A prototype for on-site generation of chlorinated disinfectant for use in rural aqueducts

Sodium hypochlorite has significant potential as a sanitation solution in hard-to-reach areas.Few studies have investigated the optimal electrolysis parameters for its production with volumes greater than 1o L.This study evaluated sodium hypochlorite production through electrolysis in a 22-L prototype and identified the optimal operating parameters.Tests were performed using graphite electrodes with areas of 68.4 cm^(2) at the laboratory scale and 1865.0 cm^(2) at the prototype scale.A design for experiments with different operating times,chloride concentrations,and electric current intensities was developed.The optimal operating time,sodium chloride concentration,and current intensity at the laboratory scale were 120 min,150 g of chloride per liter,and 3 A,respectively,leading to the production of 5.02 g/L of the disinfectant with an energy efficiency of 12.21 mg of Cl_(2) per kilojoule.At the prototype scale,the maximum sodium hypochlorite concentration of 3.99 g of chloride per liter was achieved with an operating time of 120 min,a sodium chloride concentration of 100 g of chloride per liter,and a current intensity of 70 A,reaching an energy efficiency of 42.56 mg of Cl_(2) per kilojoule.In addition,this study evaluated the influences of the chloride concentration,current intensity,and operating time on the production of sodium hypochlorite at the two scales,and formulated the equations showing the trends of sodium hypochlorite production and energy efficiency in the electrochemical systems.The 22-L prototype model for production of this oxidizing substance is promising for disinfection of large volumes of water in areas that are difficult to access.

Effects of Penicillium spp. and Trichoderma spp.on Pleurotus ostreatus Growth and Screening of Effective Disinfectants

[Objective] This study was conducted to investigate the effects of Penicillium spp. and Trichoderma spp. on the growth of Pleurotus ostreatus （oyster mushroom） and to screen effective disinfectants to control them and other pathogenic microbes. [Method] Six strains or species of Penicilliurn and Trichoderma were inocu- lated into PDA plates growing with P. ostreatus to observe the growth of their mycelia. And the inhibitory effects of hydrogen peroxide, bromogeramine bromide, 84 disinfectant, lysol, potassium permanganate, and 75% medical alcohol on Trichoderma pleuroticola, Trichoderma viride, Trichoderma harzianum, Penicillium citrinum, Penicillium thomii and Penicillium brevicompactum were detected. [Result] Confrontation test revealed that Penicillium spp. and Trichoderma spp. competed for nutrients with P. ostreatus mycelia, antagonized against the growth of P. ostreatus mycelia, invaded and twined around P. ostreatus mycelia, and also produced toxins poisoning P. ostreatus mycelia. The six disinfectants exhibited different inhibitory effects against different species of Penicillium and Trichoderma. Among them the in- hibitory effects of bromogeramine bromide against the six species of Penicillium and Trichoderma were significantly different. However, the inhibitory effects of 3% hydrogen peroxide, 84 disinfectant, 5% lysol, potassium permanganate and 75% medical alcohol were significantly different among Penicillium spp., but did not among Tri- choderma spp. [Conclusion] Bromogeramine bromide can be used to control the bacteria and fungi in mushroom production for it has significant inhibitory effects on the six species of both Penicillium and Trichoderma.

A Preliminary Study on Intensive Curing with Alcohol-based Fuels

The research investigated application effects of alcohol-based fuels in in- tensive curing. The results showed that alcohol-based fuels allow flexible adjustment of temperature and heat supplying. What＇s more, in treatment A, the cured tobac- cos are softer and brighter, with more oil content and higher proportion of first-class tobaccos. Per leaf weight increased by 0.13 g and output value per kang （a heat- able brick bed） deducting energy cost grew by 188.66 yuan. In addition, the con- tents of reducing sugar and potassium enhanced within the ranges of high-quality tobacco, and chemical components are more coordinated.

Is the Potential Interconnection between Antibiotic Susceptibility and Disinfectant Resistance a Threat to Food Safety?

The prevalence of antibiotic susceptibility and disinfectant resistance in bacterial pathogens causes a serious problem not only to food safety but also to public health, which directly or indirectly leads to treatment and disinfection failures. In this review, multidrug resistance, the mechanism of disinfectant resistance, the methods for detecting disinfectant resistance and the cross-resistance between an- tibiotics and disinfectants are summarized. More efforts should be devoted to explor- ing the professional guidance of using antibiotics and disinfectants, and to develop- ing the comprehensive detection with genetic and molecular methods is highly ex- pected.

