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.

Kinetic Study on Degradation of Micro-organics by Different UV-based advanced oxidation processes in EfOM Matrix

Effluent Organic Matter (EfOM) contains a large number of substances that are harmful to both the environment and human health. To avoid the negative effects of organic matter in EfOM, advanced treatment of organic matter is an urgent task. Four typical oxidants (H2O2, PS, PMS, NaClO) and UV-combined treatments were used to treat micro-contaminants in the presence or absence of effluent organic matter (EfOM), because the active radical species produced in these UV-AOPs are highly reactive with organic contaminants. However, the removal efficiency of trace contaminants was greatly affected by the presence of EfOM. The degradation kinetics of two representative micro-contaminants (benzoic acid (BA) and para-chlorobenzoic acid(p-CBA)) was significantly reduced in the presence of EfOM, compared to the degradation kinetics in its absence. Using the method of competitive kinetics, with BA, p-CBA and 1,4-dimethoxybenzene (DMOB) as probes, the radicals (HO·, SO4-·, ClO·) proved to be the key to reaction species in advanced oxidation processes. UV irradiation on EfOM was not primarily responsible for the degradation of micro-contaminants. The second-order rate constants of the EfOM with radicals were determined to be (5.027±0.643)×102(SO4-·), (3.192±0.153)×104 (HO·) and 1.35×106 (ClO·) (mg-C/L)-1·s-1. In addition, this study evaluated the production of three radicals based on the concept of Rct, which can better analyze its reaction mechanism.

Development of Cotton Linter Nanocellulose for Complexation of Ca, Fe, Mg and Mn in Effluent Organic Matter

Effluent organic matter (EfOM) is present in different domestic and industrial effluents, and its capacity to hold metallic ions can interfere in the wastewater treatment process. Due to the low quality of water, new sustainable technologies for this purpose have become extremely important, with the development of renewable-source nanomaterials standing out in the literature. Nanocellulose (NC) deserves to be highlighted in this context due to its physicochemical characteristics and its natural and abundant origin. In this context, the interactions between NC extracted from cotton linter, organic matter fraction (humic substances) and metal ions have been evaluated. Free metal ions (Ca, Fe, Mg and Mn) were separated by ultrafiltration and quantified by atomic absorption spectrometry. The nanomaterial obtained showed potential for the treatment of effluents containing iron even in the presence of organic matter. The probable interaction of organic matter with NC prevents the efficient removal of calcium, magnesium and manganese. For these elements, it is desirable to increase the interaction between metal and NC by modifying the surface of the nanomaterial.