Calcium Hypochlorite Research Articles

Effect of Hypochlorites on the Compressive Strength and Surface Hardness of Type V Dental Stone: An In Vitro Study

The study aimed to evaluate the compressive strength and surface hardness of a type V dental stone after hypochlorite disinfection. Two types of specimens were made according to the American Dental Association (ADA) specification no. 25 for each wet compressive strength, dry compressive strength, and surface hardness. The specimens were split into three groups with 30 samples each according to the type of disinfection. All specimens were immersed in their respective disinfecting solutions for 30 minutes at room temperature and after removal, they were left to dry for 24 hours at room temperature. Total five cycles of immersion and drying were followed. A compressive strength test was done using a universal testing machine. Wet compressive strength was tested one hour after the last cycle and dry compressive strength was tested 7 days after the last cycle. Surface hardness was measured after 48 hours using Vickers hardness test. The results were statistically analyzed. There was a statistical difference between the calcium hypochlorite and sodium hypochlorite groups for both dry and wet compressive strength. The mean wet compressive strength of calcium hypochlorite was higher when compared to the sodium hypochlorite group and it was statistically significant (p = 0.042). The results were similar and statistically significant (p = 0.003) for dry compressive strength. When the mean surface hardness of the sodium hypochlorite (As) group was compared to calcium hypochlorite the results were highly significant (p = 0.0001) with the mean surface hardness of the calcium hypochlorite group more than the sodium hypochlorite group. Calcium hypochlorite used as a disinfectant showed better compressive strength and surface hardness when compared to sodium hypochlorite as a disinfectant. Dental casts poured in the contaminated impressions which might not be disinfected at all or properly. They also come in contact with the prosthesis that might be tried inside the patient's mouth and sent to a lab for corrections without disinfecting the cast causing cross-contamination between patients, dentists, and laboratory personnel. However, immersion disinfection with sodium or calcium hypochlorite might affect important properties of the cast. Any negative effect on the mechanical or physical properties of the cast will affect the final outcome of the prosthesis.

Investigating the selectivity of calcium hypochlorite for flotation separation of chalcopyrite and pyrite pre-adsorbed collector

Investigating the selectivity of calcium hypochlorite for flotation separation of chalcopyrite and pyrite pre-adsorbed collector

Anaerobic digestion of thickened waste activated sludge under calcium hypochlorite stress: Performance stability and microbial communities

Hypochlorite pretreatment has been proven effective in enhancing waste activated sludge (WAS) anaerobic digestion performances recently. In this study, two semi-continuous anaerobic sequencing batch reactors (ASBRs), one fed with Ca(ClO)2 pretreated thickened WAS (TWAS) and one with raw TWAS, were operated at mesophilic conditions (35 °C) for 145 days. Three loading shocks were introduced to each reactor to compare the performance stability and resilience between the digestion of Ca(ClO)2 pretreated TWAS and untreated TWAS. Microbial community shifts were quantified to reveal the microbiome responses to disturbances. The results suggested that 1% Ca(ClO)2 enhanced the digestion of TWAS by inactivating and transforming the biomass to more easily digested substrates. Co-occurrence network analysis revealed that the strongest interactions in the microbial community occurred in the steady state of TWAS anaerobic digestion.

Sterilization Method for Reducing Microbial Contamination and Phenolic Compounds present in Coconut (Cocos Nucifera L.) Leaf Culture

The aim of the study was to investigate efficient sterilization methods for reducing microbial contamination and phenolic compound of coconut (Cocos nucifera L.) leaf culture. The non-chlorophyllous immature coconut leaves explant used were taken from unopened spear leaves tissue of the coconut seedling, from the apical growing regions close to the meristem of the palm sucker of about 15 months old. Murashige and Skoog (MS medium) supplemented with 2,4-Dichlorophenoxyacetic acid (2,4-D) at concentration of 30 mg/L and 6-Benzyl amino purine (BAP) at concentration of 1.5 mg/L were used for morphologic responses. Mercuric chloride, ethanol, calcium hypochlorite and sodium hypochlorite were usedto sterilize the explants at concentrations of 0.1 %, 0.2 %, 0.3 % and 0.4 % and 70-95 % of ethanol for 5 minutes. This was followed by rinsing the explants with distilled water four successive times. The sterilized explants were inoculated on MS media and were incubated at 25±2oC in the dark. Results showed that contamination was less in the cultures, particularly in explants sterilized with 70 % ethanol. Although, all the steriliants did well, but ethanol is more preferable than the rest steriliants, in solving both problems.

