Occurrence and fate of waterborne Pathogens in a wastewater treatment plant | |
| Author | Chuluun, Buyan |
| Call Number | AIT Thesis no.EV-05-6 |
| Subject(s) | Sewage disposal plants Water--Purification--Microbial removal |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science Arr Library 2 6 S[P 2005 Inter-University Program on Environmental Toxicology, Technology and Management, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | The present study of the AIT WWT plant was undertaken from September 2004 to March 2005. Overall carbonaceous removal efficiency of the AIT waste stabilization ponds was as follows: 57, 65 and 57% in terms of TSS, BOD5 and COD, respectively. The highest removal was achieved in the constructed wetland in terms of TSS and BOD;. Hydraulic retention time was found to fluctuate considerably seasonally and decreased more than twofold in the rainy season (3.2 and 5.7 days for anaerobic and facultative ponds, respectively) in comparison to the dry season (7.8 and 14.0 days, respectively). If total coliforms, fecal coliforms and E. coli occurred in the raw influent in numbers up to 108 MPN per 100 mL (respective geometric means, 4.6 x 108, 3.6 x 107 and 1.8 x 106) they were found to be reduced down to 103 MPN per 100 mL in the facultative pond effluent (respective geometric means, 5.0 x 104, 4.3 x 104 and 8.1 x 103) amounting to the removal of 4, 3 and 3 orders of magnitude for total coliforms, fecal coliforms and E. coli, respectively. Overall, it can be stated that the AIT WWT plant produced an effluent suitable for restricted irrigation, but exceeded the WHO fecal coliform guidelines for unrestricted irrigation by a factor of 3. G. lamblia was detected in the raw influent in numbers ranging from 100 to 480 cysts/L, whereas C. parvum was observed in numbers of up to 6 oocysts/L. No oo(cyst)s were detected in the effluents of facultative pond except a single case of G. lamblia cyst. The occurrence of oo(cyst)s in final pond effluents examined would indicate that accumulative retention periods up to 11 days during rainy season and about 20 days during dry season would be sufficient to complete removal of oo(cyst)s. The seasonal difference on the removal of G. lamblia cysts and C. parvum oocysts in AIT WSP system was >1 and 0.2 of log units, respectively. It can be therefore stated that the series of ponds offer a satisfactory treatment capacity for the protozoan and bacterial pathogens alike. Comparison of the removal rates and die-off rates showed a distinct trend of overall higher removal of coliform bacteria (total, fecal and E. coli) in the pond series during the dry season in comparison to the rainy season. Taking into account the fact of their vastly different geometry a possible explanation to be offered could be greater role of such factors as sedimentation (higher HRT). Though microalgal biomass (chlorophyll a) positively correlated with water temperature, pH, TSS, BODS and solar radiation and no correlation between increased microalgal biomass concentration in ponds and coliform removal rates except removal of E. coli in the facultative ponds was detected, therefore it was concluded that algae-mediated pH-dependent removal played no role in the pathogen removal both in the rainy and dry seasons. Furthermore, no correlation was observed between the coliform bacteria removal and sunlight radiation (duration/intensity) confirming important role of HRT-dependent sedimentation of pathogens in the ponds. It is concluded that the quality of canal water of Klong Neung was not compromised by the effluent of the AIT WWT plant since the receiving canal water was found to be of much more inferior quality in terms of both biogeochemical and microbiological parameters. |
| Year | 2005 |
| 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 (EV) |
| Chairperson(s) | Shipin, Oleg V. |
| Examination Committee(s) | Thammarat Koottatep;Babel, Mukand S. |
| Scholarship Donor(s) | Her Majesty the Queen of Thailand |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2005 |