The effect of advanced secondary municipal wastewater treatment on the molecular composition of dissolved organic matter

Abstract

There is a growing interest in water reuse and in recovery of nutrients from wastewater. Because many advanced treatment processes are designed to remove organic matter, a better understanding of the composition of dissolved organic matter (DOM) in wastewater is needed. To that end, we assessed DOM in the Nine Springs Wastewater Treatment Plant in Madison, Wisconsin by UV–visible spectroscopy and Fourier transform-ion cyclotron resonance mass spectrometry. Samples were collected from the influent and effluent of two different secondary treatment processes and their respective secondary clarifiers, the UV disinfection unit, and an Ostara treatment system, which produces struvite via chemical precipitation. The optical properties reveal that DOM throughout the plant is relatively aliphatic and is low in molecular weight compared to DOM in freshwater systems. Furthermore, the DOM is rich in heteroatoms (e.g., N, S, P, and Cl) and its molecular formulas are present in the lipid-, protein-, carbohydrate-, and lignin-like regions of van Krevelen diagrams. Secondary treatment produces DOM that is more aromatic and more complex, as shown by the loss of highly saturated formulas and the increase in the number of CHO, CHON, and CHOP formulas. The two secondary treatment processes produce DOM with distinct molecular compositions, while the secondary clarifiers and UV disinfection unit result in minimal changes in DOM composition. The Ostara process decreases the molecular weight of DOM, but does not otherwise alter its composition. The optical properties agree with trends in the molecular composition of DOM within the main treatment train of the Nine Springs plant.

Trace Element Removal in Distributed Drinking Water Treatment Systems by Cathodic H2O2 Production and UV Photolysis

“…Nominal masses of peaks were determined by adding the mass of a proton and a linear calibration was applied, as described previously. 29 Formulas containing C, H, O, and 13 C were considered for matching. For a formula assignment to be considered successful, the error had to be less than 0.2 ppm and it had to be part of a homologous series with more than three members (CH 4 versus O or ± CH 2 ).…”

Seasonal Variations of Dissolved Organic Matter in the East China Sea Using EEM-PARAFAC and Implications for Carbon and Nutrient Cycling

“…It has been extensively investigated regarding its composition, structure, source, sink and the migration process in the aquatic environments [2,3]. DOM can directly affect nutrient cycling [4], the toxicity of organic pollutants [5], the solubility of heavy metals [6] and the aquatic ecosystem [5,7], and also indirectly influence the atmospheric CO 2 level and global climate change [8,9].…”

Increasing Trends Towards Drinking Water Reclamation from Treated Wastewater

“…The analysis revealed that carefully planned potable water reuse projects should be able to provide a level of protection from waterborne illness and chemical contaminants comparable to (and, in some cases, better than) the level of protection the public experiences in many drinking water supplies across the nation. However, researchers [11] pointed out that the analysis was presented as an example and should not be used to endorse certain treatment schemes or to determine the risk at any particular site without site-specific analysis [7,9,11,33,[48][49][50][51][52][53].…”

“…For developing country planners and decision makers, water will be the key resource and political consideration in the coming 50 years. In many of these nations and regions, how water is managed will make the difference between peace and conflict; poverty and prosperity [1][2][3][4][5][6][7][8][9]. Across the globe, 2 out of 10 people do not have access to safe drinking water, and in the US, many states face water shortages and droughts [10].…”