Why is monitoring of organic parameters important

Turbidity more than 5 NTU can be visible to the average person while turbidity in muddy water, it exceeds NTU [ 10 ]. Groundwater normally has very low turbidity because of the natural filtration that occurs as the water penetrates through the soil [ 9 , 16 ]. Palatability, viscosity, solubility, odors, and chemical reactions are influenced by temperature [ 10 ]. Thereby, the sedimentation and chlorination processes and biological oxygen demand BOD are temperature dependent [ 11 ].

It also affects the biosorption process of the dissolved heavy metals in water [ 17 , 18 ]. Materials decayed from organic matter, namely, vegetation and inorganic matter such as soil, stones, and rocks impart color to water, which is objectionable for esthetic reasons, not for health reasons [ 10 , 20 ].

Color is measured by comparing the water sample with standard color solutions or colored glass disks [ 10 ]. The color of a water sample can be reported as follows: Apparent color is the entire water sample color and consists of both dissolved and suspended components color [ 10 ].

True color is measured after filtering the water sample to remove all suspended material [ 19 ]. Color is graded on scale of 0 clear to 70 color units. Pure water is colorless, which is equivalent to 0 color units [ 10 ]. Taste and odor in water can be caused by foreign matter such as organic materials, inorganic compounds, or dissolved gasses [ 19 ]. These materials may come from natural, domestic, or agricultural sources [ 21 ].

The numerical value of odor or taste is determined quantitatively by measuring a volume of sample A and diluting it with a volume of sample B of an odor-free distilled water so that the odor of the resulting mixture is just detectable at a total mixture volume of ml [ 19 , 22 ].

The unit of odor or taste is expressed in terms of a threshold number as follows:. Solids occur in water either in solution or in suspension [ 22 ]. These two types of solids can be identified by using a glass fiber filter that the water sample passes through [ 22 ]. By definition, the suspended solids are retained on the top of the filter and the dissolved solids pass through the filter with the water [ 10 ]. If the filtered portion of the water sample is placed in a small dish and then evaporated, the solids as a residue.

This material is usually called total dissolved solids or TDS [ 10 ]. The residue of TSS and TDS after heating to dryness for a defined period of time and at a specific temperature is defined as fixed solids.

These measures are helpful to the operators of the wastewater treatment plant because they roughly approximate the amount of organic matter existing in the total solids of wastewater, activated sludge, and industrial wastes [ 1 , 22 ]. Figure 1 describes the interrelationship of solids found in water [ 22 ].

They are calculated as follows [ 10 ]: Total solids:. Interrelationship of solids found in water [ 22 ]. Total dissolved solids:. Total suspended solids:.

Fixed and volatile suspended solids:. The electrical conductivity EC of water is a measure of the ability of a solution to carry or conduct an electrical current [ 22 ]. Since the electrical current is carried by ions in solution, the conductivity increases as the concentration [ 10 ] of ions increases. Therefore, it is one of the main parameters used to determine the suitability of water for irrigation and firefighting.

Units of its measurement are as follows: U. Pure water is not a good conductor of electricity [ 2 , 10 ]. Typical conductivity of water is as follows: Ultra-pure water: 5.

The electrical conductivity can be used to estimate the TDS value of water as follows [ 10 , 22 ]:. TDS can be used to estimate the ionic strength of water in the applications of groundwater recharging by treated wastewater [ 22 ]. The normal method of measurement is electrometric method [ 10 ]. It is defined as the negative logarithm of the hydrogen ion concentration [ 9 , 12 ]. It is a dimensionless number indicating the strength of an acidic or a basic solution [ 23 ]. As shown in Figure 2 , pH ranges from 0 to 14, with 7 being neutral.

Pure water is neutral, with a pH close to 7. Normal rainfall has a pH of approximately 5. Safe ranges of pH for drinking water are from 6. A change of 1 unit on a pH scale represents a fold change in the pH [ 10 ], so that water with pH of 7 is 10 times more acidic than water with a pH of 8, and water with a pH of 5 is times more acidic than water with a pH of 7. There are two methods available for the determination of pH: electrometric and colorimetric methods [ 10 ].

