YAOHao,XUHang,WENXin,et al.Effect of Pre-ozonation on Removal of Organic Matter during Coagulation and Sedimentation[J].China Water & Wastewater,2022,38(7):33-42.
Effect of Pre-ozonation on Removal of Organic Matter during Coagulation and Sedimentation
China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU]
volume:
第38卷
Number:
第7期
Page:
33-42
Column:
Date of publication:
2022-04-01
- Abstract:
- The effects of ozonation-enhanced coagulation and sedimentation on the removal of dissolved organic matter (DOM) were investigated, and the evolution of DOM was explored from different levels by using LC-OCD and FT-ICR MS techniques for four water samples of raw water from Changdang Lake, coagulation and sedimentation effluent, pre-ozonation effluent and ozonation-enhanced coagulation and sedimentation effluent. The optimal dosage of ozone and polyaluminum chloride (PAC) was determined to be 1.0 mg/L and 30 mg/L, respectively, and the following experiment was carried out under this optimal condition. There were mainly two kinds of organic compounds in the raw water, namely tryptophan-like and fulvic acid-like. The removal effect of organic compounds by the ozonation-enhanced coagulation and sedimentation was the best, and the removal rates of tryptophan, fulvic and humic acids were 80.75%, 77.39% and 80.28%, respectively. LC-OCD analysis indicated that the highest total concentration of hydrophilic organic compounds in the raw water was 3 776.74 ?g/L. The concentration of building blocks in the effluent of ozonation-enhanced coagulation and sedimentation increased, whereas the concentrations of other organic substances decreased. Among small molecular DOM, the proportion of CHOSP-DOM was the largest, and the proportion of CHOP-DOM was the smallest. Ozonation-enhanced coagulation and sedimentation had the greatest effect on the distribution of relative abundance of various molecules. The peaks appeared in C10H10O3 (177.06 u), C13H18O6 (269.10 u) and C15H20O7 (311.11 u), and the distribution of molecules with mass-to-charge ratio greater than 680 decreased significantly. The distribution range of small molecular DOM in raw water treated by different processes became wider, and gradually transferred to high H/C and low O/C substances. Carbohydrates, unsaturated hydrocarbons, tannins and thick cyclic compounds accounted for a small proportion in each water sample, and the total proportion was 10.90%-18.25%. The DBE average values of small molecular DOM in four water samples were 6.6, 6.5, 6.3 and 6.1, respectively, indicating that ozone played a key role in reducing aromatics or unsaturation. In general, the treatment performance of ozonation-enhanced coagulation and sedimentation process was the best, which could reduce the difficulty of organic matter treatment in the subsequent process of waterworks.
Last Update:
2022-04-01