Preparation and Evaluation of Novel Solid Chlorine Dioxide-based Disinfectant Powder in Single-pack

Objective To prepare and evaluate novel chlorine dioxide-based disinfectant powder in single-pack that is more convenient for use and transportation. Methods Orthogonal experiment was performed to determine the recipe of the disinfectant powder. Stability test, suspension quantitative bactericidal test, simulation field triM, and animal toxicity test were carded out to observe its bactericidal and toxicological effects. Results The orthogonal experiment showed that the type of water solution had no effect on the disinfectant powder and the best ratio of sodium chlorite to solid acid was 1：3. Ten grams of the disinfectant powder was fully dissolved in 20 mL water for 2 min, and diluted to 500 mL in water. After 5-10 min, the concentration of chlorine dioxide （CIO2） solution was 266 mg/L to 276 mg/L. After stored at 54℃ for 14 d, the average concentration of CIO2 was decreased by 5.03%. Suspension quantitative bactericidal test showed that the average killing logarithm （KL） value for both Staphylococcus aureus and Escherichia coli in 100 mg/L CIO2 solution for 2 min was over 5.00. In simulation field triM, the average descending KL value for Escherichia coli in the solution containing 100 mg/L CIO2 for 5 min was over 3.00. The mouse acute LD50 in the solution 5 times exceeded 5000 mg/kg. The disinfectant powder was not toxic and irritative to rabbit skin and had no mutagenic effect on mouse marrow polychromatic erythrocytes （PCE）. Conclusion The stability and bactericidal efficacy of solid chlorine dioxide-based disinfectant powder in single-pack are good. The solution containing 100 mg/L CIO2 can kill vegetative forms of bacteria. The concentration of CIO2 on the disinfecting surface of objects is 100 mg/L. The disinfectant powder is not toxic and irritative.

Enhanced Disinfection Effect of a Compound Disinfectant against Bovine Herpes Virus Type 1 at Low Temperature

A compound disinfectant, which consisted of didecyldimethylammonium chloride (DDAC), ortho-dichlorobenzene (1,2-dichlorobenzene, ODB), and chlorocresol (4-chloro-3-methylphenol, CC), and its component chemicals were individually tested for effectiveness against bovine herpes virus type 1 (BHV-1). DDAC, DDAC+ODB, DDAC+CC, and DDAC+ODB+CC showed effectiveness against BHV-1 at room temperature. However, ODB, CC, and ODB+CC showed no virucidal effects. The effects of all disinfectants tested were decreased at low temperature. DDAC showed disinfectant effects at a dilution of 1/800 and DDAC+ODB, DDAC+CC, and DDAC+ODB+CC at dilutions of 1/800 and 1/1600 at low temperature in the presence of 2% fetal bovine serum (FBS) but ODB, CC, and ODB+CC showed no virucidal effects. At low temperature and in the presence of 10% FBS, DDAC, DDAC+ODB, and DDAC+CC showed disinfectant effects at dilutions of 1/800, whereas ODB, CC, and ODB+CC showed no virucidal effects. DDAC+ ODB+CC was more effective (at 1/800 and 1/1600) than the other disinfectants under these conditions. In conclusion, a combination of three disinfectant components (DDAC+ODB+CC), enhanced the disinfectant effects at low temperature and in organic matter contamination.

Flashlight contamination and effectiveness of two disinfectants in a stomatology hospital

Aim: This study aims to assess the infection risks of flashlight contamination in a stomatology hospital and compare the disinfection effectiveness of alcohol (75%) and disinfecting wipes.Background: The flashlight is a basic non-critical medical device in oral and maxillofacial surgery wards. Wounds are mostly found in oral cavities;therefore, reusable flashlights may be a potential source of nosocomial infections (NIs). However, the microbial flora present in flashlights used in hospitals has not yet been explored. Methods: This study investigated the microbial contamination of 41 flashlights used in a stomatology hospital in Guangzhou in March 2016. Results: Results indicated that 75.6%(31/41) of the flashlights had microbial contamination. Gram-positive bacteria accounted for 72.7%(24/33)of the microbial groups contaminating the flashlights, and Gram-negative bacteria (21.2%, 7/33), and fungi (6.1%, 2/33) constituted the remaining contaminants. The predominantly isolated species was Staphyloccus (66.7%, 22/33), especially Staphylococcus aureus (24.2%, 8/33). Approximately 77.3%(17/22) of the types of bacteria detected in the hands were same as those in the corresponding flashlights. Both the bacterial overstandard and S. aureus detection rates of doctors' flashlights were higher than those of nurses' flashlights (16/17 vs. 14/23, 7/17 vs. 1/23, respectively) (P < 0.05). Moreover, both disinfectants performed excellently, and their eligibility rates were not significantly different (17/17 vs. 14/14) (P>0.05). Conclusion: Flashlights are potential causes of NIs. Disinfecting flashlights could be an effective and practical infection control method.

