Showing 13 results for Disinfection
Ar Mesdaghinia, F Vaezi, E Dehghanifard, Ah Mahvi, M Alimohammadi,
Volume 1, Issue 1 (10-2008)
Abstract
Background and Objectives: Measurement of light intensity is a recommended practice for insuring the delivery of required germicidal dose in disinfection operations by UV lamps. Use of sensitive to light chemicals which is the base of actionometeric methods could be considered as a suitable manner for estimating the intensity of UV lamp in circumstances that special radiometers are not available.
Materials and Methods: lodide-iodate mixture was used as an actinometer for this study. The light intensities of a UV lamp (LP 25W) were first determined by a special UVC radiometer at certain distances from the lamp. Then the test of determining the suitable period of time for irradiation of actinometer was accomplished. Finally، the color changes of iodide - iodate solutions at the predetermined distances were evaluated at the wavelength of 352 nm. The latter analysis can be done by a common (visible) spectrophotometer.
Results: Results indicated that use of this actinometer is more suitable at the distances of 35 to 60 cm from the center of the lamp bulb، since iodode-iodate solution has a detectable color change at this range of distance in one minute irradiation which may be considered as a reasonable time for actionmeteric operations.
Conclusion: Although all kinds of actinometers should not be regarded as precise as special radiometers and there would be need to use pure chemicals for actinometeric determination of light intensity، it can be claimed that the recommended procedure in this study which is the newest actinometeric method can be used in acceptable evaluation of UV intensity with least difficulty in providing necessary instruments.
H. Hashemi, M.m. Amin, B. Bina, H. Movahedian Attar, H. Farrokhzadeh,
Volume 3, Issue 1 (4-2010)
Abstract
Backgrounds and Objectives:Today, due to health, environmental and economical problems, of chlorine application, UV radiation is better option than chlorine for disinfection of effluent. The aim of this study was disinfection of secondary effluent with UV radiation.
Materials and Methods: Two types of UV disinfection system including low pressure (LP) and medium pressure (MP) was used to disinfection of Isfahan North Wastewater Treatment Plant (INWWTP) effluent without pretreatment. Single and combined lamps were operated to evaluate the removal of total and fecal coliforms (TC and FC), and fecal streptococcus (FS). TSS, iron, hardness, UV absorption and transmittance were analyzed in order to observe the fouling of the quartz sleeves.
Results: After using LP lamp with dose of 161 mws/cm2, TC and FC content was declined to standard level (1000 TC, and 400 FC/100ml). In addition, disinfection with MP lamp was led to FS content of 400 MPN/100 mL. Combination of LP and MP, with dose of 460 mws/cm2 could be met the environmental requirements of TC & FC, and the FS count was reached to 400 MPN/100 mL with dose of 237 mws/cm2. Maximum photo-reactivation percentage of coliforms after LP and MP lamps were appeared 15 and 3 percent respectively, while it was not observed for FS.
Conclusion: High fluctuation in secondary effluent quality of INWWTP mainly TSS concentration was caused to decline of the UVT value. Therefore, disinfection of effluent by LP, MP and even combined both systems are not applicable in conventional UV dose. Hence, using advanced process unit before UV disinfection system is necessary for removal of TSS.
A Rezaee, G Kashi, A Jonidi Jafari, A.r Khataee,
Volume 4, Issue 2 (9-2011)
Abstract
Background and objective: The conventional chemical and physical methods for water disinfection include the application of ultraviolet (UV), chlorination, and ozonation. Water disinfection by electrochemical methods has been increasingly carried out recently. The goal of this applied - analytical research is to investigate the removal of E. coli bacteria, as the index of water microbial contamination, from drinking water by electrochemistry method.
Materials and Methods: In this study, the contaminated water sample was prepared through adding 102 and 103 E. coli bacteria per ml of drinking water. The contaminated water entered into the electrochemical reactor and different conditions were studied, included pH (6, 7, and 8), number of bacterium (102 and 103 per milliliter), time (5, 10, 20, and 40 min), distance between electrodes (2,2.5, 3, and 3.5 cm), and voltage (10, 20, 30, and 40 volts).
