Companies:   Apec Water    AquaNu  Evoqua Water Technologies  ESP Water Products

Halosource  Hosptial Supply Corporation    Proctor & Gambel   (water floculation agent used to provide clean water) BioSciences Inc  Siemens   Water Research Center  

Winter Water

Water/Waistewater Training: University of Florida 

Miami Dade Water Quality Reports

Safe Aquatic Herbicides:

Solitude Lake Management

Contaminants in Tap Water

Chlorine and organic substances: As Tap or city water is subjected to chlorination with chlorine gas or sodium hypochlorite, it contains residual chlorine dissolved in the form of hypochlorous ion (CLO-_ or hypochlorous acid (HCLO). Such residual chlorine gives rise to a smell or bleaching powder odor. Tap water also contains a small amount of organic chlorine compounds, including trihalomethane compounds such as chloroform CHCl3 an bromodichloromethane (CHCl2Br, which are prooduced by reaction of chlorine with organic substances. The presence of trihalomethane compounds in tap water is drawing increasing public attention as they are carcinogenic, harmful subjstances. In addition, phytoplanktons tend to increase and propagate in water sources due to water pollution so that smelly or malodorous organic substances which presumably are metabolite or secreta of phytoplanktons are present in a small content. These substances generally referred to as “musty-smelling” substances. (Hiasa (US 5,607,595). 

Chloramines: Increasingly drinking water utilities are gradually switching over to the use of choramines – in particular, monochloramine – disinfection of drinking water. In general, chlroamines are safe in drinking water in low dosages. 

Microbiological contaminants

Total coliform Bacteria should be tested.

Inorganic contaminants:

Include antiomny, arsenic, barlum, chromium, copper, fluoride, lead nitrate, nitrite, selenium and sodium. 

Radiactive contaminants:

includ alpha emitters, combined radium and uranium. 

Methods/Substances used to Purify Water

Activated Carbon

Activated carbon refers to carbonaceous substances that are characterized primarily by their surface area, pore size distribution and sorptive and catalytic properties. Activated carbon can be made from a variety of carbonaceous materials and processed to enhance its adsorptive properties. Some common materials that are used to make activated carbon are bituminous coal, bones, coconut shells, lignit, peat, pecan shells, petroleum based residues, pulp mill black ash, surgar, wastwater treatment sludge and wood. Carbon and other adsorbents in various forms have been used for the treatment of water and as detoxifying pharmaceutical agents in medicine for many centuries. Graculated activated carbon (GAC) and powdered activated carbon (PAC) have been used in the US to control taste and odors in drinking water. Today, there are GAC beds in US water treatment plants.

Activated carbon has been used in water purification processes (Cehn, J. Biol. Chem, 242: 173-181 (1967); Nakano, Anal Biochem, 129, 64-71 (1983); Nikolaev Int. J. Art. Rog, 14: 179-185 (1991). Typical activation processes involve subjecting a carbon source such as resin wastes, coal, coal coke, petroleum coke, lignites, polymeric materials and lignocellulosic materials including pulp and paper, wood, nut shell to a thermal process (e.g., with an oxidizing gas) or a chemical process (e.g., with phosphoric acid or metal sals, such as zinc chloride). An exemplary chemical activaiton of wood based carbon with phosphoric acid (H3PO4) is disclosed in US Re. 31,093 and US 5,162,286 teaches phosphoric acid activaiton of wood based material. 

There are several differnt types of activated carobn filters commercially avilable, including service carbon, backwashable carbon and steam or hot water sanitizable carbon (Siemens Water Treatment Technologies).

–For purification of Tap Water: 

A conventional process for producing drinking water involves screening which separates out the coarse impurities, pretreatment by introducing reagents followed by flocculation and settling so as to eliminate materials in suspension, sand filtering during which ammonia is biologically  nitriified and impurities in suspension are eliminated, injetion of ozone to kill bacterai and viruses, filtering by gracular activated carbon to eliminate organic materials and chlorination (Montagnon US5,037,550). 

