Sequential Cleaning Research Articles

Technological solutions to increase the level of iron extraction from stored enrichment tailings

This article presents the main results of research on the extraction of iron from the waste of the processing plant stored in the tailings dump. The average sample was classified by granulometric composition and the content of Fe2O3 was determined by the X-ray fluorescence method for each class. It follows from the results of the sieve analysis that the most iron-rich classes are +2 mm and –0.071 mm. The iron content in the +2 mm class approximately corresponds to the iron content in the source ore. When studying samples of grades +0.1–2 mm under a microscope, it was found that magnetite and hematite are bound by clay materials into floccules, which partially disintegrate upon drying. The initial material with a moisture content of 10.7% was pre-prepared for separation: a fraction of +3 mm was dried and removed. The resulting material was separated on a wet magnetic drum separator with sequential cleaning of the non-magnetic fraction in four stages with induction on the working surface of 0.18, 0.3, 0.4, 0.5 Tl. The resulting non-magnetic fraction from wet magnetic separation was separated on a dry roller separator with induction on the working surface of 1.5 Tl. The non-magnetic fraction was divided by screening into fractions: –3+2 mm, –2+1 mm, –1+0.2 mm, –0.2+0 mm. As a result of the experiment, it was found that wet magnetic separation after pre-drying makes it possible to isolate a concentrate with a content of up to 42% by weight of Fe2O3 into an industrial product. The total yield reaches 24.5% at a magnetic field strength of 0.18 Tl. Check-cleaning, as well as dry separation, do not have a significant additional effect. The conducted research and the developed technological scheme have shown the possibility of obtaining iron ore concentrate with an iron content of more than 60% from stored tailings. At the same time, the return of iron to production is 58%.

Ecological State of Industrial Waste from the Kadamzhai Antimony Plant

Sources of release of harmful substances during enrichment are emissions from ore crushing, as well as enrichment tailings. Dusty air from places of dust formation is taken by an aspiration device and purified in a dust settling chamber with wet collection. At a metallurgical plant, there are dust and gas collectors in ore-thermal furnaces. Dust and gases from furnaces are sent for sequential cleaning and collection (water-cooled cyclones, bag filters). At this stage, dust-containing gases leak. A particular danger to the environment is the storage of waste electrolyte accumulated in salt storage tanks. The area of salt storage tanks is 76.1 thousand m2. Salt storage tanks consist of 7 cards with a total volume of 249.95 thousand m3. Currently, the environmental situation in the area of salt storage tanks for industrial waste of the Kadamzhai Antimony Plant remains critical. All the existing 7 salt accumulator cards have expired, are in disrepair, and leak industrial wastewater into the soil. Salt accumulators No. 5 and No. 8, although they have not reached the end of their service life, are also in disrepair.

Experimental study of a full-scale hexagonal wet electrostatic precipitator for collection of black carbon and particulate matter generated by a marine diesel engine

ABSTRACT Wet electrostatic precipitators have demonstrated a robust capability for removal of particulate matter by minimizing back corona and particle re-entrainment of fine particles. The absence of studies investigating the removal of black carbon particles using a wet electrostatic precipitator requires additional development/investigations. Among the operational parameters of wet electrostatic precipitators, particle residence times (<1 s) and the amount of electrostatic energy transferred to the exhaust gas are important to determine the removal efficiencies of wet electrostatic precipitators. This article reports the removal efficiency of black carbon, total particulate matter, and various particle sizes using different operating conditions in a full-scale hexagonal wet electrostatic precipitator column with sequential cleaning. The exhaust gas cleaned during the experiments was produced by a 2 MW marine engine operated on heavy fuel oil. Three key parameters, voltage-current characteristics, transferred electrostatic energy to the exhaust gas, and particle residence times were varied to evaluate their effects on removal efficiencies. The wet electrostatic precipitator was able to remove from 42.7% to 97.2% of the particulate matter and 44.8% to 95.9% of black carbon particles by varying the electrical energy input to the gas stream (5–262 J/m3) and the particle residence time (0.3–1.8 s). A change in particle residence time (0.3 to 0.95 s) showed an overall removal increase of 31.7% and revealed removal efficiency gaps of up to 24.1% between particle sizes. By investigating the removal efficiencies of different particle sizes and black carbon content, it was found that the best fit was achieved for sizes between 0.02 and 0.77 μm, indicating a black carbon size range in this order. The study indicates that a similar removal efficiency between black carbon and particulate matter could be achieved and that the main focus for improvement of black carbon removal should be found in the particle range between 0.02 and 0.77 μm. Implications: The manuscript describes a small efficient system for the removal of particle matter and black carbon particles from the exhaust gas generated by a ship engine. This manuscript is especially interesting for the International Maritime Organization (IMO) and its sub-committee on Pollution Prevention and Response (PPR). The IMO is the law-maker/the United Nations specialized agency with responsibility for atmospheric pollution by ships in international waters. The IMO agreed in 2011 on an investigation plan to gather information and to find possible black carbon control measures for future regulations, which to some extent can be delivered through this article.

