RESULTS AND DISCUSSION

3.1. Physiochemical parameter analysis Municipal solid waste composition, elapsed time, temperature, moisture and available oxygen are some of the important factors, influencing the leachate quality. The leachate quality with similar waste types may be different in landfills located in varied climatic regions. Furthermore operational practices in landfills also influence the leachate quality. The results of physico-chemical characteristics of the leachate and samples from water bodies in Mavallipura landfill are presented in Table 1.

3.1.1. pH pH values of leachate (L1, L2 and L3) of the landfill site were 7.4, 7.6, 7.5 and the pH values of the P4 (pond) and G5 (open well) water samples found to be 8.4 and 7.5. The critical reaction in MSW is the degradation of organic materials to produce carbon dioxide and a small amount of ammonia that further results in the formation of ammonium ions and carbonic acid. The carbonic acid dissociates with ease to produce hydrogen cations and bicarbonate anions, which influence the level of pH of the system. Additionally, leachate pH is also influenced by the partial pressure of the generated carbon dioxide gas that in contact with the leachate. Dissolved materials and gases shift the pH of natural water either to acidic or alkaline side. pH lower than 7 are usually softer waters and the acidity is due to carbonic, humic, fulvic and other organic acids (Mahapatra et al., 2011a,c). pH above 7 can carry a greater load of dissolved substances and are capable of supporting a good plant life. The alkaline nature of leachate is an indicator of the mature stage of the dumping site (Jorstad and Acworth, 2004).

3.1.2. Alkalinity Alkalinity is caused by bicarbonate, carbonate and hydroxyl ions. For landfill leachate, total alkalinity values are often found to be significantly higher. This is because of the biochemical decomposition, and dissolution process occurring within landfill and disposal sites. The biodegradation processes of organic matter produces significant amount of bicarbonate, which represents dissolved carbon dioxide which is also the major components of alkalinity (Mahapatra, 2011b). In this investigation, the Mavallipura leachate samples (L1, L2, L3) was found to have significantly high alkalinity values. The high alkalinity observed in this study reflects the level of biodegradation process taking place within the disposal sites. The presence of significant amounts of ash and slag from the combustion of wood, agricultural residues can potentially increase alkalinity in leachate greatly in Mavallipura landfill sites. High alkalinity values observed in this study therefore imply that there a fair chances of groundwater contamination. This might produce unpleasant odour in the water sample that is unacceptable for many users (Meenakumari, 2004).

3.1.3. Conductivity and total dissolved solids These parameters are influenced by the total amount of dissolved organic and inorganic materials present in the solution, and are used to demonstrate the degree of salinity and mineral contents of leachate. Total mineral content further refl ects the strength and overall pollutant load of the leachate. The salt content in the leachate is due to the presence of potassium, sodium, chloride, nitrate, sulphate and ammonia etc. Extremely high values for conductivity are attributable to high levels of cations and anions. High concentrations of total dissolved solids may reduce water clarity, which contributes to light limitation resulting in a decrease in photosynthesis and leads to an increase in water temperature. This affects the growth and development of the biotic components as photosynthetic bacteria and algae. High TDS limits the growth and may lead to the death of many aquatic organisms. Electrical conductivity is an indicator of dissolved inorganic ions in ground water; pond (P4) and open well (G5) showed high values (values of < 40 0e800 mS/cm: clean ground waters) in the close vicinity of landfill site implying possible cross contamination of the leachate with the ground waters

