Which term refers to removal or destruction of all pathogens in or on an object?
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Disinfection may be needed for two distinctly different situations: (1) disinfection of nets, holding facilities, and piping prior to use; and (2) disinfection of process water prior to use or before reuse. In general, the first situation is much simpler as toxicity to culture organisms is not usually a problem. In the second case, the toxicity of the disinfection agent and its residues or derivatives to non-target organisms (i.e., culture organisms) is critical and will control the disinfection process. Show
The effectiveness of a given disinfectant depends on the concentration of disinfectant, contact time, temperature, turbidity, particulate concentration, and specific microorganisms. Because the concentration of microorganisms varies widely, microorganism concentrations are typically expressed in what are called log units. If concentrations are expressed in #/ml, then the log concentration is equal to the base 10 logarithm of the actual concentration (see Table 13.1). Table 13.1. Log units as used to define microorganism concentrations Log units concentration(#/ml)61,000,0005100,000410,00031,000210011001−10.1−20.01−30.001 The effect of disinfectant concentration and contact time on the mortality of typical microorganisms is presented in Fig. 13.1. For many microorganisms, the rate of kill is a straight line on a semi-log plot. Therefore, it takes the same time to reduce the concentration of microorganisms from 1,000,000 to 100,000/ml as from 100 to 10/ml.  Fig. 13.1. Effect of disinfectant concentration and contact time on mortality of typical microorganisms. Note that a reduction in 1 log units is equal to a 90% reduction in concentration and a reduction in 2 log units is equal to a 99.0% reduction in concentration. Generally, as the concentration of disinfectant is increased, the rate of kill is increased. Therefore, to achieve a given final concentration of microorganisms, a high disinfectant concentration at a short contact time or a low concentration at a long contact time may be used. The options in disinfecting equipment are various chemicals, chlorine being the most common, and steam cleaning. Small steam generators are commonly used to disinfect culture equipment after a disease incident and work well on concrete, fiberglass, and epoxy tank surfaces but are unsuitable for most plastics or inaccessible areas, such as pipes. Chemicals can also be used to disinfect process water but only on a batch basis. Ultraviolet (UV) light is the most common method used in-line to treat process water. With some care, ozone treatment may also be useable in-line. View chapterPurchase book Read full chapter URL: https://www.sciencedirect.com/science/article/pii/S0167930902800138 Lassa FeverElisabeth Fichet-Calvet, in The Role of Animals in Emerging Viral Diseases, 2014 Disinfection: During the daily necropsy session, all the traps which contained an animal are bleached for 5 minutes, and then rinsed and left to dry at the border of the study camp. After disinfection, the cryotubes are stored in the cool box during the day. At the end of the session, all the items set on the table must be disinfected. Soft items are disinfected with alcohol (70%), hard items with disinfectant (incidine, sekusept). The table and the chairs are also disinfected. The wastes, gowns, mask are burnt in situ in the well, and everybody is allowed to remove masks when no infectious material is remaining. Disinfection of traps with bleachDisinfection of personnel with alcohol 70%Disinfection of the tubes with incidine 1%Disinfection of the tools with incidine 1%Disinfection of the tables with incidine 1%Daily burning of the labcoats and waste View chapterPurchase book Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780124051911000053 Assuring Purity of Drinking WaterJ.A. Cotruvo, ... R. Herman, in Comprehensive Water Quality and Purification, 2014 2.10.3.2 DisinfectionDisinfection is required for surface water sources, and it is also necessary for some groundwater sources in order to kill or inactivate potentially harmful organisms. Several techniques are used for this purpose, including ultraviolet (UV) light treatment, ozonation, chlorination, chlorine dioxide treatment, and chloramination. Some of the fundamental aspects of disinfection processes are presented in Chapters 1.7 and 1.9. Another function of disinfection is to prevent the growth of microorganisms in the piping of the water distribution system. Chlorine, chlorine dioxide, and chloramines provide residual disinfection for this purpose. If UV or ozone is used as an initial disinfectant, then additional disinfection must also be employed to provide residual disinfectant. One consideration with the use of residual disinfectants is that they can form DBPs, which might be harmful chemicals. For example, use of chlorine can lead to the formation of trihalomethanes and/or haloacetic acids. For this reason, many communities have modified their treatment process to use chloramine for residual disinfection. Chloramines are not nearly as effective as chlorine, ozone, or chlorine dioxide. Disinfection is essential to provide safe drinking water, and any hypothetical risk that may exist from DBPs is small compared with the risks from microbial waterborne diseases. View chapterPurchase book Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780123821829000347 Food safety in large organized eating establishmentsP. Dudeja, A. Singh, in Food Safety in the 21st Century, 2017 27.2.7 Cleaning and SanitizingCleaning and sanitizing at every point of the preparation chain has to be ensured by using proper cleaning agents, methods and cleaning schedules. Cleaning of EE involves removal of soil, food residue, dirt, grease, or other objectionable matter. Separate cleaning materials, including cloths, sponges, and mops should be used for the designated clean area. Use of disposable, single-use cloths is recommended wherever possible. Effective cleaning is essential to get rid of harmful bacteria and stop them spreading to food (Edrees, 2014). Water alone is not a very efficient cleaning agent because of its high surface tension. Adding of detergent to water facilitates the contact between water and surface soil, allowing better penetration into soil by lowering surface tension. Disinfection is the killing of infectious agents outside the body by direct exposure to chemical or physical agents. However, chemical disinfectants only work if surfaces have been thoroughly cleaned first to remove grease and other dirt. For effective disinfection, it is important to first clean the surface and remove visible dirt, food particles and debris, and then rinse to remove any residue. After this step, application of a disinfectant is done using the correct dilution and contact time, according to the manufacturer’s instructions, and then rinsing with drinking water. Sanitizers have both cleaning and disinfection properties in a single product. But cleaning and disinfecting process must still be carried out as above, to ensure that the sanitizer works effectively, that is, to first provide a clean surface and then again to disinfect. Cleaning and disinfection programs shall be continually and effectively monitored for their suitability and effectiveness once in 6 months and records maintained. Cleaning and disinfection schedule in an eating establishment as given by FSSAI are given in Tables 27.1–27.5. Disinfection methods are of two types: Table 27.1. Cleaning of Structure ComponentMinimum FrequencyEquipment and ChemicalsMethodFloors except washroom and storeEnd of each day or as requiredBrooms, damp mops, brushes, detergents, sanitizers1. Sweep the area and remove debris 2.Apply detergent and mop the area 3.Use scrub for extra soil 4.Rinse thoroughly with water 5.Remove water with mop Walls, doors, ceiling, ventilators, fans, and exhaust fansFortnightly or as requiredClean wiping clothes (one time use) brushes and detergents1.Remove dry soil 2.Rub with wet cloth or rinse with water 3.Apply detergent and wash 4.Wipe with wet cloth or rinse with water 5.Air dry Air conditionersAs per manufacturers maintenance manualDesert coolersFortnightly or as requiredWater, mop1.Remove water 2.Rub with cloth or rinse with water 3.When not in use remove water and keep dry WashroomOnce every 4 hBrooms, damp mops, brushes, detergents, sanitizers1.Sweep the area 2.Apply detergent and mop the area 3.Use scrub for extra soil 4.Rinse thoroughly with water 5.Remove water with mop ComponentLeast FrequencyEquipment and ChemicalsMethodStoreEnd of each day or as requiredBrooms and camp mops1.Sweep the area 2.Mop the area 3.Use scrub for extra soil 4.Air dry Water storage tankOnce in six monthClean wiping clothes (one time use), detergents, sanitizers1.Remove foreign matter and soil 2.Rub with wet cloth or rinse with water 3.Apply detergent and wash 4.Rinse with water and sterilizer 5.Air dry Insect Electrocuting devicesOnce a week or as requiredClean wiping clothes (one time use)1.Remove insects and other foreign matter 2.Rub with wet cloth 3.Reinstall insectocutors Waste bins and waste areasEnd of each day or as requiredWater, clean wiping clothes (one time use), detergents1.Remove foreign material and soil 2.Rub with wet cloth and rinse with water 3.Apply detergent and wash 4.Air dry Parking and open spacesEnd of each day or as requiredWater1.Sweep the area and remove debris 2.Wash parking space thoroughly with water Street lanes and other public places or the common part of building which are adhering and/or nearby food premisesEnd of each day or as requiredWater or mop1.Sweep the area and remove debris 2.Wash thoroughly with water FSSAI Table 27.2. Cleaning of Food Contact Surfaces ComponentLeast FrequencyEquipment and ChemicalsMethodWork tablesAfter useClean wiping clothes (one time use), detergents, sanitizers1. Remove food debris and soil 2.Rub with wet cloth or rinse with water 3.Apply detergent and wash 4.Wipe with wet cloth or rinse with water 5.Apply sanitizer 6.Air dry SinksAfter each useRunning water, detergents1.Remove food debris and soil 2.Rinse with water and or detergent FSSAI Table 27.3. Cleaning of Equipment ComponentLeast FrequencyEquipment and ChemicalsMethodUtensils, cutting boards, knives, other cooking equipment, service ware, crockery, and cutleryAfter useClean wiping cloths (one time use), brushes, detergents and sanitizers1. Remove food debris and soil 2.Rinse with water 3.Apply detergent and wash 4.Rinse with water 5.Apply sanitizer 6.Air dry Food processing equipment, vending machinesAs per manufacturers cleaning and maintenance manualRefrigerators, freezers and storage areas, refrigerated display countersWeekly or as requiredClean wiping cloths (one