Symptoms: Soap and sediment rings on water accessories. Soap does not foam. White deposits in pipes and plumbing fixtures as well as in the bathrooms, laundry room, water heater, kettles and glassware. Hair, skin and clothes are more dry. Complicates house cleaning chores. Also requires 60% more soap and 20% more electricity for the water heater. Changes the taste of food and drink.
Cause or source: Calcium salt (limestone) and magnesium in concentrations as low as 3.0 grains per gallon or 50 ppm-mg/l expressed in total hardness (CaCO³).
Usual treatment: Water softener by cationic ion exchange. During the process of ion exchange, the calcium salt and magnesium are replaced by sodium ions (when they are regenerated with sodium chloride) or with potassium ions (when they are regenerated with potassium chloride).
Symptom: Reddish-brown stains on plumbing fixtures, dishes and laundry. Water runs clear, but a rust colour appears when the water is heated or during cooking. The laundry has rust-coloured stains. Certain drinks, such as tea or coffee, are darker.
Cause or source: Presence of dissolved iron (Ferrous Fe²) in concentrations usually above 0.3 ppm. Water runs clear. (Do not confuse with (Ferric, Fe³+).
1. A water softener or CRF cationic ion exchanger from the Aqua Filtration Corporation, AquaMac or Filtraqua Canada brands can remove the dissolved iron (Fe²) up to concentrations of 10 ppm. In order for it to be possible to eliminate the iron by ion exchange, the untreated water must contain calcium and magnesium in concentrations of at least 5 grains/gallon for each ppm of iron. Special calculations will also have to be performed during the programming of the equipment, and a special acid (Rust Weapon) will have to be used in combination with the salt during regeneration. The water must in no case be oxidized or contain an oxidizing agent.
2. If there is no hardness in the water and the use of a cationic ion exchanger is not justified, an OxyFilter by the Aqua Filtration Corporation, AquaMac or Filtraqua Canada brands can be used with a wide range of media, usually media such as green sand or another medium with intermittent regeneration using potassium permanganate. *This method requires a pH over 6.8 and ideally below 8.
3. Certain models of catalytic OxyFilter use media that do not require regeneration with potassium permanganate, but several factors must be assessed by a professional before considering this option. *This method requires a pH over 6.8 and ideally below 8.
4. For concentrations above 10 ppm, or to simultaneously solve several water problems, an oxidation and filtration method is recommended. Oxygen, chlorine, potassium permanganate, ozone, peroxide and other oxidizing agents can be used to transform dissolved iron (Fe²) into non-dissolved iron (Fe³+), to then be able to remove it via mechanic filtration. To consider the injection of one of these oxidizing agents, it is essential that all oxidizable material or other substance that can react with an oxidizing agent have a stable concentration. If the quality of the untreated water is changeable, it can be difficult to calibrate the correct dose of the injected oxidizing agent. The oxygen agent offers greater flexibility in the case of unstable untreated water quality. When a chlorine agent is used in the presence of organic matter, it is important to be very careful about the possibility of the formation of chlorine-derived products. A combination of chlorine and another oxidizing agent or the use of an activated carbon filter can become indispensable. When chlorine is used and the elimination of the residual chlorine is desired, an activated carbon filter must be used, but it will have to be preceded by a sediment filter when the turbidity after oxygenation is over 10 utn. *This method requires a pH over 6.8 and ideally below 8. Iron Type #1 = ferruginous water (dissolved iron), water runs clear.
Symptom #1: Water is rust-coloured when cold water flows; red/rust-coloured particles deposit at the bottom of a glass after a short period of time.
Cause or source: Non-dissolved and precipitated iron (Ferric, Fe³+).
1. If all of the iron is present in this form (Ferric, Fe³+) and no dissolved iron is present (Ferrous Fe²), a multimedia sediment filter with counterflow washing may be sufficient. For best results, use a Birm filter from the Aqua Filtration Corporation, AquaMac or Filtraqua Canada brands, but only when the oxygen concentration is greater than 15% compared to the total iron concentration.