Results: The findings indicated the indirect correlation between bacteria removal efficiency and the variable distances between two electrode. The results indicated the direct correlation between bacteria removal efficiency and the variables voltage and electrolysis times. The results showed that the best conditions for removal of 102 and 103 bacteria per milliliter obtained at pH 7, electrolysis time of 10 min, distance between electrodes 2 cm, in the voltage 20 and 30 volts, respectively.
Conclusion: The results of this study indicate that voltage and electrolysis time have the most significant effect on electrolysis efficiency. Research findings showed that electrolysis is a promising method for removal of E. coli bacterium from drinking water.
M.h Dehghani, A Zarei, A.h Mahvi, Gh.r Jahed Khaniki, E.b Kia,
Volume 4, Issue 4 (3-2012)
Abstract
Background and Objectives: Free living nematodes due to their active movement and resistance to chlorination don't remove in conventional water treatment processes thus can be entered to distribution systems and cause adverse health effects. UV irradiation can be used as a method of inactivating these organisms.
Materials and Methods: This study is done to investigate the effect of ultraviolet lamp on inactivation of free living nematode (Rhabitidae) in water. The effects of duration of irradiation, turbidity, temperature, UV dose and pH are investigated in this study. Ultraviolet lamp used in this study was a 11 watt lamp with intensity of 24 µw / cm2.
Results: Contact time required to achieve 100% efficiency for larvae nematodes and adults were 9 and 10 minutes, respectively. Increase of turbidity up to 25 NTU decreased inactivation efficiency of larvae and adult nematodes from 100% to 66% and 100% to 64%, respectively. Change in pH ranged from 6 to 9 did not affect the efficiency of inactivation. With increasing temperature inactivation rate increased.
Conclusion: The results showed that there was a significant correlation between the increase in contact time, temperature rise and turbidity reduction with inactivation efficiency of lamp)p<0.001(. Also the effect of the lamp on inactivation of larvae nematode was more than the adults.
Ramin Nabizadeh Nodehi, Hassan Aslani, Mahmood Alomohammadi, Reza Nemati, Kazem Naddafi, Maryam Ghany,
Volume 5, Issue 2 (10-2012)
Abstract
MicrosoftInternetExplorer4
Background and Objectives: Irrigation of agricultural crops using wastewater will
increase, in some cases, their growth by 40 to 60 percent. However, this has a
high risks for human health because of the presence of higher number of
pathogenic organisms. The main purpose of this study was to investigate the
feasibility use of Fenton and modified Fenton with copper for the disinfection
of raw wastewater.
Materials and Methods: After primarily laboratory physicochemical and biological analysis, the
disinfection process was performed in three different phases in each process.
First, the disinfectants were injected separately, then we performed
disinfection using Fe++ and cu++ ions combined with hydrogen peroxide in order
to determine synergistic effect of each catalyst. Direct method was used for
fecal coliforms counting.
Results: Hydrogen
peroxide maximum efficiency for inactivation of fecal coliforms was only
0.66log inactivation. Fenton and modified Fenton with copper ions showed a
remarkable effect on the bacterial inactivation so that Fenton and modified
Fenton with 1 and 2 mg/l of Cu++ inactivated coliforms by 4.73, 3.28, and 4.88
log respectively.
Conclusion: Application of HP alone for the disinfection of raw wastewater is not
practicable due to low observed efficiency. However, its combination with ions
such as Fe++ and Cu++ increases HP performance in disinfection and has a
notable synergistic effect on HP
disinfection power, where, in the presence of each catalyst, hydrogen
peroxide can reduce the fecal coliforms of raw wastewater to meet the Iranian
Environmental Protection Agency Standards.
Amir Hossein Mahvi, Noushin Rastkari, Ramin Nabizadeh Nodehi, Shahrokh Nazmara, Simin Nasseri, Mahboobeh Ghoochani,
Volume 6, Issue 3 (12-2013)
Abstract
Background and Objectives:Chlorination is the most common method of water disinfection. Chlorine reaction with natural organic compounds nor removed completely during treatment process would result in forming disinfection byproducts. Followed by trihalomethanes, Haloaceticacides are the second main byproducts of chlorination in water. The research works conducted in Iran have assessed trihalomethanes. Hence, this is the first time we are reporting haloacetic acids in Iran.