3.1.4. Major anions The level of inorganic elements present in leachate is dependent principally on the ease of leaching inorganic constituents present in the MSW and the stabilization process in the landfill. In this investigation, Mavallipura landfill leachate sample was found to have considerably high concentrations of all the major anions like chlorides, nitrates, sulphates where concentration of chloride was highest, while sulphate was lowest. High chloride content in the leachate sample reflects the presence of significant amount of soluble salts in the municipal solid waste materials of the study area. High chloride content in Mavallipura landfill leachate sample can be attributed to landfill dumps, sewage ingress, and domestic effluents including animal waste disposed to the site. High concentrations of chlorides were also observed in the pond (P4) and open well (G5) close to the landfill site. Excess of chloride in water is usually taken as an index of pollution and considered as a tracer for groundwater contamination (Loizidou and Kapetanios, 1993). A high chloride content in ground water can be from pollution sources such as domestic effluents, fertilizers, septic tanks, and leachate (Mohr et al., 2006). High chloride content in ground water causes diseases related of heart and kidney. Sulphate in landfill leachate is sourced primarily from the decomposition of organic matter, soluble waste, such as construction wastes or ash, synthetic detergents and inert waste, such as dredged river sediments. Nitrates represent the most oxidized form of nitrogen found in the natural system. It is often regarded as an unambiguous indicator of domestic and agricultural pollution. In leachate sample, it is formed primarily as a result of oxidation of ammonium to nitrite and subsequently, to nitrates by nitrification process. The knowledge of nitrates and phosphates is important in predicting the nutrient status of waters as these ions are important plant nutrients which usually appear as a result of decomposition and mineralization of organic matter.

3.1.5. Major cations Constituents as calcium, magnesium, sodium, and potassium are considered to be major cations typically present in leachate. Derived from the waste material through mass transfer processes, the concentration of these cations in leachate is specific to the composition of the waste mass and the prevailing phase of stabilization in the landfill (Christensen et al., 2001 ). The high concentration of sodium around the landfill indicates the impact of leachate. The high concentration of sodium causes renal, cardiac and circulatory diseases (Mohr et al., 2006). Despite few inputs from agricultural activities, the high concentration of potassium has been reported to be an indication of the leachate effect (Eillas, 1980). Calcium is one of the most common cations found in groundwater aquifers, as it dissolves from rocks, such as limestone, marble, calcite, dolomite, gypsum, fluorite, and apatite. Magnesium is one of the principal cations associated with water hardness (Harmsen, 1983). Calcium concentrations were noticeably high in open well (G5). Sodium and potassium are both present at considerably high concentrations in all the samples. Sodium and potassium are not affected significantly by microbiological activities within the landfill site. These ions play a major role in plant physiology and are most likely derived from vegetable residues and domestic wastes. Increased concentration of potassium in ground water is often considered as an indicator of leachate pollution (Christensen et al., 2001 ). The primary source of potassium is due to weathering and erosion of potassium bearing minerals such as feldspar and leaching of fertilizer. It can have adverse health effects from exposure to increased potassium in drinking water. Excess potassium causes kidney failure, heart disease, coronary artery disease, hypertensions, and diabetes. Sodium and potassium being dominant cations are not significantly affected by microbiological activities within the landfill site. Ammonium ions can enter the aquatic environment via municipal effluent discharges and excretion of nitrogenous wastes from animal and indirect means such as air deposition, nitrogen fixation, and runoff from the agricultural lands. High ammonia levels in water bodies make it difficult for aquatic organisms to sufficiently excrete the toxicant, leading to a toxic build up in internal tissues and blood and potential death. It affects the environmental factors such as pH and temperature, can affect growth and development of aquatic animals. Furthermore, the accuracy of the analysis was verified by ion balance method. The ratios of the sum of the molar concentrations of anions and cations should be nearer to 1. From the ionic balance ratio, it is confirmed that the ratios of molar concentrations are near to 1 supporting the accuracy of various parameters determined.

Piper diagram helps in grouping similar cations and anions and characterization of water types (Piper and Darrah, 1994). The Piper diagram reveals the composition of different ions (explains ionicchemistry) in percentage and also identifies the hydrogeochemical facies. By grouping sodium (Na þ) þ potassium (K þ) together, the major cations were displayed on the trilinear Piper diagram (Freez and Cherry, 1979). Similarly, carbonate (CO32 ) þ bicarbonate (HCO3) are grouped together along with sulphates and chlorides resulting in three groups of the major anions. Central diamond shape area is a matrix transformation of the graph of anions (sulphate þ chloride/total anions) and cations (sodium þ potassium/total cations), which represents the total ionic. A few conclusions can be drawn from the piper diagram of the collected leachate samples (Fig. 1 of Supplementary material). Firstly, it indicates a predominance of select cations as Na and K in comparison to Ca and Mg. Secondly, bicarbonates and carbonates are the dominant anions found in the leachate samples compared to sulphates and chlorides. The analyzed sample can be thus categorized as the NaeHCO3 type leachate. The analysis also showed large percentages of the samples within the CaeSO4 category followed by the NaeHCO3 type. However, anions like sulphates were very meager in concentrations compared to other anions

