Knowledge of water treatment

Basic Concept

Simply put, "water treatment" is the process of removing some substances in water that are not needed for production and life through physical and chemical means.

In order to be suitable for a particular purpose and water settlement, filtration, coagulation, flocculation, and corrosion inhibition, scale inhibition and other water quality conditioning process.

As social production, life and water are closely related, so the field of water treatment involves a wide range of applications, constituting a large industrial applications.

[Edit Paragraph]Related concepts

RO pure water system water treatment preparation

The use of composite agents with good synergistic treatment effect can effectively prevent the formation of scale, microbial slime, improve the system desalination rate, water production. It can effectively prevent the formation of scale and microbial slime, increase the desalination rate and water yield of the system, and prolong the service life of RO membrane.

Adopt the compound preparation having fine coordination treatment effect , can have an effect to prevent scale , the microorganism from gluing Adopt the compound preparation having fine coordination treatment effect , can have an effect to prevent scale , the microorganism from gluing body's formation , improve systematic desalination rate , produce a water yield; Prolong RO film life time.

Risr-RO386 special scale inhibitor

Risr-RO386 Special use hinders the dirty agent

Risr-RO387 special use washes an agent

Circulation chilled water treatment

Circulation chilled water system

Ensure that the cooling water tower, chiller and other equipment in the best operating conditions, effective control of microbial flora, inhibit the production of scale, prevent corrosion of piping equipment. To achieve the purpose of reducing energy consumption and extending the service life of the equipment. Specialized development of water treatment programs, the use of professional composite water treatment agents and improve the technical service system.

Guarantee cooling water tower , cold water machine the platform waits for equipment to be in optimum operation state , effective the group controlling the microorganism bacterium , the creation restraining scale , the corrosion taking precautions against pipeline equipment's. Achieve the life time reducing energy consumption , prolonging equipment's purpose. Special case for investigation works out the water treatment scheme , adopt The special field compound water treatment preparation and perfect technical service system.

Risr-668A/B The sterilization extinguishes the algae medicinal preparation

Risr-LQ512Slow eclipse anti- filthy medicinal preparation

Risr-LQ512Slow eclipse anti filthy medicinal preparation

Risr-586Equipment cleansing agent

Boiler water treatment preparation

Adopting It is a compound preparation with good synergistic effect to prevent corrosion and scaling of boiler, stabilize boiler water quality to ensure normal operation of boiler, reduce consumption of boiler body and prolong its service life.

Adopt the compound preparation having the fine coordination treatment effect , guard against boiler corrosion and fouling, the water quality stabilizing a boiler ensures that the boiler regularity works , reduces the boiler body consumption , prolongs its life time.

Risr-GL668 composite boiler water treatment preparation

Risr-GL668 compound boiler water treatment preparation

Risr-GL658 cleans up the jar agent

Risr- GL638 Agent alkalinity is adjusted

Risr-GL638 Agent alkalinity is adjusted

Lacquer house circulation water treatment preparation

The agent is a composite agent with wide dispersing ability, and the paint sludge treated by it has good dewatering property, and the treated paint sludge is in the form of non-adhesive mass, which is easy to be salvaged for the next stage of treatment. The environmental interface of the agent is friendly and the treatment efficiency is stable. It can effectively prevent paint adhesion in the pipeline equipment brought about by the trouble, and at the same time reduce the COD content in the water body, remove the odor, improve the environment, and extend the service life of the circulating water.

The medicament belongs to compound preparation have general broad dispersing ability, the paint residue dehydration nature that the person The medicament belongs to compound preparation have general broad dispersing ability, the paint residue dehydration nature that the person is fine , the lacquer residue handling is the treatment there being no sticky time as soon as stages such as roll a shape into a ball , easy to salvage. The efficacy stabilizes upright amicable , handle face to face of the medicament environment. Can there be an effect's guarded against a paint sticky attach the harassment in what pipeline equipment brings about , at the same time, reduce wave middle COD contents , eliminate peculiar smell , improve an environment, life time prolonging recirculating water.