Sustaining Improvements in CLABSI Reduction in a Pediatric Cardiac Intensive Care Unit.

Introduction:Central line-associated bloodstream infections (CLABSIs) are preventable events that increase morbidity and mortality. The objective of this quality project was to reduce the incidence of CLABSIs in a pediatric cardiothoracic intensive care unit.Methods:Institutional review of an unacceptably high rate of CLABSIs led to the implementation of 4 new interventions. These interventions included: the use of sequential cleaning between line accesses, Kamishibai card audits, central line utilization and entry audits, and proctored simulation of line access.Results:There was a reduction in CLABSI rate from 1.52 per 1,000 central line days in 2018 to 0.37 per 1,000 central line days in 2020 and 0.32 in 2021. Additionally, central line days per 100 patient days decreased from 77 to 70 days over the study period. The cardiothoracic intensive care unit went 389 days without a CLABSI from October 2020 to November 2021.Conclusions:Implementation of multiple interventions led to a successful reduction in the incidence of CLABSIs in our unit, with a sustained reduction over 1 year.

Catalytic ozonation treatment of biochemically treated leachate from municipal waste solid using Ti–Mn oxide‐coated stainless steel mesh catalyst

AbstractBACKGROUNDLandfill leachate is a kind of complex organic wastewater, the discharge standard of which is difficult to meet after traditional biochemical treatment. In this work, a Ti–Mn stainless steel corrugated wire mesh (SSCWM) catalyst was prepared by the sol–gel method, which was used for the catalytic ozonation of biochemically treated leachate.RESULTSThe catalyst was characterized using scanning electron microscopy, energy dispersive X‐ray spectroscopy, X‐ray diffraction and X‐ray photoelectron spectroscopy techniques. The data showed that the chemical oxygen demand (COD) removal efficiency of the leachate by ozone alone, SSCWM/O3, Ti–SSCWM/O3 and Ti–Mn/SSCWM/O3 system reached 55.06%, 64.44%, 68.97% and 78.43%, respectively. The catalytic effect of different layers of Ti–Mn oxide‐coated SSCWM catalyst showed that two catalytic layers had the best activity of COD removal efficiency, reaching 87.17%, and the final COD reached the national emission standard (&lt;100 mg L−1). At the same time, the results of fluorescence spectrum and gas chromatography–mass spectrometry (GC‐MS) analysis confirmed this point. The stability of the catalyst decreased with the increase in usage times, and the final COD removal efficiency was 73.91% after six cycles of use. To understand the reason for catalyst deactivation, the adsorbed organic matter on the catalyst surface was determined by GC‐MS analysis. In addition, COD removal of the catalyst can be increased to 80.55% after in situ regeneration of the mesh catalyst by a sequential cleaning process consisting of alkali–acid–hydrogen peroxide–ethanol–water.CONCLUSIONIn short, application of the mesh catalyst in catalytic ozonation can be considered as a promising method for wastewater treatment, because of avoidance of solid–liquid separation and easy regeneration of catalytic activity. © 2020 Society of Chemical Industry

Fouling characterization and aeration performance recovery of fine-pore diffusers operated for 10 years in a full-scale wastewater treatment plant