INFLUENCE OF ALCOHOL-BASED NONSOLVENTS ON THE FORMATION AND MORPHOLOGY OF PVDF MEMBRANES IN PHASE INVERSION PROCESS

Through the preparation of PVDF membranes using various nonsolvent coagulation baths following the phase inversion process, the influence of alcohol-based nonsolvents on the formation and structure of PVDF membranes were investigated. The light scattering and light transmission measurements were used to characterize the equilibrium phase diagram and the gelation speed, respectively. The locations of the crystallization-induced gelation boundaries for various systems and precipitation processes were explained from the corresponding thermodynamic and kinetic parameters. It was found that the better affinity between alcohol-based nonsolvents and DMAc solvent caused the gelation boundaries further away from the PVDF-DMAc axis with the coagulation bath varying from water, methanol, ethanol to iso-propanol. Due to the lower exchange rate of DMAc and alcohols, the delayed demixing took place for the membrane-forming using alcohols as baths, and the delayed time became longer when the coagulation bath was changed from methanol, ethanol to iso-propanol. The characterization results of membranes indicate that the influence of nonsolvents on the phase diagram and the precipitation process are in agreement with those on the membrane morphology. The better thermodynamic stability and a low exchange diffusion rate of PVDF/DMAc/alcohols favor the liquid-solid phase separation in gelation process, and therefore yield the membranes with a porous upper surface, a particular bottom surface and symmetrical structure.

Study on a new nano-dispersing agent and its effect for increasing suspension ability of alcohol-based coatings

A study for further improving the suspension rate of alcohol-based coatings using a new nano-dispersing agent has been presented in this paper. The results of experiments show that the new nano-dispersing agent should be used in combination with organic auxiliary agent which significantly increases the suspension effect of alcohol-based coatings. By the methods, the suspension rates of 99%, 98%, 96% and 94% can be achieved at 2h, 2h, 48h and 72h, respectively. These alcohol-based coatings have characters of higher strength, lower gas evolution, better brush ability and no blister after ignition.

Chlorine poisoning caused by improper mixing of household disinfectants during the COVID-19 pandemic:Case series

BACKGROUND Misuse of disinfectants during the coronavirus disease 2019 pandemic has led to several poisoning incidents.However,there are few clinical case reports on poisoning caused by improper mixing of household disinfectants.AIM To summarize the clinical characteristics and treatment effects of chlorine poisoning caused by improper mixing of hypochlorite bleach with acidic cleaning agents.METHODS We retrospectively analyzed baseline and clinical data,clinical symptoms,and treatment methods of seven patients with chlorine poisoning who were admitted to the National Army Poisoning Treatment Center.RESULTS Among the seven patients,the average poisoning time(exposure to admission)was 57 h(4-240 h).All patients were involved in cleaning bathrooms.Chest computed tomography scans revealed bilateral lung effusions or inflammatory changes in five patients.The partial pressure of oxygen decreased in six patients,and respiratory failure occurred in one.Five patients had different degrees of increase in white blood cell count.Humidified oxygen therapy,non-invasive mechanical ventilation,anti-inflammatory corticosteroids,antioxidants,and antibiotics were administered for treatment.The average length of hospital stay was 7 d(4-9 d).All seven patients recovered and were discharged.CONCLUSION Improper mixing of household disinfectants may cause damage to the respiratory system due to chlorine poisoning.Corticosteroids may improve lung exudation in severe cases,and symptomatic supportive treatment should be performed early.