2. An OxyFilter by the Aqua Filtration Corporation, AquaMac or Filtraqua Canada brands can be used with a wide range of media, usually media such as green sand or another medium with intermittent regeneration with potassium permanganate. *This method requires a pH over 6.8 and ideally below 8.
3. Some catalytic Oxy Filter models use media that do not require regeneration with potassium permanganate, but many factors must be evaluated by a professional before considering this option. *This method requires a pH above 6.8 and ideally below 8.
4. For concentrations over 10 ppm or to simultaneously solve a number of water problems, an oxidation and filtration method is recommended. Oxygen, chlorine, potassium permanganate, ozone, peroxide and other oxidizing agents can be used to transform dissolved iron (Fe²) into non-dissolved iron (Fe³+), to make it possible to then remove it via mechanical filtration. To consider the injection of one of these oxidizing agents, it is essential that all oxydizable material or other substance that reacts with an oxidizing agent have a stable concentration. If the quality of the untreated water is changeable, it can be difficult to calibrate the correct dose of the injection of the oxidizing agent. Oxygen offers greater flexibility in the case of unstable untreated water. When chlorine is used in the presence of organic matter, it is important to pay special attention to the possibility of the formation of chlorine-derived products. A combination of chlorine and another oxidizing agent or the use of a carbon-activated filter can become indispensable. When a chlorine agent is used and the removal of the residual or free chlorine is desired, a carbon-activated filter will have to be used, but it will have to be preceded by a sediment filter in cases where the turbidity after oxidation is over 10 utn.
* For all methods listed, the pH must be greater than 6.8 and ideally below 8. To correct the pH, consult the section entitled “Acid Water”.
Symptom #2: The same symptom as symptom #1.
Cause or source #2: Intermittent iron, usually at the beginning of use or when use is occasional. Usually caused by the absorption of iron from old pipes or where pH is below 6.6.
Usual treatment: Calcite filter to simultaneously correct the pH and filter out the non-dissolved iron.
Symptom: Brownish residue that does not precipitate; can form a film or skin.
Cause or source: Organic iron (Crenothrix, Sphaerotilus, Gallionella or Sideiocapsa bacteria).
Usual treatment: Destroy the iron bacteria with a hydrochloric acid solution, chlorination, filtration or an activated carbon filter.
Symptom: Red/rust colour that forms in the sample after 24 hours, but that does not deposit. Can sometimes create agglomerates, but remains suspended.
Cause or source: Colloidal iron.
Usual treatment: Chlorination, followed by between 15 and 30 minutes retention, followed by an activated carbon filter.
Symptom: Black spots on bathroom accessories, faucets and laundry.
Cause or source: Interaction between carbon dioxide or organic materials and a manganiferous soil (concentrations above 0.05 ppm). Usually combined with iron.
1. OxyFilter by the Aqua Filtration Corporation, AquaMac or Filtraqua Canada brands. Can be a green sand filter, MTM filter or a catalytic media filter. Limits are between 2 and 15 ppm of iron and manganese combined. Many factors influence treatment. The pH must be over 6.8, and ideally between 7 and 8.
2. Softener of cationic exchange resins for the dissolved manganese only. Minimum 10 lbs of salt per cubic ft. Minimum hardness 1 grain per 0.05 ppm.
3. The other procedures generally used to remove the iron can usually be used to remove manganese. Equipment using Birm media under certain conditions. Generally with air injection. (Consult your Aqua Filtration Corporation, AquaMac or Filtraqua Canada dealer).
Symptom: Yellowish-coloured water even after iron or manganese treatment. (Colour reads over 75 APHA units). Yellowish stains on fine materials, porcelain and accessories.
Cause or source: Water that is in contact with peaty soil or plant decomposition that accumulates tannins, humic acid
1. Drinking water: reverse osmosis or other membrane technology
2. Large volumes of water: Reduction by absorption via type 1 macroporous anionic resin regenerated with NaCI, up to 3 ppm
3. Continuous chlorination with full retention, filtration and/or bleaching with activated carbon
4. Combination of methods 1 and 2
Symptom: Green stains on the sink and other porcelain accessories. Blue-green residue in water.
