Sustained Phosphorus Removal by Calcareous Materials in Long-Term (Two Years) Column Experiment

Solvei Mundbjerg Jensen,Carlos Alberto Arias,Frances Helen Blaikie,Helmer Søhoel,Hans Brix

doi:10.3390/w14050682

Solvei Mundbjerg Jensen, Carlos Alberto Arias + Show 3 more

Open Access

https://doi.org/10.3390/w14050682

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Journal: Water	Publication Date: Feb 22, 2022
Citations: 2	License type: CC BY 4.0

Affiliation: Aarhus University, Danish Technological Institute, AgResearch

Abstract

(1) Phosphorus (P) removal has proven difficult in decentralized wastewater treatment systems, and external filters installed with a highly P sorbent material have been proposed to improve the P removal. In particular, calcium (Ca) rich materials have shown promising results. (2) Eight materials (five calcareous materials, one quartz sand, and two Sol–Gel coated calcareous materials) were tested in columns fed with P-spiked tap water for two years. The experiment was operated under four periods with increased P concentration from 3.3 to 21.5 mg P L−1, and with increased surface loading rate from 18 to 227 mm d−1. After termination, the element content was measured in four column height fractions. (3) Initially, all columns removed P effectively and the calcareous materials (CAT, CAT A, and CAT C) maintained an effective removal until termination, while increases in effluent P concentration were detected already after 7 weeks for SAN and after 80–90 weeks for OPO, PHO, CAL, and HYG. The highest P content for materials were measured for the bottom fraction closest to the inlet distribution. For most materials, we observed a good agreement between the maximum sorption capacity (Qmax) and the P content in the bottom fraction; however, a discrepancy was observed for CAL, CAT A, and CAT C. (4) In conclusion, the calcareous materials provided a consistent P removal for all 24 months. Additionally, the Sol–Gel coating had a minimal effect on the P removal capacity contrary to previous findings in batch experiments for the coated materials.

Highlights

IntroductionIntroduction published maps and institutional affilAnthropogenic activities generate wastewater that, if released untreated, cause harmful consequences in receiving waters, e.g., eutrophication and deterioration of aquatic environments due to excessive nutrients
Introduction published maps and institutional affilAnthropogenic activities generate wastewater that, if released untreated, cause harmful consequences in receiving waters, e.g., eutrophication and deterioration of aquatic environments due to excessive nutrients
The calcareous materials showed a consistent P removal in the two years of operation, and all materials were hydraulicly stable throughout the period

Summary

Introduction

Introduction published maps and institutional affilAnthropogenic activities generate wastewater that, if released untreated, cause harmful consequences in receiving waters, e.g., eutrophication and deterioration of aquatic environments due to excessive nutrients. Centralized wastewater treatment solutions are not always feasible to implement, and decentralized solutions have been developed targeting the affected waters closer to the source of pollution [1]. There is a large range of decentralized solutions, with one group being nature-based solutions (NBS), covering a wide span of effective solutions such as Treatment Wetlands (TWs, known as Constructed Wetlands). TWs are human-made wetlands engineered to optimize physical and biochemical processes occurring in natural wetlands to reduce pollutants [2,3]. TWs have gained popularity as they are relatively simple to construct, maintained, and require low external energy input, making them an appropriate technology for decentralized wastewater treatment [4,5].

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