Effects of catalysts on energy content in produced hydrochar by hydrothermal carbonization of faecal sludge | |
| Author | Nutnicha Tajai |
| Call Number | AIT Thesis no.EV-15-29 |
| Subject(s) | Sewage sludge Carbonization |
| Note | A thesis submitted in partial fulfillment of the requirement for the degree of Master of Engineering in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. EV-15-29 |
| Abstract | Hydrothermal carbonization (HTC) is a thermochemical conversion process for producing carbonaceous materials, which are referred as “hydrochar”, from wet biomass at moderate temperature. HTC has been developed for overcoming challenges related to improper faecal sludge management (FSM), which are usually found in developing countries. The use of HTC not only helps to solve FSM problems, but it is also able to produce the value-added products. Previous studies show that energy content of the produced hydrochar from faecal sludge (FS) has low values. Adding catalysts is one of effective solutions to enhance the energy content of the hydrochar. This study therefore aimed to test the ability of different catalysts in enhancing the energy content of the hydrochar. A lab scale 1-L high pressure reactor was used to test four types of catalysts, including acetic acid, borax, lithium chloride, granular and powder zeolites. The FS and catalysts mixing ratios by dry weight are provided as follows; FS:acetic acid of 1:0.2, 1:0.4, and 1:0.8, FS: borax of 1:0.06, 1:0.12, and 1:0.25, FS:lithium chloride of 1:0.25, 1:0.5, and 1:1, and FS:granular zeolite of 1:0.1, 1:0.2, and 1:0.3, and FS:powder zeolite of 1:0.02, 1:0.05, and 1:0.1 were used. The experimental results showed that acetic acid was the most effective catalyst. The catalyst was accelerated the HTC mechanism, especially hydrolysis and dehydration reactions. The optimal conditions of HTC of FS using acetic acid were determined by using normalized energy yields. The highest normalized energy yields of 19.8 MJ/kg were obtained at operation temperature of 220 °C with the reaction time of 1.0 h and the FS:acetic acid mixing ratio of 1:0.4. With respect to energy consumption, HTC of FS using acetic acid as a catalyst contributed to a 70% decrease of energy requirement relative to the HTC process without catalyst. This low energy requirement leads to the minimization of the operation cost. Recirculating water, which contained acetic acid, was recommended to further reduce the operation cost and enhance the energy content of the produced hydrochar. Minimization environmental impacts and consideration economic aspect of HTC process of FS with catalysts were also discussed. |
| Year | 2015 |
| 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 | Environmental Engineering (EV) |
| Chairperson(s) | Thammarat Koottatep; |
| Examination Committee(s) | Chongrak Polprasert;Visvanathan, C.; |
| Scholarship Donor(s) | Thailand (HM Queen); |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2015 |