Cause or source: Water with high concentrations of carbon dioxide (CO²), pH generally under 6.8
Usual treatment: Use a filter with pH corrector media by the Aqua Filtration Corporation, AquaMac or Filtraqua Canada brands. Calcite pH+ for pH between 5.5 and 6.8; or a filter with a 2 to 5 mix of Corosex and calcite for a pH below 5.5 or for a high flow and short contact time. Sodium bicarbonate injection preferably followed by filtration.
Symptom: Copper plumbing deterioration and pigmentation of brass accessories and fittings. Especially in hot water where the pH is almost neutral (pH 7). Greenish spots can appear on the plumbing fixtures.
Cause or source: The corrosion caused by oxygen (O²) is usually found in surface water supplies and in deep wells in arid regions, even if they have a neutral pH. When water with a strong oxygen concentration (O²) is heated, the oxygen is free to attack the surface of metals.
Usual treatment: Injection of a polyphosphate and/or a sodium silicate solution to protect the surface of metals by reducing their exposure.
Symptom: Blackening and pigmentation of stainless steel sinks and cutlery.
Cause or source: Very strong chlorine concentration in water. In the presence of a strong oxygen concentration, the high temperature used for the drying cycle in the dishwasher accelerates corrosion.
Usual treatment: Reduce the TDS (total dissolved solids), including chlorides. Effective method, reverse osmosis Aqua Filtration Corporation, AquaMac or Filtraqua Canada or demineralisation equipment.
The natural organic matter is mostly issued from the decomposition of plants, animals and micro-organisms. They can therefore be very diverse with respect to their composition in order to establish a precise description of their average composition. They have a lot of impact on water quality parameters: colour, smell, disinfection by-products, taste, etc.
Cause or source:
Organic materials are at the origin of the degradation of water quality, therefore:
- they influence the organoleptic properties of water (smell and taste);
- they can be the cause of a certain acquired toxicity over the course of treatment, through the metabolism of certain composites, such as the formation of THM via oxidation, especially via chlorination;
- they directly influence the biological stability of water in the distribution network.
Different Analytic Methods of Organic Matter
The Different Analyses of Organic Matter
Oxydizability to potassium permanganate, KMnO4 : this analysis consists of a chemical oxidation under hot conditions (100 °C) in an acidic environment for 10 minutes.
UV absorbance: this measurement method is very convenient, but certain mineral elements are a source of interference; in addition, results can depend on the nature of the organic materials analysed. An optical density of 1 for 1 cm cells equates to an approximate value of 30 to 45 mg O2/l of KMnO4 oxydizability in an acidic environment.
Total organic carbon (TOC) and dissolved organic carbon (DOC): for surface water, TOC is in general made up of 90% dissolved organic carbon (DOC) and of 10% particular CO. The DOC represents left-over organic material after filtration through membranes of about 0.45 microns. There is a correlation between DOC and UV absorbance: UV (1 cm, 254 nm) / DOC about 0.03 to 0.04 for surface water.
Biodegradable dissolved organic carbon (BDOC) is estimated from the decrease of DOC after a long incubation period (28 days) in the presence of a bacteria suspension or fixed biomass. For surface waters, the value of the BDOC is in general at most 30% of the DOC.
The terms Bio-ROC or biorefractory DOM are reserved for the biorefractory organic carbon in the test conditions: Bio-ROC = DOC – BDOC.
Chemical oxygen demand (COD): this analysis is performed through the oxidation of organic matter by excess potassium dichromate (Cr2O7) in an acidic and heated environment.
Biochemical oxygen demand (BOD): this biochemical analysis, performed over 5 days (BOD5), measures the partial degradation of the organic material by micro-organisms (biological pathway). It is expressed in mg O2/l.
