Etiket Arşivleri: Water

Experiment 9 – Total Hardness with EDTA Method ( Kenan ÖZ )

Name of Experiment : Total Hardness with EDTA Method

Number of Experiment : 9
Submitted by : Kenan ÖZ

PURPOSE:

– To determined total hardness of water with EDTA Method.

THEORY:

Water Hardness and Alkalinity

It may be that your water hardness and alkalinity are perfect for discus but unfortunately this is not always the case. It is far easier to adjust hardness and alkalinity upwards as when keeping hard-water fishes, but lowering these values is by no means impossible. It simply involves another step in the water conditioning process. Total hardness (general hardness) is the sum combination of carbonate and noncarbonate hardness of your water. Total hardness is measured as, degrees, dH, or ppm (parts per million). One dH is 17.9 ppm. How total hardness is expressed depends upon the author and his orientation. I prefer dH simply because as a discuskeeper, I like to see smaller
numbers when I am measuring water hardness! If I were keeping African cichlids I might prefer to measure my water's hardness in ppm. Total hardness is usually not a big issue in keeping discus; alkalinity is a far more important factor in the breeding of discus. Alkalinity is sometimes referred to as carbonate hardness(KH)or buffering capacity. Alkalinity is the important factor in breeding discus and controlling the pH of the water. Alkalinity refers to the level of calcium, carbonate and bicarbonate in the water. It is measured in KH or mg/L CaCo3 or parts per million. One milligram per liter (mg/L) is the equivalent of one part per million. Soft water is 3dH and 0 to 50 mg/L CaCo3; medium soft water is 3 to 6 dH and 50 to 100 mg/L CaCo3; slightly hard water is 6 to 12 dH and 100 to 200 mg/L CaCo3; moderately hard water is 12 to 18 dH and 200 to 300 mg/L CaCo3; hard water is over 18 dH and over 300 mg/L CaCo3. The values for general hardness and alkalinity given above
do not always match each other. It is entirely possible to have a higher reading of general hardness and a lower reading of alkalinity. The lower reading for alkalinity is the more desirable for discus water. Discus will do quite well in slightly to moderately hard water. In fact, many breeders routinely keep their fish in these values to ensure proper development of the young fish, but for development of the eggs, soft to moderately soft water, particularly concerning alkalinity is critical. Therefore, it is not necessary to drastically adjust the general hardness or alkalinity when you first start to keep discus unless the values are very high.


Water Hardness and Alkalinity

Water Hardness and Alkalinity
It may be that your water hardness and alkalinity are perfect for discus but unfortunately this is not always the case. It is far easier to adjust hardness and alkalinity upwards as when keeping hard-water fishes, but lowering these values is by no means impossible. It simply involves another step in the water conditioning process. Total hardness (general hardness) is the sum combination of carbonate and noncarbonate hardness of your water. Total hardness is measured as, degrees, dH, or ppm (parts per million). One dH is 17.9 ppm. How total hardness is expressed depends upon the author and his orientation. I prefer dH simply because as a discuskeeper, I like to see smaller numbers when I am measuring water hardness! If I were keeping African cichlids I might prefer to measure my water’s hardness in ppm. Total hardness is usually not a big issue in keeping discus; alkalinity is a far more important factor in the breeding of discus. Alkalinity is sometimes referred to as carbonate hardness(KH)or buffering capacity. Alkalinity is the important factor in breeding discus and controlling the pH of the water. Alkalinity refers to the level of calcium, carbonate and bicarbonate in the water. It is measured in KH or mg/L CaCo3 or parts per million. One milligram per liter (mg/L) is the equivalent of one part per million. Soft water is 3dH and 0 to 50 mg/L CaCo3; medium soft water is 3 to 6 dH and 50 to 100 mg/L CaCo3; slightly hard water is 6 to 12 dH and 100 to 200 mg/L CaCo3; moderately hard water is 12 to 18 dH and 200 to 300 mg/L CaCo3; hard water is over 18 dH and over 300 mg/L CaCo3. The values for general hardness and alkalinity given above do not always match each other. It is entirely possible to have a higher reading of general hardness and a lower reading of alkalinity. The lower reading for alkalinity is the more desirable for discus water. Discus will do quite well in slightly to moderately hard water. In fact, many breeders routinely keep their fish in these values to ensure proper development of the young fish, but for development of the eggs, soft to moderately soft water, particularly concerning alkalinity is critical. Therefore, it is not necessary to drastically adjust the general hardness or alkalinity when you first start to keep discus unless the values are very high.

