1.Turbidity
Ideal water is colorless and completely odorless. In real water, always organic and inorganic materials are stored at different concentrations. These substances cause contamination of the water and thus turbidity.
When the dosage of Twin Oxide-Solutions can oxidize inorganic and organic substances in the water, the turbidity values will fall.
This is then also a easier proof of the effectiveness of the TwinOxide Solutions
Typische Trübungswerte (Typical turbidity values)
Medium
|
Trübungswert (NTU) Turbidity (NTU)
|
Sauberstes Wasser
Cleanest water
|
0,03
|
Trinkwasser
Drinking water
|
0,05–0,5
|
Abwasser
Wastewater
|
100–2000
|
Formazin
|
4000
|
Milch (3,5 % Fett)
Milk (3.5% fat)
|
über 100000
|
Milch (1,5 % Fett)
Milk (1.5% fat)
|
bis zu 60000
|
Kläranlagenablauf
Effluent of the WWTP
|
0,5-10
|
2.What is TDS?
You see!
Total dissolved solids
From Wikipedia, the free encyclopedia
Bottled mineral water usually contains higher TDS levels thantap water
Total Dissolved Solids (often abbreviated TDS) is a measure of the combined content of all inorganic and organic substances contained in a liquid in molecular, ionized or micro-granular (colloidal sol) suspended form. Generally the operational definition is that the solids must be small enough to survive filtration through a filter with two-micrometer (nominal size, or smaller) pores. Total dissolved solids are normally discussed only for freshwater systems, as salinity comprises some of the ions constituting the definition of TDS. The principal application of TDS is in the study of water quality for streams, rivers andlakes, although TDS is not generally considered a primary pollutant (e.g. it is not deemed to be associated with health effects) it is used as an indication of aesthetic characteristics of drinking water and as an aggregate indicator of the presence of a broad array of chemical contaminants.
Primary sources for TDS in receiving waters are agricultural and residential runoff, leaching of soil contamination and point source water pollution discharge from industrial or sewage treatment plants. The most common chemical constituents are calcium, phosphates, nitrates, sodium, potassium and chloride, which are found in nutrient runoff, general stormwater runoff and runoff from snowy climates where road de-icing salts are applied. The chemicals may becations, anions, molecules or agglomerations on the order of one thousand or fewer molecules, so long as a soluble micro-granule is formed. More exotic and harmful elements of TDS are pesticides arising from surface runoff. Certain naturally occurring total dissolved solids arise from the weathering and dissolution of rocks and soils. The United States has established a secondary water quality standard of 500 mg/l to provide for palatability of drinking water.
Total dissolved solids are differentiated from total suspended solids (TSS), in that the latter cannot pass through a sieve of two micrometers and yet are indefinitely suspended in solution. The term "settleable solids" refers to material of any size that will not remain suspended or dissolved in a holding tank not subject to motion, and excludes both TDS and TSS.[1] Settleable solids may include larger particulate matter or insoluble molecules.
calculation
TDS in ppm = ke * EC
TDS = Total Dissolved Solids
EC = conductivity
ke= 0,55 .... 0,8
often: ke= 0,64
EFFECTS OF TDS
OUTLINE
Industrial considerations: High TDS will have adverse effect to many kinds of industrial applications (either encrust or corrode metallic surfaces). Salt in intake water may interfere with chemical processes within the plant. In addition, waste water with high TDS will cause eutrophication in nature.
Health considerations: High concentration of TDS in the drinking water causes both aesthetic problems for consumers (such as undesirable taste, salty bitter). Certain mineral salts may pose health hazards. The most problematic are nitrates, sodium, barium, copper sulfates, and fluoride.
Other effects: Effect of TDS on environment (affect aquatic life, reduce water clarity, affect pH …), irrigation, and domestic.
Effects of components in TDS: High concentration of TDS causes many kinds of effects (acute, chronic and carcinogenic effects). Beside that, the effect from each component in TDS (arsenic, iron, aluminum, lead …) also causes adverse impacts.
CONTENT
1. Industrial considerations (back to outline)
High levels of total dissolved solids can adversely industrial applications requiring the use of water such as cooling tower operations, boiler feed water, food and beverage industries, and electronics manufacturers. High levels of chloride and sulfate will accelerate corrosion of metals. Concentrations of TDS above 500 mg/L result in excessive scaling in water pipes, water heaters, boilers and household appliances.
Some of these chemical species in TDS, such as phosphates and nitrates, provide the essential elements required by plants and animals for essential life processes such as metabolism and protein synthesis. In low concentrations, the freshwater ecosystem will be "limited" but in high concentration, the water can become excessively enriched in nutrients resulting in eutrophication. Eutrophication can often cause extensive algal growth or "blooms" that can choke freshwater systems by filling the stream with aquatic vegetation and demanding excessive oxygen during the night.