1. The classic sequence of coagulation-flocculation-sedimentation-filtration-disinfection: Jar tests are done first to determine the coagulant dose to use, as the latter strongly depends on the nature of the organic material present. However, the doses are usually close to 2 mg Fe/mg TOC for iron salts, and of 1 mg Al/mg TOC for aluminum salts. Though flocculation tests (the jar tests) achieve a 75% return on the elimination of organic material, the actual performance is closer to 60% for the first 3 steps. The filtration essentially serves to eliminate residual particular matter, and its effectiveness in the reduction of TOC is only very modest (a few % points). However, if the conditions required for the development of a biological film on the sand grains are fulfilled, the reduction effectiveness can increase. As to disinfection, the chemical reactant used for the inactivation of the micro-organisms can also oxidize a fraction of the remaining organic material.
2. Activated carbon in powder or grain form: specific uses
Used in powder form (PAC), it allows us to handle seasonal peaks or accidental pollution. The effectiveness of PAC depends on the nature of the pollution and the concentration of the micropollutants, on the type of carbon used (pore size) and on the PAC dose injected. Grain activated carbon (GAC) is used during filtration for finishing treatments, because it allows for the improvement of numerous parameters related to natural organic matter: colour, taste, smell, disinfection demand, THM formation potential, etc. Additionally, its use in organic filtration allows for BDOC elimination results that can go up to 80% at 18 °C, but not over 30% at 8 °C. Aqua Filtration Corporation, AquaMac and Filtraqua Canada recommend paying particular attention to monitoring the spread of micro-organisms using this method of reduction.
3. Membranes: different uses based on cut-offs
Microfiltration and ultrafiltration are generally used in the place of a classic clarification-filtration sequence; however, in certain cases, it is necessary to use pre-coagulation (large volume), for certain organic materials that are too small to be retained or due to membrane pores that are too large. Generally, the results obtained are approximately 10 to 40%, except in the case where a PAC injection is used. In this case, yields are identical to those from the clarification-filtration sequence.
Nanofiltration may allow for the correction of one or several parameters, including the reduction of organic matter. The natural organic matter elimination results, under the form of DOC and BODC, are approximately 95% (same order of magnitude for THM precursors). For drinking water only, we recommend the use of reverse osmosis that generally also resolves many other possible water quality problems.
4 : Oxidation with ozone, chlorine dioxide or chlorine: varied effects and some disadvantages
Ozone can be used in pre-oxidation or inter-oxidation; a variable fraction of DOC is then transformed into BODC, which then promotes the biological degradation of this organic matter, and therefore removes some of the problems related to bacterial regrowth in the network. The main advantage of chlorine dioxide is that it produces no (or very little) THM. That being said, it is pretty rarely used in pre-oxidation to reduce organic matter. In addition, depending on its production mode, it may be the cause of the formation of chlorite. Chlorine should be less and less frequently used in Canada in pre-chlorination due to the fact that it is very reactive with THM precursors, and especially, with humic substances. For small volumes, chlorine can be an approach to consider if there is THM monitoring afterwards.
5 : Method for the treatment of central residential water or drinking water
For the smallest volumes of water or drinking water, the continued presence of organic matter or of CO and pesticides, the use of a GAC filter followed by UV will yield some results. Membrane technology by reverse osmosis is certainly an avenue to consider in the selection. For small-volume applications, such as a building, a residence or a very small network, a chlorine pre-oxidation and coagulation or flocculation under pressure or atmospheric with decantation, followed by multimedia filtration and GAC filtration could serve as a multibarrier sequence. The whole procedure should be followed by an additional barrier for drinking water, such as reverse osmosis. If there is a strong CO, tannin or colour concentration, the chlorine demand can become problematic and the results may not be as desired. There are anionic resins that offer certain advantages. Treatment with an atmospheric reservoir and prolonged contact time yields the best results, but requires repressurisation.
Conclusions for Organic Matter
The reduction in the concentration of organic matter is essential for the production of water destined for human consumption, because this is the basis for the organoleptic properties of distributed water (colour, taste, smell) on the one hand, and for its potential toxicity on the other (presence of THM).
