| Author | Hasan, Kazi Sarwar |
| Call Number | AIT Thesis no.EV-97-18 |
| Subject(s) | Sewage--Purification--Activated sludge process
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of
Master of Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | A combined anaerobic-aerobic process was tested under shock and transient loading. The response is compared with that of aerobic process alone. A completely mixed Hydrolysis Acidogenic Reactor was integrated with aerobic process which served as anaerobic pretreatment to the influent wastewater before going to the aerobic process. This pretreatment will provide rapidly biodegradable components, in particular volatile fatty acids by conversion of large organic substrates in the influent wastewater, that can be easily taken by the microorganism in the following aerobic process and consequently increase the efficiency of the treatment process compared to the aerobic process alone. The study was carried out in a laboratory scale using synthetic wastewater where the shock loading and the transient loading was given by step up of the influent COD concentration and flow rate respectively. With the pretreatment facility provided, anaerobic-aerobic process shows higher removal efficiency and better process stability compared to aerobic process alone under shock and transient loading. COD removal efficiency was found around 80% in the aerobic process with Hydrolysis Acidogenic Reactor when the influent COD was 6000 mg/L, as compared to decreasing COD removal efficiency of around 60% in aerobic process alone. The nutrient removal was considerably higher even at high shock loading. Total phosphorus removal efficiency remained above 60% for aerobic process with Hydrolysis Acidogenic Reactor compared to only 30% removal in the aerobic process alone during a shock loading of 14.4 kg COD/m3d. Sludge bulking and sludge volume was less in aerobic process with Hydrolysis Acidogenic Reactor contrasting to high sludge bulking and large sludge volume in aerobic process alone. The transient response was almost similar for both the processes but aerobic process with Hydrolysis Acidogenic Reactor gave better removal for all the flow variations done. The result clearly shows the need for pretreatment of wastewater to encounter the shock and transient variation as well as higher removal efficiency. The anaerobic-aerobic process can reduce the sludge handling problem and desired effluent quality can be improved even during the shock loading. |
| Year | 1997 |
| 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) | Eckhardt, Heinz; |
| Examination Committee(s) | Annachhatre, Ajit P. ;Ishibashi, Yoshinobu; |
| Scholarship Donor(s) | Swedish International Development Cooperation Agency
(SIDA) ; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1997 |