Analysis of Water Chemistry

Analysis of Water Chemistry

  • Urban Stream Restoration Project

  • Outline

  • Water Chemistry Background

  • Chemistry in Urban Streams

  • Methods

  • 2003 Results

  • Comparison to 2002

  • Conclusions

  • Outline

  • Water Chemistry Background

  • Chemistry in Urban Streams

  • Methods

  • 2003 Results

  • Comparison to 2002

  • Conclusions

  • Temperature

  • Most aquatic organisms are cold-blooded and have an ideal temperature range, specific to the organism:

  • Diatoms 15-25 degrees C

  • Green algae 25-35 degrees C

  • Blue greens 30-40 degrees C

  • Salmonids – cold water fish

  • Temperature, continued

  • Affects development of invertebrates, metabolism of organisms

  • Affects dissolved oxygen (warm water holds less oxygen)

  • Warm water makes some substances more toxic (cyanide, phenol, xylene, zinc) and, if combined with low DO, they become even more toxic

  • Dissolved Oxygen

  • Oxygen that is dissolved in water

  • DO increases with cooler water and mixing of water through riffles, storms, wind

  • Nutrient loading can lead to algal blooms which result in decreased DO

  • 4-5 ppm DO is the minimum that will support large, diverse fish populations. Ideal DO is 9 ppm. Below 3 ppm, all fish die.

  • Dissolved Oxygen, continued

  • Dissolved oxygen can also be expressed as % saturation

  • 80-124% = excellent

  • 60-79% = ok

  • < 60% = poor

  • Conductivity

  • Measures the ability of water to carry an electric current

  • Measures the ions such as Na+, Cl- in the water

  • Differences in conductivity are usually due to the concentration of charged ions in solution (and ionic composition, temp.)

  • Reported as microsiemens per cm

  • pH

  • pH measures the degree of acidity or alkalinity of the water (each number is a 10-fold difference)

  • 0-6 = acid; 7 = neutral; 8-14 = base

  • Ideal for fish = 6.5 –8.2

  • Ideal for algae = 7.5 – 8.4

  • Acid waters make toxic chemicals (Al, Pb, Hg) more toxic than normal, and alter trophic structure (few plants, algae)

  • Turbidity

  • Measures the cloudiness of the water

  • Turbidity caused by plankton, chemicals, silt, etc.

  • Most common causes of excess turbidity are plankton and soil erosion (due to logging, mining, farming, construction)

  • Turbidity, continued

  • Excess Turbidity can be a problem:

  • Light can’t penetrate through the water – photosynthesis may be reduced or even stop – algae can die

  • Turbidity can clog gills of fish and shellfish –can be fatal

  • Fish cannot see to find food, but can hide better from predators

  • Phosphorus (Reactive)

  • Is necessary for plant and animal growth

  • Natural source = phosphate-containing rocks

  • Anthropogenic source = fertilizer and pesticide runoff from farming

  • Can stimulate algal growth/bloom

  • Nitrates

  • Formed by the process of nitrification (addition of O2 to NH3 by bacteria)

  • Used by plants and algae

  • Is mildly toxic, fatal at high doses

  • Large amounts (leaking sewer pipes, fertilizer runoff, etc.) can lead to algal blooms, which can alter community structure, trophic interactions and DO regimes)

  • Below 90 mg/L seems to have no effect on warm water fish, but cold water fish are sensitive

  • Alkalinity

  • A measure of the substances in water that can neutralize acid and resist changes in pH

  • Natural source = rocks

  • Ideal water for fish and aquatic organisms has a total alkalinity of 100-120 mg/L