Management of Borer and Flubendiamide Residue in Okra Using Milk-Made Bioagent and Calcium Hypochlorite

Okra is an important vegetable, and it is subject to heavy yield losses by insect pests, of which the shoot and fruit borer Earias spp. is serious. Insecticides are used against this pest, leading to insecticide residues. This study evaluates Milkoid, an LAB formulation spray in field by spraying in tandem with flubendiamide and bleaching powder (calcium hypochlorite). The results indicate that the population of epiphytic LAB density was maximum on plants sprayed with Milkoid with or without flubendiamide. The pest damage was significantly reduced after spraying flubendiamide with or without bleaching powder (3.76- 5.30%). Milkoid accelerated the degradation of flubendiamide with the dissipation rate of 70.07% on 15th day after spray. The efficacy of Milkoid in reducing the toxicity and the potential of calcium hypochlorite as an antimicrobial agent and the shoot and fruit borer management are discussed.

Calcium Hypochlorite Pretreatment Enhances Waste-Activated Sludge Degradation during Aerobic Digestion

Calcium Hypochlorite Pretreatment Enhances Waste-Activated Sludge Degradation during Aerobic Digestion

Physicochemical properties and penetration into dentinal tubules of calcium hypochlorite with surfactants.

The aim was to assess the physicochemical properties and the penetration into dentinal tubules of calcium hypochlorite solution [Ca(OCl)2], with or without surfactants. The surfactants benzalkonium chloride, cetrimide, Tween 80 and Triton X-100 were mixed at different concentrations with sodium hypochlorite solution (NaOCl), Ca(OCl)2 and distilled water (control). Once the critical micellar concentration (CMC) of the surfactants in Ca(OCl)2 and NaOCl was determined, pH, free chlorine, surface tension and free calcium ions were evaluated. The penetration into dentinal tubules of NaOCl and Ca(OCl)2, with or without benzalkonium chloride and Triton X-100 [surfactants that promoted the lowest surface tension of Ca(OCl)2], was assessed using human premolars stained with crystal violet. The statistical tests were one-way ANOVA and Tukey's post-test, Kruskal-Wallis and Dunn's post-test, two-way ANOVA and Bonferroni's post-test, and t-test; depending on the assay. The addition of surfactants reduced the surface tension of NaOCl and Ca(OCl)2, and did not alter the pH or the free available chlorine of either solution. The addition of all surfactants increased the availability of free calcium ions in Ca(OCl)2, especially benzalkonium chloride. Ca(OCl)2 exhibited lower penetration into dentinal tubules than NaOCl, and the addition of surfactants did not improve the penetration of Ca(OCl)2, but did increase the penetration of NaOCl. It can be concluded that the addition of surfactants to Ca(OCl)2 did not increase the penetration into dentinal tubules, but it did promote lower surface tension, without changing the pH or free available chlorine values, and higher availability of free calcium ions in Ca(OCl)2.

Toxic Impact of Exposure to Calcium Hypochlorite and Granular Activated Carbon on African Catfish (Clarias gariepinus): A Study of the Alterations in Hemato-Biochemical Profile and Oxidative Indices

Toxic Impact of Exposure to Calcium Hypochlorite and Granular Activated Carbon on African Catfish (Clarias gariepinus): A Study of the Alterations in Hemato-Biochemical Profile and Oxidative Indices

Evaluation of Trihalomethane Formation Risk Analysis in Swimming Pools in Eskisehir, Turkey

