1 Centre for Sustainable Technologies,
2 Centre for infrastructure, Sustainable Transportation and Urban Planning,
3 Energy and Wetlands Research Group, Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560 012, India Introduction Major challenges faced by most urban areas are the inadequate capability to handle waste generated in the region. This problem is compounded with the increased rate of urbanization and consequent urban sprawl. Due to this, most treatment facilities in metropolitan cities face serious problem of inadequate capacity. Treatment of wastewater has gained importance in recent times due to environmental problems and also impending water crisis. This demands the treatment of wastewater to meet the growing demand of rapidly urbanizing towns and cities in India. Conventional wastewater collection and treatment systems are energy and labour intensive apart from lack of adequate infrastructure and the technical expertise to manage and operate them. Due to inadequate treatment facilities the untreated wastewater gets directly into lakes and tanks. Thus, inadequate and insufficient sewage treatment have deteriorated the water quality in receiving water bodies making the later aquatic resources unfit for current as well as future use. In Bangalore, sewage streams flow through storm water courses and enter man-made water bodies. This has led to the creation of natural wetlands and anaerobic-aerobic lagoons that seem to carry out the treatment of sewage to near adequate levels. Nearly 40% of Bangalore sewage (500 MLD) enters the Bellandur-Varthur chain of lakes in Bangalore south (Chanakya et al., 2008). The extent of N (nitrogen) flowing through the Belandur-Varthur lake system is about 20-40 mg/l and earlier estimate indicating 16.4 t/d of N flow(Chanakya and Sharatchandra, 2008). This waterbody also serves as a water source for irrigation in command area and also for the downstream farmers. Varthur lake (Fig 1) was built to meet the drinking and irrigation water requirements thousand years ago (Government of Karnataka, 1990). Today, large scale land cover changes in the catchment have impaired the catchment yield. However, the shortage of water is currently supplemented by daily influx of sewage. Enrichment of nutrients (C, N and P) is evident from the profuse cover of macrophytes (Figure 2). Lower dissolved oxygen coupled with malodour and algal blooms at certain parts further substantiate the need for investigations to transform this waterbody to a sustainable and passive sewage treatment system.Technologies such as UASB (Seghezzo et al., 1998), high rate algal ponds (Shelef, 1982; Oswald et al., 1995), duckweed based ponds (Smith and Moelyowati, 2001; Cheng et al., 2002), etc. are reported but these are constrained by a need for energy or land. This communication illustrates the role of lakes and wetlands in remediation of excess nutrients that could be a cost effective approach to manage large quantum of sewage. Hence the objective here is to examine the treatment levels achieved year round in sewage fed urban water body, Varthur Lake in Bangalore. Citation: Durga Madhab Mahapatra, Chanakya H. N and T. V. Ramachandra, 2010, Sustainability and treatment potentials of an urban sewage-fed lake in Bangalore, India. Proceedings of the 17th National Symposium on Advances in Environmental Monitoring and Modeling, May 13-15, 2010, IIT Kanpur, Uttar Pradesh.
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