaning formulation.

출토 직금직물의 세척방법에 관한 연구

Excavated gold brocade, often shows signs of serious damage and contamination from environmental factors such as exposure to soil or human remains. Therefore, most of the conservation procedures are focused on the consolidation of the gold thread and on cleaning with water or organic solvents. Indiscreet cleaning using solvents could damage the gold leaf, which identifies the features of fabric. There is a need to develop cleaning protocols appropriate for relics through the careful analysis of the condition of the relics. This study finds the appropriate cleaning method for the excavated gold brocade. Four different cleaning methods, vacuum cleaning, kneaded rubber eraser cleaning, immersion wet cleaning, and absorption wet cleaning were applied to the excavated gold brocade. The degree of cleaning and damage were examined depending on the cleaning methods, changes to the physical condition (before and after cleaning) were also analyzed through the surface observation. Although immersion cleaning showed the best cleaning result, this method had a risk of damage to the gold thread. Absorption wet cleaning safely eliminated the various soluble contaminants and the rotten smell of relics. Kneaded rubber eraser was suitable for the excavated gold brocade fabric because it can be applied to selective parts, intentionally excluding some sensitive parts such as the gold thread. The vacuum cleaning method required special attention because of a possibility of suctioning off loosely attached gold leaf. Dual cleaning, the kneaded rubber eraser cleaning, followed by the absorption cleaning was the most effective method to preserve and clean excavated gold brocade.

Industrial Cleaning of Implants: Performance Validation of Cleaning Scheme

Abstract The quality of medical devices depends strongly on the proper cleaning of the devices in the line of processing. Residue-free implants are not only a benefit for the patient in the long term, but they also help to reduce the number of rejections due to insufficient surface quality. The performance of the new, fully automated aqueous immersion cleaning system revealed a very high cleaning efficiency for metallic implants. An organically based model process adjuvant was used as contaminant. Custom designed metallic bodies made of implant quality material and exhibiting different surface textures served as test coupons. The analysis of the residues was carried out using gas chromatography separation and mass spectrometry analysis. The amount of organic residues found on the test coupons was below the set quantification limit of 0.1 mg—most of the time even below the detection limit of 0.01 mg total organic compounds.

A new test for cleaning efficiency assessment of cleaners for hard surfaces

AbstractA new test was developed to assess the efficiency of no‐wiping hard‐surface cleaning. The test allows cleaner comparisons according to their ability to remove greasy soils. The chosen approach minimizes the mechanical forces applied while cleaning so that the interactions between a detergent solution and the soil to be removed can be characterized. For this, immersion cleaning was chosen, with coated stainless steel as substrate and pigmented oils as the model soil. Several parameters were studied in defined ranges using the Experimental Design method and systematic comparisons. The test shows high reliability on degreasing assessments and is there‐fore especially suited to optimization of nonionic surfactant mixes. The originality of the test lies in the possibility of keeping a visual trace of the cleaned substrate appearance by imprinting it on a piece of paper. The validation of the test leads to corroboration of several practical observations. Temperature and agitation play a major role in cleaning efficiency. Detergent solution concentration is a more relevant parameter than pH. Sodium carbonate is shown to have a higher buffering effect than pentahydrated sodium metasilicate. The test is easy to set up, highly sensitive, and can be adapted to solve the problems encountered by formulators of detergent cleaners, such as screening the best ethoxylated fatty alcohol mix for better degreasing properties.

Recycling a nonionic aqueous‐based metal‐cleaning solution with a ceramic membrane: Pilot‐scale evaluation

AbstractThe effectiveness of a zirconium dioxide (ZrO2) membrane filter was evaluated for recycling a nonionic aqueous metal cleaning bath under real‐world conditions. The pilot‐scale study consisted of four 7‐ to 16‐day filtration runs. Each processed a portion of the cleaning bath during immersion cleaning of aircraft engine and motor parts. The results indicated that the filter was effective in removing contaminants such as oil and grease and suspended solids from the process solution, thus extending the life‐span of the bath up to three times. The process bath, however, had to be replenished with surfactant additives to compensate for those removed by the filter. The fouled membrane could be effectively cleaned with its permeability fully restored for reuse.