Swimming pools are popular entertainment and sport areas that people often use. For this reason, it is crucial to determine the physicochemical properties and Trihalomethanes (THMs) concentrations of swimming pools and the effect of THMs on swimmer health. This study focuses on the physicochemical parameters and THM concentrations of six swimming pools in Eskisehir and the impacts of THMs on human health. Within the study context, physicochemical parameters were examined and swimming pool water standards of various countries and organizations were evaluated. The alkalinity, pH, temperature, hardness, and free chlorine values of the swimming pools were determined to compare with the current standards. Concentrations of chloroform (TCM), bromodichloromethane (BDCM), and dibromochloromethane (DBCM) were also determined in the collected samples. Concentrations were found to be in the range of 11.6-100.1 µg/l for BDCM, 151.5-366.4 µg/l for TCM, ND-6.95 µg/l for DBCM, and 172.1-380.7 µg/l for TTHM. From the results, it was determined that TTHM concentrations were above the limit values defined by WHO, while chloroform (except P1 and P5 pools), BDCM (except P3 pool), and DBCM concentrations were significantly below the limit values. TTHMs and chloroform concentrations were high in tap water using sodium hypochlorite as a disinfectant. BDCM and DBCM concentrations were high in pools where groundwater was used. Health risks of THMs in pools through ingestion and dermal absorption were also estimated for both women and men. In the interpretation of the result, it was also found that high concentrations of TTHMs increased the risk, and women’s ingestion-based risk values are slightly higher than men’s ingestion-based risk values. Fingerprints of THM formation in pool water are precursor parameters and it is of great importance to constantly control and take precautions. It has been observed that the use of groundwater as a water source and NaCl as a disinfectant significantly reduces THM formation in swimming pools. However, in order to reduce the BDCM and DBCM concentrations in the use of groundwater, it is recommended to measure the precursor bromide and establish the relevant limit values. The use of hypochlorite disinfectants in pools where tap water is used as a water source increases THM formation. For this reason, it is necessary to determine the amount of organic carbon as a precursor for pools using tap water as a water source and add it to the limit values. In addition, the use of calcium hypochlorite disinfectant instead of sodium hypochlorite reduces THM formation. Highlight Physicochemical properties and THMs concentrations of swimming pools and effects of trihalomethanes (THMs) on the health of swimmers. Physicochemical parameters and THM concentrations of six swimming pools were determined, and the effects of THMs’ on human health. Physicochemical parameters (alkalinity, pH, temperature, and hardness), chloroform (TCM), bromodichloromethane (BDCM), and dibromochloromethane (DBCM) were studied. As a result of the study, total THMs and TCM concentrations were high in pools where tap water, and sodium hypochlorite were used. BDCM and DBCM concentrations were high in pools where groundwater was used. High THM concentrations increase the risk, and at the same time, women’s ingestion-based risk values are slightly higher than men’s ingestion-based risk values.

Calcium Hypochlorite Promotes Dark Fermentative Hydrogen Production from Waste Activated Sludge

This study reported a high-efficiency and low-cost sludge pretreatment method using calcium hypochlorite [Ca(ClO)2] for promoting anaerobic fermentation performance. The experimental results indicated that the cumulative hydrogen yield was enhanced from 1.87 to 16.72 mL/g volatile suspended solids (VSSs) when the Ca(ClO)2 dosage was increased from 0 to 1.5 g/L and then reduced to 13.80 mL/g VSSs when the Ca(ClO)2 dosage reached 1.8 g/L. The mechanism study revealed that Ca(ClO)2 efficiently disrupted sludge extracellular polymeric substances and microbial cells, producing more soluble organics for the subsequent biochemical processes. Beyond that, the biodegradability of sludge organics was promoted by Ca(ClO)2 pretreatment. Biochemical reaction kinetic analysis indicated that the activities of microbes responsible for hydrogen consumption were severely inhibited when treated with Ca(ClO)2. The two decomposition products of Ca(ClO)2, Ca(OH)2 and HClO, positively affected the hydrogen yield, with the contribution of Ca(OH)2 being greater than HClO. Microbial community analysis illustrated that the fermentative microbes were markedly enriched by Ca(ClO)2 pretreatment, with the abundances found to be 3.21 and 45.62% in control and Ca(ClO)2-pretreated fermenters, respectively. After fermentation, the Ca(ClO)2-pretreated sludge showed better dewaterability than the control, and the organic pollutants diclofenac and sulfamethazine, as well as the fecal coliforms, were largely removed by Ca(ClO)2.

Parameters of Effluent from Bleaching Pulp with Potassium Hydroxide and Calcium Hypochlorite

Parameters of Effluent from Bleaching Pulp with Potassium Hydroxide and Calcium Hypochlorite

Enhanced methane yield through sludge two-phase anaerobic digestion process with the addition of calcium hypochlorite

