Identification of core micropollutants of Ergene River and their categorization based on spatiotemporal distribution

Ergene River is heavily utilized for irrigation of fields to grow the main stocks of rice, wheat, and sunflower of Turkey also exported to Europe; therefore, monitoring the river's water quality is crucial for public health. Although the river quality is routinely monitored, the evaluation of pollution based on micropollutants is limited. In this study, we measured 222 organic micropollutants in 300 samples collected from 75 different locations on the Ergene River between August 2017 and May 2018 using direct injection liquid chromatography-tandem spectrometry with optimized scheduled multiple reaction monitoring. In total, 165 micropollutants were detected at a range of concentrations between 1.90 ng/L and 1824.55 μg/L. Sixty-three chemical substances were recurrent micropollutants that were detected at least one location in all seasons. Among them, 41 chemical substances were identified as the core micropollutants of the Ergene River using data-driven clustering methods. Hexa(methoxymethyl)melamine, benzotriazoles, and benzalkonium chlorides were frequently detected core micropollutants with an industrial origin. Besides, diuron, carbendazim, and cadusafos were common pesticides in the river. Core micropollutants were further categorized based on their type of source and environmental behavior using Kurtosis of concentration and load data obtained for each micropollutant. As a result, the majority of the core micropollutants are recalcitrant chemicals either released from a specific source located upstream of the river or have urban and agricultural sources dispersed on the watershed. In this study, we assessed the current state of pollution in the Ergene River at the micropollutant level with a very high spatial resolution and developed a statistical approach to categorize micropollutants that can be used to monitor the extent of pollution and track pollution sources in the river.

Microwave-assisted chemical oxidation of biological waste sludge: simultaneous micropollutant degradation and sludge solubilization

Microwave-assisted hydrogen peroxide (MW/H2O2) treatment and microwave-assisted persulfate (MW/S2O8(2-)) treatment of biological waste sludge were compared in terms of simultaneous antibiotic degradation and sludge solubilization. A 2(3) full factorial design was utilized to evaluate the influences of temperature, oxidant dose, and holding time on the efficiency of these processes. Although both MW/H2O2 and MW/S2O8(2-) yielded ≥97% antibiotic degradation with 1.2g H2O2 and 0.87 g S2O8(2-) per gram total solids, respectively, at 160 °C in 15 min, MW/S2O8(2-) was found to be more promising for efficient sludge treatment at a lower temperature and a lower oxidant dosage, as it allows more effective activation of persulfate to produce the SO4(-) radical. Relative to MW/H2O2, MW/S2O8(2-) gives 48% more overall metal solubilization, twofold higher improvement in dewaterability, and the oxidation of solubilized ammonia to nitrate in a shorter treatment period.

Effects of Inorganic Anions and Humic Acid on the Photocatalytic and Ozone Oxidation of Oxytetracycline in Aqueous Solution

Oxytetracycline (OTC), a widely used tetracycline group antibiotic, was treated by TiO

QSPR Study on the Bioconcentration Factors of Nonionic Organic Compounds in Fish by Characteristic Root Index and Semiempirical Molecular Descriptors

The characteristic root index (CRI) was modeled together with four semiempirical molecular descriptors, namely-energies of the highest occupied and the lowest unoccupied molecular orbital (E(HOMO) and E(LUMO)), heat of formation (DeltaH(f)), and dipole moment (micro)-to predict the fish bioconcentration factor (BCF) of 122 nonionic organic compounds. The best fit equation found by "forward multiple linear regression" showed that the topology based CRI was the most important parameter. The addition of quantum chemical descriptors made only a slight improvement in the predictive capability of the Quantitative Structure-Property Relationship (QSPR) model. The CRI was followed by E(HOMO). A two-parameter equation with a correlation coefficient of r = 0.921 was obtained for a diverse set of nonionic organic chemicals. Statistical robustness of the developed model was validated by modified jackknife tests where random deletion of a class of compounds and specific deletion of a set of compounds were both performed. The predictive accuracy of the proposed model was compared with the commonly used K(ow) model and recently published studies in which BCF models were developed. Particular emphasis has been made to clearly define the boundaries for the application of the alternative developed model as well as the quality of estimates.