time use), brushes, and detergents1.Remove food debris and soil 2.Rub with wet cloth or rinse with water 3.Apply detergent and wash 4.Wipe with wet cloth or rinse with water 5.Dry with clean cloths/air dry FSSAI Table 27.4. Cleaning of Hand Contact Surfaces ComponentLeast FrequencyEquipment and ChemicalsMethodDoors and Door knobsDailyDamp cloths and detergents1. Remove debris 2.Apply detergent 3.Rinse or wipe with damp cloths 4.Dry with paper towels/air dry UpholsteryDailyClean wiping cloths (one time use)1.Remove food debris and soil 2.Wipe with dry cloth Fortnightly or as and when requiredSteam/chemicals1.Remove debris 2.Apply chemicals 3.Vacuum dry FSSAI Table 27.5. Cleaning of Furniture and Decorative Items ComponentLeast FrequencyEquipment and ChemicalsMethodChairs and tables, reception and cash counters, display counters held at ambient temperatureFortnightly or as requiredClean wiping cloths (one time use), brushes, and detergents1. Remove dry soil 2.Rub with wet cloth or rinse with water 3.Apply detergent and wash 4.Wipe with wet cloth or rinse with water 5.Air dry Paintings, artificial plants, and decorationsFortnightly or as requiredClean wiping cloths (one time use), brushes, and detergents1.Remove dry soil 2.Wipe with wet cloth 3.Air dry PlantsDailyWashingWaterFSSAI •nonchemical disinfection methods like heat/steam: expensive, impractical •chemical disinfection methods: commonly used disinfectants [chlorine and chlorine-releasing, quaternary ammonium, amphoteric (ampholytic) and phenolic compounds, peracetic acid]. Chlorine is the most effective disinfectant available and sodium (or calcium) hypochlorite is a cheap disinfectant commonly in use (Rusin et al., 1998). A practical disadvantage of sodium hypochlorite is the risk of corrosion to all common metals (especially aluminum and galvanized iron), except perhaps high quality stainless steel. As per the Food Safety and Standards Act (FSSA) 2006, food premises, their fixtures, fittings, equipment and utensils shall be maintained clean, and in a good state of repair and working condition. A well-planned, well-executed, and controlled cleaning and sanitation program for eating establishment (service area, kitchen, equipment, utensils) is very important to achieve a high hygienic standard. Cleaning and sanitation alone, however, will not fully ensure hygienic standard in production; since process hygiene and personal hygiene are also equally important factors. View chapterPurchase book Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780128017739000273 Advances in disinfection techniques for water reuseLarry Forney, in Handbook of Water and Energy Management in Food Processing, 2008 Publisher SummaryDisinfection is the inactivation or destruction of micro-organisms that cause disease. Disease-causing pathogenic micro-organisms include viruses, bacteria, and protozoans. Although many common wastewater treatment processes reduce the concentration of microbial pathogens, it is necessary to provide a final disinfection process that ensures safe levels of pathogens. All the disinfection treatment methods that include either chemical agents or physical treatment methods are much more effective when applied to wastewater already subjected to the processes of flocculation and filtration. The latter processes reduce the chemical demand for chemical disinfectants or increase the path length of disinfecting radiation for physical treatment methods. Disinfection of wastewater is necessary to protect water quality for subsequent use. The latter would include possible use downstream as a source of public water supply or irrigating crops. Another option is the internal reuse or recycling of treated wastewater within a given industry, such as food processing. Wastewater reuse is commonly applied to the irrigation of agricultural crops. Unfortunately, the potential for disease transmission with untreated wastewater is significant, especially, if it is used to irrigate leafy vegetables. This chapter presents that wastewater disinfection of resistant microbes can be achieved with other treatment options, including chlorine dioxide, ozone, and UV radiation. It also discusses the continuous disinfection process and reactor design, scale-up, and modeling procedures for both chemical and physical disinfection methods. It further explains the common disinfection methods and other techniques. View chapterPurchase book Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9781845691950500259 Pathogen resistance to sanitisersA.J. van Asselt, M.C. te Giffel, in Handbook of Hygiene Control in the Food Industry, 2005 Publisher SummaryDisinfection is the treatment of surfaces/equipment using physical or chemical means such that the amount of microorganisms present is reduced to an acceptable level. Disinfection reduces the amount of remaining microorganisms. This means that, in general, a disinfected surface/piece of equipment is not sterile and means that disinfection is not equal to sterilization where viable microorganisms can no longer be detected. Resistance development as a result of cleaning and disinfection is not a matter of major concern for the food industry. However, the food industry and the pharmaceutical industry have to realize that the current processes of cleaning and disinfecting need to be carried out properly in order to avoid development of resistance. Application of the right type of agent