Pakissan.com; THE QUALITY OF WATER

In case of chlorinated water there should not be C. aerogenes at all and round the year it should fall to quality class 1. Serious pollution is frequently heralded by intermediate aerogenes cloacae types and their appearance should call immediate investigation of source. Untreated deep well supplies of those from other pure sources should fall normally to class 1 and drop even to class 2 should call fall immediate attention.

The earthy taste in water is due to the presence of Actinomyces and other moulds and their spores. If they are removed even then the smell is present and some time it is due to the mould growth on tape end. They are not detectable by ordinary bacterial examination. For this purpose sample is inoculated on to nutrient agar and Krainsky’s glucose aspargin agar and incubated at 30 °C for 2 wks. Colonies will appear as small circular, entire flat plaques very adherent. Colonies may be colored and sporulation is shown in white, gray and yellow powder on the colonies.

Sulphur bactaria Beggiata and Thiothrax and iron bacteria Leptothrix ochracea, Gallionella ferruginea and Crenothrix poly spora should not be present at all. Sulphur bacteria produces musty odor while iron bacteria produces slimy reddish brown deposits.

Apart from above given bacteria, the pathogens should not be present in water.

IMPURITIES IN WATER

In addition to minerals and metals which lower the quality of water and render it unfit for drinking and other uses, there are some bacteria as well which deteriorate the water quality. Bacteria present in the water may be categorized as under:

A. Natural water bacteria which include Chromogenic and non-chromogenic bacteria, fluorescent bacteria and cocci, etc. Some of these bacteria are incapable of growth on ordinary laboratory media.

B. Bacteria from soil which include sporing and non-sporing organisms.

C. Bacteria from sewage and animal excrement which may include disease producing type i.e. typhoid and paratyphoid bacteria, food poisoning and dysentery types; putrefactive organisms, e.g. proteus type and an-aerobic spore bearing bacilli; intestinal bacteria such as the coli erogenous group, the fecal streptococci and anaerobic spore bearing bacilli.

EVALUATION OF WATER QUALITY

Water quality may be evaluated in following systematical proceedings including physical, chemical, bacteriological or biological analyses.

A. Physical Test

i. Temperature: Temperature measurement in most instances is very simple. An accurately calibrated thermometer graduated into 0.1°C, with a range of 0-50 °C is adequate for this purpose. In case of large water bodies, where reading at particular depth is required a “broken capillary” thermometer is used. Thermometer is reversed at the depth concerned, the capillary breaks and reading then remains unchanged.

ii. Color: Color is measured against various standards of which the Hazen or Platinic chloride scale is prescribed in American Public Health Association’s Standard Methods. The basis for the scale being parts per million (ppm) of platinum.

Water from upland gathering grounds, which carry beds of peat values 150-200 Hazen. Extracts from vegetable debris and soil results in lesser degree of color, sewage effluent contribute to the coloration of streams and rivers. Unless an underground source is suffering from a sensible degree of pollution by surface water, yellow brown color is entirely absent. For drinking, color showed is between 100-150 Hazen or even less.

iii. Turbidity: Turbidity is estimated against standard suspensions of a siliceous material such as foller’s earth, the silica scale being based on standardization by photometric means. The exact values are measured when metals are suspended but in case of bacterial contamination, coloring is best technique. The turbidity of those supplies conforming to the highest standard of clarity never exceeds 1 or 2 ppm a turbidity of 5 is appreciable and 10 can be regarded as decidedly objectionable.

iv. Suspended Solids: When turbidity is above 100 ppm; a gravimetric estimation may be necessary to indicate more clearly the quantity of matters in suspension. Microscopic and microchemical analysis may be applied as well.

v. Tastes and Odors: Taste and odor have no numerical values because of variation from person to person. It has got a “thresh-hold” beyond which it is not useable. Water which is chlorinated produces particular taste and odor due action with organic compound because as such chlorine has no taste and odor. Uncontaminated water from natural sources is not prone to taste or odor apart from bitter, astringent flavor of ferruginous supply and apart from some reduced or deoxygenated waters drawn from beneath impervious strata or from clay sand layers when an odor of sulphuretted hydrogen may occur.

vi. pH Value: The pH of water is 7.0, which is neutral. It is measured by pigmentation or pH meters. In natural water pH ranges from 6.8 to 8.3.

vii. Electrical Conductivity: Electrical conductivity is measured in terms of reciprocal megohms/cm³ at 20ºC. Electrical conductivity is a measure of salt dissolved in water like that of pH.