Materials and Methodology: We collected samples from surface water resources and treated water in Tehran for six consecutive months (first half, 2010). We measured temperature, pH, UV adsorption at 254 nm and TOC in each surface water sample and analyzed pH, residual chlorine, and haloacetic acids in the treated water samples.
Results: We found that TOC in surface water resources is 3.6-4.42 and 1.78-2.71 mg/l in spring and summer respectively. Moreover, haloacetic acids concentration was found to be 41.7-55.56 and 34.83-43.73 μg/l in spring and summer respectively.
Conclusion: Our results revealed that concentration of NOM, TOC, and HAAs was more in spring than summer. In addition, concentration of HAAs was depended up on NOM and TOC. Considering maximum permeable concentration of HAAs (60 μg/l) by EPA, it can be claimed that concentration of HAAs was less than the maximum permissible level in all of the samples. However, the immanency of the monitored values to the standard values can be a warning for concerned authorities in water industry.
M Sadeghi, A Charkazi, N Behnampour, A Zafarzadeh, S Garezgar, S Davoudinia, P Borgheie,
Volume 7, Issue 4 (1-2015)
Abstract
Background & Objective: Hairdressing is one of the most public places and most important from the health issues (personal and environmental) point of view. In such places, non-observance of sanitary and non-normative activities are detrimental to the health of the community. The aim of this study was to evaluate the use of disinfectants to control infectious diseases transmitted through hairdressers and infection control, as well as to determine the knowledge, attitude, and practice of barbers with reference to the infectious diseases. Materials & Methods: The study included all female hairdresser (150 hairdresser) having official work in Gorgan City. The data required were collected through a questionnaire consisted of four parts: demographic information, knowledge, attitude, and practice questions (13 questions each) respectively. Disinfectants used were assessed using a checklist. Results: It was found that the most used disinfectant was bleaching powder (74.4%). The weekly and daily disinfection frequencies were 52.63 and 33.3% respectively. The research revealed that 49.45% had not have oven or autoclave to sterilize their dressing tools. The most used antiseptic for skin and hair was alcohol. Regarding infectious diseases, the barbers mean awareness was 10.83 ± 2.03, mean attitude 54.71 ± 3.99, and the mean performance was 12.44± 1.07. There were a significant positive correlation (p<0.01) between the variables of knowledge and attitude, knowledge and behavior, and attitude and performance. Conclusion: Barbers awareness about disinfection was moderate indicating the need for education and training about the types of disinfectants and how to use them. Nevertheless, the knowledge, attitude, and practices of barbers about the disease was moderate to high. Existence of the mandatory training courses on public health and having valid certificate conducted by private sector are the main reasons for increased awareness and attitude of the barbers and beauty salon dressers about infectious diseases.
A Mogadam Arjmand, M Rezaee, S Naseri, S Eshraghi,
Volume 8, Issue 1 (8-2015)
Abstract
Background & Objectives: Cryptosporidium parvum is considered as one of the pathogenic agents transmitted by water, high resistance to conventional disinfection methods, and potency of creating various problems in water resource. Because of various problems in Cryptosporidium parvum studies, Bacillus subtilis spore is recommended as a surrogate organism for studying protozoa inactivation and evaluation of water quality. On the other hand, electrochemical process is presented as an environmental friendly and high efficient method in disinfection in recent years. The aim of this study was to propose a method for promotion of the water quality. Materials & Methods: In this study, the electrochemical system used was consisted of steel electrodes (4×8 cm), 200 mL volume, and 1-4 mg/L sodium chloride. The bacterial suspensions of Bacillus subtilis (ATCC 6633) was prepared according to the McFarland method with 103 to 106 spores/mL concentration. The microbial agent removal was evaluated by sampling and transferring water to the tripticase soy agar medium every 15 min for 60 min. The number of bacteria spores, supporting electrolyte, induced current, and reaction time were evaluated. Results: The proposed electrolysis process could not eliminate Bacillus subtilis spores at 104 to 106 spores mL-1 rate at lower than 100 mA current for 60 min. Adding sodium chloride supporting electrolyte up to 4 mg/L concentration completely eliminated Bacillus subtilis spores after 60 min. Conclusion: Adding sodium chloride as a supporting electrolyte can increase the spore removal because of increasing direct and indirect oxidation in electrolysis process. Improving water disinfection and spore removal after 60 min could be described by higher oxidant agents in anode electrode.
