The Changes Of Fluorescent Organic Matters In Water And Wastewater Treatment Processes

Chemical analysis which cannot reflect removal of pollutants rapidly and sensitively in the processes of water and wastewater treatment is commonly used for water quality detection currently. In this paper, 3-D fluorescence spectra technology was used to reflect the changes of fluorescent organic matters in water and wastewater treatment processes.The dissolved organic carbon(DOC) and ammonia nitrogen removal by each processing unit in a water treatment plant whose source water is from micro-polluted river-net. Fluorescent dissolved organic matters were detected by three-dimensional fluorescence spectrophotometer, combining with parallel factor analysis(PARAFAC). The removal of ammonia nitrogen was mainly in the biological aeration tank, and the removal rate reached 63.2%. The DOC was removed in coagulation-sedimentation, filer and ozone-activated carbon, and the conventional treatment process had a higher removal rate of 57.2%. The pre-treatment and conventional treatment process hardly removed fluorescent dissolved organic matters. However, ozone-activated carbon can effectively remove fluorescent dissolved organic matters like tryptophan-like, tyrosine-like and humic-like substance whose fluorescent peaks removal rates respectively reached 82.1%, 63.3% and 61.6%. The result showed that combining conventional treatment with biological pre-treatment and advanced ozone-activated carbon could guarantee safety of water supply.Carbon, nitrogen and phosphorus removal by DE oxidation ditch was enhanced by adding PAC flocculant all year round and methanol in winter. The results show that CODCr concentration of secondary sedimentation effluent could be decreased below 22.0 mg/L. The concentration of ammonia nitrogen, TN and TP could be decreased less than 4.0 mg/L, 12.7 mg/L, and 0.5 mg/L respectively. Fluorescent peaks removal rates of tryptophan-like had a 35.8% decrease. There was no removal effect on tyrosine-like and humic-like substance. Water quality of secondary sedimentation effluent met the standard A of the first class in Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant.Using 3D-EEM technology, a river water and treated water samples from four cities were detected and analyzed. Fluorescence peaks appeared at λex/λem=290/320 nm and λex/λem=340/425 nm, which respectively reflects the existence of protein-like and humic-like matters. The quality of water from river was extremely influenced by human activity. Pollution of downstream was more serious than upstream. Fluorescent organic matters can be hardly removed by the conventional water treatment units(coagulation, sedimentation and filtration). The advanced treatment units(ozonation and biological activated carbon filtration) are more effective. The results indicate that it is feasible to detect water quality rapidly and select water treatment process by fluorescence technology.Fluorescent organic matters could be rapidly and sensitively reflected by three-dimensional fluorescence spectra in water and wastewater treatment processes. This paper provided experiences for pollutants analysis and detection in water and wastewater treatment plant, and emergency monitoring of drinking water source pollution. It could also be used as a reference for further application of three-dimensional fluorescence technology in the security of urban water supply and the protection of drinking water sources.