Synergistic Recapturing of External and Internal Phosphorus for In Situ Eutrophication Mitigation

Abstract

In eutrophication management, many phosphorus (P) adsorbents have been developed to capture P at the laboratory scale. Existing P removal practice in freshwaters is limited due to the lack of assessment of the possibility and feasibility of controlling P level towards a very low level (such as 10 μg/L) in order to prevent the harmful algal blooms. In this study, a combined external and internal P control approach was evaluated in a simulated pilot-scale river–lake system. In total, 0.8 m3 of simulated river water was continuously supplied to be initially treated by a P adsorption column filled with a granulated lanthanum/aluminium hydroxide composite (LAH) P adsorbent. At the outlet of the column (i.e., inlet of the receiving tanks), the P concentration decreased from 230 to 20 µg/L at a flow rate of 57 L/day with a hydraulic loading rate of 45 m/day. In the receiving tanks (simulated lake), 90 g of the same adsorbent material was added into 1 m3 water for further in situ treatment, which reduced and maintained the P concentration at 10 µg/L for 5 days. The synergy of external and internal P recapture was demonstrated to be an effective strategy for maintaining the P concentration below 10 µg/L under low levels of P water input. The P removal was not significantly affected by temperature (5–30 °C), and the treatment did not substantially alter the water pH. Along with the superior P adsorption capacity, less usage of LAH could lead to reduced cost for potation eutrophication control compared with other widely used P adsorbents.

Exploring a multifunctional geoengineering material for eutrophication remediation: Simultaneously control internal nutrient load and tackle hypoxia

“…Capping treatment in lakes, by the spraying of natural materials, such as sand, clay, gravel and rock, could form a physical barrier on surficial sediments and effectively prevent nutrients from entering into the water. Synthetic materials, such as lanthanummodified bentonite (Phoslock™) and aluminium-modified zeolite (Aqual-P), have been developed to augment the functionality from existing as a purely physical barrier to additionally acting as an active P adsorbent [13,14]. Some synthetic materials have also been used to further adsorb both P and N released from sediments [15].…”

Lake and River Restoration: Method, Evaluation and Management

“…To study the application of an adsorbent in natural waters in order to achieve very low levels of P (10 µg L −1 ) for potential eutrophication control, Pan et al [21] evaluated a combined external and internal P control approach in a simulated pilot-scale river-lake system. Under such a strategy, a granulated lanthanum/aluminium hydroxide composite (LAH) adsorbent was demonstrated to be an effective material for maintaining the P concentration below 10 µg L −1 under low levels of additional P input.…”

Utilization of coal fly ash waste for effective recapture of phosphorus from waters

“…The dosing of aluminium-or iron-based salts is a common approach in sewage treatment plants in order to secure an ultra-low level effluent with respect to P (Nakarmi et al, 2020;White et al, 2021). However, as P is a non-renewable resource, not only removal, but also recovery and recapture of the discharged P is strategically important for environmental sustainability (Pan et al, 2020). Therefore, treatment by adsorption is often suggested, due to the multiple advantages of low carbon footprint, minimal waste generation and the further option for P recovery (Kang et al, 2003).…”