Abstract
This study aimed to investigate TiO2 photocatalytic degradation of synthetically-prepared greywater samples with differing compositional contents of organic matter (OM), anion concentration, and microbiological consortium. Treatment efficiency was followed through removal of organic matter content in terms of dissolved organic carbon (DOC), specific spectroscopic parameters, and bacterial inactivation. Photocatalytic degradation kinetics were expressed by pseudo first-order kinetic modeling. The best DOC removal rates were attained for greywater samples containing OM with lower molecular size fractions. In addition, either enhancing or reducing the effect of common anions as radical scavengers were observed depending on the composition and concentration of variables in the greywater matrix. Moreover, possibility of a photocatalytic disinfection process was found to be of a bacteria type specific in OM-loaded synthetic greywater samples. Photocatalytic destruction of fecal streptococci required longer irradiation periods under all conditions. Bacterial removal rates were found to be in the order of total coliform > fecal coliform > fecal streptococci, for low organic load greywater, and fecal coliform > total coliform > fecal streptococci, for high organic load greywater.
Highlights
Greywaters are defined as all polluted domestic wastewater coming from showers, hand washing basins, laundry facilities, kitchen sinks, and washing machines, excluding any discharge from toilets [1,2]
With a non-purgeable total organic carbon (TOC) concentration of 6 mg L1, the greywater sample was characterized by size exclusion chromatography with organic carbon detection and the following classes of organic compounds were detected: polysaccharides, humic substances, building blocks and, only to a very low extent, “amphiphilic and neutral organics”, which are mainly represented by low-molecular weight trace organics [5]
In order to fill the gap in the literature, this study aims to investigate the applicability of TiO2 photocatalysis on greywater treatment by monitoring organic matter (OM) degradation and bacterial inactivation kinetics simultaneously in synthetically-prepared greywater samples
Summary
Greywaters are defined as all polluted domestic wastewater coming from showers, hand washing basins, laundry facilities, kitchen sinks, and washing machines, excluding any discharge from toilets [1,2]. Depending on many different factors, e.g., inter-regional differences with regard to development, consumption, applications, etc., greywater may constitute 50%–80% of the total domestic wastewater with varying compositions in terms of its physical, chemical, and microbiological properties [3,4]. Greywater treatment technologies may comprise a wide range of alternatives, from a simple filtration and disinfection process, to involvement of physical, chemical, and biological process alone or combined [6]. Some of those treatment processes give satisfactory results for the treatment of greywater, they still have several limitations in terms of removing complex organic matter, bacterial
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