Sewage Pollution in Central India

Raipur is a fast growing city in central India due to being commercial centre for the steel, cement and forest products of the country. Large quantity (≈300 million lit/day) of untreated sewage waste water is discharged into seven reservoirs located in the city. Sewage carries excessive nutrients, heavy metals, organics, bacteria, yeast and fungi by leaking contents into the drinking water which cause acute health problems, ranging from common diarrhoea to deadly diseases such as hepatitis, cholera, typhoid fever, etc. Therefore, in this work, the microbial and chemical contamination of sewage waste of Raipur city, Chhattisgarh, India is described.


Introduction
Sewage is transported by water wastes resulting mainly from human activities such as washing, cooking, sanitation, commerce, industry, agriculture and surface runoff, etc. [1].The contaminated sewage water discharged into water reservoirs is one of the main culprits for spread of water borne diseases, air pollution and climate change [2].Sewage wastes are contaminated with heavy metals, surfactants, toxic organic compounds, bacteria, fungi, parasites, and viruses that can cause intestinal, lung, and other infections [3]- [29].About 60 percent of urban deaths in India are due to the lack of safe drinking water facilities.Further deaths due to water borne diseases are second only to malnutrition.In present study, the microbial and physicochemical characteristics of the sewage waste of a vast growing city, Raipur (capital, Chhattisgarh state, India) are described.

Study Area
Raipur city is experiencing rapid growth with corresponding increase of economic and commercial activities in an unsustainable order.The city is being the commercial center for steel, cement and forest products.More than two million people living over ≈1000 km 2 area discharges ≈300 million L/day waste flowing into seven open reservoirs constructed in the city, Figure 1.The area of sewage sinks was ranged from 2 -4 km 2 .Every year, several people are died due to outbreak of waterborne diseases i.e. jaundice, fatal diarrhea, dysentery, hepatitis, cholera, typhoid fever, etc. in every summer by mixing of the municipal waste with the drinking water.

Sample Collection
The composite water sample (100 × 5 mL from five points of each location) was collected into sterile glass bottles (500 mL) in April 2015 as prescribed in the literature [30].The pH, electrical conductivity (EC), dissolved oxygen (DO) and reduction potential (RP) values of the water were measured at spot by Hanna made sensors.The total hardness and alkalinity values were determined by the titration methods.One kilogram of the top composite sewage sludge from five points of each location (0 -10 cm) was taken from seven reservoirs in April 2015 by a stainless steel spoon and stored in a glass jar [31].Samples were transported to the laboratory and immediately stored in a freezer.

Analysis of Microbe
The microbes i.e.TBC (total bacterial count, all aerobic species of bacteria), pseudomonas, E. coli or yeast + fungi were detected by the bactaslyde (presterilized slide, coated with specially developed media of lactose and indicator) method established by Rakiro Pvt. Ltd. [32].The slide no.BS-101, BS-102 and BS-103 were used for detection of E. coli + TBC, pseudomonas + TBC and yeast-fungi + TBC, respectively.The packed slide was opened, plunged into the test liquid vertically for 20 -25 sec.The slide was shaken 3 -4 times gently to remove the excess water by putting back into the tube with tight closing.The bactaslyde was incubated for 24 hrs at 37˚C for development of colonies.After incubation, the density of the colonies grown on the slide was compared with the standard chart provided.The TBC, pseudomonas, E. coli, and yeast or fungi were marked by dark red colored colonies, respectively, Figure 2. The Salmonella bacteria in the water were detected by the pouch pack (i.e. containing organics and sulfite material) method [32].The content (10 g) of two pouches was added into a 150-mL sterilized bottle filled with 100 mL of contaminated water, and incubated for 24 hrs at 37˚C.The light blue color of the solution was turned into dark black in presence of Salmonella species, Figure 3.

Analysis of Inorganic Species
The sample was filtered through glass fibre filter (0.45 µm) for analysis of ions and metals.The F − content was analyzed by using Metrohm-720 ion meter using the fluoride selective electrode.
The Dionex chromatography DX120 equipped with anion separation columns (AS9-HC, 250 × 4 mm), cation separation column (CS12A, 250 × 4 mm) and conductivity detector was used for analysis of the ions (i.e.Na + , K + , Cl − , SO − , Mg 2+ and Ca 2+ ).A 0.25 g of the sample was digested with acids (3 mL HCl and 1 mL HNO 3 ) in a closed system with P/T MARS CEM (Varian Company) microwave oven for use of metal analysis.The Varian ICP-OES-700-ES series was used for monitoring of metals (i.e.Cr, Fe, Mn, Ni, Cu, Zn and Pb) in the extract.The GF-AAS SpectrAA 220 Zeeman was used for the analysis of As, Cd and Hg.The NCS DC 73382 CRM sediment sample was used for the quality control.

