Side-stream chemical precipitation to enhance efficiency and stability of anaerobic/aerobic activated sludge process for biological phosphorus removal | |
| Author | Verapong Chaiperm |
| Call Number | AIT Diss. no. EV-91-3 |
| Subject(s) | Sewage--Purification--Activated sludge process Sewage--Purification--Phosphate removal |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | Anaerobic/ Aerobic Activated SIudge Process Is widely used to remove phosphorus from wastewater. In this process, the microorganisms capable of taking up higher amount of phosphorus than those observed under conventional activated sludge process are responsible for high phosphorus removal performance. This process sometimes faces a problem of poor stability in phosphorus removal. Many factors have been claimed to influence phosphorus removal performance such as organic loading, nitrite, nitrate, sludge age, etc. The objectives of this study are : (1) To Investigate the effect of organic loading on ยท phosphorus removal performance and stability. (2) To evaluate the effectiveness of the Introduction of side- stream chemical precipitation. (3) To investigate contribution of each factor to phosphorus removal through material balance consecrations of phosphorus. (4) To experimentally find out substances which give adverse effects on phosphorus removal performance. Lab-scale continuous flow experiments are conducted In order to Investigate the effect of organic loading and the effectiveness of side-stream chemical precipitation. The organic loadings are varied from 1.61 to 1.17 and 0.46 kgCOD/(m3.d). The side-stream flow ratios are 0%, ~0% and 45% for each organic. loading condition. The results show that phosphorus removal performance Is affected when the organic loading decreases. Also, the unit with 45% side-stream flow clearly shows Improvement In phosphorus removal performance and stability. From material balance considerations of phosphorus, the Improved phosphorus removal performance Is dued to the Increased amount of phosphorus In chemical precipitated sludge. An semi - empirical model Is proposed In order to perform sensitivity analysis. The results show that the changes of phosphorus content of sludge, side-stream flow ratio, organic loading and performance of chemical precipitation tank In side--stream are highly sensitive to phosphorus removal performance of the process. Batch experiments are performed In order to find out substances which give adverse effects on phosphorus removal performance. Nitrite affects biological phosphorus uptake at concentration exceeding 5 mg/I as N. Nitrate does not show any effect on aerobic phosphorus uptake upto concentration of 80 mg/I as N. Also, sulphate and aluminum do not show any effect to phosphorus release and uptake characteristics upto concentrations of 900 mg/I and 100 mg/I , respectively. The effect of nitrite Is again tested with lab-scale continuous flow anaerobic/aerobic activated sludge process. The results show that biological phosphorus uptake in the aeration tank is affected by nitrite when nitrite concentration exceeds 1 O mg/I. As side-stream chemical precipitation unit is convenient for being applied with anaerobic/aerobic activated sludge process, the app li cation of this modified process is useful when the stable phosphorus removal efficiency is required. |
| Year | 1991 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Environmental Engineering and Management (EV) |
| Chairperson(s) | Mino, Takashi ;Chongrak Polprasert |
| Examination Committee(s) | Tran, Francis T. ;Verink, Johan ;Bhattacharya, Sribas C. ;Henze, M. |
| Scholarship Donor(s) | The Government of Australia |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1991 |