Excessively high and low pHs can be detrimental for the use of water. A high pH makes the taste bitter and decreases the effectiveness of the chlorine disinfection, thereby causing the need for additional chlorine [ 21 ]. The amount of oxygen in water increases as pH rises. Low-pH water will corrode or dissolve metals and other substances [ 10 ]. Pollution can modify the pH of water, which can damage animals and plants that live in the water [ 10 ]. The effects of pH on animals and plants can be summarized as follows: Most aquatic animals and plants have adapted to life in water with a specific pH and may suffer from even a slight change [ 15 ].

Even moderately acidic water low pH can decrease the number of hatched fish eggs, irritate fish and aquatic insect gills, and damage membranes [ 14 ]. Water with very low or high pH is fatal. A pH below 4 or above 10 will kill most fish, and very few animals can endure water with a pH below 3 or above 11 [ 15 ]. Amphibians are extremely endangered by low pH because their skin is very sensitive to contaminants [ 15 ].

Some scientists believe that the current decrease in amphibian population throughout the globe may be due to low pH levels induced by acid rain. The effects of pH on other chemicals in water can be summarized as follows: Heavy metals such as cadmium, lead, and chromium dissolve more easily in highly acidic water lower pH. This is important because many heavy metals become much more toxic when dissolved in water [ 21 ].

A change in the pH can change the forms of some chemicals in the water. Therefore, it may affect aquatic plants and animals [ 21 ]. For instance, ammonia is relatively harmless to fish in neutral or acidic water. However, as the water becomes more alkaline the pH increases , ammonia becomes progressively more poisonous to these same organisms.

Acidity is the measure of acids in a solution. The acidity of water is its quantitative capacity to neutralize a strong base to a selected pH level [ 10 ]. Acidity in water is usually due to carbon dioxide, mineral acids, and hydrolyzed salts such as ferric and aluminum sulfates [ 10 ].

Acids can influence many processes such as corrosion, chemical reactions and biological activities [ 10 ]. Carbon dioxide from the atmosphere or from the respiration of aquatic organisms causes acidity when dissolved in water by forming carbonic acid H 2 CO 3. The level of acidity is determined by titration with standard sodium hydroxide 0.

The alkalinity of water is its acid-neutralizing capacity comprised of the total of all titratable bases [ 10 ]. The measurement of alkalinity of water is necessary to determine the amount of lime and soda needed for water softening e.

Alkalinity is determined by titration with a standard acid solution H 2 SO 4 of 0. The high levels of either acidity or alkalinity in water may be an indication of industrial or chemical pollution. Alkalinity or acidity can also occur from natural sources such as volcanoes. The acidity and alkalinity in natural waters provide a buffering action that protects fish and other aquatic organisms from sudden changes in pH. For instance, if an acidic chemical has somehow contaminated a lake that had natural alkalinity, a neutralization reaction occurs between the acid and alkaline substances; the pH of the lake water remains unchanged.

Chlorides may enter surface water from several sources including chloride-containing rock, agricultural runoff, and wastewater. Chlorides are not usually harmful to people; however, the sodium part of table salt has been connected to kidney and heart diseases [ 25 ]. Small amounts of chlorides are essential for ordinary cell functions in animal and plant life.

There are many methods to measure the chloride concentration in water, but the normal one is the titration method by silver nitrate [ 10 ]. Chlorine Cl 2 does not occur naturally in water but is added to water and wastewater for disinfection [ 10 ]. While chlorine itself is a toxic gas, in dilute aqueous solution, it is not harmful to human health.

In drinking water, a residual of about 0. The residual concentration which is maintained in the water distribution system ensures good sanitary quality of water [ 11 ]. Chlorine can react with organics in water forming toxic compounds called trihalomethanes or THMs, which are carcinogens such as chloroform CHCl 3 [ 11 , 22 ]. Chlorine residual is normally measured by a color comparator test kit or spectrophotometer [ 10 ].