3.1.7. BOD and CODThe BOD5/COD ratio indicates the age of the waste fill (Hui, 2005) and the changes of biodegradable compounds in the leachate. Any water, having its BOD5/COD ratio more than 0.63, can hence be considered to be quite controlled due to biological activity (Naveen et al., 2013). The value of COD and BOD5/COD can characterize the age of the landfi ll. A comparison of the values of COD and BOD5/COD of the present studies with the earlier study (Hui, 2005) showed that the age of all the leachate is between 5 and 10 years. This was confirmed with the actual age of dumping of MSW. Similar studies carried earlier (Slomczynska and Slomezynski, 2004; Bhalla et al., 2012) showed that the physicochemical characteristics of leachate are highly variable over the course of a landfills life. Thus, the age of the landfill has a significant effect on leachate composition. The young leachate primarily comprises of undecomposed organic compounds that are readily biodegradable, giving rise to refractory compounds that accumulate with the exploitation of landfill and are resistant to biochemical degradation. Higher organic matter in leachate samples leads to high emissions if they are not treated, that further increases the green house gas (GHG) foot print of the area (Ramachandra and Mahapatra, 2015). The results of the present study were similar to studies conducted earlier (Granet et al., 1986) that showed low BOD5/COD (~0.1) indicative of a stabilized leachate. Unlike the present study where the BOD5/COD values of the leachate samples were ranging from 0.1 to 0.5. The studies conducted by (Chian and Dewalle, 1976) reported BOD5/COD of 0.5e0.7 indicating large amounts of biodegradable organic matter. The BOD and COD values are relatively low in the open well sample and also the ratio of BOD5/COD in the pond (0.097) is much higher than that of (0.006) open well. This is mainly due to relatively high COD values in the pond. This can be possibly due to contamination of pond with leachate from nearby MSW landfill. Assuming that the pond (P4) sample is partially contaminated with the leachate, the relatively lower BOD5/COD values may be due to contribution by algae. Moreover the pond (P4) sample is characterized not only by low BOD and COD values but also by lower BOD5/COD ratio. Prolific growth of algae in the ponds provided a green coloured appearance to the pond water (P4). High density of these algae can result in high photosynthetic activity thereby generating voluminous oxygen that help in oxidation of the contaminants in the lake at the same time providing oxygen for the heterotrophic bacteria that in turn helps in aerobic treatment of organic matter present in these ponds (Mahapatra et al., 2011a,b,c).
The presence of algae for the production of oxygen and primary productivity is essential for any healthy water body (Granet et al., 1986; Mahapatra et al., 2011b). BOD5 to COD ratio revealed medium aged leachate samples (5e10 years). However earlier studies on leachate samples showed high concentration of organic constituents that were beyond the permissible limits (Ehrig, 1989).