In this context, the treatments to be applied are chosen by taking into consideration the nature and concentrations of organic matter present in the water and the volume of water to be treated. Aqua Filtration Corporation, AquaMac and Filtraqua Canada dealers might recommend different reduction techniques for a large volume network, a small volume network, a residence or simply for drinking water.
For larger volumes, there are no miraculous procedures to eliminate all organic matter, and it is therefore important to consider the whole of a sequence of production of drinkable water as a process ensuring the progressive elimination of the quasi-totality of organic matter initially present in the untreated water.
For larger volumes, especially of surface water where the objective is to obtain a BDOC that is lower than required norms, in order to avoid bacterial regrowth in the networks, and therefore to limit the chlorine demand, the classic sequence that is most effective may be a multi-barrier system, specifically pre-oxidation ozone, followed by coagulation and flocculation, decantation, filtration media, oxidation ozone, GAC filtration, (optional UV), when chlorination residual is searched for in the distribution network.
Symptom #1: Aromatic, fishy, earthy or woody smell.
Cause or source #1: Generally caused by organic matter often present in surface waters.
Usual Treatment #1:
1. Activated carbon filter or activated carbon cartridge filter if it is only drinking water (also check out the section on Tannins)
In all cases where activated carbon is used and there is the presence of organic matter, a significant proliferation of certain micro-organisms can develop. An ultraviolet steriliser should be considered.
Symptom #2: Chlorine smell, water from municipal or private aqueducts.
Cause or source #2: Excessive chlorine concentration after treatment.
Usual treatment #2: Activated carbon filter or activated carbon cartridge filter if it is only drinking water – reverse osmosis.
Symptoms #3, 4, and 5: Smell of rotten eggs, sulphuric water. Tarnishes cutlery. Yellow/black spots on the plumbing fixtures and in bathrooms. Changes the taste and colour of certain drinks like tea and coffee. Changes the appearance and taste of foods.
Cause or source #3: Dissolved hydrogen sulfate (H2S)** present in untreated water. Often present in combination with iron or manganese and a low pH.
Usual treatment #3:
1. Oxy Filter by the Aqua Filtration Corporation, AquaMac or Filtraqua Canada brands. Maybe a green sand filter, an MTM filter, a catalytic media filter. Bounds between 4 and 6 ppm. It is important to take H2S into consideration, and the combined iron and manganese. To calculate the bounds of this treatment method, it is important to take several factors into consideration that can influence the treatment. The pH must be above 6.7.
2. For concentrations above 6 ppm or to simultaneously solve many water problems, an oxidation and filtration method is recommended. Oxygen, chlorine, potassium permanganate, ozone and peroxide can be used depending on their respective limits. This procedure must be followed by filtration. Before considering the injection of one of these oxidants, it is essential that all oxidizable matter and/or other substances that react with oxidizing agents have a stable concentration. If the quality of the untreated water is changeable, it can prove difficult to calibrate the right dosage of the injected oxidizing agent. Oxygen offers greater flexibility in the case of unstable untreated water quality. If there is organic matter present and chlorine is used, it is important to pay special attention to the possibility of the formation of chlorine by-products. A combination of chlorine and another oxidizing agent or the use of a carbon activated filter can become indispensable. If chlorine is used and the elimination of the residual or free chlorine is desired, the carbon activated filter will have to be used, but it will have to be preceded by a sediment filter if the turbidity after oxidation is greater than 10 utn. *This method requires a pH over 6.8 and ideally below 8.
Cause or source #4: Interaction between sulfates and bacteria in the untreated water producing traces of hydrogen sulphate (H2S), generally more frequent in warm water.
Usual treatment #4: Disinfect the entire plumbing with chlorine. Install a continuous chlorine injection system. Chlorination followed by filtration and activated carbon to remove the chlorine residual, if desired. To get more information on the other factors to consider before selecting this method, please see the detailed information on chlorination systems.
Cause or source #5: The magnesium anode rod in the hot water tank reacts with the water (electrical or gas).