Risr-TZ618A Organic paint resin dispersant ( lacquer fog flocculating agent)

Risr-TZ618B suspension agent

Waste water treatment preparation

Waste water treatment Preparation

Adopt reasonable water treatment process, with the depth of water treatment, the treated water can reach GB5084-1992, CECS61-94 water recycling water standards, etc., and can be recycled for a long time, saving a lot of water resources.

Adopt the rational water treatment handicraft, the depth coordinating water's handles, water reclaims in processing water but reaching GB5084 -1992 , CECS61-94 using water standard to wait , to be able to cycle for a long time to be put into use, save large amount of water resource.

Risr-601 Environmental protection type COD special use eliminates an agent

Risr-601 environmental protection type COD special use eliminates an agent

MRisr- 2688 heavy metal catches an agent

MRisr-2688 heavy

The water treatment method can be summarized in three ways: ① the most commonly used is to remove some or all of the impurities in the raw water to obtain the required water quality; ② by adding new components in the raw water to obtain the required water quality; ③ the processing of raw water does not involve the removal of impurities or the addition of new components.

Softening water treatment: chemical "resin" treatment, such as hard water softening.

Commonly used wastewater treatment technologies are biochemical methods, such as activated sludge method (Activated Sludge Process), biological lamination method (Fixed Biofilm Processes), mixed biological method (Combined Biological Processes), etc.; physical-chemical methods, such as granular filtration (Granular Biofilm Process), and so on. Filtration (Granular Media Filtration), Activated Carbon Adsorption, Chemical Precipitation, Membrane Processes, etc. Natural treatment methods, such as Stabilization Ponds. Natural treatment methods, such as Stabilization Ponds (Stabilization Ponds), oxidation ditch method (Aerated or Facultative Lagoons), artificial wetlands (Constructed Wetlands), chemical color Seth resin treatment method.

[edit]Water Treatment Methods

Water Treatment Process:

Wastewater treatment in general consists of the following three levels of treatment: primary treatment is it through mechanical treatment, such as grating, sedimentation or air flotation, to remove the sewage contained in the stone, gravel, and fats and oils. Secondary treatment is biological treatment, the pollutants in the sewage are degraded and converted into sludge by microorganisms. Tertiary treatment is the deeper treatment of the effluent, which involves nutrient removal and disinfection of the effluent by chlorination, ultraviolet radiation or ozone technology. There may be wastewater treatment processes that do not include all of the above processes, depending on the goals of the treatment and the quality of the water.

Mechanical treatment section

The mechanical (primary) treatment section consists of structures such as grids, sedimentation tanks, primary sedimentation tanks, etc. It aims at removing coarse particles and suspended solids, and the principle of treatment lies in the physical separation of solids and liquids to separate pollutants from sewage, and this is the most commonly adopted method of sewage treatment. Mechanical (primary) treatment is a necessary project for all sewage treatment processes (although sometimes some processes omit the primary sedimentation tank), municipal wastewater primary treatment of BOD5 and SS typical removal rate of 25% and 50%, respectively. In biological phosphorus denitrification type wastewater treatment plant, generally do not recommend aeration sedimentation tank to avoid rapid degradation of organic matter removal; in the original sewage water quality characteristics are not conducive to the removal of phosphorus denitrification of the case, the initial sedimentation of the setting or not, as well as set up according to the water quality of the special note of the subsequent process to be carefully analyzed and considered in order to ensure and improve the quality of influent in order to remove phosphorus in addition to the denitrification of the subsequent process.