is important to achieve the desired chemical effect. As microorganisms evolve and adapt to disinfecting strategies, the development of more effective cleaning and disinfecting strategies and new tools to monitor the efficiency of these strategies would continue. View chapterPurchase book Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9781855739574500049 GAS CHROMATOGRAPHY | Environmental ApplicationsM.T. Galceran, F.J. Santos, in Encyclopedia of Analytical Science (Second Edition), 2005 Disinfection By-ProductsDisinfection of drinking water is one of the major public health triumphs of the twentieth century. Today, most of the pathogenic microorganisms in water are killed when oxidizing chemicals such as chlorine, ozone, chlorine dioxide, and chloramines are added to the water in municipal treatment plants. Nevertheless, chemical DBPs are produced when disinfectants react with natural organic matter present in water. Trihalomethanes (THMs) are the main DBPs formed when chlorine is used but other compounds such as haloacetic acids (HAAs), haloacetonitriles (HANs), and haloketones (HKs) are also found in drinking water. The presence of DBPs in drinking water is a health hazard and may also cause unpleasant taste and odor. For these reasons, the occurrence of DBPs in drinking water has been evaluated and regulatory legislation has been established. Purge-and-trap, liquid–liquid extraction, SPE, and headspace extraction are the most common preconcentration techniques used as a first step for control of DBPs in drinking water. Moreover, in the last few years SPME has been proposed for the analysis of several DBPs, with very good results. Table 2 provides a summary of the USEPA methods proposed for the analysis of DBPs in drinking water. For quantification of the halogenated high-priority compounds (THMs, HAAs, HANs, and HKs), GC is the technique of choice. Several detection systems have been used but ECD is the most popular due to its low cost and the high selectivity provided by this detector for halogenated compounds. Nevertheless, single quadrupole GC–MS instruments in SIM mode and ion-trap analyzers in full scan or MS/MS are also frequently used. Some DBPs are not amenable to GC analysis and have to be derivatized. For instance, HAAs are mainly deprotonated, so they cannot be extracted from water and injected into a GC column. Methylation with diazomethane or acidic methanol is the approach proposed for the analysis of these compounds (Table 2). Aldehydes, which are mainly formed when ozone is used as disinfection reagent, are polar compounds, making it difficult to separate DBPs from the water matrix. Therefore, derivatizing agents that convert the polar groups into less polar ones are used. For instance, these compounds are analyzed by GC after oximation with pentafluorobenzylhydroxylamine (PFBHA). In general, capillary columns with stationary phases such as the nonpolar methylpolysiloxane (DB-1), the slightly polar ones with 5% of phenyl groups such as DB-5 and the DB-624 specially designed for the analysis of volatile priority pollutants, are employed to control DBPs in water. These columns are used for THM, nitriles, ketones, and methylated HAAs. The more polar stationary phase, 14% cyanopropylphenyl methylpolysiloxane, such as DB-1701 and CPSil19 CB, is currently used for analysis of the PFBHA derivatized aldehydes. Figure 1 shows as an example of the chromatogram of a water sample spiked with aldehydes. Table 2. EPA methods for the analysis of disinfection by-products (DBPs) in drinking water CompoundsEPA methodProcedureTrihalomethanes502.2Purge and trap, GC-photoionization-electrolytic conductivity detectionTrihalomethanes524.2Purge and trap, GC–MSTrihalomethanes551.1Liquid–liquid extraction, GC-ECDHaloacetic acids552Liquid–liquid extraction, diazomethane methylation, GC-ECDHaloacetic acids552.1Anion exchange resin, acidic methanol methylation, GC-ECDHaloacetic acids552.2Liquid–liquid extraction, acidic methanol methylation, GC-ECDHaloacetic acids552.3Liquid–liquid microextraction, acidic methanol methylation, GC-ECDAldehydes, ketones556Oximation, liquid–liquid extraction, GC-ECD What is it called when we remove pathogens?Disinfection describes a process that eliminates many or all pathogenic microorganisms, except bacterial spores, on inanimate objects (Tables 1 and 2). In health-care settings, objects usually are disinfected by liquid chemicals or wet pasteurization.
What is the destruction of pathogenic microorganisms?Thermal or chemical destruction of pathogenic and other types of microorganisms. Disinfection is less lethal than sterilization because it destroys most recognized pathogenic microorganisms but not necessarily all microbial forms (e.g., bacterial spores).
What is the term for complete destruction or inactivation of all forms of microorganisms on an object?Sterilization: Sterilization is defined as a process of complete elimination or destruction of all forms of microbial life (i.e., both vegetative and spore forms), which is carried out by various physical and chemical methods.
What is sterilization and disinfection?Disinfection and sterilization are both decontamination processes. While disinfection is the process of eliminating or reducing harmful microorganisms from inanimate objects and surfaces, sterilization is the process of killing all microorganisms.
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