CHEMISTRY PROJECT Checking bacterial contamination in drinking water by testing sulphide ion and also testing the hardness of water B.AISHWAR YA I. Stagnant water is highly unsafe because it contains lots of bacteria.2 WHAT DOES IMPROVED DRINKING WATER AND SANITATION MEAN? Improved drinking-water source An improved drinking-water source is defined as one that. gas works. paints and chemical plants are responsible for water pollution. 1. Sulphide ions are present in water when anaerobic bacteria decompose organic matter or reduce sulphates to sulphides. leather industry. 1. is protected from outside contamination. by nature of its construction or through active intervention. an improved sanitation facility is defined as one that hygienically separates human excreta from human contact. Improved sanitation facilities For MDG monitoring.1 INTRODUCTION Water available these days is highly polluted in urban areas.3 DRINKING WATER QUALITY . 1. sewage works. Pollutants from paper mill. in particular from contamination with faecal matter. and radiological characteristics of water. biological. physical. then.Water quality refers to the chemical. It is most frequently used by reference to a set of standards against which compliance can be assessed. It is necessary that drinking water sources should be tested regularly to know whether water is meeting the prescribed standards for drinking or not and. The most common standards used to assess water quality relate to health of ecosystems.4 DRINKING WATER QUALITY GUIDELINES AND STANDARDS The Bureau of Indian Standards (BIS) has specified drinking water quality standards in India to provide safe drinking water to the people. the . and drinking water. 1. It is a measure of the condition of water relative to the requirements of one or more biotic species and or to any human need or purpose. if not. safety of human contact. Keeping in view requirement of preparing Uniform Drinking Water Quality Monitoring Protocol. . that water is considered unfit for human consumption. Government of India in 2005. This is known as Uniform Protocol for Water Quality Monitoring. Definition of drinking water quality BIS has set specifications in IS–10500 and subsequently the revised edition of IS 10500: 2012 in Uniform Drinking Water Quality Monitoring protocol. brought out by Ministry of Water Resources. Acceptable limits and permissible limit in absence of alternate source. A need has arisen to have a separate uniform protocol for Drinking Water Quality Monitoring in view of increasing risk of gynogenic and anthropogenic contamination.e. If any parameter exceeds the limit. the Ministry of Drinking Water and Sanitation (MDWS). Government of India constituted an Expert Group which prepared the Protocol. The Drinking Water Quality Monitoring protocol describes specific requirements for monitoring drinking water quality with a view to ensure provision of safe drinking water to the consumers.extent of contamination/ unacceptability and the follow-up required. Some parameters apart from those mentioned in IS 10500: 2012 may also be measured if the States deem it necessary. This standard has two limits i. Apart from BIS specification for drinking water. there is one more guideline for water quality. TASTE AGREEABLE AGREEABLE 5. pH VALUE 6. MAGNESIUM (mg/l) 30 100 . TURBIDITY 1 5 4. TOTAL HARDNESS (mg/l) 200 600 8. TOTAL ALKANITY (mg/l) 200 600 7.5 AGREEABLE 3. ODOUR AGREEABLE AGREEABLE 2. TOTAL DISSOLVED SOLIDS(G/L) 500 2000 6.NO.8. TEST PARAMETER DRINKING WATER SCPECIFICATION REQUIREMEN T PERMISSIBLE LIMIT IN THE ABSENCE OF ALTERNATE SOURCE 1.5 . CALCIUM (mg/l) 75 200 9.S. SULPHATE (mg/l) 200 400 13. CHLORIDE(mg/ l) 250 1000 11.2 1 12. RESIDUAL FREE CHLORINE(mg/ l) 0.0 1.5 15 IRON (mg/l) 0.10. 2.3 NO RELAXATION II. NITRATE NITROGEN (mg/l) 45 NO RELAXATION 14 FLUORIDE (mg/l) 1.1 TESTING FOR MICROBIAL CONTAMINATION Microbial Contamination Test is conducted on non-sterile products to check: . viruses. Faeces can be a source of pathogenic bacteria. the greatest microbial risks are associated with ingestion of water that is contaminated with human or animal (including bird) faeces. The preferred strategy is a management approach that places the primary emphasis on preventing or reducing the entry of pathogens into water sources and reducing reliance on treatment processes for removal of pathogens. protozoa and helminths.