Sewage biochemical treatment

Sewage biochemical treatment belongs to the second level of treatment to remove non-sedimentable suspended solids and dissolved biodegradable organic matter for the main purpose, the process composition of a variety of different methods can be divided into the activated sludge method, the AB method, the A/O method, the A2/O method, the SBR method, oxidation ditch, stabilization of ponds, the land treatment method, and other methods of treatment. Recently, most of the urban sewage treatment plants use activated sludge method. The principle of biological treatment is through biological action, especially the role of microorganisms, to complete the decomposition of organic matter and the synthesis of living organisms, organic pollutants into harmless gas products (CO2), liquid products (water) and organic-rich solid products (microbial population or biological sludge); excess biological sludge in the settling tank by the sedimentation tank solid-liquid separation from the purified wastewater is removed.

In the sewage biochemical treatment process, the factors affecting the activity of microorganisms can be divided into two categories of matrix and environment:

First, the matrix category includes nutrients, such as organic compounds that are predominantly carbon, nitrogen, phosphorus, and other nutrients, as well as iron, zinc, manganese, and other trace elements; in addition, also includes some toxic and harmful chemicals, such as phenols, benzene compounds, etc., and also includes some heavy metal ions, such as phenol, benzene, etc. In addition, it also includes some toxic chemicals such as phenols, benzene and other compounds, as well as some heavy metal ions such as copper, cadmium, lead ions and so on.

Second, the environmental impact factors are:

(1) temperature. The effect of temperature on microorganisms is very broad, although in the high-temperature environment (50 ℃ ~ 70 ℃) and low-temperature environment (-5 ~ 0 ℃) are also active in some classes of bacteria, but the vast majority of microorganisms in the wastewater treatment of the most suitable for the growth of the temperature range is 20-30 ℃. In the appropriate temperature range, the physiological activities of microorganisms, their activity with the increase in temperature and enhance the treatment effect is also better. Beyond this range, the activity of microorganisms deteriorates and the biological reaction process is affected. Generally, the highest and lowest limits for controlling the reaction process are 35℃ and 10℃ respectively.

(2) PH value. Activated sludge system microorganisms optimal pH range is 6.5-8.5, acidic or alkaline environment is not conducive to the survival and growth of microorganisms, serious sludge flocculation will be destroyed, the bacterial colloid disintegration, the treatment effect of the sharp deterioration.

(3) dissolved oxygen. For aerobic biological reaction, it is vital to maintain a certain concentration of dissolved oxygen in the mixture. When the dissolved oxygen in the environment is higher than 0.3mg / l, parthenogenetic bacteria and aerobic bacteria are aerobic respiration; when the dissolved oxygen is lower than 0.2-0.3mg / l close to zero, the parthenogenetic bacteria are transferred to anaerobic respiration, the vast majority of the aerobic bacteria basically stop respiration, while some of the aerobic bacteria (most of them are filamentous bacteria) may also be good growth, often leading to sludge expansion after the dominance in the system. In general, the dissolved oxygen at the exit of the aeration tank to maintain 2mg / l or so appropriate, too high is to increase energy consumption, the economy is not cost-effective.

In all the factors affecting the substrate class factors and PH value is determined by the quality of the influent water, the control of these factors, mainly by the daily monitoring and the strict implementation of relevant regulations and laws. For general urban sewage, most of these factors do not constitute too much impact, the parameters can basically be maintained within the appropriate range. Temperature changes related to climate, for 10,000 tons of municipal wastewater treatment plant, especially when using activated sludge process, the control of temperature is difficult to implement, economically and engineering are not very feasible. Therefore, it is generally through the appropriate selection of design parameters to meet the treatment requirements of different temperature variations in order to achieve the treatment objectives. Therefore, the main target of process control falls on the activated sludge itself and the environmental factors that can be changed by means of regulation, and the main task of control is to take appropriate measures to overcome the influence of external factors on the activated sludge system, so that it can continue to play a stable role.

The key to realizing the process control of the biological reaction system lies in the selection of the control object or control parameter, which is closely related to the treatment process or treatment target.

As mentioned before, dissolved oxygen is a very important indicator parameter in the type and process of biological reaction, it can intuitively and relatively quickly reflect the operating conditions of the entire system, easy to operate and manage, instruments, instrumentation installation and maintenance is also relatively simple, which is also the reason that in the past decade China's new wastewater treatment plants are basically realized on-site and online monitoring of dissolved oxygen.