Conventionally, water purifying devices have been used for domestic purposes in order to remove harfmful and smelly substances. In early water purifiers, it has been customary to use granular activated charcoal which is capable of removing resiude chlorine as well. It is believed that residual chlorine is removed by chemical adsorption at the active sites located at the surface of activated charcoal and thus adsorption capability of granula activated charcoal is dependent on the specific surface area of activated charcoal. In constrast, trihalemthanes and smelly organic substances are believed to be physically adsorbed by activated charcoal, with the hydrated molecules being trapped in the micropores of activated charcoal. In recent water purifiers, activated carbon fibers manufactured by carbonizing acrylic or phenolic fibers follwoed by activation have been increaseingly used because of the iproved adsorption speed as compared with granular activated charcoal and due to the advantage of having a narrower pore diameter distribution. In this instance, typical water purifiers markedted today are designed such that carttridges of activated carbon fibers are replaced each 6 months or a year. (Hiasa (US 5,607,595). 

Mouri 9US2005/0181931) discloses a removing agent for heavy metal such as chromium, manganese, cadmium, lead and mercury, particularly lead in water containing synthetic zeolite in which 10% or more of the total amount of exchangeable cation is substituted with magnesium ion and 60% or more is substituted with magnesium and calcium ion and activated carbon at a ratio of 2:98 to 50:50. In addition, the concurrent sue of this calcium and magnesium type zeolite with activated carbon at a specific ratio allows a superior adsorbent, which does not remove calciu and magensium ion and can efficiently remove residual chlorine and trihalomethane. 

–Filters with Activated Carbon:

Farrelly (US2009/0188854) discloses a filter device comrpising a housing for securing to a source and having an upstream filter elelment of coarse particle size and downstream filter element of fine filter size. Granulated activated carbon materials dervied form charcoal is provided in the filter chambers for removing and elimating bacteria such as E coli as well as chemical and metals including iron form water.

Mitchel (US2003/0217963) discloses a filter for providing potable water. The filter includes a housing having an inlet and outlet and a filter materials in the housing formed at least in part from activated carbon filter particles.

Air Stripping: is a process of moving air through contaminated groundwater or surface water in an above group treatment system. Air stripping removes chemicals called “volatile organic compounds” or “VOCs”. VOC easily evaporate, which means they can change from a liquid to a gas. The air passing through contaminated water helps evaporate VOCs faster. After treating the water, the air and chemical vapors are collected and either removed or vented outside if VOC levels are low enough. Air tripping is commonly used at public water treatment plants, particularly where the water contains organic materials. 

–Particular Schemes using Activated Carbon

—-AC-CEX–AEX

Hall (US 4,474,620) disclsoes a water purificaiton aprratus which has an untreated water reservoir at the top. The untreated water flows by gravity through a series of three water treatment beds containing AC, CEX and AEX. The media in each chamber is in cartridge form and may be easily removed. Treated water from the final chamber is collected in a reservoir. 

Flocculant/Disinfectant Powders

–Ferric sulfate –calcium hypochlorite

P&G has developed a pwodered derric sulfate (a flocculant) and calcium hypochlorite (a disnfectant) for the purification of water. One opens the sachet, adds the contents to an open bucket containing 10 liters of sater, stirs for 5 minutes, let the solids settle to the bottom of the bucket, strains the water through a cotton cloth into a second containing and waits 20 mninutes for the hypochlorite to inactivate the microorganisms.

Ozonation    see Water Research Center

Reverse Osmosis: 

Reverse osmosis (RO) membranes provide a cost effective water purificaiton solution for wastewater reclamation facilities and are an integral part of many public water treatment plants. Advantages of RO systems are that (1) they are simple to design and operate, have low mintenance requirements and are modular in nature, making expansion easier, (2) both inorganic and organic contaminatns can be removed, (3) there is no effect on the material being recvoered and RO prcoesses can reduce the volume of waste streams so that these can be treated more efficiently and cost effectively by other processes such as incineration. In addition, RO systems can replace or be used in conjunction with other treatment processes such as oxidation, adsorption, stripping or biological treatment to produce high quality water. 