Fouling characterization and aeration performance recovery of fine-pore diffusers operated for 10 years in a full-scale wastewater treatment plant were investigated to elucidate fouling mechanisms and develop cleaning strategy. The performance decline of diffusers was observed with dynamic wet pressure increased by 3.2 times and standard oxygen transfer efficiency dropped to 73%, which contributed to 15.0% increase in total energy consumption. Oxygen-affinity, filamentous and extracellular polymeric substances secreting bacteria tended to accumulate on the diffuser surface. External (mainly biofilm growth), internal (organic and inorganic matters) and irrecoverable (mainly material aging) foulants accounted for 34.1%, 45.4% and 20.1% of total fouling, respectively. HCl cleaning failed to restore aeration efficiency because it eliminated structural support formed by inorganics, leaving organic foulants broken into smaller fragments and distributed more dispersed. NaClO showed better cleaning efficiency by effectively removing organic foulants. Sequential cleaning by NaClO and HCl, which achieved the best recovery, was recommended.

Validasi Metode Analisis Residu Mometasone furoate dan CIP100 Setelah Proses Pembersihan Peralatan Produksi di Industri Farmasi “XYZ”

In this study, the HPLC and Total Organic Carbon (TOC) analysis methods have been developed and validated for the determination of the amount of Mometasone furoate and CIP100 residues on the surface of production equipment and to confirm the efficiency of the cleaning procedure. Mometasone furoate and CIP100 have been chosen based on the worst case assessment approach. The limit of mometasone furoate contamination that has been determined is 100 ug/swab and the specified limit of CIP100 contamination is 100 ug/swab which should not be exceeded during sequential cleaning of the equipment. Mometasone furoate shows good linearity in the range 0.1-1.0 ppm for the HPLC method and CIP100 2.0-10.0 ppm for TOC Analysis. The percentage of recovery from stainless steel plates using swab sampling techniques was found in the limits of 95.12% and 99.93% respectively in the HPLC and TOC methods. Both methods are simple, inexpensive, short analysis time and high sensitivity for quantitative determination of Mometasone furoate and CIP100 on the surface of manufacturing equipment well below the contamination limit. The validated method meets the requirements for demonstration of the validation of residual cleaning of mometasone furoate and CIP100 on the surface of production equipment

Comparative Study of Cleaning Efficacy of Different Concentrations of Sodium Hypochlorite on Nickel-Titanium Endodontic Instruments.

Objective: The objective of this study was to develop an effective cleaning procedure for Nickel-Titanium instruments. Materials and method: Twelve newly sterilized Nickel-Titanium(Ni-Ti) instruments were contaminated by preparing canals of extracted teeth and subjected to both mechanical and chemical cleaning procedures under various concentration of sodium hypochlorite. Debris on flutes was scored after staining with Van Gieson’s solution at X20 magnification using a stereomicroscope. Results: This study showed that a sequential cleaning procedure including combined mechanical and chemical removal with 12% Sodium Hypochlorite (NaOCl) solution is an effective procedure of removing debris from Nickel Titanium hand instruments. Conclusion: The result of this study has shown that a sequential cleaning procedure including combined mechanical and chemical removal with 12% Sodium Hypochlorite solution is an effective procedure of removing debris from Ni-Ti instruments.

Will 1-stage implant salvage after periprosthetic breast infection ever be routine? A 6-year successful experience.

Concomitant with the recent increase in breast augmentations has been an increase in periprosthetic infections necessitating further surgery. The conventional treatment of periprosthetic infections has been a multistage procedure involving explantation, control of infection, and reimplantation. The authors describe a 1-stage salvage procedure for the management of periprosthetic infections. This technique may become the standard for managing infection following cosmetic breast surgery. The authors performed a retrospective review of all patients who had periprosthetic infection following cosmetic breast augmentation. The treatment included explantation, sequential cleaning of the wound, and immediate insertion of a new prosthesis and drain. All patients received intravenous antibiotics postoperatively. Of 3012 patients undergoing primary breast augmentation, periprosthetic infection developed in 17 patients. These 17 patients underwent 1-stage implant salvage. Patients were monitored for ≤6 years. All implants were retained; aesthetic results were satisfactory; and no significant adverse events were recorded after implant salvage. One-stage implant salvage for periprosthetic infection has similar outcomes to conventional multistage procedures and may be preferred by patients. 4.

