Evaluation of heating and drying treatment technologies towards E. coli and total coliforms inactivation in freshly separated faecal matters | |
| Author | Ngowi, Victor John |
| Call Number | AIT Thesis no.UWEM-14-05 |
| Subject(s) | Sewage--Purification--Activated sludge process Sewage--Purification |
| Note | 89 leaves : ill. |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. UWEM-14-04 |
| Abstract | This research investigates the performance of indirect heating and drying of fresh excreta sludge as the feasible small scale technologies for pa thogen inactivation . The disinfection s process es were done in two approaches. The first one was inactivation by means of supplied hot water via pipe (indirect heating system). Heated water at specified temperatures of 40 ̊C, 50 ̊C, 60 ̊C and 65 ̊C were circulated with the aid of pump via 16 mm poly ethylene pipe distributed at the bottom (underneath) surface in all three chambers. After disinfection process the hot water was re - circulated back to the boiler. The second approach was by blowing hot air to 3 dying chambers arranged in parallel. The temperatures here were maintained at 65 ̊ C , and 75 ̊ C . The excreta sludge was collected from Thalathai market toilet and the experiment was set in the AIT EEM research station. Parameters like ambient temperature , relative humidity, Total coliforms , E. coli , moisture contents, T S, pH, TKN, COD w ere monitored and analysed. By i ndirect heating method , at 50 ̊C, the t otal coliforms and E. coli achieved 4.4 and 3 MPN/g dry weight log reductions respectively within 20 days. In comparison with the control, 2 log (MPN/g dry weight) reductions were achiev ed after 20 days. At the same temperature and duration, moisture content of a thin lay er of sludge decreased from 87% to 5 %. At 60 and 65 ̊C the decay in all aspects was almost similar . Total coliforms achieved 5 log (MPN/g dry weight) reductions within 8 days while E. coli achieved 4.2 log (MPN/g dry weight) reductions in 5 days. At this point moisture dropped from 92% to 5 % within 5 days. The batch (thin layer ) of sludge done at 40 ̊C achieved 1 log MPN/g dry weight reduction for both t otal coliforms and E. coli within 17 days while m oisture reduction was from 88% to 10 %. Hot air blown at 65 ̊C in a thin layer of sludge attained 3.1 and 3.7 log (MPN/g dry weight) reduction for E . coli and t otal coliforms in duration of 20 and 24 hours respectively. Moistu re c ontent was drained out from 87% to 8 % within 16 hours. At 75 ̊C a complete reduction s of t otal coliforms and E. c oli w ere achieved after 12 hours . The initial average values of TKN were around 17 mg/L. After draining out the moisture the final values w ere between 30 - 50 mg/L. The model obtained obeyed first order kinetic equation . Based on this research findings , the more economical and efficient technology is hot air drying method. The amount of energy consumed is 7 times lower than energy consumed by i ndirect heating approach . Treated excreta should be used as soil conditioner because it was treated to the level which will not pose health risk to human being. For further studies, the experiment should be repeated by using freely available energy i.e. solar energy or biogas. The indirect heating setup should be located in place where it will not be affected by the solar intensity. Lastly, e xami nation should be done on whether faecal coliforms indicator pathogens are more resistant to temperature compare d to other groups as suggested by the literature . |
| Year | 2014 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. UWEM-14-05 |
| Type | Thesis |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Urban Water Engineering and Management (UWEM) |
| Chairperson(s) | Thammarat Koottatep;Vossenberg, Jack Van De |
| Examination Committee(s) | Shipin, Oleg V.;Shrestha, Sangam |
| Scholarship Donor(s) | Netherlands Fellowship Program |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology - UNESCO-IHE, 2014 |