If high concentrations are consumed in drinking water, there may be objectionable tastes or unwanted laxative effects [ 26 ], but there is no significant danger to public health. There are four forms of nitrogen in water and wastewater: organic nitrogen, ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen [ 10 ]. If water is contaminated with sewage, most of the nitrogen is in the forms of organic and ammonia, which are transformed by microbes to form nitrites and nitrates [ 22 ].

Nitrogen in the nitrate form is a basic nutrient to the growth of plants and can be a growth-limiting nutrient factor [ 10 ]. A high concentration of nitrate in surface water can stimulate the rapid growth of the algae which degrades the water quality [ 22 ]. This method should be used when preparing all sample containers and glassware for monitoring nitrates and phosphorus.

In general, sample away from the streambank in the main current. Never sample stagnant water. The outside curve of the stream is often a good place to sample, since the main current tends to hug this bank.

In shallow stretches, carefully wade into the center current to collect the sample. A boat will be required for deep sites. Try to maneuver the boat into the center of the main current to collect the water sample. To collect water samples using screw-cap sample bottles, use the following procedures Fig. These may include: Introduced pollutants, such as pesticides, metals, and oil Constituents found naturally in water that can nevertheless be affected by human sources, such as dissolved oxygen, bacteria, and nutrients The magnitude of their effects can be influenced by properties such as pH and temperature.

Water quality monitoring can be used for many purposes: To identify whether waters are meeting designated uses. All states have established specific criteria limits on pollutants identifying what concentrations of chemical pollutants are allowable in their waters.

When chemical pollutants exceed maximum or minimum allowable concentrations, waters might no longer be able to support the beneficial uses such as fishing, swimming, and drinking for which they have been designated.

Designated uses and the specific criteria that protect them along with antidegradation statements say waters should not be allowed to deteriorate below existing or anticipated uses together form water quality standards. State water quality professionals assess water quality by comparing the concentrations of chemical pollutants found in streams to the criteria in the state's standards, and so judge whether streams are meeting their designated uses.

Water quality monitoring, however, might be inadequate for determining whether aquatic life uses are being met in a stream. While some constituents such as dissolved oxygen and temperature are important to maintaining healthy fish and aquatic insect populations, other factors, such as the physical structure of the stream and the condition of the habitat, play an equal or greater role.

Biological monitoring methods see Chapter 4 are generally better suited to determining whether aquatic life is supported. To identify specific pollutants and sources of pollution. Water quality monitoring helps link sources of pollution to a stream quality problem because it identifies specific problem pollutants.

Since certain activities tend to generate certain pollutants e. To end on the regulatory aspect, these decrees set, both for raw and treated water, microbiological, physicochemical, organoleptic taste and smell quality limit values and parameters indicative of radioactivity. According to the EMA and the FDA, once the treatment has been carried out, the quality of the water used to produce water for pharmaceutical use must meet the criteria for drinking water.

Analytical monitoring guarantor of pretreatment Today, the key physicochemical parameters can be easily monitored on a continuous basis, which will guarantee that the quality of the incoming water does not deteriorate, and indeed, does not cause problems with the efficiency of the producer of water for pharmaceutical use ultrafiltration, mixed bed resin, multi-stage reverse osmosis device, EDI, thermocompressor etc. The simplest recommended parameters to monitor are the following although this list is not exhaustive:.

Although ammonium is of natural origin, the water must not however contain more than 0. Ammonium is quite simply a source of nitrogen of nutrients for bacteria. In addition, in the nitratation phenomenon transformation of ammonium into nitrates , other bacteria that practice anoxic respiration use nitrates as a source of oxygen, called bound oxygen, to respire. This results in the formation of nitrites which have known harmful effects on health.

