Influence of Carbon Agglomerate Formation on Micropollutants Removal in Combined PAC-Membrane Filtration Processes for Advanced Wastewater Treatment

Grit Hoffmann,Matthias Martschin,Stefan Panglisch,Ivana Ivančev-Tumbas,Karthik Rathinam

doi:10.3390/w13243578

Grit Hoffmann, Matthias Martschin + Show 3 more

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https://doi.org/10.3390/w13243578

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Abstract

Micropollutants (MPs) are ubiquitous in wastewater and are not effectively removed by the existing conventional treatment processes, resulting in increased environmental pollution. Nowadays, dosing of powdered activated carbon (PAC) prior to membrane filtration has emerged as an advanced wastewater treatment method for MPs removal. This study investigated the carbon agglomerate formation in the PAC stock suspension and its influence on MPs removal in PAC-capillary membrane filtration processes at both lab- and pilot-scale levels. Both lab- and pilot-scale membrane filtration results revealed that MPs removal efficiency is affected with the increase of PAC concentration in the stock suspension. For example, one of the investigated pilot tests showed a significantly reduced removal of good adsorbable MPs (from 57 to 17%) when stock suspension concentration was increased from 0.2 to 20 g/L. It is assumed that PAC agglomerates led to a slower adsorption kinetic and an inhomogeneous distribution of PAC in the membrane system. Maintaining PAC concentration in the stock suspension as low as possible (below 0.2 g/L for investigated PAC) certainly would help to avoid agglomeration problems and enhance the overall performance of the processes.

Highlights

X-ray contrast media, the commeasured three media, the complexing agent benzotriazole and the sweetener acesulfame are subject to strong fluctuations in the influent and, in the effluent of the wastewater treatment plant
The measured pharmaceuticals, on the other hand, show smaller deviations, since these are presumably always administered to patients in the catchment area of the wastewater treatment plant in plexing agent benzotriazole and the sweetener acesulfame are subject to strong fluctuations in the influent and, in the effluent of the wastewater treatment plant
Results of pilot scale in OUT/IN mode investigations are shown in Figure 9 and confirm that the concentration of the powdered activated carbon (PAC) stock suspension significantly affect the MPs removal

Summary

Introduction

The term “micropollutants” (MPs) is increasingly appearing in the scientific literature in the field of advanced wastewater treatment. This is due to their ecotoxicity and the increased stress that MPs such as pharmaceuticals, flame retardants, biocides and other industrial chemicals exerted on the aquatic environment [1], and because they cannot be adequately eliminated by conventional treatment processes [2]. Urban wastewater treatment plants (WWTPs) have turned out to be one of the primary point sources for MPs followed by hospitals and animal husbandry, and it has been found out that the concentration levels of several MPs in the aquatic ecosystems were in the range known to cause acute and chronic toxicity [3]. Existing conventional secondary treatment processes are incapable of removing some of MPs that are found already in wastewater [4], 4.0/)

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