Usual treatment #5: Remove the magnesium anode rod from the hot water tank. Replace with an alternative anode, such as one made out of aluminum, if desired.
Symptom #6: Detergent smell, water that foams while running, sewer or septic tank smell (Consult the section entitled “Nitrate-Nitrite”).
Cause or source #6: Septic tank installation “sweating” and infiltration into the subterranean water.
Usual treatment #6: Localise and eliminate the source of the infiltration. Then hyperchlorate the well and/or the distribution plumbing. The activated carbon can absorb a limited quantity of septic and detergent odours. However, the drinkability of the water will be questionable.
Odour #7 (Petroleum)
Symptom #7: Smell of gas, petroleum, gasoline, oil (hydrocarbons).
Cause or source #7: Leakage of a gas or oil tank that gets into the water distribution or aquifer.
Usual treatment #7: Localise and eliminate the source of the leakage. Then hyperchlorate the well and/or the distribution plumbing.
Activated carbon can absorb a limited amount of most hydrocarbons. An air injection installation that is 40 :1 air/water, with intensive mixing and exposure, will usually significantly extend the carbon’s lifespan.
Even if chlorination is not recognised as a treatment method for this problem, Aqua Filtration Corporation, AquaMac and Filtraqua Canada retailers may recommend a chlorine injection and adequate retention time of at least 40 minutes followed by an activated carbon filter, which can yield acceptable results.
Symptom #8: Methane gas smell or cloudy water.
Cause or source #8: Natural process of decomposition, putrefaction and decay of organic matter, from (1) an old abandoned landfill site or (b) an oil field.
Usual treatment #8: Atmospheric ventilation system requiring repressurisation of the plumbing network. Ventilate the gas in an appropriate place. Free methane gas can be flammable and explosive. Because of the water source, a microbiological analysis is recommended. A system designed expressly by AquaWaterEau Corporation and available from the Aqua Filtration Corporation, AquaMac or Filtraqua Canada retailers, that combines atmospheric ventilation and chlorination can eliminate the volatile gases, tastes, smells, organics and micro-organisms (bateria, coliform, etc.).
Symptom #9: Smell of phenol or other chemical.
Cause or source #9: Excessive use of pesticides, herbicides, phenol for agriculture or an industrial application that leaks into the water distribution or aquifer.
Usual treatment #9: Carbon activated filter or activated carbon cartridge filter if it is only for drinking water, reverse osmosis (it is important to perform regular monitoring).
Symptom #1: Dirty, mineral, brackish or alkaline water. Laxative effect under some circumstances. Can stain aluminum.
Cause or source #1: Strong sodium or magnesium or total dissolved solids or alkalinity concentrations - NaCl, Na2SO4, MgSO4. SO4, CI, HCO3, TDS.
Usual treatment #1:
1. No cost-effective treatment for concentrations above 2000 ppm.
2. For drinking water: reverse osmosis or distillation.
3. Membrane technology: nanofiltration – reverse osmosis.
4. Demineralisation with a mix of anionic/cationic resins.
Symptom #2: Bitter, metallic taste.
Cause or source #2:
1. Very low pH 4.5-5.5.
2. Strong iron concentrations (over 3.0 ppm Fe).
Usual treatment #2:
1. Correct by raising the pH, usually with a calcite medium. Injection of sodium bicarbonate or caustic (see the section titled “Acid Water”).
2. Consult the section entitled “Iron”.
Symptom #1: Mud, silt, slime, sand, clay and sediment. Abrasive cleaning water texture or residue and deposits in toilets and sinks. Generally does not stick and is easily removable
Cause or source #1: Suspended matter or matter precipitated in surface waters or in unsealed wells. Varies during big climatic events (rain). Very fine sand or silt that passed through the sieve of a pump or coagulation treatment system
Usual treatment #1: Depending on the granulometrics, may be removed with a simple vortex sand trap or cyclone, a multimedia, calcite or FA-Sed5 filter, or a filtering cartridge. In the case of very fine particles, ultrafiltration membranes or a coagulation process may be required.
