Using Molecular Weight-Based Fluorescent Detector to Characterize Dissolved EffluentOrganic Matter in Oxidation Ditch with Algae

Implementation microalgae has been considered for enhancing effluent wastewater quality. However, algae can cause environmental issues due to algae released extracellular organic matter, algal organic matter, instead of bacteria-derived organic matter in the biological process. The objectives of this study are to investigate the characteristics of dissolved effluent organic matter as algal-derived organic and bacteria-derived organic during the oxidation ditch process. Experiments were conducted in the oxidation ditch without algae, with Spirulina platensis and Chlorella vulgaris. The results showed dissolved effluent organic matter increased into higher dissolved organic carbon, more aromatic and hydrophobic than that before treatment. Fluorescence spectroscopy identified two component, namely aromatic protein-like at excitation/emission 230/345 nm and soluble microbial products-like at 320/345 nm after treatment, instead of fulvic acid-like at 230/420 nm and humic acid-like at 320/420 nm in raw wastewater. Fractionation of dissolved organic fluorescence based on average molecular weight cut-offs (MWCOs) has obtained that fractions aromatic protein-like, fulvic acid-like, humic acid-like, and soluble microbial products-like has respectively a high MWCOs 50,000 Da, a high to low MWCOs <1650 Da, medium MWCOs 1650 Da to low MWCOs. Biological oxidation ditch under symbiosis algal-bacteria generated humic acid-like and fulvic acid-like with a higher MWCOs than oxidation without algal. The quality and quantity of dissolved effluent organic matter in oxidation ditch algal reactor has been significant affected by algal-bacteria symbiotic.

Effect of the Recycling Process on Drinking Water Treatment: Evaluation Based on Fluorescence EEM Analysis Using the Peak-Picking Technique and Self-Organizing Map

The recycling process is applied in many water treatment plants (WTPs), although this process can lead to adverse effects. The effect of the recycling process on the characteristics of dissolved organic matter was evaluated based on a fluorescence excitation-emission matrix using the peak-picking technique and self-organizing map (SOM). In this study, an evaluation of two WTPs, one with and one without a recycling system, was carried out. Both WTPs show moderate efficiency during the coagulation–flocculation process in removing DOC, fulvic acid-like, humic acid-like, and tryptophan-like substances. The recycling process causes increased values of fulvic acid-like, humic acid-like, and tryptophan-like substances and specific ultraviolet absorbance (SUVA) after the filtration process of about 31.0%, 35.7%, 22.2%, and 6%, respectively. Meanwhile, the WTP without recycling showed a reduction in the level of fulvic acid-like, humic acid-like, and tryptophan-like substances and SUVA by 23.3%, 52.9%, 27.8%, and 21.1%, respectively. Moreover, SOM analysis based on the peak-picking technique can determine differences in sample clusters due to the recycling process.