An Environmental Disinfection Odyssey: Evaluation of Sequential Interventions to Improve Disinfection of Clostridium difficile Isolation Rooms

OBJECTIVE. Effective disinfection of hospital rooms after discharge of patients with Clostridium difficile infection (CDI) is necessary to prevent transmission. We evaluated the impact of sequential cleaning and disinfection interventions by culturing high-touch surfaces in CDI rooms after cleaning. DESIGN. Prospective intervention. SETTING. A Veterans Affairs hospital. INTERVENTIONS. During a 21-month period, 3 sequential tiered interventions were implemented: (1) fluorescent markers to provide monitoring and feedback on thoroughness of cleaning facility-wide, (2) addition of an automated ultraviolet radiation device for adjunctive disinfection of CDI rooms, and (3) enhanced standard disinfection of CDI rooms, including a dedicated daily disinfection team and implementation of a process requiring supervisory assessment and clearance of terminally cleaned CDI rooms. To determine the impact of the interventions, cultures were obtained from CDI rooms after cleaning and disinfection. RESULTS. The fluorescent marker intervention improved the thoroughness of cleaning of high-touch surfaces (from 47% to 81% marker removal; P < .0001). Relative to the baseline period, the prevalence of positive cultures from CDI rooms was reduced by 14% (P=.024), 48% (P <.001), and 89% (P=.006) with interventions 1, 2, and 3, respectively. During the baseline period, 67% of CDI rooms had positive cultures after disinfection, whereas during interventions periods 1, 2, and 3 the percentages of CDI rooms with positive cultures after disinfection were reduced to 57%, 35%, and 7%, respectively. CONCLUSIONS. An intervention that included formation of a dedicated daily disinfection team and implementation of a standardized process for clearing CDI rooms achieved consistent CDI room disinfection. Culturing of CDI rooms provides a valuable tool to drive improvements in environmental disinfection.

Treatment of Anaerobically Digested Cattle Manure Wastewater by Tubular Ultrafiltration Membrane

A resurgent interest in anaerobic treatment of organic wastes intrigues the subsequent wastewater purification and nutrient recovery. This study investigated the feasibility of tubular ultrafiltration to treat anaerobically digested wastewater (AnDW) in the pilot-scale. Due to the gel-layer filtration mechanism, which primarily governed the AnDW wastewater passing through the membrane module, the change of operating pressure in the experimental conditions showed a minor effect on the permeate flux, while the cross-flow tangential velocity showed a significant effect on the permeate flux. A permeate flux on average of 22 l m−2 h−1 was obtained when the feed superficial-velocity was up to 2 m s−1. The permeate flux decreased with increasing suspended solid concentration, implying a potential advantage of preliminary solid-liquid separation such as mechanical centrifugation. Irrespective of the arranged order of the sequential cleaning, the fouled membrane can be successfully cleaned using specific cleaning agents, which included a weak acid, a detergent, and an oxidant, respectively. A commercial detergent, namely KLD II, exhibited the greatest contribution to the flux recovery during the sequential cleaning.

Potential Sequential Exposures to 2-Butoxyethanol After Use of a Hard-Surface Cleaner

ABSTRACT Professional workers and consumers frequently use hard-surface cleaning products and these products may contain glycol ethers (GEs), such as 2-Butoxyethanol (2-BE). Governmental agencies have set exposure limits for some chemicals used in cleaning products and these exposure limits have been used as guides to protect human health. The study objectives were to determine realistic inhalation exposures for professional workers performing multiple, sequential cleaning tasks and compare the exposures to the acute reference exposure level (REL), which California established for 2-BE. The ConsExpo model was acceptable for evaluating exposure based on a comparison of its predictions to experimentally measured 2-BE vapor concentrations from hard-surface cleaning. The typical worker exposure was predicted for a cleaning scenario consisting of three bathrooms and three kitchens (or three bedrooms) in a 1-h period. This exposure scenario would not be expected to result in significant health consequences because the predicted exposure was much lower than the REL. The predicted chronic and aggregate exposures were also acceptable. This analysis identified two important variables that affect inhalation exposure: cleaners should be used with adequate ventilation and wet wiping towels should be properly disposed so that they are not a source of continuing exposure.