3.2. Heavy metal and elemental analysis of solidsThe metal analysis showed high concentrations of iron in the leachate, followed by zinc, and nickel. The concentrations of chromium, copper, cadmium and lead were low. These trace elements are considered to be dangerous pollutant. In a living system they are capable of disrupting normal functions of a cell by virtue of their capacity to form strong metallic bonds with a number of functional macromolecules at the same time causing clump formation. Minute concentrations of chromium can cause nausea and vomiting and is also toxic to crops. Lead causes anemia, brain damage, anorexia, mental deficiency, vomiting and even death in human beings (Maddock and Taylor, 1977; Bulut et al., 2006) and is toxic even at lower concentrations. Cadmium has been reported to cause agonistic and antagonistic effects on hormones and enzymes leading to lots of malformations like renal damage (Lewis, 1991; Donalson, 1980) and are toxic at low concentrations also (Kale et al., 2010). Both cadmium and lead have been classified as carcinogens (USEPA, 1999). Other trace metals, such as Ni, Zn, Cu have also been reported for various health problems with possibility of bio-accumulation in the food web (Langston, 1990). The oven dried leachate solids showed the presence of trace metals as Hg, Sn, Cr, Ni, Zn, Co and Fe as shown in the SEM-EDXA analysis. High S percentage (~8%) at a low redox value indicate the possible formation of metal sulphides. Leachate ponds at anaerobic conditions with a higher quantum of sulphates with the availability of organic C promote the growth of sulphate reducing bacteria. Most of the heavy metals react with hydrogen sulphide and leads to the formation of highly insoluble metal sulphides (Mahapatra, 2015). Bacterial sulphate reduction results in the precipitation of dissolved metals as metal sulphide solids. Other trace metals as copper, lead, zinc, cadmium, etc., also form highly insoluble sulphide compounds in contact with the low concentration of hydrogen sulphide. Most of the trace elements are readily fixed as sulphides and get accumulated in soils, and because this process is largely irreversible, repeated applications of amounts more than plant needs eventually results in soil contamination rendering it non-productive (Ahmed, 2012). Heavy metals often get removed from the aqueous leachate phase through physical forces of settling, flocculation and sedimentation attributed to the specific gravity of the particulate matter (ITRC, 2003). Flocculation is enhanced by high pH, suspended matter, ionic strength and by the presence of algal groups (Matagi et al., 1998). Apart from the physical processes, the chemical removal processes mostly the adsorption, oxidation and hydrolysis of metals, precipitation and co-precipitation play a critical role in concentrating heavy metals. During sedimentation, heavy metals are adsorbed to the soil particles by either cation exchange or chemisorption. Heavy metals are mostly adsorbed to the clay and organic matter present in the leachate by electrostatic attraction (Patrick and Verloo., 1998).

The SEM EDXA analysis showed the presence of clay-like substances as they comprise of Aluminium phyllosilicates with Al (~6%), Si (~8%) and O (~36%) that can help in metal trapping through cation exchange capacity. The total capacity of a soil for retaining or holding exchangeable cations is called cation exchange capacity (CEC). CEC influences the soil's ability to hold onto essential nutrients and provides a buffer against soil acidification. CEC increases with certain substrates with increasing clay and organic matter content. Cation exchange involves the physical attachment of cations (positively charged ions) to the surfaces of clay and organic matter by electrostatic attraction. However, chemisorption represents a stronger and permanent form of bonding than cation exchange. High incidence of Fe in leachate also indicates the formation of insoluble compounds through hydrolysis and oxidation that can occur in leachate ponds. This leads to the formation of a variety of oxides, oxo-hydroxides, and hydroxides (Woulds and Ngwenya, 2004). Iron removal depends on pH, oxidationereduction potential and the presence of various anions (ITRC, 2003).

Precipitation depends on the solubility product Ksp of the metal involved, pH of the redox environment and concentration of metal ions and relevant anions. In this study precipitation from a saturated solution of a sparingly soluble heavy metal salt could have taken place at the low redox conditions. Similarly there are ample chances of co-precipitation which is also an adsorptive phenomenon in rapidly settling systems largely in the presence of Fe where usually heavy metal co-precipitates with secondary minerals in leachate ponds. Metals as Cu, Ni, Zn, Mn, etc., are co-precipitated in Fe oxides (Stumm and Morgan, 1981 ). Metals become associated with iron oxides as a result of co-precipitation and adsorption phenomena (Stumm and Morgan,1981 ). SEM-EDXA analysis shows high C and O values with a higher incidence of Ca and other divalent cations. This can lead to the formation of CaCO3 and other trace metal carbonates. Carbonate formation can take place when bacterial production of bicarbonate alkalinity in sediments is substantial (ITRC, 2003). Carbonate precipitation is especially effective for the removal of lead and nickel (Lin, 1995).
The elemental composition was determined by SEM-EDXA analysis where two representative EDXA analyses were performed per sample and is provided in Table 2. The analysis showed a common trend of high quantities of C in all the samples i.e. from L1 to L3 indicating higher organic C (50e61%) in the sample that also correlates with high COD, and BOD values analyzed during the physico-chemical analysis. The C can also exist in the form of metal carbonates as indicated in section 5. The N values ranged from 2.2 to 5.8% also indicating the presence of organic matter. Higher oxygen values ranging from 22 to 37% revealed organic matter and minerals in the form of oxides and hydroxides. Among the cations, Na predominated in all the leachate samples (5.8e12%). And among the anions, Cl levels were relatively high (up to ~5%) compared to other anionic radicals. The elemental composition of the leachate solids is given in Table 2.