Tertiary treatment:

Tertiary treatment is the depth of water treatment, now our sewage treatment plant into the actual application is not much. It will be after the secondary treatment of water for denitrogenation, dephosphorization, activated carbon adsorption or reverse osmosis to remove the remaining pollutants in the water, and ozone or chlorine disinfection to kill bacteria and viruses, and then the water will be treated into the waterway, as toilet flushing, spraying the streets, watering the green belts, industrial water, fire prevention and other water sources.

It can be seen that the role of the sewage treatment process is only through biological degradation and solid-liquid separation, in order to purify the sewage at the same time the pollutants will be enriched to the sludge, including the primary treatment section of the primary sludge, secondary treatment section of the residual activated sludge and tertiary treatment of chemical sludge. As these sludge contains a large amount of organic matter and pathogens, and is very easy to rot and odor, it is easy to cause secondary pollution, the task of eliminating pollution has not been completed. Sludge must be properly disposed of through certain volume reduction, volume reduction and stabilization of harmless treatment wells. The success or failure of sludge treatment and disposal has an important impact on sewage plants and must be emphasized. If the sludge is not treated, the sludge will have to be discharged with the treated effluent and the purification effect of the sewage plant will be canceled out. So in practice, the sludge treatment in the sewage treatment process is also quite critical.

General water treatment methods and principles

Commonly used water treatment methods are: (a) sediment filtration, (b) hard water softening, (c) activated carbon adsorption, (d) deionization, (e) reverse osmosis, (f) over the filtration method, (g) distillation, (h) ultraviolet disinfection, etc., and now the principles of these treatments and the function of the method is explained here.

A sediment filtration method: sediment filtration method is the purpose of the water source of suspended particulate matter or colloidal material to remove the clean. If these particles are not removed, the dialysis water will cause damage to other precision filter membranes or even blockage of the waterway. This is the oldest and simplest method of water purification, so this step is often used in the initial stages of water purification or, if necessary, a few more filters are added to the piping to remove larger impurities. Filtration of suspended particulate matter used in many types of filters, such as mesh filters, sand filters (such as quartz sand, etc.) or membrane filters. As long as the size of the particles is larger than the size of these holes, they will be blocked. Ions dissolved in water cannot be blocked. If the filter is not replaced or cleaned for a long time, the particulate matter accumulated on the filter will be more and more, and the water flow rate and water pressure will be gradually reduced. People are the use of water pressure and water pressure difference to determine the degree of blockage of the filter. Therefore, the filter should be backflushed regularly to eliminate the accumulation of impurities on it, and also to replace the filter in a fixed period of time.

Sediment filtration method there is a problem worth noting, because the particulate matter is constantly blocked and accumulated, these substances may be bacteria on the surface of the propagation, and the release of toxic substances through the filter, resulting in a pyrogenic reaction, so it is necessary to frequently replace the filter, in principle, the pressure difference between the water inlet and outlet water rises up to the original five times, you need to change out of the filter.

Second, hard water softening method: the softening of hard water need to use the ion exchange method, its purpose is to use cation exchange resin to sodium ions to exchange hard water calcium and magnesium ions, * this to reduce the concentration of calcium and magnesium ions in the water source. The softening reaction formula is as follows:

Ca2++2Na-EX→Ca-EX2+2Na+1

Mg2++2Na-EX→Mg-EX2+2Na+1

EX in the formula represents the ion-exchange resins, which will release Na+ ions that were originally contained in the ion exchange resins, after combining Ca2+ and Mg2+. The Na+ ions that were in the ion exchange resin are released.