Advanced oxidation of a reactive dyebath effluent: comparison of O3, H2O2/UV-C and TiO2/UV-A processes

In the present study the treatment efficiency of different AOPs (O3/OH- H2O2/UV-C and TiO2/UV-A) were compared for the oxidation of simulated reactive dyebath effluent containing a mixture of monochlorotriazine type reactive dyes and various dye auxiliary chemicals at typical concentrations encountered in exhausted reactive dyebath liquors. A525 (color), UV280 (aromaticity) and TOC removal rates were assessed to screen the most appropriate oxidative process in terms of reactive dyebath effluent treatment. Special emphasis was laid on the effect of reaction pH and applied oxidant (O3, H2O2) dose on the observed reaction kinetics. It was established that the investigated AOPs were negatively affected by the Na2CO3 content (= 867 mg/L) which is always present at high concentrations in dychouse effluents since it is applied as a pH buffer and dye fixation agent during the reactive dyeing process. The ozonation reaction exhibited almost instantaneous decolorization kinetics and a reasonable TOC reduction rate. It appeared to be stable under the investigated advanced oxidation conditions and outranked the other studied AOPs based on the above mentioned criteria. Besides, the electrical energy requirements based on the EE/O parameter (the electrical energy required per order of pollutant removal in 1 m3 wastewater) was calculated for the homogenous AOPs in terms of decolorization kinetics. In view of the electrical energy efficiency, ozonation and H2O2/UV-C oxidation at the selected treatment conditions appear to be promising candidates for full-scale dyehouse effluent decolorization.

Homogenous and heterogenous advanced oxidation of two commercial reactive dyes

Two commercial reactive dyes, the azo dye Reactive Black 5 and the copper phythalocyanine dye Reactive Blue 21, have been treated at a concentration of 75 mg l(-1) by titanium dioxide mediated photocatalytic (TiO2/UV), dark and UV-light assisted Fenton (Fe2+/H2O2) and Fenton-like (Fe3+/H2O2) processes in acidic medium. For the treatment of Reactive Black 5, all investigated advanced oxidation processes were quite effective in terms of colour, COD as well as TOC removal. Moreover, the relative growth inhibition of the azo dye towards the marine algae Dunaliella tertiolecta that was initially 70%, did not exhibit an increase during the studied advanced oxidation reactions and complete detoxification at the end of the treatment period could be achieved for all investigated treatment processes. However, for Reactive Blue 21, abatement in COD and UV-VIS absorbance values was mainly due to the adsorption of the dye on the photocatalyst surface and/or the coagulative effect of Fe3+/Fe2+ ions. Although only a limited fraction of the copper phythalocyanine dye underwent oxidative degradation, 47% of the total copper in the dye was already released after 1 h photocatalytic treatment.

Photochemical treatment of simulated dyehouse effluents by novel TiO2 photocatalysts: experience with the thin film fixed bed (TFFB) and double skin sheet (DSS) reactor

This study has been undertaken to provide a rather practical assessment of the heterogeneous photocatalytic treatment of two simulated reactive dye-bath effluents via three commercial TiO2 types (Degussa P25, Millennium PC 500 and Sachtleben Mikroanatas), which were employed in fixed film and suspended photochemical reactor configurations. The obtained results have clearly revealed that the inherent advantage of eliminating a proceeding photocatalyst separation step did not justify the significantly lower treatment performance of the thin film fixed bed (TFFB) reactor, which is directly reflected in the values obtained for percent photonic efficiencies (% zeta), first-order decolourisation rate constants (kd) and the collector area requirements per unit of mineralisation rate (CA/M), as compared to the more recently developed suspended double skin sheet (DSS) photoreactor. Generally speaking, Degussa P25 was found to be most efficient among the investigated TiO2 photocatalyst types.