2. Health Considerations (back to outline)
Some of the individual components of TDS can have effects on human health. The US EPA has a suggested level of 500 mg/l listed in the Secondary Drinking Water Standards. Inverse relationships were reported between TDS concentrations in drinking water and the incidence of cancer, coronary heart disease, arteriosclerotic heart disease and cardiovascular disease. Total mortality rates were reported to be inversely correlated with TDS levels in drinking water.
1. The most important aspect of TDS with respect to drinking water quality is its effect on taste. The palatability of drinking water with a TDS level less than 600 mg/L is generally considered to be good. Drinking water supplies with TDS levels greater than 1200 mg/L are unpalatable to most consumers.
2. An aesthetic objective of 500 mg/L should ensure palatability and prevent excessive scaling. However, it should be noted that at low levels TDS contributes to the palatability of drinking water.
G Potential Health Effects
Source: http://www.elitewater.com/tds.htm,http://www.water-research.net/totaldissolvedsolids.htm
http://www.water.ncsu.edu/watershedss/info/salinity.html
An elevated total dissolved solids (TDS) concentration is not a health hazard. The TDS concentration is a secondary drinking water standard and therefore is regulated because it is more of an aesthetic rather than a health hazard. An elevated TDS indicates the following:
1) The concentration of the dissolved ions may cause the water to be corrosive, salty or brackish taste, result in scale formation, and interfere and decrease efficiency of hot water heaters; and
2) Many contain elevated levels of ions that are above the Primary or Secondary Drinking Water Standards, such as: an elevated level of nitrate, arsenic, aluminum, copper, lead, etc.
3. Other effects (back to outline)
² Environmental effects
· Concentration of total dissolved solids that are too high or too low may limit the growth and may lead to the death of many aquatic organisms.
· High concentrations of total dissolved solids may reduce water clarity, which contributes to a decrease in photosynthesis and lead to an increase in water temperature. Many aquatic organisms cannot survive in high temperatures.
· It is possible for dissolved ions to affect the pH of the body of water, which in turn may influence the overall health of many aquatic species.
· If TDS levels are high, especially due to dissolved salts, many forms of aquatic life are affected. The salts act to dehydrate the skin of animals.
· High TDS concentrations may add a laxative effect to the water or cause the water to have an unpleasant mineral taste.
· High TDS makes ice cubes cloudy, softer, and faster melting.
Some freshwater organisms are able to tolerate low dissolved solids levels. If a total dissolved solids increase in the water body, a shift to more salinity-tolerant species can be expected.
High salinity may interfere with the growth of aquatic vegetation. Salt may decrease the osmotic pressure, causing water to flow out of the plant to achieve equilibrium. Less water can be absorbed by the plant, causing stunted growth and reduced yields. High salt concentrations may cause leaf tip and marginal leaf burn, bleaching, or defoliation.
Estuarine aquatic life is generally tolerant of fluctuating salinity levels. Under natural conditions, estuarine water may fluctuate between fresh and brackish, depending on the flow rate of the river discharging into the estuary. Aquatic biota inhabit zones in the estuary according to preferred salinity levels. Thus, if the volume of fresh water entering the estuary fluctuates sufficiently to cause a change in the isohaline (areas of similar salinity) patterns, species may be displaced and the ecosystem disrupted.
Urban runoff containing high salt concentrations (e.g., from de-icing) may create saline layers in receiving lakes. Salt water has a higher density than freshwater and tends to sink and form a dense layer in the hypolimnion. This saline layer does not mix with remainder of the lake water, leading to decreased dissolved oxygen levels in the hypolimnion.
² Irrigation effects
Carbonate deposits may clog pipes and coat the inside of water holding tanks. Extreme hardness may interfere with chemical processes.
Inadequate drainage or excessive evaporation from agricultural fields may lead to an accumulation of salts in the soil.
Salt in the soil may harm crops. Certain salt constituents alone can prove toxic to some plant varieties. Also, high salt concentrations in the soil around plant roots may cause plant dehydration by reversing osmotic conditions (water will flow out of the plant in an attempt to achieve equilibrium). In some cases, rather than destroying a crop, elevated salt levels may simply reduce crop yields and leave the plants prone to disease.
² Domestic effects
Hard water is objectionable because of the formation of scale in boilers, water heaters, radiators, and pipes with resultant decrease in the rate of flow and heat transfer as well as in increased corrosion. In addition to its effect on soap consumption, excessive hardness can shorten the wearing ability of fabrics and toughen cooked vegetables.
4. The optimal amount of total dissolved solids in water (back to outline)
- A constant level of minerals in the water is necessary for aquatic life. Changes in the amounts of dissolved solids can be harmful because the density of total dissolved solids determines the flow of water in and out of an organism’s cells.