3.3. Statistical relationship The data collected from various locations were analyzed with Paleontological Statistics software (PAST 2.14). Correlation analysis was performed and is elucidated in Table 3, and the level of significance is assessed at three different confidence intervals as mentioned in Table 3. Firstly at high confidence levels (~99.9% i.e. p < 0.001) Sulphide, Chloride and Fe are significantly correlated with COD. Fe and sulphates correlated with alkalinity. The heavy metals like Pb were significantly correlated with Cd. Ions as Na and Cl were significantly correlated with Conductivity and the presence of Ammo.-N respectively. Correlation at 99% and 95% can be viewed from Table 3.

Multiparametric tests like detrended correspondence analysis (DCA) help in reduction of the dimensionalities which is because of a complex relationship of the species to the environment and the physico-chemical parameters and helps in establishing linkages through correlations between environmental, biological, and chemical variables with the help of ordination axis. The steps to run DCA have been provided in Appendix 1 in the supplementary material. The detrended correspondence analysis indicated a unimodal response of variance. Usually, such statistical analysis is used to show affinities and differences between species and sites to avoid the arc-shaped distribution of the samples when there is a single strong gradient affecting the samples (Gauch, 1982). Some environmental parameters in the form of physico-chemical variables were considered to interpret the patterns observed with DCA: mainly biological and chemical variables in leachate were considered: nitrates, nitrites, ammonium, phosphates, BOD, COD total bacterial and algal counts. The contribution of the environmental, biological and chemical variables to explain species-sites variance obtained in the DCA was analyzed by Pearson correlations using environmental variables and values of the locations in the ordination Axes 1 and 2 in the multivariate analysis. Neither the environmental nor the biota data were transformed for the analysis. Results from the DCA analysis for coverage values of samples collected from the various locations are elucidated in Fig. 2. The leachate samples are distributed along the plane defined by the two first axes. Axes 1 and 2 account for 80.98% of the total variance of the data set (73.61% and 7.37%, for axes 1 and 2, respectively). On the first axis, samples were dominated by algal species i.e. Spirulina

sp. collected from location 4 i.e. P4, situated close to the ordination axis (Fig. 2), are opposed to samples dominated by bacteria. The Axis 2 explains the variability of the bacterial population in relation to L3. This explains higher bacterial abundance at L3. A big central group is represented by the mostly the abundance of metals, with other ionic parameters links to samples L1 and L2 are situated with values between axis 2 to 3 (see Fig. 3).

