Performance of Hybrid Photocatalytic-Ceramic Membrane System for the Treatment of Secondary Effluent

Abstract

Evaluation of an advanced wastewater treatment system that combines photocatalysis with ceramic membrane filtration for the treatment of secondary effluent was undertaken. The results showed that, after photocatalysis and ceramic membrane filtration, the removal of dissolved organic carbon and UV254 was 60% and 54%, respectively, at a concentration of 4 g/L of TiO2. Dissolved organic matter (DOM) present in the secondary effluent was characterised with a liquid chromatography-organic carbon detector (LC-OCD) technique. The results showed low removal of humics, building blocks, the other oxidation by-products and no removal of biopolymers after TiO2/UV photocatalytic treatment. This suggested that the radical non-selective oxidation mechanisms of TiO2/UV process resulted in secondary effluent in which all of the DOM fractions were present. However, the hybrid system was effective for removing biopolymers with the exception of low molecular weight (LMW) compounds acids, which accumulated from the beginning of the reaction. In addition, monitoring of the DOM fractions with LC-OCD analysis demonstrated that the reduction of the effluent aromaticity was not firmly correlated with the removal of humic substances for the combined processes.

Particle size distribution as a major characteristic of domestic wastewater: implications for the modeling and design of membrane bioreactors

“…It should be also mentioned that other PSD methods are available, based on instrumental methods with the following specific uses: (i) gel filtration chromatography, 50 used for separation, de‐saltation and molecular weight estimation of proteins; (ii) gel permeation chromatography, 51 used for recognition of major features of apparent distribution of effluent organic matter; (iii) liquid chromatography–organic carbon detector, 52 used for quantification of biopolymers, humic substances, building blocks and low‐molecular‐weight organic fractions; (iv) flow field‐flow fractionation, 53 used for characterization of various natural colloids in surface water, soil suspensions and groundwater; (v) laser diffraction spectroscopy, used for analysis of suspension particle sizes; (vi) digital image analysis, 54 used for characterization of floc size distribution and determination of sludge floc structure; and (vii) sodium dodecylsulfate–polyacrylamide gel electrophoresis, 55 used for the size‐based separation and analysis of proteins in biological systems.…”