Chemical characterization and anaerobic treatment of bitumen fume condensate using a membrane bioreactor.

Bitumen fume condensate (BFC) is a hazardous wastewater generated at asphalt reclamation and production sites. BFC contains a wide variety of potentially toxic organic pollutants that negatively affect anaerobic processes. In this study, we chemically characterized BFC produced at an industrial site and evaluated its degradation under anaerobic conditions. Analyses identified about 900 compounds including acetate, polycyclic aromatic hydrocarbons, phenolic compounds, and metal ions. We estimated the half maximal inhibitory concentrations (IC50) of methanogenesis of 120, 224, and 990 mgCOD·L-1 for three types of anaerobic biomass, which indicated the enrichment and adaptation potentials of methanogenic biomass to the wastewater constituents. We operated an AnMBR (7.0 L, 35 °C) for 188 days with a mixture of BFC, phenol, acetate, and nutrients. The reactor showed a maximum average COD removal efficiency of 87.7 ± 7.0 %, that corresponded to an organic conversion rate of 286 ± 71 mgCOD-1·L-1d-1. The microbial characterization of the reactor's biomass showed the acetoclastic methanogen Methanosaeta as the most abundant microorganism (43 %), whereas the aromatic and phenol degrader Syntrophorhabdus was continuously present with abundances up to 11.5 %. The obtained results offer the possibility for the application of AnMBRs for the treatment of BFC or other petrochemical wastewater.

Formation and control of disinfection by-products from iodinated contrast media attenuation through sequential treatment processes of ozone-low pressure ultraviolet light followed by chlorination.

Different groups of disinfection by-products (DBPs) were studied through the degradation of iopamidol by the sequential oxidation process of ozone-low pressure ultraviolet light (O3-LPUV) followed by chlorination. This paper investigates the attenuation of iopamidol under this sequential treatment and the effect of chlorine contact time (30 min versus 3 days) to control the formation potential of DBPs: trihalomethanes (THMs), haloacetonitriles (HANs) and haloacetamides (HAMs). Thirty target DBPs among the 9 iodinated-DBPs (I-DBPs), were monitored throughout the sequential treatment. Results showed that O3-LPUV removed up to 99% of iopamidol, while ozone and LPUV alone removed only 90% and 76% respectively. After chlorine addition, O3-LPUV yielded 56% lower I-DBPs than LPUV. Increasing chlorine contact time resulted in higher concentrations of all DBP groups (THMs, HANs, and HAMs), with the exception of I-DBPs. One new iodinated-haloacetamide, namely chloroiodoacetamide (CIACM) and one iodoacetonitrile (IACN) were detected. These results suggest the iodine incorporated in iopamidol may be a precursor for iodinated-nitrogenous-DBPs, which are currently not well studied.

Exploring the genotoxicity triggers in the MP UV/H2O2-chloramination treatment of bisphenol A through bioassay coupled with non-targeted analysis.

Bisphenol A (BPA) is a well-known xenoestrogen, and UV/H2O2 advanced oxidation process (AOP) is one of the most effective technologies to remove BPA from water. Using BPA spiked tap water, a batch-scale photochemical experiment was conducted to investigate whether BPA can pose a genotoxicity concern during the medium pressure (MP) UV/H2O2 treatment and the post-chloramination. Samples at different UV exposure and post-chloramination durations were collected and analyzed by CALUX® gene reporter assays regarding estrogen receptor α (ERα) and p53 transcriptional activity. MP UV/H2O2 process did not cause extra estrogenic effects from the degradation of BPA, whereas genotoxicity occurred when the treated water was exposed with monochloramine. Seven frequently reported nitrogenous disinfection byproducts (N-DBPs) were detected, but none of them were responsible for the observed genotoxicity. Employed with gas chromatography-quadrupole time-of-flight mass spectrometry (GC-QTOF-MS), four compounds possibly contributed to the genotoxicity were tentatively identified and two of them with aminooxy- or cyano- group were considered as "new" N-DBPs. This study demonstrated that by-products differ from their parent compounds in toxicity can be formed in the UV oxidation with post-disinfection process, which should become a cause for concern.

A direct injection liquid chromatography tandem mass spectrometry method for the kinetic study on iodinated contrast media (ICMs) removal in natural water.

Iodinated contrast media (ICMs) are a class of X-ray contrast media worldwide utilized for radiographic procedures. Since they cannot be removed efficiently during water treatment, they can be found in surface and groundwater. In this work, a rapid and sensitive direct injection liquid chromatography-tandem (LC-MS/MS) method for the simultaneous analysis of seven ICMs media (iopamidol, ioxitalamic acid, diatrizoic acid, iothalamic acid, iohexol, iomeprol and iopromide) in complex aqueous matrices has been developed and validated. The MDLs for the analytes ranged from 0.7 to 21 ng L-1 in ultrapure water, and recoveries ranged from 86 to 100% in drinking water, 85-103% in groundwater and 84-105% in WWTP effluent. A stereo-isomer for iopromide was separated. This analytic method was applied to investigate the removal of target ICMs by low pressure ultra violet light (LPUV) advanced oxidation processes with three oxidants, hydrogen peroxide, free chlorine and monochloramine in groundwater. Results showed that the addition of oxidants did not enhance attenuation of ICMs, since fluence-based decay apparent rate constants were similar (KUV = 3.2 × 10-3, KUV-Cl2 = 3.6 × 10-3 and KUV-NH2 = 3.4 × 10-3 10-3 cm2 mJ-1). This yielded direct photolysis is the main mechanism to attenuate target ICMs.