B. Chemical Tests

Organic Tests

i. Ammonical Nitrogen: Ammonia in water is present in a free form and as such it is not an impurity. But when it acts with Cl₂ then it reduces the lateral strength to form bactericidal effects in chloramination of water. In laboratories it is measured by distillation of mildly alkalized water, the ammonia in distillate being measured from the coloration produced with Nessler’s reagent.

ii. Nitrate and Nitrite: Reduction of nitrate produces nitrite and nitrate is a product of oxidation process of Nitrogen compounds. At one hand it determines the amount of organic matter in water and purity and bacteria present on the other hand. In normal water they must be under 15 to 30 ppm. A high nitrated water say 150 ppm, produces toxic effect for babies fed on the dried milk which is reconstituted before use. Nitrite is measured by the Griess Ilosvay method and nitrate by Devarda’s alloy method by color matching.

iii. Biochemical Oxygen Demand (BOD): BOD of water is that depletion of oxygen in solution brought about in the breaking down of organic matter by aerobic bacteria. They give a better visualization of organic matter in water. Standard BOD for good water is 1 ppm and for satisfactory 2 ppm beyond this limits it is not useable for drinking.

Inorganic Tests

i. Alkalinity: Bicarbonate salts of Ca, Mg and Na together constitute alkalinity in water. The CaHCO₃ form the temporary hard water. In natural water it may range from 200 to 400 ppm, depending upon source. Alkalinity is measured by simple acidimetric methods employing indicator such as methyl orange and phenolphthalein. Calcium and magnesium salts other than carbonates and bicarbonates such as sulphate and nitrate form the hardness in water. Hard water destroys the soap and this is used as a crude technique to measure these salts.

ii. Chloride; Sulphates; Silica; Phosphate and Total Solids: Rain water and oceanic water contains chloride upto 5 ppm but streams, rivers and underground water contains from 10 to 20 ppm. This is the standard for drinking and 100 ppm indicates the pollution in water. Chloride is measured by titration with standard silver nitrate solution using potassium chromate as an indicator. The quantities of sulphates are considered to be similar to chloride in standard requirement and quantity in different waters. Sulphates are determined by gravimetric estimations following precipitation as barium-sulphate.

Amount of silica present may vary from 10 to 30 ppm as SiO₂. Silica is determined by matching the color of the molybdate complex or by gravimetric estimation. Phosphate in natural waters occurs to the extent of parts per 10 million. For useable quality it must be at 1 ppm level. Orthophosphate can be measured by matching the blue complex, which is produced from phosphomolybdate on addition of reducing agent i.e. stannous chloride. Total solids are measured by drying at 180 °C the water.

iii. Na, K, Fe, Cu, Pb and F: Sodium and potassium are no more danger to the water quality. They are measured by gravimetric method.

Iron occurs as Ferrous Carbonate. Its appreciable amount causes bitter taste and help to grow the Iron bacteria in water. It must be under 0.2 to 0.3 ppm in normal water. It is estimated by simple calorimetric procedure with the thiocyanate. Copper is also measured by this method by using rubanic acid.

Lead must be less than 0.1 ppm in drinking water as it is heavily toxic metal. It is estimated by new organic reagent procedure.

Flourine upto 1.5 ppm is useful for dental caries. Fluorine is estimated by matching the fading produced in a lake between zirconium and alizarin.

C.Bacteriological Tests

The purpose of the bacteriological tests is as fellow:

· To determine the degree of excremental pollution in new and old sources of supply.

· To assess a treatment for use.

· To ascertain the efficiency of purification at various stages.

· To locate the cause of immediate contamination.

· To ensure the final quality of distribution.

For the bacterial count and assessment following test are conducted.

i. Coli-aerogenes Test: Among the many methods used, plating is convenient and quicker one. The presumptive culture is plated out on Maconkey agar or eosins methylene blue agar and incubated at 37 °C in order to obtain single, discrete and pure colonies. For further differential test following five tests are conducted.

i). Acid and gas Maconkey broth or brilliant green bile broth at 44°C.

ii). Test for production of indole in a peptone water culture at 37°C.

iii). Methyl red test carried out in glucose phosphate incubated at 30°C.

iv). Citrate utilization test in Koser’s medium at 37°C.

v). Production of acid and gas in lactose peptone water at 37°C.

ii. Clostridium Welchii Test: Among different methods used, one easy to conduct and quick one is, sulphite reduction test based on the fact that C. Welchii produces a colony with a conspicuous black zone of iron sulphide when grown on agar containing glucose, sodium sulphite and iron. In order to destroy non-sporing organisms the water should be heated to 80 °C for 10 minutes before mixing with molten medium. The plate should be incubated at 44 °C for 48 hrs. The C. Welchii appear as large black area 3 to 5 mm or more in diameter with irregular edges. This chemical reduction soon fades, revealing an opaque colony in center.