The loadings on Axis 1 indicated that the axis is positively impacted with location P4 and algal abundance. Similarly, loadings on Axis 2 indicate strong correlations between location G5 with pH and Ca values. However, loadings on Axis 3 indicate a high correlation between metals and other physico-chemical parameters and negative correlations with the microbes. The cluster analysis helped in grouping the samples based on spatial similarities of the five locations with varied concentrations and nature in the leachate ponds, surface and ground water samples. The Wards method showed two separate clusters that illustrate variations in the nature and type of the samples based on (a) physico-chemical parameters (b) trace metal concentrations and (c) biological sample abundance and distribution. The results showed Cluster I (~55% similarity) comprised of two samples P-4 and G-5. Cluster II comprised of a sub-cluster that consisting of samples L1 and L2 and a lone sample L3. The sub-cluster and the lone sample L-3 were having ~60% similarity. However, the samples within the sub-cluster that comprise of L1 and L2 had a similarity value of> 90%. This indicates L1 and L2 are more or less leachate sample of a similar nature while leachate sample L3 is slightly different as it located a little away from the landfi ll. This matches with the similarity of the samples considering its physico-chemical characteristics. The L3 samples have more organic matter and thus are different from the samples L1 and L2. Contrary to these samples the G5 and P4 samples are completely different. Also, G5 and P4 are different within the cluster I. The cluster analysis shows a clear cut distinction between the samples collected from the leachate ponds (L1-L3) and surface and ground water (P4 and G5), that proves dissimilarity in their nature. Such analysis helps in identifi cation of impacted sites for better management practices.

3.4. Biological sample analysis Biological analysis data are a more reliable assessment of longterm ecological changes in the quality of pond systems compared to its rapidly changing physico-chemical characteristics that are faster to analyze (Mahapatra, 2015). Biological indicators can portray the changes in water bodies that help in understanding the systems dynamics and aids in identifying key drivers by causal effect relationships (Mahapatra and Ramachandra, 2013; Mahapatra et al., 2013b,c). Biological communities exposed to pollutants integrate both past and present environmental phenomena.
The leachate samples collected from locations L1 to L3 were studied through the scanning electron microscope. The results showed (Fig. 4) that the leachate samples were dominated by bacteria especially different kinds of bacillus i.e. individual bacillus cells, diplo-bacillus and strepto-bacillus followed by coccus, spirochete and vibrio and the total bacterial count ranged from 3 to 4 log orders. Some filamentous cyanobacteria were also observed in the leachate samples. A complete bacterial analysis requires high throughput bio-molecular tools or culture based assays. Classifi- cation using advanced molecular analysis of the bacteria present in leachate samples has been carried out by Zhang et al. (2011).
Detailed phylogenetic analysis of the bacterial population is presently being undertaken that will be communicated shortly. However the samples collected from the Pond (P4), were prolifically dominated by Spirulina sp. with a very high cell count of 105 cells/ml. The abundance ofSpirulina was significantly correlated with high ionic conductivity, pH and dissolved oxygen (Mahapatra et al., 2013b). The sample collected from the openwell (G5) showed (Fig. 4) low bacterial counts but revealed the presence of different algal species mostly comprising of green algae and euglenoids. In short the microbial analysis revealed myriads of bacterial populations mainly bacillus, coccus, and spirochete. Contrary to this the surface water in the pond samples showed higher incidence of single species of cyanobacteria i.e. Cyanophyceae indicating an altogether different environment compared to the leachate sites. The open well samples, however, showed different algal populations with low bacterial counts.

3.5. Leachate pollution index (LPI) LPI values have been calculated for leachate samples of Mavallipura landfill site as per the procedure summarized in Table 4. Mercury, arsenic, and cyanide have not been identified in the leachate samples. Hence, no weightage for these trace metals were provided for LPI calculation. In this study, a detailed analysis of total coliform bacteria and phenolic compounds has not been carried out. The highest leachate pollution index was observed in L1 owing to potential toxicity and higher metal, inorganic and organics concentrations. Significantly high ammo.-N and organic-N were recorded in these samples pressing on immediate treatment for the stalled leachate fractions in these MSW landfill sites. Earlier studies have showed that high ammonia and alkalinity are toxic for duckweeds (Clement and Merlin, 1995). High N also poses a greater risk of nutrient enrichment and consequent eutrophication in receiving waters and is more harmful to aquatic animals in gaseous ammonia form. The ammonia in the gaseous form produces odor problems in the nearby area (Moreno et al., 2014). Generally, phenolic compounds are found to be very less in most of the Indian landfill leachates (Devnita Polley, 2013). Thus in this study to bring out the effect of background pollution index, LPI has been calculated.

