A bench-scale assessment of enhanced coagulation-filtration for greywater in decentralized system

Frederick Akpomie; Andrea Szabolcsik-Izbéki; Ildikó Bodnar

doi:10.1016/j.rineng.2025.107639

A bench-scale assessment of enhanced coagulation-filtration for greywater in decentralized system

Frederick Akpomie, Andrea Szabolcsik-Izbéki, Ildikó Bodnar

Belfast School of Architecture & the Be

University of Debrecen

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Abstract

This study evaluates the effectiveness of an enhanced coagulation-filtration (CF) process with post-filtration for treating bathroom greywater (BGW) for non-potable reuse applications. A bench-scale experiment assessed two cost-effective inorganic coagulants, ferric chloride (FeCl₃) and hydrated lime (Ca(OH)₂), as well as their combination, using synthetic bathroom greywater (SBGW) to determine optimal treatment conditions. The CF process, with an optimal combined concentration of FeCl₃ at 250 mgL-1 and Ca(OH)₂ at 148 mgL-1 achieved an ideal zeta potential range of -5 mV to 5 mV for SBGW, resulting in superior impurities removal. Jar tests under varying conditions (mixing speed, contact time, and sedimentation) confirmed these findings, and optimized conditions were validated with real bathroom greywater (RBGW) samples, exhibiting slight variations due to BGW quality differences. The FeCl₃ dosage was adjusted (220-250 mgL-1), while the Ca(OH)2 dose was kept constant (148 mgL-1) for all RBGWs. The tested enhanced CF process demonstrated high removal efficiencies for turbidity (99±0.5%), chemical oxygen demand (COD) (96±3.4%), biochemical oxygen demand (BOD5) (98±1.3%), and anionic detergents (99±0.5%) values of BGW samples, as well as reducing the number of colonies for Escherichia coli (99%), and Coliforms/Total Count TTC (99%), meeting EU Regulation 2020/741 requirements for water reuse in irrigation. Statistical analysis supports the novelty of enhanced CF, proving its superior effectiveness compared to single ferric chloride coagulation method, making it a promising decentralized greywater treatment solution for European countries.

Original language	English
Article number	107639
Pages (from-to)	1-15
Number of pages	15
Journal	Results in Engineering
Volume	28
Early online date	13 Oct 2025
DOIs	https://doi.org/10.1016/j.rineng.2025.107639
Publication status	Published (in print/issue) - 30 Dec 2025

Bibliographical note

Data Access Statement

All data generated or analyzed during this study are included in this published article.
Data will be made available on request.

Keywords

Enhanced coagulation-flocculation
Greywater treatment
Irrigation
Lime aided ferric chloride
Water reuse

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1016/j.rineng.2025.107639Licence: CC BY

1-s2.0-S2590123025036928-mainFinal published version, 3.94 MBLicence: CC BY

Cite this

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title = "A bench-scale assessment of enhanced coagulation-filtration for greywater in decentralized system",

abstract = "This study evaluates the effectiveness of an enhanced coagulation-filtration (CF) process with post-filtration for treating bathroom greywater (BGW) for non-potable reuse applications. A bench-scale experiment assessed two cost-effective inorganic coagulants, ferric chloride (FeCl₃) and hydrated lime (Ca(OH)₂), as well as their combination, using synthetic bathroom greywater (SBGW) to determine optimal treatment conditions. The CF process, with an optimal combined concentration of FeCl₃ at 250 mgL-1 and Ca(OH)₂ at 148 mgL-1 achieved an ideal zeta potential range of -5 mV to 5 mV for SBGW, resulting in superior impurities removal. Jar tests under varying conditions (mixing speed, contact time, and sedimentation) confirmed these findings, and optimized conditions were validated with real bathroom greywater (RBGW) samples, exhibiting slight variations due to BGW quality differences. The FeCl₃ dosage was adjusted (220-250 mgL-1), while the Ca(OH)2 dose was kept constant (148 mgL-1) for all RBGWs. The tested enhanced CF process demonstrated high removal efficiencies for turbidity (99±0.5\%), chemical oxygen demand (COD) (96±3.4\%), biochemical oxygen demand (BOD5) (98±1.3\%), and anionic detergents (99±0.5\%) values of BGW samples, as well as reducing the number of colonies for Escherichia coli (99\%), and Coliforms/Total Count TTC (99\%), meeting EU Regulation 2020/741 requirements for water reuse in irrigation. Statistical analysis supports the novelty of enhanced CF, proving its superior effectiveness compared to single ferric chloride coagulation method, making it a promising decentralized greywater treatment solution for European countries.",