Water Filtration:

Products:  LifeSaver Bottle

Filtration is a physical process that occurs when liquids, gases, dissolved or suspended matter adhere to the surface of, or in the pores of, an absorbent medium. Filtration of contaminants depends highly on the amount of contaminant, size of the contaminant particle, and the charge of the contaminant particle. Depending on the household’s water needs, pretreatment before filtration may include the addition of coagulants and powdered activated carbon, adjustments in pH or chlorine concentration levels, and other pretreatment processes in order to protect the filter’s membrane surface. See CDC

Physical removal of waterborne Crytosporidium oocysts and Giardia cysts is ultimately achieved by properly functioning conventional filters, providing that effective pretreatment of the water is applied. Disinfection by chemical or physical methods is finally required to inactivate/remove the infectious life stages of these organisms. See Bentancourt

Membrane filtration systems have long been used for water and waste-water treatment, with applications primarily in reverse osmosis plants in water-scarce regions. Of the membrane filters, ultrafiltration membranes with a typical pore size between 0.002 and 0.1 μm have shown higher removal of pathogens such as Cryptosporidium, Giardia, and bacteria, viruses, and parasites. See Francis

Katouli evaluated the efficiency of five membrane filters for recovery of Cryptosporidium parvum oocysts and Giardia lamblia cysts. These filters included the Pall Life Sciences Envirochek (EC) standard filtration and Envirochek high-volume (EC-HV) membrane filters, the Millipore flatbed membrane filter, the Sartorius flatbed membrane filter (SMF), and the Filta-Max (FM) depth filter. Distilled and surface water samples were spiked with 10 oocysts and 10 cysts/liter. They also evaluated the recovery efficiency of the EC and EC-HV filters after a 5-s backwash postfiltration. The backwashing was not applied to the other filtration methods because of the design of the filters. Oocysts and cysts were visualized by using a fluorescent monoclonal antibody staining technique. For distilled water, the highest percent recovery for both the oocysts and cysts was obtained with the FM depth filter. However, when a 5-s backwash was applied, the EC-HV membrane filter (EC-HV-R) was superior to other filters for recovery of both oocysts (n
53 15.4 per 10 liters) and cysts (n
59 11.5 per 10 liters). This was followed by results of the FM depth filter (oocysts, 28.2 8, P
0.015; cysts, 49.8 12.2, P
0.4260), and SMF (oocysts, 16.2 2.8, P
0.0079; cysts, 35.2 3, P
0.0079). Similar results were obtained with surface water samples. Giardia cysts were recovered at higher rates than were Cryptosporidium oocysts with all five filters, regardless of backwashing. Although the time differences for completion of filtration process were not significantly different among the procedures, the EC-HV filtration with 5-s backwash was less labor demanding.

Absorption: In Tata Swach, adsorption is through rice husk ash (activated silica and activated carbon) which is impregnated with silver nanoparticles to target microbes.

Coagulation and filtration is one of the most common water treatment techniques used by larger water systems, used for removing particulates and turbidity from surface water. A coagulant (typically either iron or aluminum salts with polymeric materials) is added and mixed with the influent water. The larger particles formed by coagulation are then removed from the water by filtration (typically sand, anthracite coal, or a combination of the two). See EPA

Microfiltration: A microfiltration filter has a pore size of approximately 0.1 micron (pore size ranges vary by filter from 0.05 micron to 5 micron). Microfiltration has a very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia). Microfiltration has a moderate effectiveness in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli); Microfiltration is not effective in removing viruses (for example, Enteric, Hepatitis A, Norovirus, Rotavirus); Microfiltration is also not effective for removing chemicals. See CDC

Ultrafiltration:  An ultrafiltration filter has a pore size of approximately 0.01 micron (pore size ranges vary by filter from 0.001 micron to 0.05 micron; Molecular Weight Cut Off (MWCO) of 13,000 to 200,000 Daltons). Ultrafiltration filters remove particles based on size, weight, and charge; Ultrafiltration has a very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia); Ultrafiltration has a very high effectiveness in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli); Ultrafiltration has a moderate effectiveness in removing viruses (for example, Enteric, Hepatitis A, Norovirus, Rotavirus); Ultrafiltration has a low effectiveness in removing chemicals. See CDC

