Introduction

Pollution caused by the tanneries has been in sharp focus in many countries of South East Asia for more than a decade. Though a great deal of work has been done by all these countries in tackling various facets of these problems, there is no denying the fact that much more remains to be done. As elsewhere, the tannery industry in India produces all three categories of waste water, solid waste, and air emissions. However, waste water is by far the most important environment challenge faced by Indian industries (Zafarruddin, 1995). The pollution from tanneries and options for the treatment of effluent was studied by (Jawahar, Chinnadurai, & Ponselvan, 1998). Successful bioremediation requires not only the knowledge of the microorganisms that can degrade a particular compound but also an understanding of the pathways involved in the degradation both at physiological and molecular levels (Ghosh, Philip, & Bandyopadhyay, 2005). Biological treatment of effluent may become an economically and environmentally attractive alternative to the present Physico-chemical methods of treatment (Reid & Seifert, 1982). Microorganisms possess a metabolic machinery of immense versatility, aiding the breakdown of pollutants. In the course of evolution and rapid industrialization, microorganisms have been exposed to numerous chemicals and thereby adapted to their presence by developing necessary enzymes which aid in metabolizing such compounds. However, biodegradation is not feasible if the compounds have structural features never ever found in nature or if the microorganisms never encountered them during evolution. The intent of the work is to identify natural isolates and to study the physiological, biochemical capacities of the strains to biodegrade tannery effluent. Isolated microbial strains capable of withstanding high BOD. (Kumar et al., 1998; Stolz, 2001; Yamini & Lalithakumari, 2001; Zaoyan et al., 1992) have worked intensely on this aspect. The present study deals with the characterization tannery effluent biodegradation of certain important parameters viz. pH, BOD, and COD using Bacillus cereus and Pseudomonas aeruginosa in the untreated tannery waste water.

Materials and Methods

In the present investigation, waste water was collected from a tannery in Dindigul District, Tamil Nadu, and India. The waste water samples were gathered raw as well as from the final discharge point where in the effluent from all the stages of processing are released together. The waste water was collected in polystyrene containers [2 litres capacity] and were brought to the laboratory with due care and stored at -20oC.

The Physico-chemical parameters such as odour, colour, temperature, pH, (EC), Total dissolved solids (TDS), Biological oxygen demand (BOD), Total suspended solids (TSS), Chemical oxygen demand (COD), grease and Oil Chloride (Cl) and Total hardness of the effluent was analyzed following Standard methods outlined by (APHA, 1989). Calcium (Ca), Potassium (K), Sodium (Na), and Sulphate were determined (Jackson, 1958).

Serial dilution technique were used to tannery waste water for isolation of bacteria (Chaturvedi, 1992). After the identification of the bacteria, culture was carried out in the laboratory to be used for the biotreatment of the tannery effluent. Bacteria such as Bacillus cereus and was used for the treatment of tannery waste water.

Bioremediation of Tannery waste water Using of Bacteria

Approximately 10 g (fresh weight) of Bacillus cereus, and of Pseudomonas aeruginosa were transferred to experimental jars containing 1000 ml of different concentrations (25%, 50%, 75%, and 100%) of tannery effluent. They were kept in an orbit shaker for 48 hrs and maintained at 28±20C. Three important physicochemical parameters such as pH, BOD, and COD were estimated before and after 48 hrs (2 days) to check the degradation process by the bacteria.

Statistical analysis

The results obtained in various treatments were tested through the method of analysis of Variance (ANOVA) (Steel & Torrie, 1980). The ANOVA was conducted both within and between blocks to ascertain the effect of the control and the different concentrations of effluent on the degree of inhibition. The experimental data was statistically analyzed by adopting the procedure described by (Panse & Sukhatme, 1967).