M.s Mansoury, H Godini, Gh Shams Khorramabadi,
Volume 8, Issue 2 (8-2015)
Abstract
Background and Objective: Natural organic matters (NOM) are known as precursors to disinfection byproducts. As conventional treatment processes cannot get disinfection by-product standards, novel methods have been increasingly applied for the removal of disinfection by-products precursors. The UV/ZnO process is one of the advanced oxidation processes using photocatalytic technology. The present study aims to investigate the effect of UV/ZnO photocatalytic technology on the NOM removal from aqueous solution. Materials and methods: This study was conducted in a lab-scale batch photocatalytic reactor. The volume of reactor was 1liter and covered with UV lamps. Peristaltic pump was used for complete mixing. Humic acid is a key component of natural organic matter and it was used in this study. Each of the samples taken from the UV/ZnO process and other processes were analyzed for their UV absorbance at 254 nm by spectrophotometric. Initial concentration of Humic acid, contact time, pH, and UV irradiation were investigated. Results: The highest efficiency of the UV/ZnO photocatalytic process for removal of Humic acid from aqueous solution was achieved at initial concentration = 2 mg/L, contact time = 120 min, UV irradiation = 3950 µw/cm2, and pH=3. In this process, the removal efficiency for 2 mg/L humic acid was 100 % at 2h retention time. Conclusion: The research showed that performance of system was increased by increasing contact time and UV irradiation and was decreased by increasing HA initial concentration and pH and UV radiation with ZnO agent could not remove NOM lonely. Photocatalytic system using zinc oxide immobilized on glass have high performance to remove humic acid from aqueous solution. The UV/ZnO process was efficient and environmental friendly for natural organic matter removal.
H Aslani, R Nabizadeh,
Volume 8, Issue 4 (3-2016)
Abstract
Background and Objectives: Considering the complexity, cost, and time-consuming techniques of detecting Cryptosporidium oocysts and Giardia cysts, B. subtilits spores have been introduced as microbial indicators of these pathogens to evaluate the efficacy of disinfection studies. The present study was aimed to investigate the feasibility of B. subtilis spores inactivation using hydrogen peroxide combined with copper and silver ions. A new glutaraldehyde based compound used for surface disinfection was also tested.
Materials and Methods: In order to sporulation, vegetative bacteria were allowed to grow on a medium with insufficient nutrients, and after 5 days incubation at 37˚C, spores were washed and purified. Spore suspension was used to prepare synthetic water. Disinfection efficiency was reported as logarithmic decrease of initial spore count.
Results: This research found that none of the disinfection compounds was able to spore inactivation in low initial concentration. The highest spore reduction efficiency was related to HP/Cu+2 with 1.48 log inactivation, and HP/Ag+ compound placed in the second rank with 1.03 log reduction. Maximum spore reduction of 0.6 log was achieved when glutaraldehyde based disinfectant was used in disinfection process.
Conclusion: According to the results, it can be concluded that spores are very resistant even to combination of disinfectants. Spore reduction potential of the studied compounds was as follows: HP/Cu+2> HP/Ag+> glutaraldehyde based compound.
Hasan Rahmani, Masoumeh Kazemi Mashkani, Faezeh Asgari Tarazoj,
Volume 14, Issue 3 (12-2021)
Abstract
Background and Objective: Hospitals are the center of infection transmission due to their special conditions. In order to reduce microorganisms from the equipment and in the hospital environment, disinfection and sterilization methods are required. The aim of this study was to investigate the types of disinfectants used in Kashan hospitals.
Materials and Methods: In this descriptive cross-sectional study, Kashan hospitals were selected in 2019 by simple random sampling and the relevant checklist was completed. The required information was collected and analyzed by interviewing an environmental health expert and observing different parts of the hospital and visiting the disinfectant warehouse.