Single wafer plasma etching. 1. Al and Al/Si alloys : R. F. Reichelderfer. Solid St. Technol., 160 (April 1982)

Eutectic mixture of choline chloride (CC) and malonic acid (MA) in a molar ratio of 1:1 has been evaluated as a potential chemical system for the removal of residues produced by CF4/O2 plasma etching of copper coated with DUV photoresist. Immersion cleaning was performed in the liquid at the eutectic composition at 40 and 70 °C. Residue removal rate was screened using scanning electron microscopy and verified using X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy measurements. The results presented in this paper show that choline chloride–malonic acid eutectic is effective in removing post-etch residues and has the potential to function as a back end of line cleaning formulation.

The Microflora of Milking Equipment Cleansed by Chemical Methods

Summary: The incidence of the main types of bacteria among 2,856 isolated on Yeastrel‐milk agar incubated at 30° from 121 rinses of dairy equipment cleansed by chemical methods, showed that micrococci were dominant in low colony count (<104/ft2) rinses of equipment treated by immersion cleaning in caustic soda or cleansed in detergent‐hypochlorite solutions, whereas nonpigmented Gram‐negative rods were dominant in low count rinses of equipment cleansed with detergent‐sterilizers containing quaternary ammonium compounds. Gram‐negative rods were dominant and streptococci frequent in high count (<2·5 × 105/ft2) rinses irrespective of the chemical used. A high proportion of the streptococci and coli‐aerogenes organisms gave acid reactions in litmus milk after 72 h at 22°, many of the anaerogenic Gram‐negative rods and several of the aerobic sporeformers gave proteolytic reactions, whereas the majority of the micrococci, corynebacteria and other asporogenous Gram‐positive rods showed no change. Bacteria isolated from high count rinses were more active in producing milk spoilage reactions at 22° than those isolated from low count rinses.

Destruction ofBacillus subtilisspores with solutions of sodium hydroxide

SummaryThe rate of destruction ofBacillus subtilisspores by sodium hydroxide solutions in the range of atmospheric temperatures 34—82 °F was studied: (a) to provide information which might be used in practice for immersion cleaning of dairy utensils in sodium hydroxide solutions at low atmospheric temperatures, and (b) to examine the nature of the disinfection curves by slowing down the rate of disinfection. The results expressed as a three-dimensional graph showed that an increase in temperature from 34 to 82 °F had a more marked effect on spore destruction than an increase in concentration of sodium hydroxide from 1·5 to 5·0%. The overall effect could be expressed aswheret= time in hours for the 99% destruction ofB. subtilisspores,C= concentration of NaOH (%, w/v) and θ = temperature, °F. Since the time for the 99% destruction ofB. subtilisspores by a 2% NaOH solution at 34 °F is 5 times that of a 5% solution, immersion cleaning in cold climates might be assisted by increasing the concentration of NaOH from the normal 2–3 to 5%. Results in disinfection tests at low temperatures were more variable than had been observed in previous work at higher temperatures. These surprising results prevented a careful study of the nature of the disinfection curves and confirmed previous conclusions that such curves are basically sigmoid.

BACTERIOLOGICAL STUDIES OF IMMERSION CLEANING OF MILKING EQUIPMENT ON COMMERCIAL FARMS

SUMMARY: A study has been made of the immersion cleaning technique as applied on commercial farms. In an initial survey bacteriological results for rinses and swabs of the milking equipment were satisfactory on most farms, but on one farm the results were very disappointing. Further investigations at this farm showed that the poor results were caused partly by sporing bacteria which survived the caustic soda treatment, presumably in the spore state, and partly by non‐sporing organisms, chiefly chromobacteria and micrococci.These non‐sporing organisms are found in abundance on the surface of dirty wash troughs, and under certain conditions re‐contamination of the milking equipment can occur during the rinsing operation. Suggested modifications to the original immersion cleaning technique include the use of hot water for the before‐milking hypochlorite rinse, brushing the equipment in the after‐milking rinse to remove extraneous dirt, regular cleansing of the wash trough and the monthly cleansing of the basket and bin.

628. Further studies of immersion cleaning of milking equipment

Further studies of immersion cleaning have shown that no deposition of calcium soap and inorganic calcium salts occurs if the immersion solution contains ethylene diamine tetraacetic acid. Compared with results for the previous year there was a marked improvement in the bacteriological state of liners as a result of the absence of calcium deposits. It has also been shown that the addition of tetramethylthiuram disulphide to the rubber mix from which liners are made gives useful bactericidal properties. The intensity of the bactericidal action was little reduced after liners had been in farm use for 4 months.