  • Groundwater has higher alkalinity than surface water

  • Hardness

  • The amount of Calcium and Magnesium in the water (the two minerals mostly responsible)

  • Natural source = rocks

  • Limestone = hard water, granite = not hard water

  • Hardness, continued

  • Soft water can be a problem: in soft water, heavy metals are more poisonous, some chemicals are more toxic, drinking soft water over long periods can increase chance of heart attack

  • 0 – 60 = soft water

  • 61-120 = moderately hard water

  • 121-180 = hard water

  • 181+ = very hard water

  • Hardness and alkalinity are related

  • Outline

  • Water Chemistry Background

  • Chemistry in Urban Streams

  • Methods

  • 2003 Results

  • Comparison to 2002

  • Conclusions

  • Physical Effects of Urbanization Related to Water Chemistry

  • Riparian Vegetation Removal

  • Decreased Groundwater Recharge

  • Heat Island Effect

  • Increased Surface Runoff / Impervious Surfaces

  • Leaky Storm-water / Sewage Pipes

  • Point Source Pollution

  • Trends in Water Chemistry

  • Temperature increases

  • Nitrate increases

  • Phosphorus increases

  • Conductivity increases (Increased ion concentration)

  • O2 demand increases

  • Outline

  • Water Chemistry Background

  • Chemistry in Urban Streams

  • Methods

  • 2003 Results

  • Comparison to 2002

  • Conclusions

  • Field Measurements

  • Dissolved Oxygen

  • Temperature

  • Conductivity

  • pH

  • Water Collection For Laboratory Analysis

  • Grab Samples

  • Three replicates (from multiple samples)

  • Measured within 24 hours (few exceptions)

  • Laboratory Analysis

  • Nitrate

  • Reactive

Phosphorus

  • Alkalinity

  • Hardness

  • Turbidity

  • Outline

  • Chemistry in Urban Streams

  • Water Chemistry Measurements and Theory

  • Methods

  • 2003 Results

  • Comparison to 2002

  • Conclusions

  • Field Measurements 2003

  • Turbidity

  • All values for 2003 <5 jtu

  • For 2002, all but one sampling date <5 jtu

  • The one date for 2002 >5 was during a storm event

  • Reactive Phosphorus 2003

  • Nitrate 2003

  • Alkalinity 2003

  • Hardness 2003

  • Outline

  • Chemistry in Urban Streams

  • Water Chemistry Measurements and Theory

  • Methods

  • 2003 Results

  • Comparison to 2002

  • Conclusions

  • Field Measurement PB

  • Field Measurement For SAL

  • Paint Branch

  • Stewart April Lane

  • Outline

  • Chemistry in Urban Streams

  • Water Chemistry Measurements and Theory

  • Methods

  • 2003 Results

  • Comparison to 2002

  • Conclusions

Between Site Differences

  • Land use – increased runoff cause increased input of particular constituents

  • Natural site variation – Substrate type

Between Years

  • Increased snow caused more runoff increased use of road-salt

  • Drought (temperature, DO)

“. . . Rivers and the inhabitants of the watery element were made for wise men to contemplate, and fools to pass by without consideration, . . . for you may note, that the waters are Nature’s storehouse, in which she locks up her wonders.”

  Izaak Walton

  (from Ward, 1992)

Laboratory‎ > Water Purification Steps

What specific water purification methods are there?

Water that is distributed in cities or communities is treated extensively. Specific water purification steps are taken, in order to make the water meet current water standards.

Purification methods can be divided up into settling of suspended matter, physical/ chemical treatment of colloids and biological treatment. All these treatment methods have several different applications.

How do specific water purification methods work?

1 Physical water purification

Physical water purification is primarily concerned with filtration techniques. Filtration is a purification instrument to remove solids from liquids. There are several different filtration techniques. A typical filter consists of a tank, the filter media and a controller to enable backflow.

Screens

Filtration through screens is usually done at the beginning of the water purification process. The shape of the screens depends on the particles that have to be removed.