This study investigated the effects of calcium hypochlorite (Ca(ClO)2) on biomethane generation from sludge two-phase anaerobic digestion system. In first (acidogenic) phase, volatile fatty acids (VFAs) were largely generated when pretreated by Ca(ClO)2, while the methane yield was severely inhibited. In second (methanogenic) phase, the methane yield was observably enhanced by Ca(ClO)2. Further calculation showed that the total methane yield from the two phases was firstly promoted from 156.0 ± 4.5 to 269.9 ± 5.2 mL when Ca(ClO)2 dosage enhanced from 0 to 1.6 g/L, which then reduced to 235.4 ± 5.5 mL when Ca(ClO)2 content reached 2.0 g/L. Mechanism analysis showed that the suppression of Ca(ClO)2 on coenzyme F420 activity was relieved in methanogenic phase, and the abundances of functional microbes in methanogenic phase were enriched when added with Ca(ClO)2. The Ca(ClO)2-based method well realized the balance between efficacy and economy, possessing outstanding potential for large-scale applications.

Waste sludge disintegration and bound water reduction by chemical oxidation: A comparative study

Waste sludge disintegration and bound water reduction was investigated by comparative chemical oxidation using calcium hypochlorite, hydrogen peroxide, peroxymonusulfate and peroxydisulfate in the study. Response surface methodology (RSM) with Box-Benhken Design (BBD) was used to determine operating parameters namely initial pH (2–10), oxidant dosage (5–85 mg/g TSS), and Fe2+ to oxidant ratio; 0.2-2) and disintegration time (20–100 min). According to ANOVA results, determination coefficient (R2) was found 93.2%, 76.3%, 84% and 84.8% for each oxidant, respectively. Under the optimum operating conditions, disintegration degree in terms of chemical oxygen demand (DDCOD) was calculated 11.09%, 5.23%, 10.75%, and 5.34%, respectively. Furthermore, bound water reduction (BWR) of waste sludge increased after the disintegration process, and 33.52%, 24.56%, 44.63% and 32.80% BWR values were obtained under the same operating conditions. Results show that the higher DDCOD and BWR values were achieved by calcium hypochlorite and peroxymonosulfate treatment.

Disinfection with calcium hypochlorite and colloidal silver in the content of phenols of red and blue corn sprouts

The production of sprouts for human consumption represents a healthy option to combat the effects of oxidative stress, due to the bioactive compounds that are synthesized during germination. The safety of sprouts is an essential requirement. In this study, calcium hypochlorite and colloidal silver were used as options for not alter the nutraceutical content of corn sprouts and eliminate dangerous pathogens for human food. Treatments based on calcium hypochlorite in high concentrations (0.4%) were more efficient for food safety, but with the disadvantage of reducing the content of free phenols in blue corn only from 374.55 mg to 261.06 mg / 100 g. Colloidal silver at dose of 1.4 ppm, has a pathogen control similar to calcium hypochlorite without reducing the content of free phenols, even increasing it. The best treatment to treat corn seeds for sprout production is colloidal silver at 1.4 ppm

Comparison of commercial disinfectants and an in loco-produced solution: free residual chlorine decay in human supply waters

Abstract The disinfection process is used in the treatment of water for human supply to promote sanitary safety and provide users with drinking water that meets potability standards. Thus, it is necessary to sustain a minimal concentration of free residual chlorine (FRC) throughout the entire distribution system. The present study investigated the decay process of FRC concentration in water destined for human supply. The decay was evaluated in bench-scale testing, using sodium hypochlorite, calcium hypochlorite, sodium dichloroisocyanurate (organic chlorine) as disinfectant agents, and also an alternative disinfectant solution (ADS) produced in loco, with oxidizing and disinfectant properties, which is being used in Brazilian sanitation industry. To evaluate the decay, four models were fitted: first-order, nth-order, limited first-order and parallel first-order, hence determining the corresponding parameters which describe the decay speed of the FRC concentration in water. Achieved results demonstrated that all models were statistically significant and predictive. However, the parallel first-order model produced the best fit. Regarding the evaluated disinfectants, there was preeminence of the ADS solution when compared to the others, since it imparted a higher FRC over time, a behavior indicated by lower values for reaction rate constant in all models and when compared to other disinfectants used in this study.