Short- and long-term fouling characteristics of reverse osmosis membrane at full scale leachate treatment plant

This research is focused on characterizing the foulants on a reverse osmosis (RO) membrane taken from a full-scale leachate treatment plant in Thailand. The system consists of a physico-chemical pre-treatment unit and RO system and has been in operation for 2 years. Ferric chloride (FeCl(3)) was added to the open-jet sedimentation tank at 2.0-2.5 g/l dosage for chemical coagulation. The supernatant from the sedimentation tank was polished using a pressurized sand filter prior to entering the RO system. The RO unit consists of seven pressurized vessels and 42 membrane elements (6 elements in each vessel). The recovery ratio and operating pressure in the RO system were maintained at 50% and 1.5-2.5 MPa. Fouled membranes obtained from short-term (6 months) and long-term operation (2 years) were taken from the system and analyzed by autopsy and sequential cleaning methods. The analysis of foulants on the membrane surfaces revealed that Fe deposits at 3.11 g/m(2). For short-term operated membranes, water cleaning could recover 32.14 and 7.45% of initial pure water flux on the 1st and 6th membrane elements. NaOH cleaning, however, recovered more than 90% of initial flux, much higher than that of HCl solution in both elements. For long-term operated membranes, pure water flux recovery was below 5% for both 1st and 6th elements. Sequential cleaning by NaOH followed by HCl yielded the best results. Nevertheless, flux recovery through sequential cleaning of long-term operated membranes was only 35.3 and 19.1% for the 1st and the 6th elements, respectively.

A Successful Salvage Protocol for Breast Implants

Sir: Breast augmentation is the most common procedure in cosmetic surgery. For many years, the presence of infection in the setting of breast prostheses has necessitated implant removal and delayed reinsertion.1–5 Although successful salvage of prostheses in the presence of periprosthetic infections has been reported before, it is not a generally accepted practice. We review our experience with implant salvage in patients with periprosthetic infections following cosmetic breast surgery with implants for a 1-year period. The protocol included a “sequential cleaning,” an implant replacement, and prolonged postoperative antibiotics. Six patients, all with silicone cohesive gel prostheses, underwent implant salvage. Patients with periprosthetic infections were submitted to this protocol if they manifested the following criteria: clinical infection symptoms, no sign of sepsis (clinical and/or laboratorial), and implant exposure less than 48 hours. The risks involved in saving the implant were systematically clarified to the patients, as the procedure could be successful or not. Wound swabs from the pocket were sent for culture and sensitivity testing. The implant was removed. The sequential cleaning steps were as follows: The cavity of the capsule was scrubbed with chlorhexidine gluconate 2% scrub, and an abdominal swab wet with chlorhexidine alcohol 0.5% solution was left in the pocket for 5 minutes. The cavity of the capsule was scrubbed with abdominal swabs full of half-strength hydrogen peroxide, and an abdominal swab wet with half-strength hydrogen peroxide was left in the pocket for 5 minutes. The cavity was then irrigated with copious amounts of normal saline, approximately 2 liters. The cavity of the capsule was scrubbed with povidone-iodine surgical scrubs, an abdominal swab wet with povidone-iodine was left in the pocket for 5 minutes, and then a drain was positioned. Subsequently, a new implant was placed in the pocket and the scar was closed in four layers with nonabsorbable sutures. A solution consisting of 1.5 g of cefuroxime diluted with 18 ml of saline plus 80 mg of gentamicin (2-ml ampule) plus 40 ml of povidone-iodine was given through the drain. The drain was kept closed for 4 hours. Postoperatively, patients received intravenous antibiotics, 1.5 g cefuroxime (three times per day) plus gentamicin 120 mg (one dose) for 24 hours. Patients were discharged from the hospital without drains and with oral ciprofloxacin 500 mg (three times per day) for up to 10 days. The antibiotics should be adjusted according to the antibiogram result. The patients were followed closely for 8 months. Five of the patients had periprosthetic infections following simple primary breast enlargement, and one was associated with a mastopexy procedure. Of these six patients, Pseudomonas aeruginosa was isolated in one, Staphylococcus aureus was isolated in three, and mixed flora was isolated in two. All patients managed to keep their implants and, at more than 1-year follow-up, there were no signs of rejection or capsular contracture in any of the patients. DISCLOSURE The authors have no financial interest to declare in relation to the content of this article. Marcos Sforza, M.D. Dolan Park Hospital Bromsgrove, United Kingdom Katarina Andjelkov, M.D., Ph.D. University of Belgrade Belgrade, Serbia Renato Zaccheddu, M.D. Dolan Park Hospital Bromsgrove, United Kingdom