There are modular variants of U. F purifiers which are suitable for community scale like SkyHydrant, Lifestraw Family and also mobile variants like Jaldoot and Perferctor E. Several stationary household UF purifiers are available like Moselle, Jaltara and Waterife Little Star Gold. See Kedare

There is a unique experiment with plant xylem-based ultrafiltration. Bacteria up to 3 LRV can get filtered out with sapwood (predominantly xylem) of trees like pine which is easily available, inexpensive, biodegradable and suitable for resource-constrained environments. See Kedare

Nanofiltration:  A nanofiltration filter has a pore size of approximately 0.001 micron (pore size ranges vary by filter from 0.008 micron to 0.01 micron; Molecular Weight Cut Off (MWCO) of 200 to 2000 Daltons); Nanofiltration filters remove particles based on size, weight, and charge; Nanofiltration has a very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia); Nanofiltration has a very high effectiveness in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli); Nanofiltration has a very high effectiveness in removing viruses (for example, Enteric, Hepatitis A, Norovirus, Rotavirus); Nanofiltration has a moderate effectiveness in removing chemicals.

Reverse Osmosis: Links of interest: Elsevier. EPA.   Companies: See AquaSana

Reverse Osmosis Systems use a process that reverses the flow of water in a natural process of osmosis so that water passes from a more concentrated solution to a more dilute solution through a semi-permeable membrane. Pre- and post-filters are often incorporated along with the reverse osmosis membrane itself. A reverse osmosis filter has a pore size of approximately 0.0001 micron. Reverse Osmosis Systems have a very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia);  Reverse Osmosis Systems have a very high effectiveness in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli); Reverse Osmosis Systems have a very high effectiveness in removing viruses (for example, Enteric, Hepatitis A, Norovirus, Rotavirus); Reverse Osmosis Systems will remove common chemical contaminants (metal ions, aqueous salts), including sodium, chloride, copper, chromium, and lead; may reduce arsenic, fluoride, radium, sulfate, calcium, magnesium, potassium, nitrate, and phosphorous, See CDC

Unlike activated carbon filtration technology that uses certain materials to attract contaminants that bind like magnets, reverse osmosis uses a semi-permeable membrane for filtration. Think of it like a mosquito net. Reverse osmosis forces water through a semipermeable membrane, leaving all particles larger than the net behind.  It uses a considerable amount of water pressure, making it the most effective water purification technique on the market. See AquaSana

Solar Water Disinfection

Companies: GoSun

Products: GoSun Flow. Solvaten.

Solar water disinfection is a sort of portable water purification that cleans water through solar energy in order to remove contaminants such as bacteria, viruses, and protozoa. It does so through a mixture of electricity generated by solar PV panels, solar heating, or solar ultraviolet light collection. Solar disinfection, which combines thermal and UV radiation, has been repeatedly shown to be effective for eliminating microbial pathogens and reduce diarrhoeal morbidity (Hobbins 2004) including epidemic cholera (Conroy 2001). Among the most practical and economical is the “SODIS” system, developed and promoted by the Swiss Federal Institute for Environmental Science and Technology.

It is well documented that solar energy can be an effective means of cleaning contaminated water. This is because ultraviolet (UV) light destroys the formation of DNA linkages in microorganisms, thereby preventing them from reproducing and thus rendering them harmless. The World Health Organization  lists solar disinfection in clear bottles by the combined action of UV radiation, as well as thermal disinfection (pasteurization) in opaque vessels with sunlight from solar cookers or reflectors and combination systems employing chemical coagulation-flocculation as some of the most promising and accessible technologies for household water treatment. See Climate Technology Center

SODIS: 

Popularly abbreviated as SODIS, solar water disinfection is a simple, safe, economical and effective method of disinfecting contaminated water. The method simply involves the use of sunlight and plastic PET bottles for purifying or improving the quality of drinking water.  See Water Treatment Plants

Solar disinfection (SODIS) was developed in the 1980s to inexpensively disinfect water used for oral rehydration solutions. In 1991, the Swiss Federal Institute for Environmental Science and Technology began to investigate and implement SODIS as a household water treatment option to prevent diarrhea in developing countries. Users of SODIS fill 0.3-2.0 liter plastic soda bottles with low-turbidity water, shake them to oxygenate, and place the bottles on a roof or rack for 6 hours (if sunny) or 2 days (if cloudy). The combined effects of ultra-violet light (UV)-induced DNA damage, thermal inactivation, and photo-oxidative destruction inactivate disease-causing organisms. See CDC

