Community scale food waste-based anaerobic digester with centralized monitoring system | |
| Author | Srinivas, Ravipati Aditya |
| Call Number | AIT Thesis no.ET-17-07 |
| Subject(s) | Anaerobic digestion (Sewage purification) Food waste--Economic aspects |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Energy |
| Publisher | Asian Institute of Technology |
| Abstract | Anaerobic Digestion is a well-established renewable energy technology that produces methane gas which can be used to substitute fossil fuels. On the other hand, anaerobic digestion is highly susceptible to process imbalances. Therefore, it is worthwhile to incorporate anaerobic digestion process monitoring and control equipment to prevent system failure and to improve the performance of digester. This study is intended to design and develop a suitable community scale food waste based anaerobic digester of 0.92m3 (25kg food waste per day) in AIT. The anaerobic digester design provides the detailed study from food waste collection and separation phase, to appropriate selection and sizing of pumps, stirrer, and piping material till the digestate handling phase. All the results and experiences obtained from the bench-scale CSTR are applied in designing the community scale food waste based anaerobic digester. The digester is designed in such a way that there is a possibility of installing all the monitoring equipment such as pH, Temperature, and ORP electrodes, and the control equipment namely Programmable Logic Controller to monitor and control anaerobic digestion process parameters such as pH and Temperature. This study was mainly focused on the centralized monitoring of two anaerobic digesters. Therefore, a biogas composition monitoring equipment (Ambisense system)which also serves the purpose of centralized monitoring is installed in the bench scale CSTR and its performance was tested. The results showed that the biogas composition monitoring equipment which is used for centralized monitoring can identify any process imbalances in the digester can be clearly observed from the monitoring data in the central server such as the fall in methane content below 50% or if the carbon dioxide content exceeds 40% or the other particulate matter such as ammonia, and hydrogen sulfide exceeds more than allowable limits indicates a sign of process deviation. From the bench scale experience, the installation of a water trap was made mandatory to remove the moisture content (allowable limit is 4-8%) in the biogas that enters the monitoring equipment to prevent the damage of the equipment. An economic and environmental sustainability analysis was conducted to evaluate the project feasibility of designed community level anaerobic digester with centralized monitoring and control equipment. Various alternative sources for direct revenue generation such as biogas as a substitute to LPG, fuel in CHP plant, petrol and diesel are considered and the sources for indirect revenue generation are elimination of waste collection and disposal costs, and revenue in the form of carbon credits are considered for economic analysis. The results indicated that the project will not be feasible if community scale anaerobic digester is made run at 25kg food waste per day. Rather, it would be economically feasible to run the community scale digester at a minimum of 40kg and above food waste per day, which will generate a positive NPV and a 10% rate of return along with a payback period of 9 years. To reduce the payback period less than 5 years, the anaerobic digester need to be fed at a daily feeding rate of 70kg or more food waste. |
| Year | 2017 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Energy Technology (ET) |
| Chairperson(s) | Salam,Abdul P.; |
| Examination Committee(s) | Kumar, Sivanappan;Visvanathan, C.; |
| Scholarship Donor(s) | Asian Institute of Technology Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2017 |