In the present study, GRAS microorganisms were used for the treatment of polluted river water. GRAS microorganisms are those microorganisms which are Generally Referred As Safe for humans. Bioremediation is one of the method to treat contaminated water, soil and air with the help of live microorganisms. Total four microorganisms were isolated from different water and cow dung samples and identified on the basis of morphology and biochemical testing. They were namely Streptococcus salivarius subsp. thermophilus, Staphylococcus hominis subsp. hominis, Staphylococcus xylosus, Bacillus licheniformis. Bacillus licheniformis showed the highest potential to degrade the organic matter present in the polluted water on the basis of BOD testing.
The earth has an abundance amount of water, but unfortunately, only a small percentage (about 0.3%), is even usable by humans. The other 99.7% is in the oceans, soils, icecaps, and floating in the atmosphere. Climate change has also altered the global hydrological cycle. Even though a very less amount of water is usable, even much of the 0.3% that is usable is unattainable. The distribution of water is as: ocean water: 97.2 %, glaciers and other ice: 2.15 %, groundwater: 0.61 %, freshwater lakes: 0.009 %, inland seas: 0.008 %, soil moisture: 0.005 %, atmosphere: 0.001 %, rivers: 0.0001 %.
The Yamuna river, a tributary of Ganga, is one of the most polluted river in India. The daily stretch of river Yamuna is nearly 22 km but here it turns into sewer due to various reasons like industrial disposal, religious offering of flowers, food and immersion of idols, clothes washing, cattle bathing, municipal waste water disposal, agricultural runoff resulting in the change in physico-chemical characteristics of water. Population explosion is also one of the factor for increase in the area of polluted water.
The untreated discharge in water bodies consumes oxygen killing aquatic life forms. It also affects human health. Approximately 30,000 people die every day in developing countries because of unsanitary water supply (World Health Organisation survey, 1980)  Many fatal diseases are caused due to intake of polluted water and 14000 people die everyday because of this reason.
Bioremediation is a process in which living microorganisms are used to treat organic or inorganic contaminants present in water, soil or air in lesser toxic forms. This method of treating contaminants using microbes was invented by George M. Robinson. The microbes used to bioremediate the wastewater can be indegenous to that area or can be isolated from different place and used in the contaminated area.
Bioremediation takes longer time to treat pollutants in water still it is a better replacement of chemical treatment as it is economical, ecofriendly and possibly more cost-effective. Generally recognised as safe microbes or GRAS microbes were used in the present study as a tool of bioremediation.
In sterile bottles, 98 ml of water sample was taken and 2 ml of each isolated microbial culture were added to them and mixed and incubated at 37 degree Celsius for 48 hours at 120 RPM. After 48 hours the samples were centrifuged at 1000 RPM for 20 minutes and then pH, TDS, acidity and alkalinity for every microbe were measured using the volumetric method.
According to CPCB manual, the water sample(33% diluted) was filled in BOD bottles and 1 ml of each isolated microbial culture were inoculated in each BOD bottle and incubated at 20 degree Celsius for 5 days. After 5 days of incubation, initial and final DO were calculated in duplets.
ISOLATION AND CHARACTERIZATION OF ISOLATED MICROBIAL CULTURE
Total 10 bacterial species were isolated from water and cow dung samples located at different sites, in which 6 were showing positive pathogenicity test, so, for further testing only 4 bacterial species were characterized on the basis of morphological and biochemical characteristics.
These were Streptococcus salivarius subsp. thermophilus, Staphylococcus hominis subsp. hominis, Staphylococcus xylosus and Bacillus licheniformis.
EFFECT OF ISOLATED BACTERIAL SPECIES ON WATER SAMPLE
- ODOUR: Initially, the odour of water sample was very septic. After treatment with bacterial cultures, there was no noticeable change in odour.
- COLOUR: The colour of water sample was yellow in beginning but after treatment with bacterial cultures, the colour changed to pale yellow.
- pH : Initially, pH was slightly acidic but after treatment with bacterial cultures, pH was increased and became basic due to degradation of protein and amino acids present in the water sample by the activity of inoculated microorganisms and the indigenous microorganisms in the water sample.
- TDS: Initially, TDS was less but after treatment with bacterial cultures, TDS increased due to the activity of bacterial species inoculated and indigenous microrganisms in the water sample. Maximum TDS increase was shown by Bacillus licheniformis which means this bacteria degrade more organic matter present in the water sample than other bacterial species which resulted in increase in TDS.
- ACIDITY: Acidity was higher initially but after the treatment, acidity decreased due to the activity of microorganisms which were used in the treatment of water sample. Maximum reduction of acidity was shown by Bacillus licheniformis which was 54%.
- TOTAL ALKALINITY: Total alkalinity of water sample was very high but after the treatment, total alkalinity decreased due to the degradation of organic matter present in the water sample by the microorganism used in treatment. Maximum alkalinity reduction was shown by the bacterial species Streptococcus salivarius subsp. thermophilus, which was 79% of initially alkalinity.
- BOD: BOD of water sample was less but after treatment, sample BOD increased which means that the microbes consumed more dissolved oxygen to degrade the organic matter already present in the water sample as compared to the indigenous microbes of the water sample. Maximum consumption of dissolved oxygen was shown by Bacillus licheniformis, which means that this bacterial species had more capacity to degrade the organic matter present in the water sample than other bacterial species which is used in bioremediation of water sample.
All the parameters of water sample were not in permissible limit according to CPCB guidelines. What we observed in our project that those microorganisms isolated from different sites, they showed enough reduction in acidity, alkalinity and they also increased the BOD which means they consumed more dissolved oxygen then indigenous bacterial species of the water sample. Maximum acidity reduction was shown by Bacillus licheniformis, which was 54% of initial value and maximum alkalinity reduction was shown by Streptococcus salivarius subsp. thermophilus which was 79% of initial value and maximum consumption of dissolved oxygen was shown by Bacillus licheniformis, which means that Bacillus licheniformis had the most capacity to degrade organic matter as compared to the other organisms which were used in bioremediation in this project.