A Moringa Oleifera Disinfectant-Sand Filter Integration： A Review of an Alternative Sustainable Technology for Household Water Treatment

This review provides an insight and up-to-date information on the application of Moringa oleifera seeds, the short falls of existing technologies as a coagulant and disinfectant in domestic water treatment. While the coagulant properties are well reported, the disinfectant properties are not well studied. Literatures on low cost alternative technologies such as the application of hiocoagulants and slow sand filters are extensively reported. However, there is limited work addressing the limitations of these technologies that have restricted its widespread use to solve the global soaring water crises. Slow sand filters have a very slow filtration rate that depends on the biofilm layer which takes about 17 days to form. Moringa oleifera treated water cannot last more than 48 hours without bacteria regrowth. Investigation of the best method of isolating coagulant component continues with differing opinions over the nature of its coagulant ingredient not resolved in ongoing literature. An attempt was made in this paper to highlight the advantages of a Moringa disinfectant sand filter hybrid system that can purify water. Microbiological advantages of this system in providing a 100% removal of pathogens, and engineering considerations such as water treatment within an hour residence time, faster flow rates, less clogging and backwashing could be some of the advantages ofa Moringa sand filter system. The need to focus on integrating Moringa and sand filter systems for more practical applications is recommended.

Effects of some common additives on the antimicrobial activities of alcohol-based hand sanitizers

Objective: To study the effects of some common additives on the antimicrobial activities of alcohol-based hand sanitizers. Methods: The antibacterial activities of varying aqueous concentrations of ethanol and isopropyl alcohol were tested by the agar well diffusion method. The influences of different concentrations of glycerin was similarly tested. Finally, isopropyl alcohol and benzalkonium chloride were combined in different ratios within the sate use concentrations of each, and the effects of these combinations were compared with values obtained for the two agents used alone. Statistical methods, such as student t test and one-way ANOVA were used when appropriate to evaluate the differences in activity. Results: The activities of the alcohols showed marked concentration dependence, and both showed peak activity at 85%-95% concentration range. Over the concentration range of 60%-100%, isopropyl alcohol inhibited more bacterial and fungal organisms than ethanol, though the inhibition zone diameters it produced were not statistically different from those of ethanol for organisms which were sensitive to both of them.Addition of glycerin reduced the antimicrobial activities of the isopropyl alcohol, as shown by reduction in the inhibition zone diameters produced in vitro, which may be due to reduced drug diffusion with increase in viscosity. Addition of benzalkonium to isopropyl alcohol systems improved the activity of the alcohol, but the overall activity of the combination was not superior to that seen in the use of benzalkonium alone. Conclusion: Alcohol-based hand sanitizers should not be used outside the concentration range of 85%-95% and isopropyl alcohol inhibits more bacterial and fungal organisms than ethanol for most concentrations. Inclusion of benzalkonium improves the antimicrobial spectrum and activity of isopropyl alcohol, and the combination may justifiably be used to achieve both immediate and long lasting effect. Glycerin may adversely affect the antimicrobial activities of isopropyl alcohol-based hand sanitizers and should be used with caution.

Testing the Efficiency of Acacia Bark (Galool-Asal) as Disinfectant for Polluted Waters

Acacia bark efficiency for disinfecting polluted water for the purpose of using it for drinking purposes was tested. Five polluted water samples were collected from different locations in Jordan, namely, King Abdullah Canal, an Agricultural pond in the Jordan Valley, Yajouz wells, Hazeir spring, and Wadi-Seer spring. Different volumes of the water samples were treated with 10 g of the shredded acacia bark (obtained from Somalia) for different retention times. The volumes used were 1 L, 2.5 L, and 5 L and the detention times were 2, 4, and 24 hours. The samples were tested for total coliform, E. coli, electrical conductivity, pH, total dissolved solids, turbidity and color before and after treatment with the acacia bark. Results revealed that the optimum conditions for disinfection were: 1 L polluted water treated with 10 g acacia bark for 24 hours. Log removals of about 2.5 for E. coli were obtained under these conditions. Higher removals could be achieved by using larger amounts of the acacia bark, but the chemical water quality regarding turbidity and color will not be suitable for drinking purposes and levels of tannic acids present in the acacia bark might reach toxic levels. Toxic levels will not be reached if 1 glass of water/kg body weight every 4 - 5 hours daily is consumed.