A New Approach to Assess the Retention of Allergen (Der f 1 and Der p 1) on Anionic and Nonanionic Cotton Bedding Sheets After a Vigorous Sequential Cleaning Regime as Assessed by ELISA

Anionic surfaces can interact with a variety of biological molecules and when used on bedding material may have the potential of binding with and sequestering protein allergens such as those produced by dust mites. However, no method exists to evaluate the efficacy of this claim. The purpose of this study was to develop a method using enzyme-linked immunosorbent assay (ELISA) to evaluate the capability of anionic treated cotton bedding sheet material to retain medically important dust mite allergens in direct comparison with nonanionic cotton bedding sheet material from a single manufacturer. Anionic, and nonanionic cotton bedding sheets were challenged singularly with water suspended pulverized dust mite Dermatophagoides farinae, water suspended pulverized dust mite D. pteronyssinus, or water alone as a negative control. All dried inoculums were subjected to four sequential extraction series using water in the first two separate extractions and water with surfactant in the last two separate extractions. All four extractions were assessed by ELISA using monoclonal antibodies specific for medically important protein allergens Der f 1 (D. farinae) or Der p 1 (D. pteronyssinus), respectively. There were a total of 25 replicates for each assessment. Our findings demonstrate that nearly all of the Der f 1 and Der p 1 was released from the nonanionic fabric after the first water extraction. Conversely, most of the Der f 1 and Der p 1 allergens were retained by the anionic fabric after both water extractions and was released only after surfactant was used. Our data indicated that &gt;80% of Der f 1 and Der p 1 was released from the nonanionic fabric after the initial two water extractions while 80% of Der f 1 and Der p 1 was retained by anionic fabric after the same extractions. The method proved to be robust and data was reproducible. Protein extraction using less stringent to high stringent conditions demonstrated the effectiveness of anionic fabric in retaining dust mite proteins that cause allergy. This method can be used to assess other materials while allergists should consider the use of anionic bedding as it effectively retained dust mite allergens Der f 1 and Der p 1 until laundering can remove them from the household.

A Cleaning Process for Fine Particles of Silicon Nitride

Fundamental phenomena affecting the cleaning process have been studied for particles, where p-type Czochralski silicon wafers are used. The removal ratio of particles is by the conventional mixed cleaning process, which employs =1:2:50 (APM) with 9.2. Most particles are firmly reattached to the surface after the etching is finished because particles are attractive to the surface. When higher ultrasonic power is applied for removal of particles, peeling occurs at a high ratio in wide patterns. However, a higher removal ratio can be attained by utilizing a sequential cleaning process. After etching of the surface in APM, removal of floating particles is performed in highly alkaline media without including APM. Because higher repulsive forces are formed in this highly alkaline media, the removal ratio increases to 0.93 at ultrasonic powers of . Peeling is not a serious problem at this power.