It can be seen that the LPI value for the L1 is the highest while the LPI value for the L3 is found to be the lowest. Higher LPI presses the need for treatment of Mavallipura landfill leachate, followed by continuous monitoring. Aerobic biological treatment process with extended aeration is required for treatment of Mavallipura leachate as it has a high organic strength. The high ammo.-N can be treated by nitrification followed by denitrification. Comparatively lower values of LPI for L3 are attributable to low concentrations of heavy metals in the leachate. However, the individual contaminants shall meet the discharge standards before discharge of leachate into any surrounding water bodies. The results indicate that the L1 and L2 have relatively high LPI value in comparison with the L3 and forms a different group/cluster, evident from the cluster analysis and therefore are not stabilized, with relatively high contamination potential and needs physico-chemical and biological treatment to prevent any further detrimental effects on surrounding eco-system and water environment. Mavallipura leachate samples can, therefore, pose a threat to the environment and human health and hence, measures and continuous monitoring must be ensured. Similar studies conducted on leachate samples (Devnita Polley, 2013) for Dhapa landfill site (KLS), Kolkata, India showed a relatively high LPI (40.32) on the other hand relative low LPI values of ~26 were observed (Slomczynska and Slomczynski, 2004) that further decreases to ~7.03 upon treatment that was under permissible limits.

3.6. Water quality index (WQI) The surface water bodies near the Mavallipura landfill site are important sources of water for human activities. Unprecedented and continuous lobbying of MSW in the nearby landfill site can affect the water quality and thus the health of the local community. In the present purview of MSW disposal, with steep and unstable slopes, there can be ample chances of leachate runoff to the low lying water bodies. This also affects the ground water quality in the immediate vicinity. Therefore, WQI that surrogates and weights the water quality offers a useful representation of the overall quality of water for public use, gauzing the appropriateness of the water for further use and other utilitarian values. Table 5 shows the calculations for WQI values of pond (P4) and open well (G5) samples near the same landfill area.

Water quality index of the present water body is established from necessary physico-chemical parameters. The values of various physico-chemical parameters for calculation of water quality index are presented in Table 5. Based on earlier studies this water quality rating clearly shows that the status of the water body is eutrophic, and it is unsuitable for drinking and also observed that the pollution load is relatively high. Similar observations were recorded earlier (Yogendra and Puttaiah, 2008), where low DO, high BOD, and nitrates showed high WQI and thus nutrient enrichment in the urban water body Gopishettykere, in Shimoga town, Karnataka. High concentrations of sulphates, chlorides, and nitrates observed from the present study indicate unsuitability of this water for domestic use. The above water quality is also supported by the variations in physiochemical parameters. Total dissolved solids and electrical conductivity were found to be very high. Major anions like chloride are one of the most important parameters in assessing the water quality. The higher concentration of chlorides indicates a higher degree of organic pollution. The concentration of dissolved oxygen indicates the distribution of fl ora and fauna. Biochemical oxygen demand (BOD) indicates the organic load in water bodies. Higher BOD values are found in the polluted water. The results revealed that quality of ground water resources in Mavallipura landfi ll is deteriorating day by day; largely as a result of the poor practice of solid waste management. Hence, an effective precautionary plan is required for the sustainable management, which can be used as a guideline in the regulation and supervision of ground water operations. The WQI values elucidate poor ground water in these areas and necessitate immediate action and investigations for identifying possible sources of contamination and consequential deterioration. Moreover, proper management strategies and effective precautionary plans are required for the appropriate treatment and management of solid waste that safeguards our future water resources.

The present study highlights the present status and the quality of the landfi ll leachate, through various characterization techniques and shows high organic matter, inorganic nutrients and trace metals in leachate that can potentially contaminate the surface and the ground water resources precipitation through runoff and leaching respectively. Diverse microbial population found in the study can further screened for biological treatment of landfi ll leachate. This study shows a need for better collection, containment and treatment of the landfi ll leachate to avoid environmental externalities and health hazards that addresses sustainable waste management in cities. Such type of studies would lead to devising vital strategies with proper actions and management plan for abating environmental pollution and safeguarding the future water resources