Sand filtration

Sand filtration is a frequently used, very robust method to remove suspended solids from water. The filter medium consists of a multiple layer of sand with a variety in size and specific gravity. When water flows through the filter, the suspended solids precipitate in the sand layers as residue and the water, which is reduced in suspended solids, flows out of the filter. When the filters are loaded with particles the flow-direction is reversed, in order to regenerate it. Smaller suspended solids have the ability to pass through a sand filter, so that secondary filtration is often required.

Cross flow filtration

Cross flow membrane filtration removes both salts and dissolved organic matter, using a permeable membrane that only permeates the contaminants. The remaining concentrate flows along across the membrane and out of the system and the permeate is removed as it flows along the other side of the membrane.

There are several different membrane filtration techniques, these are: micro filtration, ultra filtration, nano filtration and Reversed Osmosis (RO). Which one of these techniques is implemented depends upon the kind of compounds that needs to be removed and their particle size. Below, the techniques of membrane filtration are clarified.

1) Microfiltration

Microfiltration is a membrane separation technique in which very fine particles or other suspended matters, with a particle size in the range of 0.1 to 1.5 microns, are separated from a liquid. It is capable of removing suspended solids, bacteria or other impurities. Microfiltration membranes have a nominal pore size of 0.2 microns.

2) Ultrafiltration

Ultrafiltration is a membrane separation technique in which very fine particles or other suspended matters, with a particle size in the range of 0.005 to 0.1 microns, are separated from a liquid. It is capable of removing salts, proteins and other impurities within its range. Ultrafiltration membranes have a nominal pore size of 0.0025 to 0.1 microns.

3) Nanofiltration

Nanofiltration is a membrane separation technique in which very fine particles or other suspended matters, with a particle size in the range of approximately

0.0001 to 0.005 microns, are separated from a liquid. It is capable of removing viruses, pesticides and herbicides.

4) Reversed Osmosis (RO)

Reversed Osmosis, or RO, is the finest available membrane separation technique. RO separates very fine particles or other suspended matters, with a particle size up to

0.001 microns, from a liquid. It is capable of removing metal ions and fully removing aqueous salts.

Cartridge filtration

Cartridge filtration units consist of fibres. They generally operate most effectively and economically on applications having contamination levels of less than 100 ppm. For heavier contamination applications, cartridges are normally used as final polishing filters.

2 Chemical water purification

Chemical water purification is concerned with a lot of different methods. Which methods are applied depends on the kind of contamination in the (waste)water. Below, many of these chemical purification techniques are summed up.

Chemical addition

There are various situations in which chemicals are added, for instance to prevent the formation of certain reaction products. Below, a few of these additions are summed up:

– Chelating agents are often added to water, in order to prevent negative effects of hardness, caused by the deposition of calcium and magnesium.

– Oxidizing agents are added to act as a biocide, or to neutralize reducing agents.

– Reducing agents are added to neutralize oxidizing agents, such as ozone and chlorine. They also help prevent the degradation of purification membranes.

Clarification

Clarification is a multi-step process to remove suspended solids. First, coagulants are added. Coagulants reduce the charges of ions, so that they will accumulate into larger particles called flocs. The flocs then settle by gravity in settling tanks or are removed as the water flows through a gravity filter. Particles larger than 25 microns are effectively removed by clarification. Water that is treated through clarification may still contain some suspended solids and therefore needs further treatment.

Deionisation and softening

Deionisation is commonly processed through ion exchange. Ion exchange systems consist of a tank with small beds of synthetic resin, which is treated to selectively absorb certain cations or anions and replace them by counter-ions. The process of ion exchange lasts, until all available spaces are filled up with ions. The ion-exchanging device than has to be regenerated by suitable chemicals.

One of the most commonly used ion exchangers is a water softener. This device removes calcium and magnesium ions from hard water, by replacing them with other positively charged ions, such as sodium.

