Investigation of acidogenic stage in up-flow thermophilic septic tank for the treatment of combined wastewater form gasoline stations | |
| Author | Usatip Kunsit |
| Call Number | AIT Thesis no.EV-20-13 |
| Subject(s) | Septic tanks--Environmental aspects Biotechnology Wastewater--Treatment |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | The gas station including with other service i.e. coffee shop is growing continuously. The complex substrate (FOG and caffeine) from this specific wastewater (the combination between blackwater and grey water from coffee shop) should be considered. By the conventional treatment unit (septic tank and oil and grease trap), it cannot perform well and the effluent cannot be compliance with the national effluent standard. To develop 2-stage anaerobic process that many studies reveal its performance to deal with the complex substrates, the optimum temperature of both phases in this innovation should be determined. The caffeine has a significant effect to primary producers and other microorganisms from previous studies. Thus, with the biological treatment process of this developed septic tank, this chemical can influence to our system in some ways. FOG is hard to treat by the single stage of AD. It can cause the operational problem such as clogging. Especially, anaerobes are very sensitive to oil-rich matters. First phase of this study determined the optimum temperature in acidogenic stage by batch test. In Duran bottle, the anaerobic process was performed. The varying of temperature at 30, 40, 50 and 60 °C, was operated and VFAs production was observed as the key’s selection for optimum temperature to operate in labscale. By the results, 40 °C could perform well in terms of VFAs production. In this batch test also found that too low COD in substrate has significant results in underestimation of VFAs production. And mixing should be applied in batch test to improve the entrapping of COD in sludge layer. The dominant acid product of 30 °C is propionic acid while in 40, 50 and 60 °C is acetic acid. According to caffeine’s effect study in acidogenic batch test, there was no significant effect from this substance to this biological process. And it could observe from the chromatogram by HPLC, two unknown peaks were found. It can be caffeine derivatives. It has changed among its peak areas. Then, the lab-scale of 2-stage upflow septic tank was operated. The acidogenic reactor is 50 L round-shape and two methanogenic reactors are 21 L UTST. With total HRT less than 24h, first stage reactor was operated at 50 °C, HRT 6 h. and later phase was operated at 40 and 50 °C with HRT 12h. The overall treatment performance between methanogenic reactors operated at 40 and 50 °C was not different significantly in percentage of TCOD, SCOD, TS and VS removal. Due to low organic loading rate in influent, acidogenic reactor operated at 50 °C could be measured the lower VFAs concentration in effluent than in methanogenic reactor and higher methane production was also observed. With neutral pH could detected, the condition in acidogenic reactor was preferred by methanogens than acidogens. Temperature had effects to biological process. The same operation conditions with both methanogenic reactors excepted for temperature, the higher percentage of methane production could be determined at 50 °C reactor of methanogenic stage. |
| Year | 2020 |
| 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 and Management (EV) |
| Chairperson(s) | Thammarat Koottatep; |
| Examination Committee(s) | Chongrak Polprasert;Xue, Wenchao;Tatchai Pussayanavin; |
| Scholarship Donor(s) | Royal Thai Government;AIT Fellowship; |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2020 |