Treatment Technology of Backwash Water

• Main Authors: Cheng-pang Yang, 楊正邦
• Other Authors: Jhy-chern Liu
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/90187867272292332134

碩士 === 國立臺灣科技大學 === 化學工程系 === 93 === The objective of this study was to investigate the treatment and recycle of the backwash water. The coagulation efficiency of backwash water resulting from Chang-Hsing and Swan-Sea were compared. The characteristics of backwash water of Chang-Hsing Water Treatment Plant varied considerably among samples taken at different times, while those of Swan-Sea did not. The use of polyaluminum chloride（PACl）and alum both could yield satisfactory turbidity removal. The addition of polymers, such as chitosan and Cat-Floc reduced the dosage of PACl required to achieve effective coagulation-flocculation. In study of backwash water mixed with raw water by certain ratio through jat test. Results revealed that backwash water recycling did not deteriorate the treated water quality. In pilot study in Chang-Hsing Water Treatment Plant, two recycling mode were selected: intermittent recycling mode（10 min for each hour）at a ratio of 1:7, and the continuous recycling mode at a ratio of 1:42. Results showed that the intermittent recycling mode had less chance to affect the effluent quality than the continuous recycling mode. In addition, two important parameters were studied, namely: backwash water recycle ratio（4, 6 and 8%）, and backwash water type（direct recycle, 3-min pre-sedimentation, and 10-min pre-sedimentation）in pilot study of Swan-Sea.