| Author | Khatiwada, Nawa Raj |
| Call Number | AIT Thesis no. EV-95-24 |
| Subject(s) | Sewage|xPurification--Activated sludge process
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| Note | A thesis submitted in the partial fulfillment of the requirements for the degree of Master of Engineering. |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. EV-95-24 |
| Abstract | Laboratory scale experiments on electrochemical precipitation (ECP) treatment of activated sludge were conducted to investigate the effects on settleability, dewaterability, fecal coliform reduction and types of complex compounds formed. The ECP consists of a direct current (DC) power supply, iron electrode plates and activated sludge as electrolyte solution. Monopolar as well as bipolar electrodes were used in the experiments and current and voltage applied to the ECP unit was controlled by a variable voltage transformer. Four different types of activated sludges were used in the experiment. The effect of ECP treatmet was found more prominent with bipolar electrodes and applied current greater than 2 amp ( 2.4 amp/m2) and the results showed a significant increase in temperature, pH, and total suspended solids (TSS) of the sludge with increasing operating time (OT). ECP treatment of excess sludge from laboratory unit (obtained from starch synthetic wastewater) and a domestic wastewater treatment plant resulted in significant reduction on sludge volume index (SVI), specific resistance to filtration (SRF) and capillary suction time (CST) values indicating improved settleability and dewaterability. ECP treatment of severely bulking activated sludge from the wastewater treatment plants of rice cracker and fish processing factories resulted in significant reduction on SRF and CST values where as it showed very less effect on SVI reduction. For the four types of sludges mentioned, with 5 amp applied current (6 amp/m2) power consumption for one hour treatment varied in the range of 0.4 - 8 kWh/kg dry solids (DS) depending upon the conductivity and the concentration of the sludge. With 5 amp current (6 amp/m2) electrode plate consumption rate was about 0.05 kg per hour per m2 of anode surface area and corresponding power consumption was found in the range of 0.06 - 0.24 kWhfm2. With higher current (about 10 amp) and with 60 min of OT about 1.7 log reduction on fecal coliform density was obtained. X-ray diffractometric analysis of treated ECP sludge showed Fe203 and KFe02 as major Fe complex compound formed during the ECP treatment. |
| Year | 1995 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. EV-95-24 |
| 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) | Chongrak Polprasert |
| Examination Committee(s) | Stoll, Uwe;Yang, Byung-Soo |
| Scholarship Donor(s) | Government of Finland |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology,1995 |