Elimination of Micropollutants during Post-Treatment of Hospital Wastewater with Powdered Activated Carbon, Ozone, and UV

Abstract

A pilot-scale hospital wastewater treatment plant consisting of a primary clarifier, membrane bioreactor, and five post-treatment technologies including ozone (O3), O3/H2O2, powdered activated carbon (PAC), and low pressure UV light with and without TiO2 was operated to test the elimination efficiencies for 56 micropollutants. The extent of the elimination of the selected micropollutants (pharmaceuticals, metabolites and industrial chemicals) was successfully correlated to physical-chemical properties or molecular structure. By mass loading, 95% of all measured micropollutants in the biologically treated hospital wastewater feeding the post-treatments consisted of iodinated contrast media (ICM). The elimination of ICM by the tested post-treatment technologies was 50-65% when using 1.08 g O3/gDOC, 23 mg/L PAC, or a UV dose of 2400 J/m(2) (254 nm). For the total load of analyzed pharmaceuticals and metabolites excluding ICM the elimination by ozonation, PAC, and UV at the same conditions was 90%, 86%, and 33%, respectively. Thus, the majority of analyzed substances can be efficiently eliminated by ozonation (which also provides disinfection) or PAC (which provides micropollutants removal, not only transformation). Some micropollutants recalcitrant to those two post-treatments, such as the ICM diatrizoate, can be substantially removed only by high doses of UV (96% at 7200 J/m(2)). The tested combined treatments (O3/H2O2 and UV/TiO2) did not improve the elimination compared to the single treatments (O3 and UV).

Insights into the mechanism of electrochemical ozone production via water splitting on the Ni and Sb doped SnO2 catalyst

“…[1][2][3][4][5] O 3 is a strong oxidant, the second strongest after chlorine, with an oxidation potential of 2.07 V. For this reason, it is a viable option as a replacement for chlorine as a water disinfectant. When using O 3 as a disinfectant, the main advantage over chlorine is that few harmful by-products are produced whereas chlorine produces halogenated complexes on reaction.…”

“…The applications of O 3 are not limited to water treatment as more recent studies outline its application in healthcare 6,7 , sterilization 8,9 and chemical synthesis 10 . The traditional method of generating O 3 is via a Cold Corona Discharge Reactor which occurs via the following reaction: …”

Recent Advances in Water Management: Saving, Treatment and Reuse

“…Adsorption/removal of a pollutant by GAC/PAC is governed by the following mechanisms: (i) the electron donor-acceptor complex; (ii) the π-π dispersion interactions; (iii) hydrophobic interactions; and (iv) solvent effects that controls the solubility, reactivity and reaction kinetics [192,193]. The key properties of an adsorbent that can affect the efficacy of adsorption process include but are not limited to surface area, dose, surface chemistry and morphology, while water partitioning coefficient (log K ow ), acid dissociation coefficient (pK a ), molecular structure and size of the pollutants can influence the extent of adsorption by GAC/PAC [194]. In previous studies, efficient removal of PhACs has been achieved by GAC having larger pore size, because it can effectively adsorb pollutants with different shapes and size.…”

Treatment Alternatives for Micropollutant Removal in Wastewater

“…Advantages of using PAC is that continuously provide fresh carbon and can be used in certain circumstances when the concentration's of contaminants rise in water bodies (Snyder et al, 2007). Study done by Kovalova et al (2013), PAC treatment was used to evaluate removal efficiencies of micropollutants in MBR treated hospital wastewater. In this study retention time was chosen as 2 days and PAC dosages were also selected as 8, 23 and 43 mg/L.…”