Effect of abrasives on the glossiness and reflectance of anodized aluminum alloys

Blasting can eliminate or change the surface texture of as-rolled aluminum alloy by indentation to roughen the alloy’s surface. We investigated the effects of the blasting conditions on the glossiness and reflectance of Al1050-H16 and Al5052-H32 alloys in this study. As-rolled sheets were blasted at various pressures, and then removed for sequential cleaning, chemical polishing, and anodizing steps. After each step the samples were measured by micro-TRI-gloss meter and spectrophotometer to compare the effects produced by the abrasive powders and processing variables. Polyhedral alumina and round iron powders were used as the blasting media. The glossiness (Gs(60°)) decreased as the root mean square roughness (Rq) increased, regardless of the shape of the abrasive powders. The abrasives powders could cause wear and/or fracturing during the blasting process as well as fine debris, which could become embedded in the blasted surface. When an aluminum alloy was blasted with iron powders, the glossiness value after alkaline etching and chemical polishing was greater than that after being blasted with alumina; while the anodized Al5052-H32 alloy’s surface became more yellowish in color.

A comparative evaluation of the cleaning efficacy of three different agents on rotary nickel-titanium endodontic instruments- An in-vitro study

Cleaning of endodontic instruments is important to prevent cross contamination between patients and facilitate sterilization, thus achieving the goal of three dimensional obturation. The aim of this study was to develop an effective cleaning procedure for rotary Ni-Ti instruments. New sterilized Ni-Ti rotary instruments were contaminated by preparing canals of extracted teeth and subjected to both mechanical and chemical cleaning procedures followed by placing in an ultrasonic bath. This study showed that a sequential cleaning procedure including combined mechanical and chemical removal with 2% glutaraldchyde followed by ultrasonic bath is an effective procedure of removing debris from rotary Ni- Ti instruments.

Chemical Cleaning of Microfiltration Membranes Fouled by Whey

AbstractMillipore hydrophobic polyvinylidene fluoride (PVDF) microfiltration membranes were used for whey processing. Fouled membranes were cleaned with acid (HCl), alkaline (NaOH) and surfactant (Triton‐X100). The latter resulted in maximum flux recovery and resistance removal. Hydrochloric acid had a moderate effect and sodium hydroxide was the weakest cleaning agent. This is due to the cleaning strength of emulsifiers compared to acid or alkali. However acids are more efficient than alkaline solutions for removal of mineral compounds which remain on the membrane surface.Cleaning efficiency depends on the concentration of cleaning agent being higher for higher surfactant concentration. For acids and alkali, the efficiency increases with increasing the concentration of the reagent reaches a maximum (optimum concentration) and then decreases. This can be explained by changes in permeability of the deposit layer with the concentration of the cleaning agent. Another explanation is the breakage of proteins by acid or alkali which produces more fouling materials and causes less cleaning efficiency.Operating conditions affect the cleaning process. At higher stirring speeds (turbulent flow) or longer cleaning time better removal of deposits and higher cleaning efficiency were observed. The sequential cleaning process may or may not improve the cleaning efficiency. When acidic cleaning was followed by washing with a surfactant an improvement was achieved. This can be attributed to the incomplete removal of deposits by acid. However further cleaning with acid can not improve the cleaning efficiency.During whey processing fouling occurs by deposition of foulants of mostly proteins and macromolecules on the membrane surface or in the membrane matrix. Large substances (compared to the membrane pores) settle on the membrane surface and the small species penetrate and are adsorbed in the membrane pores. Cleaning dissolves and removes the adsorbed foulants from the membrane.

Surface Analysis of Bearing Steels After Solvent Treatments. II: Lubricant-Coated Bearing Surfaces

The performance of miniature instrument bearings in aircraft and marine guidance system is adversely affected by the presence of trace contaminants on the contacting surfaces. Effective cleaning of such bearings prior to assembly in these critical system is, therefore, of utmost importance. The authors' previous study critically examined the specific effects of the various current Navy solvent-cleaning procedures on specially cleaned bearing steel reference surfaces. In the present study, reference surfaces of 440C bearing steels were coated with very thin films of either a formulated synthetic hydrocarbon or a formulated polyol ester instrument lubricant and characterized by wettability, Auger electron and X-ray photoelectron spectroscopies. These coated surfaces were subjected to standard sequential cleaning procedures as well as to individual solvents at two Navy facilities, and then reanalyzed by the same methods, including Fourier transform infrared spectroscopy. Results are discussed in terms of cle...