Commercially available ion exchange resins are spherical, synthetic organic polymer electrolytes. Resin matrix (resin matrix) hidden sodium chloride, in the process of hard water softening, sodium ions will gradually be used up, the softening effect of the exchange resin will gradually decrease, then the need to make the reduction (regeneration) work, that is, every fixed period of time to add a specific concentration of brine, generally 10%, the reaction is as follows:

Ca Hard Water Syndrome. Hard water softener will also cause bacterial reproduction problems, so the equipment needs to have a backwash function, after a period of time to backwash once to prevent too many impurities adsorbed on it. Another noteworthy problem is hypernatremia, because the dialysis water softening and re-reduction process is * timer to control the normal situation of reduction occurs mostly in the middle of the night, which is * valve in the control, if there is a malfunction, a large amount of brine will be flooded into the water supply, which will cause the patient's hypernatremia.

Third, activated carbon: Activated carbon is made of wood, wood chips, fruit kernels, coconut shells, coal or petroleum dregs and other substances at high temperatures in the dry distillation of carbonization, made after the need for hot air or water vapor to be activated. Its main function is to remove chlorine and chloramines as well as other dissolved organic substances with a molecular weight of 60 to 300 daltons. Activated carbon surface is granular, the internal is porous, there are many holes about 1Onm ~ lA size of the capillary, 1g of the internal surface area of the activated carbon as high as 700-1400m2, and these capillary surface and the surface of the particles is the adsorption of the role of the place. Factors affecting the ability of the activated carbon to remove organic matter is the area of the activated carbon itself, the size of the pore and the molecular weight of the organic matter to be removed and its polarity (Polarity), it is the main * physical adsorption capacity to exclude debris, when the adsorption capacity up to the saturation of the adsorption of excessive impurities will fall down to contaminate the downstream of the water quality, so it must be timed to use the backwash to remove the adsorption of its way to remove the impurities on the way.

This activated carbon filter if the adsorption capacity is significantly reduced, must be updated. Determine the difference between the TOC concentration of the influent and effluent water (or the difference in the number of bacteria) is one of the bases for considering the replacement of activated carbon. Some reverse osmosis membrane chlorine tolerance is not good, so before reverse osmosis to have active carbon treatment, so that chlorine can be effectively adsorbed by the activated carbon, but the pores on the activated carbon adsorption of bacteria are easy to reproduce and grow, at the same time for the removal of molecules of larger organics, the efficacy of the activated carbon is limited, so it must be * reverse osmosis membrane in the back of the reinforcement.

Fourth, the deionization method: The purpose of the deionization method is to dissolve the inorganic ions in the water to exclude the same as hard water softeners, but also the use of the principle of ion exchange resins. In this use two kinds of resin - cation exchange resin and anion exchange resin. The cation exchange resin utilizes hydrogen ions (H+) to exchange cations; while the anion exchange resin utilizes hydroxide ions (OH-) to exchange anions, and the hydrogen ions and hydroxide ions combine with each other to form neutral water, and the reaction equation is as follows:

M+x+xH-Re→M-M-Rex+xH+1

A-z+zOH-Re→A-Rez +zOH-1

In the above equation, M+x is the cation, x is the valence number, M+x cation exchanges with the hydrogen ion of H-Re on the cation resin, A-z is the anion, z is the valence number, A-z releases OH- ions when it combines with the anion exchange resin, and the combination of H+ ions and OH- ions makes neutral water.

These resins also need to be restored after the adsorption capacity is exhausted. Cation exchange resins need strong acids to be restored; on the contrary, anions need strong bases to be restored. The adsorption capacity of cation exchange resins for various cations varies, and their strengths and relative relationships are as follows:

Ba2+>Pb2+>Sr2+>Ca2+>Ni2+>Cd2+>CU2+>Co2+>Zn2+>Mg2+>Ag1+>Cs1+>Cs1+>Cs1+>Cs1+>Cs1+>Cs1+>Cs1+>Cs1+>Cs1+> and gt;Cs1+>K1+>NH41+>Na1+>H1+

The strengths of affinity of the anion exchange resin for each anion are as follows:

S02-4+>I->NO3->NO2->Cl->HCO3->OH->F-

If the anion exchange resin is consumed and not restored, fluorine, which has the weakest adsorption, will gradually appear in the dialysis water, resulting in chondropathy, osteoporosis, and other bone pathologies; if the cation exchange resin is consumed, hydrogen ions will also appear in the dialysis water, resulting in an increase in the acidity of the water quality, so the deionization function is effective or not, and needs to be monitored from time to time. Generally, the resistance coefficient (resistivity) or conductivity of the water quality is used to determine the effectiveness of the deionization function. Deionization method used by the ion exchange resin can also cause bacterial reproduction caused by bacteremia, which is worth noting.

V. Reverse Osmosis: Reverse Osmosis can effectively remove inorganic and organic matter dissolved in water, bacteria, pyrogens and other particles, and is the most important part of the treatment of dialysis water. To understand the principle of "reverse osmosis", it is necessary to explain the concept of "osmosis" first. The so-called osmosis refers to a semi-permeable membrane separating two different concentrations of solution, in which the solute can not pass through the semi-permeable membrane, the concentration of the lower side of the water molecules will pass through the semi-permeable membrane to reach the concentration of the other side of the higher side, until both sides of the concentration of the two sides of the same until. Before reaching equilibrium, you can gradually apply pressure on the side of the higher concentration, the aforementioned water molecules will temporarily stop the state of movement, at this time the required pressure is called "osmotic pressure (osmotic pressure)", if the force exerted is greater than the osmotic pressure, then the movement of water will be in the opposite direction, that is, from a high concentration of a case to the side of a low concentration, this phenomenon is called "reverse osmosis". This phenomenon is called "reverse osmosis". The purification effect of reverse osmosis can reach the level of ions, for monovalent ions (monovalent ions) exclusion rate (rejection rate) up to 90%-98%, and bivalent ions (divalent ions) up to 95%-99% or so (molecular weight of the substance can be prevented from passing through the more than 200 dalton).

Reverse osmosis water treatment commonly used semi-permeable membrane materials are fibrous membrane (cellulosic), aromatic polycondensate amines (aromatic polyamides), polyimide or polyfuranes, etc., as for the structure of the shape of the spiral (spiral wound), hollow fiber (hollow fiber) and tubular. As for its structural shape, there are spiral wound, hollow fiber and tubular. Among these materials, cellulose membrane has the advantage of high chlorine resistance, but its service life will be shortened under alkaline conditions (pH ≥ 8.0) or the presence of bacteria, while polyamide has the disadvantage of poor resistance to chlorine and chloramines. The decision as to which material is preferred is not yet conclusive.

If the reverse osmosis is not properly pre-treated before the osmosis membrane is prone to dirt accumulation, such as calcium, magnesium, iron and other ions, resulting in a decline in the reverse osmosis function; some membranes (such as polyamide) are easily destroyed by chlorine and chlorine-ammonia, so before the reverse osmosis membrane should be activated carbon and softeners and other pre-treatment. Although the price of reverse osmosis is higher, because the pore size of the reverse osmosis membrane is about l0A or less, it can exclude bacteria, viruses and pyrogens and even a variety of dissolved ions, so it is best to prepare this step in the preparation of hemodialysis dialysis water.

Sixth, over the filtration method: over the filtration method and reverse osmosis method is similar to the use of semi-permeable membranes, but it can not control the removal of ions, because the pore size of the membrane is larger, about 10-200A between. It can only remove bacteria, viruses, pyrogens and particulate matter, but not water-soluble ions. The main function of ultrafiltration is to act as a pre-treatment for reverse osmosis to prevent the reverse osmosis membrane from being contaminated by bacteria. It can also be used in the final step of water treatment to prevent bacterial contamination of upstream water in the pipeline. Generally use the inlet water pressure and outlet water pressure difference to determine whether the over-filtration membrane is effective, similar to the activated carbon, usually to reverse flushing method to remove the impurities attached to it.