• The level of microbial (bacterial and fungal) contamination • Presence/ absence of certain pathogenic microorganism in order to assure product safety. from catchment to consumer. Safety is increased if multiple barriers are in place. including protection of water resources. In general terms. to prevent the contamination of drinking-water or to reduce contamination to levels not injurious to health. 2.2 WHO GUIDELINES FOR MICROBIAL CONTAMINATION Securing the microbial safety of drinking-water supplies is based on the use of multiple barriers. proper selection and operation of a series of treatment steps and management of distribution systems (piped or otherwise) to maintain and protect treated water quality. . in a shower or air conditioning system) and inhaled. 2. thrives in warm waters. Here is a list of EPA regulated bacteria/viruses in drinking water. living in the intestines of infected humans or animals. animals or plants.3 BACTERIA AND CONTAMINATION Both bacteria and viruses are microorganisms regulated by EPA’s Maximum Contaminant Levels (MCLs) criteria. this bacteria in water is a health risk if aerosolized (e. despite many form’s ability to aid in water pollution control. such as polioviruses.. disease-causing organisms that can be found in pre-treated and/or inadequately treated water. Viruses are the smallest form of microorganisms capable of causing disease. echoviruses and coxsackieviruses. resulting in a type of pneumonia known as Legionnaires disease.2. Enteroviruses are small viruses. and their health risks: Legionella.4 INFECTIVE DOSE . in addition to the three different polioviruses are 62-nonpolio enteroviruses that can cause disease in humans ranging from gastroenteritis to meningitis. bacteria are typically single-celled microorganisms that can also cause health problems in humans. a bacteria found naturally in the environment — typically in water. particularly those of a faecal origin infectious to humans by waterborne transmission.g. COMMON TYPES OF BACTERIA AND VIRUSES Various types of bacteria/viruses are categorized as pathogens. . Part of the demonstration of pathogenicity involves reproducing the disease in suitable hosts. Table 7. Experimental studies in which healthy adult volunteers are exposed to known numbers of pathogens provide information. behaviour and resistance. extrapolation to more vulnerable subpopulations is an issue that remains to be studied in more detail.1 provides general information on pathogens that are of relevance for drinking-water supply management.Waterborne infections The pathogens that may be transmitted through contaminated drinking-water are diverse in characteristics.logical studies and case histories. Waterborne transmission of the pathogens listed has been confirmed by epidemic. but these data are applicable to only a part of the exposed population. 2.5 CULTURE MEDIA 2.1 NUTRIENT PADS Nutrient pad sets for colony counting by the membrane filter method.5. These nutrient pad sets are dehydrated culture media that are already sterilised and individually inserted in Petri . or learn from. put in test tubes. The special feature of this alternative to agar media is the long shelf life of 24 month by storage at room temperature. The growing environment used will depend on what the researcher wants to do with. All nutrient pad set types are supplied with the appropriate membrane filters (pore size and colour). Each has specific advantages and disadvantages. the microbes.dishes. The powder is dissolved in water. 2. which are also presterilized and individually packaged. Nutrient Broth Bacterial Growth Medium Nutrient broth is typically made of a powdered beef extract that contains peptones (broken down proteins). Jell-o-like agar. and are supplied in 47.or 50mm diameters.5.2 BROTHS The two main types of bacterial growth media used are liquid broth and solid. and sterilized. The membrane filters are customized to meet the requirements of microbial detection. . The test is a simple modification of the multiple-tube procedure.1 This test is based on the principle that coliforms and other pollution indicator organisms should not be present in a 100 mL water sample. Lactose is the fermentable carbohydrate. vitamin.6. and amino acids sources are provided by Enzymatic Digest of Gelatine. Enzymatic Digest of Casein. inhibiting many organisms except coliforms. Sodium Lauryl Sulphate is the selective agent.1 One 100 mL test sample is inoculated into a single culture bottle to obtain qualitative information on the presence or absence of coliforms. . Dipotassium Phosphate and Monopotassium Phosphate provide buffering capacity.Broth is convenient.2-4 Comparative studies with the membrane filter procedure indicate the P-A test may maximize coliform detection in samples containing many organisms that could overgrow coliform colonies and cause problems in detection. Sodium Chloride maintains the osmotic balance of the medium. EPA.1 PRESENCE-ABSENCE The Presence-Absence (P-A) test is a presumptive detection for coliforms in water. as most bacteria will grown in this type of medium. 