An Improved Configuration of Vertical-Flow Mesh Tube Filters for Seawater Pretreatment: Performance, Cleaning, and Energy Consumption

Dong-Ho Kim,Chulmin Lee,Thanh-Tin Nguyen,Changkyoo Choi,Sang-Jun Ahn,Rusnang Syamsul Adha,In S Kim,Hee-Jong Son

doi:10.3390/w12102804

Dong-Ho Kim, Chulmin Lee + Show 6 more

Open Access

https://doi.org/10.3390/w12102804

Copy DOI

Abstract

Roughing filters are types of porous media filter used in pretreatment systems where the raw water contains a large amount of suspended particles (SPs) and organic matter. Mesh tube filtration (MTF) media are roughing-filter media composed of low-density polyethylene used for SP removal during wastewater treatment. In this study, we present an improved MTF design—a porous filter bed (PFB), which exhibits superior SP removal performance compared to conventional MTF media. We then compare the applicability of MTF and PFB to both the primary pretreatment process for seawater desalination and the water reuse process. In bench-scale SP removal experiments, PFB shows removal rates of 46.7%, 68.0%, 67.6%, and 68.4% at hydraulic retention times of 15, 20, 30, and 60 min, respectively, which are better than those of MTF. The specific energy consumption (SEC) of batch dissolved air flotation (DAF) was known to range from 0.035 to 0.047 kWh/m3, whereas the SEC calculated for pilot-scale MTF and PFB is 0.027 kWh/m3 and minimum energy for influent supply, respectively. This suggests that PFB can compete with DAF as a primary pretreatment process. MTF predominantly removes SPs by sedimentation, whereas SP removal in PFB typically occurs via deposition of SPs on the mesh tube media.

Highlights

Seawater contains a variety of dissolved and colloidal foulants and natural organic matter (NOM) that are difficult and costly to remove [1,2]
In the floc of suspended particles (SPs) deposited on the horizontal-flow roughing filter media, the particles sink to the bottom of the filter bed under the influence of gravity after floc aggregation; it is difficult to use a horizontal-flow roughing filter in coarse media filters such as Mesh tube filtration (MTF) beds
The current MTF structure has not been verified as an optimized mesh tube filter bed structure, and various types of filter bed designs have been devised to improve the performance of the filter bed

Summary

Introduction

Seawater contains a variety of dissolved and colloidal foulants (iron, manganese, silica, etc.) and natural organic matter (NOM) that are difficult and costly to remove [1,2]. Pretreatment processes are essential to remove any suspended particles (SPs) in seawater and protect the membrane systems of seawater desalination plants; such processes include microfiltration (MF), ultra-filtration (UF) and reverse osmosis (RO) [3]. Porous media filtration is a water treatment process that has long been used to effectively remove SPs from water [4,5]. Filtration methods include slow sand filtration and roughing filtration [4]. Slow sand filters effectively remove SPs and do not require chemicals or electrical. Water 2020, 12, 2804 energy for operation; these filters need to lower the turbidity of the influent to operate efficiently. Under conditions of high microbial activity in summer and when the raw water is turbid, filter blockage due to bio-clogging will occur more quickly, necessitating pretreatment [6]

Objectives

Methods

Results

Conclusion