| Author | Joshi, Deepak Lal |
| Call Number | AIT Diss. no. EV-93-1 |
| Subject(s) | Sewage--Purification--Biological treatment
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| Note | A dissertation submitted in partial fulfillment of the requirement for the degree of Doctor of Engineering |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. EV-93-1 |
| Abstract | The Reversing Anaerobic Upflow System (RAUS) providing a new low cost anaerobic treatment of industrial wastewater was developed and compared with fixed bed (FB) and upflow anaerobic sludge blanket (UASB) reactors. RAUS consisted of two interconnected vessels functioning alternatively as a reactor and a settler at set time intervals. Two laboratory-scale RAUS reactors with volumes of 10.2 and 26.5 1 respectively were investigated for the treatment of synthetic fiber production wastewater with average COD of 20 g/l. Five 130 1 pilot-scale RAUS reactors were operated at ambient conditions to treat this wastewater for determining the optimum feeding and flow reversion pattern in the system. On-site research was conducted using reactors, with volumes ranging from 130 1 to 3.1 m3 at different industries such as a slaughter-house, pineapple canning , distillery and synthetic fiber production factories . The principle of intermittent feeding and flow reversion in RAUS improved the characteristics of sludge such as specific activity, settleability and thus the sludge enrichment. The feeding principle in RAUS enhanced the gas sludge separation and reduced the sludge washout from the reactor without the need of carrier materials as in the fixed bed reactor and the internal separator as in UASB. The intermittent feeding pattern in RAUS improved the reactor performance in terms of coping with shock loading and temperature drop as well as COD removal and gas production rate. For minimum sludge washout, the connection level between the two sides of RAUS was found to be at about the mid-height of the reactor system. A mathematical model of sludge transport was proposed to explain the reduction of sludge washout in the effluent from RAUS. Synthetic fiber production wastewater exhibited difficulty in treatment due to its very poor nutrient content (COD:N:P = 3000:2.5:1) and very low alkalinity (about 30 mg/l as Caco3 ) and needed close monitoring of pH . Volatile fatty acids (VFA) of more than 1000 mg/ 1 in the effluent indicated process inhibition. The maximum organic loading achieved for this wastewater was about 4.5 kg COD/(m3.d) at a HRT of 6 days. Nevertheless, this wastewater was highly degradable with COD remova l of 80 to 90 percent. The biogas production was 430 Nl/(g ·CODremoved) with methane content of 65 to 73 percent . The optimum feeding pattern for RAUS in treating synthetic fiber production wastewater was found to be 1 hour feeding and 3 hours stop and flow reversion every 4 hours. The source of inoculum was a valuable factor for the start-up of reactors. Sludge well adapted to slaughter house wastewater showed an increase of specific methanogenic activity to 0.48 g cH4-coD/(g VSS . d) from an initial value of 0.09 after 150 days of reactor operation, while the activity of sludge from the reactor inoculated with sludge from anaerobic pond treating mung-bean starch wastewater increased to 0.26 g CH4-coD/(g VSS.d) within the same period. On-site research with different types of wastewater such as from distillery, slaughter-house and synthetic fiber production showed that the COD removal efficiency was independent of the reactor type but the achievable organic loading was different for different reactor type. |
| Year | 1993 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. EV-93-1 |
| 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) | Chongrak Polprasert |
| Examination Committee(s) | Verink, Johan;Tentscher, Wolfgang;Athapol Noomhorm;Seyfried, C. F. |
| Scholarship Donor(s) | GTZ, Germany |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1993 |