Results and Discussion

The water quality parameters of the tannery effluent were analyzed, and its results are presented in Table 1. The results of the analysis showed that the tannery effluent was grey colored with a disagreeable odour, acidic pH, with high organic and inorganic load indicating high EC, BOD, COD, TSS, TDS Total hardness, calcium, magnesium, sodium, chloride, and sulphate. Based upon the dominant bacteria, Bacillus cereus and Pseudomonas aeruginosa were individually used to reduce the pH, BOD, and COD in the effluent. Laboratory scale biodegradation of tannery in different concentrations (viz 25%, 50%, 75% and 100%) using the above bacteria. Three important physicochemical parameters, namely pH, BOD, and COD, were analyzed in the biotreated tannery effluent after 48 hours of incubation.

Results of the tannery effluent treated with the Bacteria Bacillus cereus and Pseudomonas aeruginosa at different concentrations (25%, 50%, 75%, and 100%) for 48 hrs is shown in Table 3; Table 2 & Table 4, (Figure 2; Figure 1 & Figure 3). The pH of tannery effluent before (control) and after biodegradation (48 hrs) by bacteria is shown in Table 2 (Figure 1). The BOD of tannery effluent before (control) and after biodegradation (48hrs) by individual bacteria is shown in Table 3, (Figure 2). The COD of tannery effluent before (control) and after biodegradation (48 hrs) by individual bacteria is shown in Table 4, (Figure 3). In all the concentrations of tannery effluent, Bacillus cereus was found to reduce pH, BOD, and COD to the maximum extent, followed by the bacterium Pseudomonas aeruginosa. The decrease in pH, BOD, and COD values in the biotreated effluent is statistically significant P<0.008.

Remarkable achievements of environmental biotechnology include the cleanup of waste water, especially from tanneries and other industries. Bioremediation is addressed as one example of environmental biotechnology. Because of its similarly minimal effort and for the most part benevolent ecological effect, bioremediation offers an attractive alternative and/or supplement to more conventional clean-up technologies. The use of microbes to concentrate pollutants is an emerging research area. Microorganisms, bacteria, and fungi are nature's original recyclers. Their capability to transform natural and synthetic chemicals into sources of energy and raw materials for their own growth suggests at hat expensive chemical or physical remediation processes might be replaced or supplemented with biological processes that are lower in cost and more environmentally benign.

In the present investigation, the Physico-chemical characteristics of the untreated effluent have revealed that it is acidic with high pH, BOD, and COD, organic matter, unpleasant odour, and colour. The present study has revealed that high levels of BOD in the tannery effluents indicating high organic load. The present investigation is in agreement with the studies on tannery effluent (Kulkarni, 1992). Further, the presence of organic matter will promote anaerobic action leading to the accumulation of toxic compounds in the water bodies (Goel, 2000). In the present investigation, a high level of COD in the tannery is recorded. (Raj, Sankaran, Sreenath, Kumaran, & Mohan, 1996) have recorded higher values of COD from the tannery effluent of Chrompet. Further high COD may be due to a high amount of inorganic compounds which are not affected by the bacterial decomposition (Nagarajan & Ramachandramoorthy, 2002).

(Saleem, Ahmad, & Ahmad, 2014) reported high potential of Bacillus cereus for bioremediation of pulp and industrial paper waste, and the decreased of chemical oxygen demand and biological oxygen demand about 61 and 66 %, respectively, by Bacillus cereus. (Noorjahan, 2014) observed a non-native Bacillus sp showed Biodegradation of Industrial effluent reduction percentage range of 56-95%.

Conclusion

Microbes in the environment play an important role in the cycling and fate of organic chemicals and can destroy them through bioremediation. The present study reveals that Bacillus cereus and Pseudomonas aeruginosa are able to reduce the pH, BOD, and COD in all concentrations of the tannery effluent. Studies also reveal that Bacillus cereus was more efficient and has a high degrading ability to reduce pH, BOD, and COD than Pseudomonas aeruginosa. Hence it may be suggested that Bacillus cereus and Pseudomonas aeruginosa will be beneficial for biodegradation and purification of effluents.

Acknowledgement

I would like to express my special thanks of gratitude to our college management and Principal. I would also like to extend my gratitude to our HOD for providing me with all the facility that was required.