Elif Pehlivanoglu-Mantas

Measurement of dissolved organic nitrogen forms in wastewater effluents: Concentrations, size distribution and NDMA formation potential

Dissolved organic nitrogen (DON), which may act as a nutrient and a disinfection by-product precursor, accounts for most of the dissolved nitrogen in nitrified-denitrified wastewater effluents. To gain insight into the behavior of wastewater-derived DON in engineered and natural systems, samples from treatment plants employing a range of different processes were characterized by several different methods. Dissolved free and combined amino acids accounted for the majority of the identifiable DON. Combined amino acids typically accounted for less than 10-20% of the wastewater-derived DON. Other organic-nitrogen containing species such as EDTA and humic substances from the water source only accounted for a few percent of the remaining DON. The remaining DON mainly consisted of hydrophilic, low-molecular weight compounds, capable of passing through a 1kDa ultrafilter. This fraction of the DON also contained most of the precursors of N-nitrosodimethylamine (NDMA). The chemical properties of wastewater-derived DON pose challenges to designers of wastewater treatment plants because most physical and chemical treatment processes will not remove low-molecular weight, hydrophilic compounds.

Wastewater-Derived Dissolved Organic Nitrogen: Analytical Methods, Characterization, and Effects—A Review

Wastewater-derived dissolved organic nitrogen (DON) accounts for up to 80% of dissolved nitrogen in nitrified-denitrified effluent. The sturdiness of DON measurements hindered the characterization of DON, especially in wastewater matrix, leading to an unsatisfying knowledge level. Measurement of DON and DON species is imortant not only as a measure of treatibility of wastewater in treatment plants, but also for the possible algal growth-stimulating effects after their discharge into receiving waters. In addition, wastewater-derived DON compounds may act as precursors to several disinfection by-products during intentional or unintentional reuse of wastewater. A review of DON compounds in wastewater and wastewater effluents is given.

Seasonal variation of diclofenac concentration and its relation with wastewater characteristics at two municipal wastewater treatment plants in Turkey

The pharmaceutically active compound diclofenac has been monitored during one year at separate treatment units of two municipal wastewater treatment plants (WWTPs) to evaluate its seasonal variation and the removal efficiency. Conventional wastewater characterization was also performed to assess the possible relationship between conventional parameters and diclofenac. Diclofenac concentrations in the influent and effluent of both WWTPs were detected in the range of 295-1376 and 119-1012ng/L, respectively. Results indicated that the higher diclofenac removal efficiency was observed in summer season in both WWTPs. Although a consistency in diclofenac removal was observed in WWTP_1, significant fluctuation was observed at WWTP_2 based on seasonal evaluation. The main removal mechanism of diclofenac in the WWTPs was most often biological (55%), followed by UV disinfection (27%). When diclofenac removal was evaluated in terms of the treatment units in WWTPs, a significant increase was achieved at the treatment plant including UV disinfection unit. Based on the statistical analysis, higher correlation was observed between diclofenac and suspended solids concentrations among conventional parameters in the influent whereas the removal of diclofenac was highly correlated with nitrogen removal efficiency.

Occurrence of THM and NDMA precursors in a watershed: Effect of seasons and anthropogenic pollution

In pristine watersheds, natural organic matter is the main source of disinfection by-product (DBP) precursors. However, the presence of point or non-point pollution sources in watersheds may lead to increased levels of DBP precursors which in turn form DBPs in the drinking water treatment plant upon chlorination or chloramination. In this study, water samples were collected from a lake used to obtain drinking water for Istanbul as well as its tributaries to investigate the presence of the precursors of two disinfection by-products, trihalomethanes (THM) and N-nitrosodimethylamine (NDMA). In addition, the effect of seasons and the possible relationships between these precursors and water quality parameters were evaluated. The concentrations of THM and NDMA precursors measured as total THM formation potential (TTHMFP) and NDMA formation potential (NDMAFP) ranged between 126 and 1523μg/L THM and <2 and 1648ng/L NDMA, respectively. Such wide ranges imply that some of the tributaries are affected by anthropogenic pollution sources, which is also supported by high DOC, Cl(-) and NH(3) concentrations. No significant correlation was found between the water quality parameters and DBP formation potential, except for a weak correlation between NDMAFP and DOC concentrations. The effect of the sampling location was more pronounced than the seasonal variation due to anthropogenic pollution in some tributaries and no significant correlation was obtained between the seasons and water quality parameters.

Optimization of diclofenac quantification from wastewater treatment plant sludge by ultrasonication assisted extraction

A rapid quantification method of diclofenac from sludge samples through ultrasonication assisted extraction and solid phase extraction (SPE) was developed and used for the quantification of diclofenac concentrations in sludge samples with liquid chromatography/tandem mass spectrometry (LC-MS/MS). Although the concentration of diclofenac in sludge samples taken from different units of wastewater treatment plants in Istanbul was below the limit of quantification (LOQ; 5ng/g), an optimized method for sludge samples along with the total mass balances in a wastewater treatment plant can be used to determine the phase with which diclofenac is mostly associated. Hence, the results will provide information on fate and transport of diclofenac, as well as on the necessity of alternative removal processes. In addition, since the optimization procedure is provided in detail, it is possible for other researchers to use this procedure as a starting point for the determination of other emerging pollutants in wastewater sludge samples.

Removal of Nonylphenol and Octylphenol from Aqueous Solutions by a Novel Nano-Composite (ZVI/Fullerene)

Nonylphenol (NP) and octylphenol (OP) are considered as endocrine disrupting compounds and they restrict the reuse potential of wastewater. Therefore, innovative and reliable technologies are required for elimination of these compounds from waste streams. In this study, we consider use of iron nanoparticles (nZVI) (0.1 mM; 2 mM) and also a composite of nZVI/fullerene nanoparticles (aq-nC60) (0.1 mM nZVI/2.5 ppm aq-nC60; 2 mM nZVI/2.5 ppm aq-nC60) for the removal of 25 μg/L NP and OP concentrations. The nano-composite was synthesized according to chemical reduction method and was characterized using XRD, particle size distribution and zeta potential measurements. NP and OP concentrations were quantified with a GC-MS. The results demonstrated that 0.1 mM nZVI alone resulted in 6% and 17% decrease in NP and OP concentrations, respectively. However, when the nZVI concentration was increased to 2 mM, the removal efficiency increased to 59% for NP and 32% for OP. When compared with NP, lower removal rates were achieved for OP regardless of the nZVI concentration. Although NP and OP have similar chemical structures, OP has a branched arrangement and this structure is anticipated to cause a decrease in the active adsorption sites and lower removal efficiency for OP. Highest removal was obtained with 0.1 mM nZVI/2.5 ppm aq-nC60 for both NP and OP. Our results show that nZVI/aq-nC60 holds a potential for elimination of NP and OP from wastewater sources.