Evaluation and treatment of wastes from the tapioca starch industry | |
| Author | Yothin Unkulvasapaul |
| Call Number | AIT Thesis no. 836 |
| Subject(s) | Tapioca Sewage disposal Factory and trade waste |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering of the Asian Institute of Technology, Bangkok, Thailand. |
| Publisher | Asian Institute of Technology |
| Abstract | The characteristics and volumes of wastes from four second-grade tapioca starch plants were evaluated, and the performance of multistage anaerobic-facultative ponds treating these wastes were studied. Two main sources of process wastes were identified as the wash water and the supernatant from sedimentation tanks. The average volumes of these wastes were found to be 9 and 12 m3/ton of starch produced, respectively. The average BOD5 of wash water, supernatant and combined wastewater were found to be 1192, 4148 and 2491 mg/l, respectively, and nitrogen and phosphorus concentrations were found to be low in both streams. Pilot scale oxidation ponds were constructed at a second-grade starch plant in Chonburi, Thailand, where a combination of tap water and well water is used as process water. Well water contained high chloride concentrations because of the proximity of the well to the sea and consequently, wastewaters from the plant contained high chloride levels. However, this did not appear to be inhibitory to the oxidation ponds, The first-stage anaerobic pond was loaded at 7511 lb BOD5/acre-day with a detention time of 5.95 days and gave a BOD5 reduction of 60.5%. Second, third and fourth stage ponds loaded at the same BOD5 level achieved little further BOD5 reduction. It was found that in order to obtain an effluent with low BOD5, it was necessary to keep loadings in the second and third stages low. Second and third stage pond loaded at 500 and 80 lb BOD5/acre-day with detention times of 8 and 28.6 days gave BOD5 removals of 35.9 and 84.9%, respectively, rated on the input BOD5 to those ponds. From this study it is recommended that two anaerobic ponds followed by a facultative pond loaded at 6000, 2000 and 100 lb BOD5/acre-day would give a satisfactory total BOD5 removal. Suspended solids removals were found to be satisfactory in all the systems studied notwithstanding the detention times. A pilot-scale aerated lagoon was also investigated as treatment for the effluent from the first-stage anaerobic pond. At a detention time of 8 days, COD reduction was 90.2%, but the effluent contained high suspended solids levels and would require further sedimentation before discharge. |
| Year | 1975 |
| Type | Thesis |
| School | Student Research Before 1980 |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Thesis (Year <=1979) |
| Chairperson(s) | Pescod, M.B. ;Htun, Maung Nay |
| Scholarship Donor(s) | Canadian Government |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1975 |