Chlorinated cyanurates and potassium salt of peroxymonosulphate as antimicrobial and antibiofilm agents for drinking water disinfection

The understanding of microbial susceptibility to disinfectants is an important step to provide drinking water (DW) of adequate microbiological quality. In drinking water distribution systems (DWDS) the application of disinfectants is the main approach to control microorganisms. Although chlorine has been commonly used for DW treatment, the increase of microbial resistance and the production of harmful disinfection by-products promote the necessity to seek new alternatives. This study evaluated the antimicrobial activity of sodium dichloroisocyanurate (NaDCC), trichloroisocyanuric acid (TCCA), and pentapotassium bis(peroxymonosulphate) bis(sulphate) (OXONE) against two emerging pathogens isolated from DW, Acinetobacter calcoaceticus and Stenotrophomonas maltophilia. Free chlorine from calcium hypochlorite was used for comparison. The dose and time-responses against planktonic bacteria were performed as well as the assessment of the effects on membrane integrity. Moreover, the effects against 48 h-old biofilms formed on polyvinyl chloride and stainless steel were evaluated in terms of biofilm culturability and removal. Minimum bactericidal concentrations of 2.1 and 3.1 mg/L for NaDCC, 2.5 and 3.8 mg/L for TCCA, 340 and 690 mg/L for OXONE, and 0.80 and 1.0 mg/L for free chlorine alone were obtained against S. maltophilia and A. calcoaceticus, respectively. The kinetic modeling revealed that NaDCC and TCCA caused similar inactivation rates and the time for first log reduction by OXONE was less than 10 min, for both bacteria. All the disinfectants triggered significant bacterial cytoplasmic membrane destabilization, even at sub-lethal concentrations. A 30 min treatment with the disinfectants allowed a reduction in the biofilm culturability up to 5 log. OXONE was the disinfectant with the best efficiency against both bacterial biofilms. However, none of the disinfectants caused significant biofilm removal (reduction < 1 log cells/cm2). This study highlights NaDCC, TCCA, and OXONE as promising alternatives to free chlorine for DW disinfection, particularly for planktonic growth control and biofilm culturability reduction.

OPTIMIZATION OF PRICKLY PEAR CACTI (Opuntia spp.) MICROPROPAGATION USING AN EXPERIMENTAL DESIGN METHOD

In Morocco, despite the adaptation of the prickly pear cactus (Opuntia spp) to edaphoclimatic conditions, differing from those that prevail in the countries from which it originates, this introduced species is regressing due to biotic and abiotic stresses that impact its survival. Hence, finding innovative technologies to preserve this species are essential. However, the success of in vitro micropropagation technologies is hinged upon the initial disinfection step. In this work we have tested several solutions and exposure time mixtures for disinfection across three different explants, as well as the adoption of hormonal combinations for the induction/regeneration step that allow for efficient micropropagation of cacti. We aimed to produce healthy regenerable vitroplants capable of effectively preserving themselves under aseptic conditions. We describe a specific protocol based on the type of areoles: (1) cladode without areolas (CWA); (2) areolas with shredded glochids (ASG); and (3) areolas with intact glochids (AIG). For each of these areoles, the disinfectant concentration and contact time were optimized and various hormonal combinations were tested for induction/regeneration. The optimal design meeting I-optimality criterion was used to predict the optimal combination by maximizing desirability. The disinfection combination that used 4.23% calcium hypochlorite (w:v), 0.4% Tween 20 (v:v), and 10 minutes of exposure time reduced the contamination frequency to 0.002% with a necrosis rate of less than 0.33% in explants with AIG. This type was the only one that gave responses in the induction/regeneration phase, which allowed us to predict the best rate of caulogenesis (71.74%) under a hormonal combination of 5.3 mg/L of BenzylAminopurine (BAP) and 0.59 mg/L of 1-Naphthaleneacetic acid (ANA). Furthermore, the highest callogenesis rate of 94.45% was obtained by a hormonal combination of 6 mg/L of BAP and 0.59 mg/L of ANA. The explant’s rhizognesis was carried out with a concentration of 0.5 mg / l ANA, before acclimatization on a substrate containing soil and sand in a ratio of 3:1. In conclusion, these protocols provide easy and cost-effective means to multiply cacti in vitro to preserve them in areas where their culture has been destroyed by cochineal.

Cover Fuel Cells 6/2021

Fuel CellsVolume 21, Issue 6 p. 489-489 COVER PICTUREFree Access Cover Fuel Cells 6/2021 First published: 21 December 2021 https://doi.org/10.1002/fuce.2021701061AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract The cover image is based on the Original Research Paper Cathodic reduction of oxidizing gas generated by low-temperature decomposition of hydrated calcium hypochlorite for flow cell by Fumihiro Kodera et al., https://doi.org/10.1002/fuce.202100101. Volume21, Issue6December 2021Pages 489-489 RelatedInformation

First report of Pythium aphanidermatum causing root rot of head lettuce in China.