Effect of Disinfectants on Elastic Modulus, Flexural Strength and Color Stability of Denture Base Resins

Objective: Infection control protocols dictate the disinfection of dentures. There are no products available which are designed for the specific use of disinfecting dentures. The objective of this study was to investigate the impact of chemical disinfectants on elastic modulus, flexural strength and color stability of denture base resins. Methods: 256 specimens from four acrylic denture base resins were manufactured. Two cold-curing denture base resins: PalaXpress (Heraeus Kulzer, Hanau, Germany), Futura Gen (Schuetz Dental, Ro&szlig;bach, Germany) and two heat-curing denture base resins: Paladon 65 (Heraeus Kulzer, Hanau, Germany), FuturAcryl 2000 (Schuetz Dental, Ro&szlig;bach, Germany) were used. Three chemical disinfecting agents were tested: Impresept, D050 Instru-Gen, Stammopur DR. Specimens were stored in distilled water and in chemical disinfecting agents. They were divided randomly into groups. E-Modulus and flexural strength were measured using the three-point bending test. Color changes (ΔE) were determined spectrophotometrically. Results: The disinfection agents showed no significant influence on the E-modulus compared to distilled water (Acrylic vs. distilled water from (Futura Gen) 2688.80 ± 230.78 vs. 2766.60 ± 91.22 MPa to (PalaXpress) 3004.20 ± 26.40 vs. 2851.00 ± 95.23 MPa). Flexural strength after storage in distilled water and disinfection did not differ significantly (Acrylic vs. distilled water from (Paladon65) 27.28 ± 1.30 vs. 28.42 ± 0.84 N/mm2, (p > 0.05) to (PalaXpress) 30.88 ± 0.25 vs. 29.68 ± 0.79 N/mm2, p < 0.001). Disinfection caused a significant color change with Impresept of Paladon 65 (p ≤ 0.001), FuturaAcryl 2000 with Stammopur DR and D 050 Instru-Gen (p ≤ 0.001). Conclusions: The investigated disinfection agents did not influence elastic modulus and flexural strength of denture base resins negatively. ΔE-values were in a range of 1 to 2. Thus, the detected color changes may be marginal. Clinical relevance: Single use disinfections are feasible for acrylic dentures regarding to elastic modulus and flexural strength.

Studies of non-metallic organic disinfectants on inactivation of avian influenza viruses

Six different kinds of non-metallic or organic disinfectants were obtained in this research study including “Neutral Electrolyzed Water”, “M22” organic disinfectant solution, Superoxy Food Wash disinfectant, Hydrogen Peroxide, Clorox Germicidal Bleach and Clidox-S. The effectiveness of these disinfectants was studied against various subtypes of avian influenza virus (AIV). The virus-disinfectant mixtures were prepared in serial dilutions of each disinfectant with a constant virus titer and incubated at ambient temperature in different time intervals for virus inactivation. The virus inactivation results were determined by virus recovery in embryonating chicken eggs. Among the six different kinds of nonmetallic disinfectants obtained for this research project, Neutral Electrolyzed Water, “M22” solution, Clorox Germicidal Bleach and Clidox-S were effectively inactivated AIV with appropriate working dilutions and reaction times. Superoxy Food Wash disinfectant and Hydrogen Peroxide were found having limited effect on virus inactivation with extended exposure times of more than 2 hours. These research findings provide scientific data to poultry industry with guidelines to select and use non-metallic organic disinfectants for poultry flock sanitation and disinfection to effectively prevent and control of avian influenza outbreaks.

Disinfectant for Urinary Infection Caused by <i>Escherichia coli</i>by Using Natural Oils

According to the WHO analysis, antibacterial treatment which is preferred for treating peptic ulcers and oral health problems are considered as a major improvement in the treatment but are responsible for several health problems that include vomiting, diarrhea and the increase in the bacterial resistance is a major concern. So, there is an urgent need for a good therapeutic alternative which is effective. Usage of essential oils to treat different ailments is found to be extremely effective with no side effects. Thus, essential oils are gaining importance in treatments due to their antibacterial, antifungal, antiprotozoal properties. Essential oils are also used as aroma therapeutic agents. They are complex mixture of low molecular weight compounds that include terpenoids, phenylpropanoids, oxygenated derivatives (aldehydes, ketones, alcohols, esters) which greatly differ in composition in different essential oils are the major components present. The bioactive properties and their medical potential are widely used in pharmaceutical industries. In this study, we use these essential oils to prepare a disinfectant and analyze the antimicrobial properties using the agar diffusion method. Our major concern in this study is to decrease the growth of Escherichia coli which causes urinary infection, by using disinfectant prepared using a mixture of essential oils of particular concentration.