- Drinking water may have a TDS reading of 25-250 mg/L. Drinking water should not exceed 500 mg/L TDS.
- Distilled water will have a TDS reading that will range from 0.5-1.5 mg/L.
- The amount of TDS ranges from 100-20,000 mg/L in rivers and may be higher in groundwater.
- Seawater may contain 35,00 mg/L of TDS.
- Lakes and streams may have a TDS reading of 50-250 mg/L.
Designated Use Limits
|
TDS (mg/l)
|
Human Consumption
|
500 TDS
|
Irrigation
|
500-1,000 (dependent upon crop sensitivity)
|
250 mg/l chloride
| |
Brewing
| |
Light beer
|
500
|
Dark beer
|
1,000
|
Pulp and paper
| |
Fine paper
|
200
|
Groundwood paper
|
500
|
Boiler feed water
|
50 to 3,000 depending on pressure
|
Canning/Freezing
|
850
|
Aquatic Life
|
Varies, depending on natural conditions
|
TH= Hard Water
3. What is Hard Water?
Hard water is water that has high mineral content (in contrast with "soft water"). Hard water is formed when waterpercolates through deposits of calcium and magnesium-containing minerals such as limestone, chalk and dolomite.
Hard drinking water is generally not harmful to one's health,[1] but can pose serious problems in industrial settings, where water hardness is monitored to avoid costly breakdowns in boilers, cooling towers, and other equipment that handles water. In domestic settings, hard water is often indicated by a lack of suds formation when soap is agitated in water, and by the formation of limescale in kettles and water heaters. Wherever water hardness is a concern, water softening is commonly used to reduce hard water's adverse effects.
Sources of hardness[edit]
Water's hardness is determined by the concentration of multivalent cations in the water. Multivalent cations are cations (positively charged metal complexes) with a charge greater than 1+. Usually, the cations have the charge of 2+. Common cations found in hard water include Ca2+ and Mg2+. These ions enter a water supply by leaching from minerals within an aquifer. Common calcium-containing minerals are calcite and gypsum. A common magnesium mineral is dolomite (which also contains calcium). Rainwaterand distilled water are soft, because they contain few ions.[2]
- CaCO3 (s) + CO2 (aq) + H2O (l) ⇋ Ca2+ (aq) + 2HCO3− (aq)
The reaction can go in either direction. Rain containing dissolved carbon dioxide can react with calcium carbonate and carry calcium ions away with it. The calcium carbonate may be re-deposited as calcite as the carbon dioxide is lost to atmosphere, sometimes forming stalactites and stalagmites.
Calcium and magnesium ions can sometimes be removed by water softeners.[3]
Temporary hardness[edit]
Temporary hardness is a type of water hardness caused by the presence of dissolved bicarbonate minerals (calcium bicarbonate and magnesium bicarbonate). When dissolved these minerals yield calcium and magnesium cations (Ca2+, Mg2+) and carbonate and bicarbonate anions (CO32-, HCO3-). The presence of the metal cations makes the water hard. However, unlike the permanent hardness caused by sulfate and chloride compounds, this "temporary" hardness can be reduced either by boiling the water, or by the addition of lime (calcium hydroxide) through the softening process of lime softening.[4] Boiling promotes the formation of carbonate from the bicarbonate and precipitates calcium carbonate out of solution, leaving water that is softer upon cooling.
Permanent hardness[edit]
See also: Carbonate hardness
Permanent hardness is hardness (mineral content) that cannot be removed by boiling. When this is the case, it is usually caused by the presence of calcium sulfate and/ormagnesium sulfates in the water, which do not precipitate out as the temperature increases. Ions causing permanent hardness of water can be removed using a water softener, or ion exchange column.
Total Permanent Hardness = Calcium Hardness + Magnesium Hardness
The calcium and magnesium hardness is the concentration of calcium and magnesium ions expressed as equivalent of calcium carbonate.
Total permanent water hardness expressed as equivalent of CaCO3 can be calculated with the following formula: Total Permanent Hardness (CaCO3) = 2.5(Ca2+) + 4.1(Mg2+).[citation needed]
Measurement[edit]
Hardness can be quantified by instrumental analysis. The total water hardness is the sum of the molar concentrations of Ca2+ and Mg2+, in mol/L or mmol/L units. Although water hardness usually measures only the total concentrations of calcium and magnesium (the two most prevalent divalent metal ions), iron, aluminium, and manganese can also be present at elevated levels in some locations. The presence of iron characteristically confers a brownish (rust-like) colour to the calcification, instead of white (the color of most of the other compounds).
Water hardness is often not expressed as a molar concentration, but rather in various units, such as degrees of general hardness (dGH), German degrees (°dH), parts per million (ppm, mg/L, or American degrees), grains per gallon (gpg), English degrees (°e, e, or °Clark), or French degrees (°F). The table below shows conversion factors between the various units.