Water Quality Index
For this study, ten parameters i.e. pH, EC, DO, hardness, alkalinity, Mg, Ca, Cl − , 3 NO − and 2 4 SO − were cho- sen for computation of water quality index (WQI) by using the standard values recommended by WHO and BIS [22] [23].The weighed arithmetic method was employed for calculation of the WQI of sewage water bodies with the help of following expression.
q n = Quality rating of the nth water quality parameter; V n = Estimated value of the nth parameter of a given water; S n = Standard permissible value of the nth parameter; V io = Ideal value of the nth parameter of pure water (i.e., 0 for all other parameters except pH) and Dissolved oxygen (7.0 and 14.6 mg/L, respectively); W n = Unit weight for the nth parameter; K = Proportionality constant.

Physical, Chemical and Microbial Characteristic of Sewage Water
The physical, chemical and microbial characteristics of the water are presented in Tables 1-4.The water was colored with offensive smell.The value of pH, EC, DO, RP, total hardness (TH) and alkalinity was ranged from 6.9 -7.The EC and TH value was observed to be higher than the recommended values reported for the water [22] [23].
The RP value was found to be 4-times less than the recommended value of 650 mV [23].
The chromatograms of indicative bacteria (i.e. total coliform, E. coli, pseudomonas and salmonella), yeast and fungi are shown in Figure 2 and Figure 3. Their extreme concentrations were observed in all sewage water reservoirs, ranging from 10 4 to 10 7 per mL Table 4.The positive test for Salmonella bacteria was marked for all sewage reservoirs.The microbial contamination levels in the sewage water was found to be higher than the microbe contents reported in the water of other region of the country [15]- [21].The mean WQI value for seven sewage water reservoirs was found to be 191, indicating unsuitability for drinking purpose of the animals, Table 5.The EC, hardness, alkalinity, organic matters, nitrate and microbe levels are main deteriorating components of the sewage waste.

Correlation Coefficient and Sources
The species (i.e.F − , Cl − , NH + , Na + , K + , Mg 2+ , Ca 2+ , As, Cr, Fe, Mn, Ni, Cu, Zn, Cd and Pb) among themselves had either poor or negative correlation in the waste water, indicating origins from the multiple diverse sources.The correlation coefficient matrix for the chemical species (i.e.As, P, S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Cd, Pb and Hg) in the solid waste are presented in Table 7.The ferro alloy elements (i.e.P, S, Cr, Mn, Ni, Cu and Zn) and Ca among themselves had good correlations, showing origin from sources i.e.

Conclusion
Several chemicals and microbes i.e. heavy metals, nitrate, nutrients, total coliform, Escherichia, pseudomonas, salmonella, yeast and fungi were found to be present in the sewage waste at extremely high levels.The increased prevalence rate of the acute water borne diseases in the summer season is expected due to high multiplication rates of microbes and mixing of the waste with the drinking water supplies i.e. pond, lake, well and shallow tube well.The drinking water contamination could be controlled by improving the sanitary infrastructure with provision of good hygiene system to the population.

Figure 1 .
Figure 1.Representation of sampling locations in Raipur city, India.

Table 1 .
Physical characteristics of sewage water.

Table 2 .
Chemical characteristics of sewage water, mg/L.

Table 3 .
Contamination levels of sewage water with As and other heavy metals, mg/L.

Table 4 .
Microbial contamination levels of sewage water.Total Bacterial Count (comprises of all the aerobic species of bacteria present in the sample), E. coli = Escherichia coli.

Table 5 .
Water quality index of sewage water.

Table 6 .
Concentration of element in solid sewage, mg/kg.

Table 7 .
Correlation matrix of elements in solid sewage waste., industrial and vehicular effluents.Other species had either poor or negative correlations, indicating origin by multiple diverse sources i.e. wasted food materials, leaded pipes, automobile tire rust, vehicular emissions, industrial discharges, runoff water, etc.The major sources of microbes in the sewages are assumed from the human and animal excreta. domestic