Ammonium can be monitored and controlled with simple analyzers, by a selective probe for example. The principle is simple: the sample passes into an analysis chamber in which are immersed a probe with a selective membrane and the reference electrode. The ammonium ions passing into the measurement probe across the membrane will vary its potential relative to the reference electrode in proportion to their concentration Nernst law. Although there are very successful complex analyzers for measuring TOC by thermal and chemical oxidation, there are also very simple methods for the ongoing detection of a source of organic pollution in this quality of water, using optical measurement: measurement of UV absorption at nm or SAC This is the absorption of the sample at a wavelength of nm over a known measuring cell distance.

At this wavelength, the light absorbed by the sample is directly proportional to the dissolved organic molecules. On water matrices with a stable composition, it is even possible to make precise correlations with TOC, DCO, based on recalibration of the apparatus after several comparative measurements in the laboratory, by entering the slope-intercept characteristics in the software slope and offset in the common language of instrumentists.

Conversely, this technique cannot be used on water with very high loads and will not be sufficiently accurate for purified water. This concentration should not exceed 10 ppm in raw water drawn from the natural environment. On pH analyzers, there is therefore always a temperature probe, either separate, or combined. A solution is called acid when the pH is below 7, basic when it is above 7 and neutral when the pH is equal to 7. Chlorine is the most commonly used disinfectant agent that is added to water.

Indeed drinking water must be disinfected and disinfecting it must always contain a residual amount of active chlorine residual. In practice, for this quality of water there is a simple measurement method based on 3 electrode amperometry. A defined voltage of mV is applied to the terminals of a platinum anode and cathode, continuously corrected by a reference electrode, which confers greater stability on the sensor. The value is converted to free chlorine in a pH-dependent manner. Specific case of chlorine: Active chlorine will combine with ammonia to form what is called combined chlorine or chloramines.

In summary, all the chlorine added above this quantity remains in the form of residual free chlorine, in drinking water, the free chlorine residual must be 0. This combined chlorine is partly responsible for the taste and smell of water.

It can be understood therefore why water must contain a low basic quantity of ammonium, to limit input of chlorine.

Effectively, the free chlorine will be consumed and must always be present in sufficient quantity to provide disinfection, therefore it must be monitored, indeed regulated. And it is therefore all these forms of chlorine free and combined which constitute total chlorine, and it is understandable that a reduction in free chlorine and an increase in total chlorine will cause ammonia pollution.

The addition of the DPD, in buffered medium, in the presence of potassium iodide, after a two-minute reaction, reveals total chlorine in the form of a pink complex, whose intensity is directly proportional to its concentration.

This intensity is read with a spectrophotometer at a wavelength of around nm. In practice, the analyzer shown above produces this measurement: liquid reagents are added to a chamber into which the sample is introduced, then stored for two minutes by means of a solenoid valve before being read by the photometer, followed by evacuation and rinsing, until the next cycle.

NB: the chlorine will be removed by chemical means sodium bisulfite or physical means active carbon as the resins or filtration membranes downstream very sensitive to chlorine and chloramines, and must not be damaged. Measurement of the absence of total chlorine upstream of these processes is essential.

Only the colorimetric method performs this role satisfactorily, as it is not subject to the depolarization phenomenon unlike amperometric sensors. This constant k is a value that is linked to the constitution of the measurement electrode: it is the ratio between the distance separating the electrodes and their surface area:. Thus, conductivity, in association with temperature conveys the total mineralization level of water. In practice, for inline measurement, manufacturers have developed sensors most often composed of 2 or 4 electrodes in noble materials stainless steel, titanium, platinum , according to the principle referred to previously.

Voltage is applied to the electrodes in contact with the solution to be analyzed. The conductance allows the conductivity, concentration or specific resistance of the solution to be calculated. Turbidity defines the cloudy appearance of the water.

The elements responsible are in fact, colloids derived from the humic decomposition of plants and animals, which are particles in the order of microns with an electronegative charge and which do not settle, because they constantly repel each other. Colloids are a substrate for bacterial growth, and it is because of this that the lower the turbidity level, the better the water quality for this parameter. The term limpid water is commonly used.

Turbidity is measured using optical technology, in accordance with a standard agreed on by all manufacturers, so that everyone presents a result on the basis of the same reference document. This is the ISO standard.