Fontan discloses water samples of 0, 5, and 30 nephelometric turbidity units (NTU) spiked with Cryptosporidium parvumoocysts were exposed to natural sunlight using a 25-L static solar reactor fitted with a compound parabolic collector (CPC). The global oocyst viability was calculated by the evaluation of the inclusion/exclusion of the fluorogenic vital dye propidium iodide and the spontaneous excystation. After an exposure time of 8 hours, the global oocyst viabilities were 21.8 ± 3.1%, 31.3 ± 12.9%, and 45.0 ± 10.0% for turbidity levels of 0, 5, and 30 NTU, respectively, and these values were significantly lower (P < 0.05) than the initial global viability of the isolate (92.1 ± 0.9%). The 25-L static solar reactor that was evaluated can be an alternative system to the conventional solar water disinfection process for improving the microbiological quality of drinking water on a household level, and moreover, it enables treatment of larger volumes of water (> 10 times). See Fontan

Solar radiation and heat produced by the sun have a synergistic effect in killing cysts of Giardia duodenalis and Entamoeba histolytica/dispar when temperatures rise above 50°C, with complete death at 56°C, using painted 2‐l PET containers. See Mduluza

However, despite an extensive SODIS promotion campaign Coliford found only moderate compliance with the intervention and no strong evidence for a substantive reduction in diarrhoea among children. These results suggest that there is a need for better evidence of how the well-established laboratory efficacy of this home-based water treatment method translates into field effectiveness under various cultural settings and intervention intensities. Further global promotion of SODIS for general use should be undertaken with care until such evidence is available. See Coliford 

Ion Exchange

During ion exchange treatment, water is passed through a resin containing exchangeable ions. Stronger binding ions displace weaker binding ions and are removed from the water. There are two types of ion exchange—anion exchange and cation exchange. Anion exchange resins generally exchange chloride for anionic contaminants, like uranium. Cation exchange resins generally exchange sodium or potassium for cationic contaminants, such as radium. Mixed bed resins with cation and anion exchange media in two layers are available for systems that need to remove both radium and uranium.  Ion exchange is also effective for the removal of beta particles and photon emitters. See EPA

Chemical Treatment 

Chlorination is a simple, affordable and scalable method of water disinfection through the use of sodium hypochlorite NaOCl (liquid) (Fig. 6), NaDCC (solid) and calcium hypochlorite (Ca(OCl)2) (solid). It gives residual protection due to the availability of free chlorine; however, there may not be any improvement in terms of turbidity. With a dosage of 2 mg/L for about 0.5 h, chlorination can offer about 3 LRV of enteric bacteria. For a reduction in turbidity as well as microbial disinfection, combined methods such as coagulant/flocculant as well as chemical disinfectant powders/tablets are used. See Kaderi.

Chlorine in one form or another is by far the most commonly used chemical for the disinfection of water supplies. It is also active for other purposes assocIated with water treatment and supply, such as prevention of algal, bacterial and general slime growths in treatment plants and pipeworks, control of tastes and odours, and removal of ¡ron, manganese and colour See WHO

Other Water Purification Techniques:

Distillation Systems use a process of heating water to the boiling point and then collecting the water vapor as it condenses, leaving many of the contaminants behind. Distillation Systems have a very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia); Distillation Systems have a very high effectiveness in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli); Distillation Systems have a very high effectiveness in removing viruses (for example, Enteric, Hepatitis A, Norovirus, Rotavirus); Distillation Systems will remove common chemical contaminants, including arsenic, barium, cadmium, chromium, lead, nitrate, sodium, sulfate, and many organic chemicals.  See CDC

