INDIGENOUS AND EFFECTIVE MICROORGANISMS (EMOs) IN WASTEWATER TREATMENT

The waste management either solid or liquid is of paramount necessity. Due to increased urbanization and migration of people to cities in search for job has resulted in increased consumption of natural resources and accumulation of enormous waste. In addition, intensive agriculture practices to fulfill food requirement has enabled forced usage of synthetic compounds without understanding its adverse impact on the environment. Several industries among developing nations dispose waste into water bodies and this has raised concerns among large population. In recent years, biochemical or biological degradation of pollutants has received a great attention because of the sole reason that it has a potential to degrade wide arrays of recalcitrant pollutants including xenobiotics (Mueller et al., 1991; Barbeau et al., 1997; Cameron et al., 2000; Tripathi and Garg, 2013). Further, it is considered to be more safe and economic process when compared to other bioremediation processes.

Nevertheless, extensive studies on the biodegradation have now enabled to use a group of particular microorganisms or microbial consortia in removal of complex recalcitrant in the environment. Earlier findings suggest that indigenous microorganism own a potential to degrade wide range of pollutants (Cai et al., 2013; Kumar and Gopal, 2015). However, time involved is essentially more as these develop a mechanism of degradation naturally, under the favorable conditions which are termed as natural attenuation. Further, one of the key constraints is fluctuating environmental factors as these microorganisms are veiy sensitive to environmental conditions (pH, temperature, and type of pollutant). Nevertheless, approaches such as cell-free enzymes front such sensitive organisms have been found to address this issue. Several microorganisms have been isolated from the wide array of contaminated sites that are known to effectively degrade the pollutants under laboratory conditions. In situ bioremediation techniques especially bioaugmentation and biostimulation are more interesting than that of those ex-situ processes (Tyagi et al., 1993). The bioaugmentation approach is receiving a great deal of attention as it involves the usage of exogenous microorganisms for bioremediation of pollutants. Additionally, it can involve either the use of an individual group or consortia of microorganisms. However, recent studies suggest that consortia of microorganisms are comparatively more efficient on contrary to individual group of microorganisms.

In 1970s, for the first time, Teruo Higa at the University of Ryukyus, Okinawa, Japan, proposed the concept of effective microorganism for bioremediation of a wide range of pollutants (Higa, 1989, 1991, 1994; Higa and Chinen, 1998). The EMOs involve consortia of microorganisms such as lactic acid bacteria (.Lactobacillus plantarum, Lactobacillus casei, and Streptococcus lactis), photosynthetic bacteria (Rhodopseudo- monaspalustrus and Rhodobacter spaeroides) and yeasts (Saccharomyces cerevisiae and Candida utilis), actinomycetes (Streptomyces albus and Streptomyces griseus). Teruo and James (1994) identified more than 80 beneficial species of microorganisms. The selected potential microorganisms for efficient degradation allow degrading a wide array of pollutants. The approach of EMOs has now gained much appreciation and is been followed across globe for removal of pollutants among different environments. These microorganisms have a tendency to glow under both aerobic as well as anaerobic conditions. Additionally, the combination of microorganisms used in developing this mixture is in such a maimer that they are symbiotic against each other and work efficiently under different substrates. Further, the medium used for cultivation of these EMO is very economic and has shown to be efficient after storing for long duration. EMOs are widely used as insect repellent, foliar spray and as compost (PSDC, 2009; Zakaria et al., 2010).

On contrary, IMOs are mixture of naturally occurring group of microorganisms present over the contaminated sites. The efficiency of IMO technology was proven to be reliable and ecofriendly when compared to intensive or chemical fanning. The IMO technology improves soil and plant health, and benefits other soil-inhabiting organisms. This approach has been largely followed by fanners of many Southeast Asian countries and has been employed for home gardening as well as commercial fanning. IMO has also been reported to facilitate the removal of unpleasant odor among the poultry andpiggeiy (Kumar and Gopal, 2015) (Tables 11.1 and 11.2).

POTENTIALITY OF IMOs AND EMOs

Wastewater generated from different sources shows wide variations. Generally, industrial wastewaters comprise suspended, colloidal, and dissolved particles, including complex organic matter. The chemical composition may significantly contribute for increase in the acidity or alkalinity (Cheryan and Rajagopalan, 1998; Verma et al., 2012). These

factors have profound effects on the growth and survivability of IMO. The potential of EM technology is that it can effectively degrade complex compounds such as xenobiotics and organic matter present in the waste- water. As aforementioned, EM has been also found to subsidize the growth of pathogenic microorganisms in wastewater, such as fecal coli- form bacteria. It reduces the BOD, COD, TSS, total, and fecal coliforms and significantly minimizes the usage of chemicals such as alum, lime, chlorine for treatment, and contributes in cost reduction. Sludge volume greatly reduces up to 20%. It may also aid in the maintenance of the right pH, which greatly influences the growth of wide bacteria and largely subsidizes the foul smell. No design alteration in the ETP is required, and it can be directly applied to natural streams. More interestingly, this technology is found to be simple, natural, economic, and environment friendly (El-Sherbiny et al., 2001; Shalaby, 2011).

A study by Okuda and Higa (1995) demonstrated that the application of EM to the sewage water significantly reduced the BOD and COD up to 93% and 20%, respectively. Further, a decrease in suspended solids up to 94% was also reported on contrary to untreated water. Additionally, the decrease in nitrogen and phosphorus content was observed. This treated water when evaluated for the cucumber cultivation they found some promising results; EM treated water showed increased plant survival, leaf size, and diy weight. In addition, they observed the increase in vitamin C, and chlorophyll content, and root activity was also found to be enhanced among EM treated water. The sewage sludge after wastewater treatment was also evaluated for use as fertilizer for tomato cultivation and then study indicated that EM treated sludge of 500 g and 1 Kg resulted in increased plant height, leaf number and fresh weight on contrary to untreated and bare soil. Thus then study indicated that application of EM for sewage treatment could offer multiple facets and can be exploited for recycling the water as well as the sludge.

Studies also show that the increased concentrations of heavy metals in the wastewater have a significant effect on the EM activity. A study of Sheng et al. (2008) reported the adverse effects of heavy metals on EM and then study highlighted that various heavy metals found across the wastewater severely affect the DNA of EM. Wherein then study mainly focused on the assessment of heavy metals (As³*, Cd²⁺, Cr³⁺, Cu^:+, Hg²⁺, Pb²⁺, and Zn²⁺) on EM DNA using in vitro assay (Comet assay). Their study demonstrated that the damage of the DNA of EM were negatively correlated with their treatment capability and that EM bacteria can withstand up to maximum concentrations of 0.05 mg/L for As³⁺, 0.2 mg/L for Hg²⁺, 0.5 mg/L for Cd²⁺, Cr³⁺, and Cu²⁺, and 1 mg/L for Pb²⁺ and Zn²'. Further concluded that As³⁺ at 0.05 mg/L concentration and Hg²' at 0.20 mg/L concentration DNA damage was more and their ability of waste- water treatment reduced drastically.