The various alternative units represent an equivalent mass of calcium oxide (CaO) or calcium carbonate (CaCO3) that, when dissolved in a unit volume of pure water, would result in the same total molar concentration of Mg2+ and Ca2+. The different conversion factors arise from the fact that equivalent masses of calcium oxide and calcium carbonates differ, and that different mass and volume units are used. The units are as follows:
- Parts per million (ppm) is usually defined as 1 mg/L CaCO3 (the definition used below).[18] It is equivalent to mg/L without chemical compound specified, and to American degree.
- Grains per Gallon (gpg) is defined as 1 grain (64.8 mg) of calcium carbonate per U.S. gallon (3.79 litres), or 17.118 ppm.
- a mmol/L is equivalent to 100.09 mg/L CaCO3 or 40.08 mg/L Ca2+.
- A degree of General Hardness (dGH or 'German degree (°dH, deutsche Härte))' is defined as 10 mg/L CaO or 17.848 ppm.
- A Clark degree (°Clark) or English degrees (°e or e) is defined as one grain (64.8 mg) of CaCO3 per Imperial gallon (4.55 litres) of water, equivalent to 14.254 ppm.
- A French degree (°F or f) is defined as 10 mg/L CaCO3, equivalent to 10 ppm. The lowercase f is often used to prevent confusion with degrees Fahrenheit.
http://www.unitedutilities.com/documents/Water-Quality-Standards.pdf
http://www.waterbase.uwm.edu/people/jwaples/waples%20MARINE%20CHEM%20Feb%202003.pdf
4.What is COD?
In environmental chemistry, the chemical oxygen demand (COD) test is commonly used to indirectly measure the amount of organic compounds in water. Most applications of COD determine the amount of organic pollutants found in surface water (e.g. lakes and rivers) or wastewater, making COD a useful measure of water quality. It is expressed in milligrams per liter (mg/L) also referred to as ppm (parts per million), which indicates the mass of oxygen consumed per liter of solution.
Government regulation[edit]
Many governments impose strict regulations regarding the maximum chemical oxygen demand allowed in wastewater before they can be returned to the environment. For example, in Switzerland, a maximum oxygen demand between 200 and 1000 mg/L must be reached before wastewater or industrial water can be returned to the environment[2].
Biochemical oxygen demand or B.O.D is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. The term also refers to a chemical procedure for determining this amount. This is not a precise quantitative test, although it is widely used as an indication of the organic quality of water.[1] The BOD value is most commonly expressed in milligrams of oxygen consumed per litre of sample during 5 days of incubation at 20 °C and is often used as a robust surrogate of the degree of organic pollution of water.
BOD can be used as a gauge of the effectiveness of wastewater treatment plants. It is listed as a conventional pollutant in the U.S. Clean Water Act.
BOD is similar in function to chemical oxygen demand (COD), in that both measure the amount of organic compounds in water. However, COD is less specific, since it measures everything that can be chemically oxidized, rather than just levels of biologically active organic matter.
Typical BOD values[edit]
Most pristine rivers will have a 5-day carbonaceous BOD below 1 mg/L. Moderately polluted rivers may have a BOD value in the range of 2 to 8 mg/L. Municipal sewage that is efficiently treated by a three-stage process would have a value of about 20 mg/L or less. Untreated sewage varies, but averages around 600 mg/L in Europe and as low as 200 mg/L in the U.S., or where there is severe groundwater or surface water Infiltration/Inflow. (The generally lower values in the U.S. derive from the much greater water use per capita than in other parts of the world.)[1]
Calculating Oxidant Dose to Remove BOD or COD
OXIDANTS
*****
The calculation used to estimate dosage in a water system is:
Oxidant Dosage (ppm) = ((Mw of Oxidant)/16n) x COD
Where Mw is the molecular weight of the oxidant, n is the number of reactive oxygens generated and COD is the Chemical Oxygen Demand of the water.
Oxidant
|
Dosage in mg/l ( = ppm)
|
Chlorine
|
4,5 x COD
|
Hydrogenperoxide
|
3,25 x COD
|
Ozone
|
3 x COD
|
Permanganate
|
2,48 x COD
|
Ferrate
|
1,71 x COD
|
Chlorine Dioxide
|
0,279 x COD
|
Example for Chlorine Dioxide
Thus, for a system with 20 ppm COD, it will take a calculated 5,58 ppm chlorine dioxide to convert the COD to non-oxidizable species
Use off a TwinOxide-0,3%-Chlorine Dioxide Solution:
For a system with 20 ppm COD you need 1,86 ml/L !
Links zu Themen der Wasser-Messtechnik
Parameter der Wasserqualität
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