Ultraviolet Treatment with pre-filtration is a treatment process that uses ultraviolet light to disinfect water or reduce the amount of bacteria present.Ultraviolet Treatment Systems have a very high effectiveness in removing protozoa (for example, Cryptosporidium, Giardia); Ultraviolet Treatment Systems have a very high effectiveness in removing bacteria (for example, Campylobacter, Salmonella, Shigella, E. coli); Ultraviolet Treatment Systems have a high effectiveness in removing viruses (for example, Enteric, Hepatitis A, Norovirus, Rotavirus); Ultraviolet Treatment Systems are not effective in removing chemicals. See CDC

Aquaguard Compact is an example of UV-based purifier. See Kedare

Water Softeners use ion exchange technology for chemical or ion removal to reduce the amount of hardness (calcium, magnesium) in the water; they can also be designed to remove iron and manganese, heavy metals, some radioactivity, nitrates, arsenic, chromium, selenium, and sulfate. They do not protect against protozoa, bacteria, and viruses. See CDC

Herbal Remedies: 

–Tulsi leaves (Ocmium sanctum) & Neem leaves (Azadirachta indica) have the capacity to purify water. See Tanushree

–Moringa oleifera Lam belongs to the family Moringaceae and is a valuable plant, found in many countries of the tropics and subtropics. Its leaves, fruit, flowers and immature pods are used as a highly nutritive vegetable in many countries, particularly in India, Pakistan, Philippines, Hawaii and many parts of Africa. Seed extract is observed to have a protective effect by decreasing liver lipid peroxides and is antihypertensive.  M. oleifera roots, leaves, seed, fruit, flowers, bark and immature pods are used as cardiac and circulatory stimulants, contain antipyretic, antiepileptic, antitumor, antiinflammatory, antiulcer, diuretic, antihypertensive, cholesterol lowering, antispasmodic, antidiabetic, hepatoprotective, antioxidant, antibacterial and antifungal activities, and are being used for the treatment of various ailments in the indigenous system of medicine.  Moringa oleifera seed powder has shown a significant reduction of turbidity and coliform count when it was used at smaller concentrations without altering the pH of the water. Moreover, the extracts of the seed with different solvents showed antibacterial activity to all the four test organisms, i.e., Escherichia coli (ATCC2592), E. coli (clinical isolate), Salmonella typhii (clinical isolate) and Shigella dysenteriae(clinical isolate). The acetone extract is the most effective in inhibiting and killing the test organisms at a very low concentration (MIC and MBC = 6.25 mg/mL) for Salmonella typhii (clinical isolate). The present study has suggested that the acetone extracts of M. oleifera seeds have potential as antibacterial compounds against pathogens and their ability to either block or circumvent resistance mechanisms could improve the treatment and eradication of microbial strains. Thus, plant seed extracts could be used in the treatment of infectious diseases caused by microbes. See Husen

Crushed Moringa seeds clarify and purify water to suit domestic use and lower the bacterial concentration in the water making it safe for drinking. By using Moringa seeds people will no longer be depending on expensive means originating from the West. Using Moringa to purify water replaces chemicals such as aluminum sulfate, which are dangerous to people and the environment, and are expensive. Moringa oleifera seeds treat water on two levels, acting both as a coagulant and an antimicrobial agent. It is generally accepted that Moringa works as a coagulant due to positively charged, water-soluble proteins, which bind with negatively charged particles (silt, clay, bacteria, toxins, etc) allowing the resulting “flocs” to settle to the bottom or be removed by filtration. The antimicrobial aspects of Moringa continue to be researched. Findings support recombinant proteins both removing microorganisms by coagulation as well as acting directly as growth inhibitors of the microorganisms. While there is ongoing research being conducted on the nature and characteristics of these components, it is accepted that treatments with Moringa solutions will remove 90-99.9% of the impurities in water. See Miricle Trees

Emergency Disinfection of Water  See EPA

Detection and Monitoring of Water

Cabelli discuses a membrane filter procedure for enumerating Escherichia coli was developed and evaluated. The method quantifies E. coli within 24 h without requiring subculture and identification of isolates. It incorporates a primary selective-differential medium for gram-negative, lactose-fermenting bacteria; resuscitation of weakened organisms by incubation for 2 h at 35 degrees C before incubation at 44.5 degrees C for 18 to 22 h; and an in situ urease test to differentiate E. coli from other thermotolerant, lactose-positive organisms.  See Cabelli