Seventh, distillation: distillation is an ancient but also effective water treatment method, it can remove any non-volatile impurities, but can not exclude volatile pollutants, it requires a large storage tank to store the tank and delivery pipe is an important cause of contamination, hemodialysis water is not used to deal with this way.

Eight, ultraviolet disinfection: ultraviolet disinfection is one of the commonly used methods, its sterilization mechanism is to destroy the life of bacterial nucleic acid genetic material, so that it can not reproduce, the most important reaction is the nucleic acid molecules within the pyrimidine salt group into a double (dimer). Generally, the artificial 253.7nm wavelength of ultraviolet energy is used in low-pressure mercury discharge lamps. The principle of UV germicidal lamps is the same as that of fluorescent lamps, except that the inner tube is not coated with fluorescent material, and the material of the tube is quartz glass with a high UV penetration rate. The general UV device according to the use of irradiation type, immersion type and water type.

The ultraviolet light used in hemodialysis dilution water is placed in the water storage tank to the pipeline between the dialysis machine, that is, all the dialysis water in the use of the water before the use of ultraviolet radiation, in order to achieve the effect of complete sterilization. The most susceptible to UV light are Pseudomonas aeruginosa and E. coli; on the contrary, the more tolerant are Bacillus subtilis. Because the ultraviolet disinfection method is safe, economical, less selective of bacteria, water quality will not change, so in recent years has been widely used in this way, for example, the ship's drinking water is often used in this disinfection method

[Edit Paragraph]Three ways of water treatment in the field

On the field of water is not to be treated before drinking, each person is a different idea of each person. Some people think that the wilderness is sparsely populated, that there will be what pollution, drink it all right. In fact, as long as we are such amateurs can get to, that there can be what really no pollution in the place? In fact, even if there is no pollution, it does not mean that there is no virus, bacteria, or all kinds of harmful substances in the water. In the conditions permit, can be treated or the best. Nowadays, the main ways of water treatment are boiling, water purification drugs and filters Boiling This is the most practical and effective means. The disadvantages are that it is a waste of fuel (with the exception of the zip stoves I've described) and it is time consuming. Using water purification tablets is sort of a chemical approach to purification, mostly using chlorine and iodine. The mainstay of the market is the use of iodine. For example, in the picture above, the white bottle is iodine tablets. Iodine tablets need to be stored away from light and moisture. The advantages of water purification tablets are that they are cheap, convenient and lightweight. They are time-consuming, and you can't drink them until about 20 minutes after you add them to the water purification tablets. The disadvantage is that there is an odor and color. This can be solved by post-processing, such as the bottle of yellow tablets above, is used to deodorize. Or add some Fruity Jane or something. Secondly, there is a major virus that cannot be removed, cryptosporidium, which is probably the most common water parasite. Thirdly, they are prone to allergies and can react chemically with certain foods or utensils. Overall, water purification tablets have a big market because they are lightweight, cheap and small. One thing to keep in mind when using them is to always wait at least 20 minutes, and secondly, don't use them continuously for more than a week. Purification filters There are actually two classifications in this, filters and filter purifiers. The main difference is that filters remove bacteria and parasites by filtration. Er filter purifiers remove bacteria and parasites in addition to viruses. (Classification based on REI) Filters A filter purifier in general removes viruses by chemically going out on top of filtration, such as iodizing, so it also has the drawbacks of the water purification tablets that chemically purify the water in front of it. The one posted above is claimed to be the only water purifier that does not use chemical means to remove viruses. The advantage of using a purification and filtration unit is that the water is instantly available, with little to no wait, and it is almost always the safest way to purify water (if you use a filtration purifier). The disadvantages are that they are expensive, rarely less than $60 USD, and the cost of the cartridges is high later on. They are bulky and heavy, almost always costing more than 1 lbs. They also require frequent maintenance when in use and are prone to clogging. Each of the three ways has its own strengths, how to choose is each person's point of view.