On-Site Assessment of a Cryogenic Disinfectant for the Alpine Environment and Outer Packaging of Frozen Items

Objective To study the effectiveness and feasibility of cryogenic disinfectants in different cold scenarios and analyze the key points of on-site cryogenic disinfection.Methods Qingdao and Suifenhe were selected as application sites for the manual or mechanical spraying of cryogenic disinfectants.The same amount of disinfectant(3,000 mg/L)was applied on cold chain food packaging,cold chain containers,transport vehicles,alpine environments,and article surfaces.The killing log value of the cryogenic disinfectant against the indicator microorganisms(Staphylococcus aureus and Escherichia coli)was used to evaluate the on-site disinfection effect.Results When using 3,000 mg/L with an action time of 10 min on the ground in alpine regions,the surface of frozen items,cold-chain containers,and cold chain food packaging in supermarkets,all external surfaces were successfully disinfected,with a pass rate of 100%.The disinfection pass rates for cold chain food packaging and cold chain transport vehicles of centralized supervised warehouses and food processing enterprises were 12.5%(15/120),81.67%(49/60),and 93.33%(14/15),respectively;yet,the surfaces were not fully sprayed.Conclusion Cryogenic disinfectants are effective in disinfecting alpine environments and the outer packaging of frozen items.The application of cryogenic disinfectants should be regulated to ensure that they cover all surfaces of the disinfected object,thus ensuring effective cryogenic disinfection.

A comparative effect of 3 disinfectants on heterotrophic bacteria, iron bacteria and sulfate-reducing bacteria

The disinfection effect of chlorine dioxide, chlorine and their mixture on heterotrophic bacteria, iron bacteria and sulfate-reducing bacteria in circulating cooling water was studied. The results of the test indicated that high purity chlorine dioxide was the most effective biocide in the 3 disinfectants, and with a dosage of 0.5 mg/L, chlorine dioxide could obtain perfect effect. High purity chloride dioxide could have the excellent effect with the pH value of 6 to 10, and could keep it within 72 h. Chlorine and their mixture couldn’t reach the effect of chlorine dioxide.

Experimental study on disinfection effect of different dose of rapid hand disinfectant

Purpose:To investigate the appropriate antiseptic handrubbing method.Methods:Seventy-four clinical nurses were randomly divided into two groups based on the number of disinfectant presses used,with group 1 using one-press and group 2 using twopresses.Sterilizing effects as a function of presses were compared and analyzed between the two groups.Results:Prior to hand disinfection,the hand sampling region resulted in 72 colony forming units for the 74 nurses.Following disinfection,only 2 colony forming units(p<0.001)were found.The analysis of drying time effects on the disinfection rate between the two groups showed a significant difference(p?0.049).Conclusion:In an effort to reduce the incidence of nosocomial infection,the medical personnel should sufficiently dry hands following handrubbing with disinfectant in a strict accordance with the six part washing technique for antiseptic handrubbing.

Corrosion Behaviors of Disinfectants on Dental Unit Waterlines

To investigate the corrosion behaviors and antibacterial effects of sodium hypochlorite(NaClO)and hydrogen peroxide silver ion(HPSI)disinfectants with different concentrations against dental unit waterlines and provide guidance and reference for the use of chemical disinfectants,polyurethane tubes were immersed in ultrapure water(control group),0.1%NaClO,0.5%NaClO,1.0%NaClO,2.5%HPSI,5.0%HPSI,and 10%HPSI solutions for 6,12,and 18 weeks.Contact angles and Fourier transform infrared spectra were detected.Surface morphologies were observed using scanning electron microscopy and antibacterial activity was evaluated using Gram-positive Staphylococcus aureus(S.aureus).The results showed that sodium hypochlorite and hydrogen peroxide silver ion disinfectants presented good antibacterial activity against S.aureus.However,sodium hypochlorite could cause serious damage to the water pipes where corrosion pits and cracks were observed,and increasing the concentration of sodium hypochlorite could accelerate the corrosion process.Hydrogen peroxide silver ion disinfectants had no obvious damage to the water pipes.Therefore,hydrogen peroxide silver ion disinfectants are recommended to use for controlling bacterial infection in dental unit waterlines which can reduce the damage to the water pipes.