Harvesting energy through wastewater management in Bhopal city

Abstract

India is a fast growing and developing nation where the population and urbanization is on an exponential growth. This growth is giving rise to the growing concern of greenhouse gas emissions from many sources out of which wastewater (sewage) treatment plants are one such inventories. Development demands high usage of fossil fuels or non-renewable sources for the production of energy. On the other hand, the increase in population results in the increase in the generation of wastewater. Sewerage systems are one of the most important physical infrastructures of a city, but still India lack in the availability of these treatment facilities to fulfil the required capacity for the treatment of wastewater and its discharge. The total treatment capacity of the country is nearly to treat 30% of the total wastewater generated in the entire nation. Most of the urban local bodies fail to develop the required and adequate infrastructure for the wastewater handling and its safe disposal without any environmental hazards. Even with the available infrastructure, it is a challenging task to operate and maintain the wastewater treatment facilities because of the high cost of energy and human resources and hence the urban local bodies mostly suffer the financial dilemma as the entire wastewater treatment process becomes highly unsustainable. Other than the financial constraints, the major environmental issue is that the wastewater treatment plants are responsible for the emissions of greenhouse gases from direct emissions (emissions from sewage) and in-direct emissions (energy demand and consumption). The study highlights the issue of GHG emissions from the treatment plants by the calculations and estimation of the total emissions from the wastewater management in the study area of Bhopal City and also assessing the potential of harvesting energy by the capturing of biogas generated from the WWTPs to use it as a fuel for the production of energy. This can be a sustainable solution for the energy crises and a mitigation measure for the greenhouse gas emissions. The baseline scenario of the existing wastewater management prevailing in the study area was established and the suitable treatment techniques and its process and challenges in the context of Indian cities were understood by literature and V primary case study done at two Indian cities. To calculate the emissions from the wastewater treatment plants, the method adopted was the GHG Protocol proposed by World Business Council for the sustainable development and World Resource Institute and the guidelines of IPCC were used. It was found that the emissions cap was large from the treatment plants and shall be taken into account to look after their mitigation action. Further the study assessed the total amount of energy which can be harvested from the capturing of these emissions. Along with this, the initial cost, area requirement, location analysis and annual O&M costs were estimated for the treatment method for the biogas based sewage treatment plants and proposed treatment method in the proposed sewage project in the study area. This estimation was compared to justify the feasibility of the treatment method proposed in the study over the economic life of the treatment plant. The study suggests that the biogas based wastewater treatment plants can be a solution for sustainable wastewater management and a clean mitigation measure to achieve the reduction in GHG emissions to the desired targets. The study forms the basis for the development of the strategic planning and promotes the GHG reduction measures through wastewater management.