Symptom #2: Gray fiber in the water
Cause or source #2: Organic matter — algae, etc. Usually in surface waters. Sulfur bacterium
Usual treatment #2: Continuous chlorination and sediment, calcite or activated carbon filter.
The main sources of nitrates-nitrites are agricultural fertilisers, manure, sanitary discharges and decomposing plant and animal organisms. They leach to the surface waters and underground waters by rain and snowmelt. The infiltrations are therefore most significant in the spring and fall.
The presence of nitrates-nitrites in water
Beyond 5 mg/l
It is important to note that a nitrate-nitrite concentration above 5 mg/l justifies regular monitoring, at least twice per year, because concentrations may vary over time.
Beyond 10 mg/l
If the concentration of nitrate-nitrite detected in the water exceeds the standards set forth in drinking water regulations, or 10 mg/l, this water must not be used in foods given to babies under 6 months of age or to pregnant women. The population in general must also as much as possible avoid regularly consuming water where the nitrate-nitrite concentrations exceed the established standards.
Symptom: Brown residue or reflection.
Cause or source: Deterioration of the activated carbon caused by excessive chlorine concentrations.
Usual treatment: Replace the activated carbon media or cartridge as soon as possible. Can lead to the release of substances accumulated in high concentrations.
Symptom: White or milky water
Cause or source:
1 : Precipitates that form during the heating of water and disappear quickly.
2. Strong non-dissolved oxygen concentrations often caused by the installation of a pump in poor condition.
3. Excessive concentrations of coagulants generally from a filtration plant or a poorly calibrated treatment system.
1. Regularly drain the hot water tank to remove precipitates.
2. The water generally quickly clears itself.
3. Reduce the concentration of coagulants as needed, and check the quality of filters to ensure their effectiveness. Use a blocked filter to encourage the passage of precipitates and coagulants.
Symptom: White or milky water, possible smell of methane gas depending on the concentrations.
Cause or source: Presence of methane gas in the water. Common in regions where there has already been ground petrifaction: swamps, marshy, flooded or submerged areas.
Usual treatment: Atmospheric ventilation system requiring repressurisation of the plumbing network. Ventilate gases in an appropriate area. Free methane gas can be explosive and flammable.
Symptom: It’s impossible to raise the pH with calcite. Greenish and reddish stains on the plumbing fixtures. Disintegration of the plumbing fixtures.
Cause or source: Mineral acids H2SO4 and HCI from mine water mixing with surface water. A pH below 4.3 indicates the presence of FMA.
Usual treatment: Injection of caustic soda or sodium bicarbonate.
Symptom: Very thin impermeable film that forms on the surface of the water. Tastes like varnish.
Cause or source: Kerosene, gas, petroleum, diesel from a reservoir leak and infiltration in the ground.
1. Short term: activated carbon adsorbent or membrane technology (ultra- or nanofiltration or reverse osmosis).
2. Long-term: eliminate the problem at source. Chlorination followed by activated carbon can be considered in the context of a pilot project. Membrane technology.
Symptom: No symptoms of colour, taste or smell. Generally a health risk beyond 0.05 ppm.
Cause or source: Contaminated ground water in certain regions — industrial, agricultural or herbicide contamination.
1. Reverse osmosis (RO) can eliminate up to 90% or distillation.
2. Demineralisation with mixed anionic/cationic resins (adjust the conductivity to 250 000 ohms).
3. In the presence of hardness (required), a reduction can be performed simultaneously with calcium and magnesium; use a strong concentration of brine for 15 lb regeneration. NaCI/pi3.
4. A new generation green sand filter (GreenSand Plus) can reduce levels of certain types of arsenic. In all cases, the data remain insufficient to confirm effectiveness. A small scale pilot project should be considered.
5. Certain types of new generation media have the capacity to reduce levels of certain types of arsenic by absorption and they are also available. In all cases, the data remain insufficient to confirm effectiveness. A small scale pilot project should be considered.