Effects of different bed media on nitrogen removal in constructed wetlands treating faecal sludge | |
| Author | Nguyen Thai Hoa |
| Call Number | AIT Thesis no.EV-07-30 |
| Subject(s) | Constructed wetlands Sewage sludge |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Environmental Engineering and Management. |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. EV-07-30 |
| Abstract | This study was conducted to determine the efficiency of nitrogen (N) removal by vertical flow constructed wetlands which using different bed media treating faecal sludge. Five lab-scale constructed wetland units were setup which using small gravel (CW-G), plastic filters (circular shape) (CW-PF), broken brick (CW-B), plastic bottle segments (CW-PB) and charcoal (CW-C). Cattails (Typha latifolia), an emergent plant, were planted in these wetland beds. The cattail plants grew very well after feeding the faecal sludge especially plants of CW-C, however afterward plants in this CW unit grew gradually, while cattail plants of CW-PF and CW-PB grew relatively fast until the end of operation time. There was not remarkable in growth of plants of CW-G and CW-B. The maximum total nitrogen (TN) and total Kjeldahl nitrogen (TKN) removal was obtained at CW-PB unit at the sludge loading rates of 250 kg TS/m2.yr. Based on the N mass balance in all CW units, N retained in dried sludge and N unaccounted played significant roles of 77 -82% in the removal of N in these 5 CW units. CW-G and CW-B; CW-PF and CW-PB had a similar N distribution in N mass balance, respectively because of having similar characteristics bed media. Only CW-C had higher N content in percolate and lower unaccounted N. Fluorescence in situ hybridization (FISH) was performing to study the nitrogen transforming microbial community, and its variations with time courses in the constructed wetland units. FISH results revealed most bacteria (EUB338) in the range of 17-53% of total microorganism presented in the CW units. Nitrifier species -(NSO1225 and NIT3) and denitrifiers (RRP1088) were occurring simultaneously in only CW-PB. There was no Nitrobacter species (NIT3) and denitrifiers (RRP1088) in CW-C or-may be they were out of detection limit. |
| Year | 2007 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. EV-07-30 |
| 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) | Thammarat Koottatep.; |
| Examination Committee(s) | Polprasert, Chongrak;Annachattre, Ajit P.;Kone, Doulaye; |
| Scholarship Donor(s) | FRANCE;AIT Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2007 |