For specific information on water softening move to the water softener FAQ

Disinfection

Disinfection is one of the most important steps in the purification of water from cities and communities. It serves the purpose of killing the present undesired microrganisms in the water; therefore disinfectants are often referred to as biocides. There are a variety of techniques available to disinfect fluids and surfaces, such as: ozone disinfection, chlorine disinfection and UV disinfection.

Chlorine has a downside: it can react to chloramines and chlorinated hydrocarbons, which are dangerous carcinogens. To prevent this problem chlorine dioxide can be applied. Chlorine dioxide is an effective biocide at concentrations as low as

0.1 ppm and over a wide pH range. ClO2 penetrates the bacteria cell wall and reacts with vital amino acids in the cytoplasm of the cell to kill the organism. The by-product of this reaction is chlorite. Toxicological studies have shown that the chlorine dioxide disinfection by-product, chlorite, poses no significant adverse risk to human health.

Ozone has been used for disinfection of drinking water in the municipal water industry in Europe for over a hundred years and is used by a large number of water companies, where ozone generator capacities up to the range of a hundred kilograms per hour are common. When ozone faces odours, bacteria or viruses, the extra atom of oxygen destroys them completely by oxidation. During this process the extra atom of oxygen is destroyed and there are no odours, bacteria or extra atoms left. Ozone is not only an effective disinfectant, it is also particularly safe to use.

UV-radiation is also used for disinfection nowadays. When exposed to sunlight, germs are killed and bacteria and fungi are prevented from spreading. This natural disinfection process can be utilised most effectively by applying UV radiation in a controlled way.

Distillation

Distillation is the collection of water vapour, after boiling the wastewater. With a properly designed system removal of organic and inorganic contaminants and biological impurities can be obtained, because most contaminants do not vaporize. Water will than pass to the condensate and the contaminants will remain in the evaporation unit.

Electro dialysis

Electro dialysis is a technique that employs an electrical current and special membranes, which are semi permeable to ions, based on their charge. Membranes that permeate cations and membranes that permeate anions are placed alternately, with flow channels between them, and electrodes are placed on each side of the membranes. The electrodes draw their counter ions through the membranes, so that these are removed from the water.

pH-adjustment

Municipal water is often pH-adjusted, in order to prevent corrosion from pipes and to prevent dissolution of lead into water supplies. The pH is brought up or down through addition of hydrogen chloride, in case of a basic liquid, or natrium hydroxide, in case of an acidic liquid. The pH will be converted to approximately 7 to 7.5, after addition of certain concentrations of these substances.

Scavenging

Most naturally occurring organics have a slightly negative charge. Organic scavenging is done by addition of strong-base anion resin. The organics will fill up the resin and when it is loaded it is regenerated with high concentrations of sodium chloride.

3 Biological water purification

Biological water purification is performed to lower the organic load of dissolved organic compounds. Microrganisms, mainly bacteria, do the decomposition of these compounds. There are two main categories of biological treatment: aerobic treatment and anaerobic treatment.

The Biological Oxygen Demand (BOD) defines the organic load. In aerobic systems the water is aerated with compressed air (in some cases merely oxygen), whereas anaerobic systems run under oxygen free conditions.

Water

Water simply doesn’t behave like other liquids
Functions
Water Content of Some Foods
Structure
Water is Polar!!!!
Water has relatively large dipole moment
Hydrogen Bonds Exist Between Water Molecules
Unique Properties of Water
Tetrahedral structure
LIQUID STATE
Solid State
GASEOUS STATE
KINDS OF WATER (DEGREE OF WATER BINDNESS)
Water activity (aw)
Relationship Water Content & Water Activity
Water Activity of Common Food Products
In summary
Factors that Influence Water Activity
Moisture Sorption Isotherms (MSI)
Moisture Sorption Isotherm
Zones in Isotherms
WATER ZONES ANALOGY
Moisture Sorption Isotherm
Adsorption & Resorption
Sorption and Desorption
Water Sorption Hysteresis
Chemical/Biochemical Stability
Some important points in Aw/Stability Diagram
aw affects the textural properties of foods
Water activity affects the storage stability of deydrated products (powders)
Moisture migration of multicomponent products
Shelf-life/Packaging