2.6 TEST METHODS 2. and Beef Extract.S. PROCEDURE The nitrogen. even those with widely different aero tolerances (oxygen requirements).1 The P-A test is described in standard methods for water testing1 and U. through the presence or absence of lactose fermentation. or catalytic chemistry.6. There are many discrete entities that are easily detected but difficult to count. The MPN method involves taking the original solution or sample. is a method of getting quantitative data on concentrations of discrete items from positive/negative (incidence) data. otherwise known as the method of Poisson zeroes. to use the number of positive and negative samples to estimate the original concentration within the appropriate order of magnitude.3 MEMBRANE FILTRATION MENTHOD . and assessing presence/absence in multiple subdivisions. Any sort of amplification reaction or catalysis reaction obliterates easy quantification but allows presence to be detected very sensitively. 2.Bromcresol Purple is used as an indicator dye.2 MOST PROBABLE NUMBER The most probable number method. A suite of replicates at any given concentration allow finer resolution. 2. and subdividing it by orders of magnitude (frequently 10× or 2×).6. enzyme action. lactosefermenting organisms turn the medium from purple to yellow with or without gas production. Common examples include microorganism growth. The degree of dilution at which absence begins to appear indicates that the items have been diluted so much that there are many subsamples in which none appear. The MF Technique was accepted by the U. whereas the MPN procedure only indicates the presence or absence of an approximate number or organisms (indicated by turbidity in test tubes). Useful for bacterial monitoring in the pharmaceutical. cosmetics. In the 1978 publication. the U. EPA for microbiological testing of potable water in the 11th edition of Standard Methods for the Examination of Water and Wastewater. Used to monitor drinking water in government laboratories. Reduces preparation time as compared to many traditional methods. Microbiological Methods for Monitoring the Environment.S. Allows isolation and enumeration of discrete colonies of bacteria.The Membrane Filter (MF) Technique was introduced in the late 1950s as an alternative to the Most Probable Number (MPN) procedure for microbiological analysis of water samples. electronics. EPA stated that the MF Technique is preferred for water testing because it permits analysis of larger samples in less time. Effective and acceptable technique. ADVANTAGES OF MF TECHNIQUE Permits testing of large sample volumes.S. and food and beverage industries. The MF Technique offers the advantage of isolating discrete colonies of bacteria. . Provides presence or absence information within 24 hours. 05M Starch solution as indicator. MATERIALS REQUIRED : Cadmium acetate 50g Zinc acetate 50g Distilled water 500mL Iodine solution 0. care should be taken at the time of sampling to exclude air by flushing it with nitrogen or carbon dioxide. EXPERIMENT AIM : To test the contamination of water by bacteria by checking the sulphide ions concentration and find out cause of contamination. Spread Plate. THEORY: Sulphide ions are readily oxidised therefore. or MPN techniques. The best way is to 'fix' the sample immediately after solution. HCl Na2 S2 O3 0. PROCEDURE: . Allows for removal of bacteriostatic or cidal agents that would not be removed in Pour Plate. This is a difficult process. III.025M Conc. Take 50g of cadmium acetate and 50g and 50g of zinc acetate and dissolve in water.+ Na2S4O6 + 2Na+ . Repeat the same procedure with other samples of water. Titrate the excess of iodine against 0. Take 100 mL of fixed sample solution in titration flask. Take 20mL of cadmium-zinc acetate solution and add 80 mL of sample of given water to obtain a total volume of about 100 mL. ENDPOINT : Blue to colourless. CHEMICAL REACTION : I2 + H2S = 2HI + S I2 + 2Na2S2O3 = 2I.025 M iodine solution. Add starch solution as indicator. Calculate the amount of S-2 ions in the original samples from the amount of iodine used in reaction with H2S. Add immediately 15mL of 50% of HCl solution in water. Neutralize the solution with a little excess of alkali.05 M Na2S2O3 . Add 20 mL of 0.