Head lettuce (Lactuca sativa L.) is an important crop for fresh consumption in China. In Shandong Province, head lettuce is planted in spring and in autumn each year. Because of the on-and-off rain for three weeks, head lettuce plants planted directly into the field in Jiyang City, in July 2017, 20% of the plants rapidly showed symptoms of rotting, water-soaked lesions on roots and stem bases, and then death. The diseased plants first appeared in low-lying areas prone to water accumulation. One-millimeter pieces were excised from water-soaked roots and stem bases, dipped in a 0.2% calcium hypochlorite solution for 10 min, then placed on V8 medium, and incubated in the dark at 28°C for 5 d. Two Pythium-like strains were isolated from the roots and stems. The isolates transferred to CMA and grown for 7 d, and the morphological characteristics of the two isolates on corn meal agar (CMA) were white with dense, cottony, aerial and well-branched mycelia. The two isolates produced sporangia, oogonia, antheridia and oospores. Most of the sporangia were lobate. The oogonia were smooth, nearly globose and terminal. Oospores were globose, smooth and aplerotic. The average dimensions of 50 oogonia and oospores respectively ranged from 19.5 to 25.2 (av. 23.1) µm and 17.8 to 22.3 (av. 19.9) µm. The antheridia were broadly sac-shaped. The isolates morphological characteristics were consistent with P. aphanidermatum (van der Plaats-Niterink, 1981). The COI gene and ITS region of the rDNA were amplified and sequenced using primers FM55/FM52R (Long et al. 2012) and ITS1/ITS4 (White et al. 1990), respectively. The two aligned COI sequences were identical for both isolates, as were the two ITS sequences. BLASTn analysis of the 1,133-bp COI sequence (accession no. MT952703) resulted in a 100% identity with accession number AY129164 from Lactuca sativa, which belongs to P. aphanidermatum, and the 808-bp ITS sequence (accession no. MT921597) showed a 99% identity with Genbank accession number HQ643442 belonging to P. aphanidermatum. Koch's postulates were conducted by first soaking corn kernels for 24 h in water, and then autoclaving for 2 h at 121˚C. Isolate SDHL-1 was grown on CMA for 10 days, after which agar plugs were transferred to the sterilized corn kernels and incubated at 28℃ for approximately 15 d, until the corn kernels were covered in white hyphae. Ten healthy head lettuce plants were transplanted into a sterilized loam potting soil artificially infested with the corn inoculum (3 g inoculum per 100 g loam mixture). Inoculated plants and noninoculated controls were maintained in a greenhouse at 28°C and 100% relative humidity with a 12-h photoperiod; the experiment was repeated once. All twenty inoculated plants exhibited symptoms within one week similar to those observed. Pythium aphanidermatum was recovered only from the water-soaked roots and stem bases of inoculated plants and the re-isolated cultures again identified based on morphological characteristics and sequencing of the ITS and COI genes. No symptoms were observed on the control plants. Sclerotinia sclerotiorum is reported to cause stem base rot of L. sativa in China (Zhou et al. 2011). To our knowledge, however, this is the first report of root rot of head lettuce caused by Pythium aphanidermatum. Identification of the pathogen will assist in devising strategies to reduce yield loss.

Chlorine As a Disinfectant in Water Treatment

Abstract: Disinfection of treated water is a necessary process. For this, chlorine and its products are widely used. During the treatment process, chlorine is added to drinking water as elemental chlorine, sodium hypochlorite solution or dry calcium hypochlorite. When applied to water, each of these forms “free chlorine”, which destroys pathogenic organisms. If adequate water treatment is not readily available, the impact on public health can be devastating. Worldwide, about 1.2 billion people lack access to safe drinking water, and about 2.4 billion people lack sanitation. As per WHO, 3.4 million people die from waterrelated diseases. Drinking water chlorination will remain a cornerstone of disinfection. This is because of the wide range of benefits provided by chlorine. However, alternative disinfectants including ozone and UV radiation are available, all disinfection methods have unique benefits, limitations and costs. So, an engineer has to consider all the pros and cons of a disinfectant method properly before deciding the one to adopt. Keywords: Disinfection, Gaseous Chlorination, Sodium Hypochlorite, Calcium Hypochlorite, Ultraviolet, Ozone, Chlorine dioxide