iii. Faecal Streptococcus Test: For this widely practiced test is Tellurite method. Strepto-cocci will grow in fecal origin, a concentration of potassium tellurite, which is inhibitory gram –ve and C. aerogenes strains. A volume is incubated at 37 °C and positive tubes indicate blackening of medium which is further confirmed by microscopic examination, fermentation and heat resistance tests.

iv. Biological Test: Biological tests are conducted to evaluate the water quality for algae, protozoa, protifera and polyzoa, etc. There are essentially two methods by which plankton organisms can be counted under the microscope. In one type of the method the organism are counted direct in a drop of sample under standardized conditions. The alternative is to separate the plankton from a known volume of water and perform the count on this concentrate. In this case, far fewer fields of view needs to be examined than with a direct examination and by suitable concentration it is possible to count the plankton even when very few organisms are present.

TREATMENT OF WATER FOR QUALITY

To render water consumable for human and livestock following treatments are recommended.

A. Water Softening

To make water consummated its calcium, magnesium, bicarbonates, sulphate and chlorides are essentially to be removed first. For this purpose following two methods are widely used.

i). Clark’s Method: On a large scale it is used to remove temporary hardness of water for this purpose Ca(OH)₂ is added.

ii). Ion Exchange Method: This method is applied for softening permanent as well as temporary hard water. For this purpose sodium zeolite is used. By passing concentrated NaCl from Ca-Zeolite, Na₂-Zeolite is regained. The reaction, which occurs, is as follow:

Ca²⁺ + Na₂-Zeolite

Ca-Zeolite + 2Na⁺

Ca⁺²-Zeolite + 2NaCl Na²⁺-Zeolite + CaCl₂

B. Control of Biologics

Growth of Plankton and Algae in river water is seasonal so it is useless to have the storage. Plankton growth can be controlled by using algicide which include cupper sulphate and chlorine.

i. Cupper Sulphate: Depending upon the degree of Biologics development, CuSO₄ can be sprayed under pressure varying from 0.1 to 5 ppm. It is advisable to give first treatment of 0.5 ppm and repeated after a day with 1.0 to 2.0 ppm, if no effect has been produced.

ii. Chlorine: Chlorine is applied prior to the addition of water to the reservoir. It is used from 5 to 10 ppm.

C. Bacterial Control

Reduction in organic matter by oxidation and reduction in hardness occurs as a result of algal action. To control the bacteria following two procedures are applied.

i. Chlorination: Chlorination is described earlier and chlorination stages include: Simple chlorination; Ammaria chlorine treatment (Chloramination); Super chlorination, Dechlorination and Break point chlorination.

ii. Ozonization: It is done with O₃, which is produced from passage of high voltage current from air. The O₃ is very unstable and react with oxidizing agent which produces sterilization effect. If we compare chlorination with ozonization then it is as:

Chlorination is simple but ozonization requires a complex procedure and apparatus. But it is over ruled when it gives the advantage of odorless and tasteless water. The residium of chlorine in water supplies give advantage of combating accidental contamination which is not possible in case of ozone. There is a maintenance expenses for ozone plant but not in case of chlorine. Finally the cost is high in case ozone but negligible in case of chlorine.

D. Pollution Control

Every source of pollution must be avoided to contaminate water. Few scientists have mentioned the measures that includes are such as (i) Avoid the water plant installations at public places. (ii) Afforestation should be done to avoid the soil source of contamination. For this purpose conifer trees should be planted. (iii) Care should be paid to the proper disposal of the sewerage water so that it can’t contaminate water in pipe supply and at large scale as well.

EPILOGUE

The problem is not the supply of water; earth has virtually the same amount of water today as it did when dinosaurs roamed the planet. The problem is simply people – or increasing numbers and or flagrant abuse of one of or most precious, and limited, resources. It is upto us that we need to use the water resource judiciously, stop polluting this resource, follow the hygienic standards to maintain its quality and purity, follow measures to reduce the further degradation of the environment leading to water pollution and above all to conserve this vital resource for our coming generations.

PREAMBLE

WATER USE

Water Use for Animals

WATER CYCLE

WATER QUALITY IN NATURE

WATER

QUALITY FOR HUMAN AND ANIMALS

Local Sample

Table 6.

The guideline values of WHO (1985)

for domestic use of water.

Chemical Parameters

Bacteriological Parameters

Untreated water