Transformations of particles, metal elements and natural organic matter in different water treatment processes.
Characterizing natural organic matter (NOM), particles and elements in different water treatment processes can give a useful information to optimize water treatment operations. In this article, transformations of particles, metal elements and NOM in a pilot-scale water treatment plant were investigated by laser light granularity system, particle counter, glass-fiber membrane filtration, inductively coupled plasma-optical emission spectroscopy, ultra filtration and resin absorbents fractionation. The results showed that particles, NOM and trihalomethane formation precursors were removed synergistically by sequential treatment of different processes. Pre-ozonation markedly changed the polarity and molecular weight of NOM, and it could be conducive to the following coagulation process through destabilizing particles and colloids; mid-ozonation enhanced the subsequent granular activated carbon (GAC) filtration process by decreasing molecular weight of organic matters. Coagulation-flotation and GAC were more efficient in removing fixed suspended solids and larger particles; while sand-filtration was more efficient in removing volatile suspended solids and smaller particles. Flotation performed better than sedimentation in terms of particle and NOM removal. The type of coagulant could greatly affect the performance of coagulation-flotation. Pre-hydrolyzed composite coagulant (HPAC) was superior to FeCl3 concerning the removals of hydrophobic dissolved organic carbon and volatile suspended solids. The leakages of flocs from sand-filtration and microorganisms from GAC should be mitigated to ensure the reliability of the whole treatment system.
Yan
Ming-Quan
MQ
State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Wang
Dong-Sheng
DS
Shi
Bao-You
BY
Wei
Qun-Shan
QS
Qu
Jiu-Hui
JH
Tang
Hong-Xiao
HX
D002244:Carbon / Q000032:analysis / Q000737:chemistry; D002712:Chlorides; D005290:Ferric Compounds / Q000737:chemistry; D005427:Flocculation; D008670:Metals / Q000032:analysis / Q000737:chemistry*; D009391:Nephelometry and Turbidimetry; D010126:Ozone / Q000737:chemistry; D010316:Particle Size; D014873:Water Pollutants / Q000032:analysis / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
D002712:Chlorides; D005290:Ferric Compounds; D008670:Metals; D014873:Water Pollutants; D010126:Ozone; D002244:Carbon; C024555:ferric chloride