The objective of the Sapthip Wastewater Biogas and Renewable Energy Project for Thailand is to reduce greenhouse gas emissions from the fossil fuel used at the Sapthip Co., Ltd. bioethanol plant and from the methane produced from the plant's wastewater through the recovery of methane from wastewater treatment and the use of the recovered methane and solid residue from plant operation as fuel. There are two components to the project, the first component being wastewater system with biogas collection. The system will recover and combust the biogas, the majority of which is methane (CH4), a greenhouse gases that, without the project, will have been released directly into the atmosphere by the open-lagoon wastewater treatment systems commonly used in Thailand.
The wastewater undergoes a staged treatment process that relies on up-flow anaerobic sludge blanket (UASB) reactors to generate and capture most of the methane-containing biogas used in the project. Finally, the second component is the renewable energy use. Two 20-ton-per-hour-capacity boilers will be employed to supply the average of 20 tons per hour of steam required for the ethanol plant and to provide sufficient backup capacity in cases of plant shutdown or maintenance. Instead of being dependent on the fossil fuel coal, the boilers will utilize a combination of renewable energy, including the biogas recovered from the wastewater treatment process (58,000 cubic meters per day) and the solid residue ('wet cake') from the distillation column which is dried using waste heat from the boiler (30 tons per day). It is anticipated the boiler will rely on 70 percent biogas and 30 percent wet cake for energy. Excess biogas produced during operation will be used for on-site electricity generation using commercially available biogas-fired generators, reducing greenhouse gas emissions through the substitution for fossil fuel based grid electricity that will have been used by the plant without the project.
Contributing to Sustainable Development:
- Reduce the methane emissions that would have been released from an open anaerobic lagoon through an advanced wastewater treatment.
- Improve the local air quality and human health. The closed anaerobic treatment proposed will also limit bad odor and possible health hazard caused by the methane released to the surrounding, thus minimizing pollution to the environment.
- Reduce the risk of groundwater contamination from insecure open anaerobic ponds which are a series of earth pond to closed anaerobic digesters which are concrete tanks. Improvement of treated wastewater quality will also reduce the risk to harm the environment.
- Provide job opportunities to unskilled labor during construction and skilled labor during operation and maintenance of equipment and systems.
- The project activity will establish a positive model of wastewater treatment practice for other ethanol plants as well as agro-industrial plants. The project activity will apply advanced and environmentally friendly technologies in treating wastewater and associated utilization, which can be replicated on other ethanol plants enhancing effectiveness of environmental protection system of the ethanol plant.