Results: Due to the type of services provided and the possible resistance of the existing microorganisms, the studied hospitals use certain types of disinfectants. Bleach and sayasept- HP were the most widely used disinfectants.
Conclusion: The results showed that since the disinfection is performed by service personnel and help of health workers, informing them about the incidence and prevalence of nosocomial infections, loss of life and financial damage caused by these diseases is very important. In addition, the effective roles of these individuals in the optimal elimination of environmental pathogens and consequently the reduction of nosocomial infections are crucial.
Zohreh Akbari Jonoush, Abbas Rezaee, Ali Ghaffarinejad,
Volume 15, Issue 2 (8-2022)
Abstract
Background and Objective: This study aimed to provide an effective electro-catalytic system for the simultaneous reduction of nitrate and disinfection of contaminated water by the electro-catalytic performance of Ni-Fe/Fe3O4 cathode.
Materials and Methods: At first, the Ni-Fe electrode was synthesized by the electro-deposition process. Then its physical properties were analyzed by scanning electron microscopy (FESEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, and photoelectron X-ray spectroscopy (XPS). Simultaneous disinfection and reduction of nitrate were performed under the following conditions: 15 mg Fe3O4 nanoparticles, pH 6.5, NaCl 10 mM, 50 mg/L nitrate, 105 CFU/mL and current density 4 mA/cm2.
Results: According to the results obtained in the absence of nitrate, 100 % of Escherichia coli bacteria were disinfected after 12 minutes. In the presence of nitrate, the time of complete disinfection increased to 120 minutes. In the absence of bacteria, 83% of nitrate was removed in 240 minutes, and in the presence of bacteria, the nitrate reduction efficiency increased slightly to 88%. In the nitrate reduction process, nitrite (0.22 mg/L) and ammonium (3.6 mg/L) were produced. In the presence of bacteria, the amounts of nitrite and ammonium produced increased to 0.42 mg/L and 7.3 mg/L.
Conclusion: The results show the outstanding ability of Ni-Fe/Fe3O4 electrode in electro-catalytic reduction of nitrate and disinfection of contaminated water separately and simultaneously with high efficiency and high selectivity to nitrogen.
Fatemeh Momeniha, Mohammad Kouhkan, Hoda Safamanesh, Parviz Yarahmadzahi, Mohammad Osman Khodayari, Ali Mohammadi, Amir Hossein Mahvi,
Volume 16, Issue 2 (9-2023)
Abstract
Background and Objective: Due to the importance of managing medical sharps waste and the potential harm caused by these types of waste, the use of safe technologies that simultaneously encapsulate and reduce their volume is considered one of the essential needs for managing medical waste in hospitals and other healthcare facilities. The main objective of this study was to investigate the efficiency of disinfecting and encapsulating device for medical sharps waste.
Materials and Methods: This device provides the process of containment and encapsulation of medical sharps waste by creating a stable protective foam without oxidation through inductive heat in a closed environment, preventing the dispersion and release of these wastes. Gas samples from the device's output were collected using the NIOSH 1501 method and analyzed using GC-MS. The performance efficiency of the device was evaluated based on the biological monitoring of the indicator bacterium Bacillus stearothermophilus.
Results: The results showed that the average concentration of BTEX gases (benzene, toluene, ethylbenzene, and xylenes) and other volatile organic compounds in the device's output was within the permissible limit. The concentrations of Benzene, Toluene, Ethylbenzene and Xylene gases were 0.04, 0.033, 0.029, and 0.029 ppm, respectively. The results of biological monitoring showed that the reduction of the microbial load was 9999.99 (Log 6) and the decontamination process was acceptable.
Additionally, this device has the advantage of reducing the volume of sharp and plastic objects during the encapsulation process, which can be further used in plastic pyrolysis/recycling industries.
Conclusion: It is hoped that by using this innovative and domestic device in the decontamination units of hospitals across the country, we can take an effective step towards improving medical waste management, reducing waste production, reducing hospital costs, and preserving and enhancing the country's health.