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author = "Frederick Akpomie and Andrea Szabolcsik-Izb{\'e}ki and Ildik{\'o} Bodnar",

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AU - Bodnar, Ildikó

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Y1 - 2025/12/30

N2 - This study evaluates the effectiveness of an enhanced coagulation-filtration (CF) process with post-filtration for treating bathroom greywater (BGW) for non-potable reuse applications. A bench-scale experiment assessed two cost-effective inorganic coagulants, ferric chloride (FeCl₃) and hydrated lime (Ca(OH)₂), as well as their combination, using synthetic bathroom greywater (SBGW) to determine optimal treatment conditions. The CF process, with an optimal combined concentration of FeCl₃ at 250 mgL-1 and Ca(OH)₂ at 148 mgL-1 achieved an ideal zeta potential range of -5 mV to 5 mV for SBGW, resulting in superior impurities removal. Jar tests under varying conditions (mixing speed, contact time, and sedimentation) confirmed these findings, and optimized conditions were validated with real bathroom greywater (RBGW) samples, exhibiting slight variations due to BGW quality differences. The FeCl₃ dosage was adjusted (220-250 mgL-1), while the Ca(OH)2 dose was kept constant (148 mgL-1) for all RBGWs. The tested enhanced CF process demonstrated high removal efficiencies for turbidity (99±0.5%), chemical oxygen demand (COD) (96±3.4%), biochemical oxygen demand (BOD5) (98±1.3%), and anionic detergents (99±0.5%) values of BGW samples, as well as reducing the number of colonies for Escherichia coli (99%), and Coliforms/Total Count TTC (99%), meeting EU Regulation 2020/741 requirements for water reuse in irrigation. Statistical analysis supports the novelty of enhanced CF, proving its superior effectiveness compared to single ferric chloride coagulation method, making it a promising decentralized greywater treatment solution for European countries.

AB - This study evaluates the effectiveness of an enhanced coagulation-filtration (CF) process with post-filtration for treating bathroom greywater (BGW) for non-potable reuse applications. A bench-scale experiment assessed two cost-effective inorganic coagulants, ferric chloride (FeCl₃) and hydrated lime (Ca(OH)₂), as well as their combination, using synthetic bathroom greywater (SBGW) to determine optimal treatment conditions. The CF process, with an optimal combined concentration of FeCl₃ at 250 mgL-1 and Ca(OH)₂ at 148 mgL-1 achieved an ideal zeta potential range of -5 mV to 5 mV for SBGW, resulting in superior impurities removal. Jar tests under varying conditions (mixing speed, contact time, and sedimentation) confirmed these findings, and optimized conditions were validated with real bathroom greywater (RBGW) samples, exhibiting slight variations due to BGW quality differences. The FeCl₃ dosage was adjusted (220-250 mgL-1), while the Ca(OH)2 dose was kept constant (148 mgL-1) for all RBGWs. The tested enhanced CF process demonstrated high removal efficiencies for turbidity (99±0.5%), chemical oxygen demand (COD) (96±3.4%), biochemical oxygen demand (BOD5) (98±1.3%), and anionic detergents (99±0.5%) values of BGW samples, as well as reducing the number of colonies for Escherichia coli (99%), and Coliforms/Total Count TTC (99%), meeting EU Regulation 2020/741 requirements for water reuse in irrigation. Statistical analysis supports the novelty of enhanced CF, proving its superior effectiveness compared to single ferric chloride coagulation method, making it a promising decentralized greywater treatment solution for European countries.

KW - Enhanced coagulation-flocculation

KW - Greywater treatment

KW - Irrigation

KW - Lime aided ferric chloride

KW - Water reuse

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DO - 10.1016/j.rineng.2025.107639

M3 - Article

SN - 2590-1230

VL - 28

SP - 1

EP - 15

JO - Results in Engineering

JF - Results in Engineering

M1 - 107639

ER -

A bench-scale assessment of enhanced coagulation-filtration for greywater in decentralized system

Abstract

Bibliographical note

Data Access Statement

Keywords

UN SDGs

Access to Document

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