Grantee Research Project Results
2022 Progress Report: Novel Mineral-Hydrogel Composites for Effective Nutrient Removal to Manage Harmful Algal Blooms
EPA Grant Number: R840084Title: Novel Mineral-Hydrogel Composites for Effective Nutrient Removal to Manage Harmful Algal Blooms
Investigators: Jun, Young-Shin , Tang, Yinjie
Institution: Washington University in St. Louis
EPA Project Officer: Ludwig-Monty, Sarah
Project Period: September 1, 2020 through August 31, 2023 (Extended to August 31, 2024)
Project Period Covered by this Report: September 1, 2021 through August 31,2022
Project Amount: $800,486
RFA: Approaches to Reduce Nutrient Loadings for Harmful Algal Blooms Management (2020) RFA Text | Recipients Lists
Research Category: Harmful Algal Blooms , Water
Objective:
Harmful algal blooms (HABs), which can produce cyanobacterial toxins, degrade water quality, threaten public health, harm ecosytems, and impact the economic output of industries such as fisheries and tourism. One major contribution to HABS is nutrient pollution from anthropogenic activities. To reduce nutrient pollution, we develop novel mineral-hydrogel composites to effectively remove phosphorus and nitrogen, and we determine their effects on algal growth. Calcium alginate hydrogels seeded with calcium phosphate (CaP), wollastonite (CaSiO3), or struvite (MgNH4PO4) are synthesized for effective phosphate (P) and ammonium (N) removal and recovery. We further demonstrate the mineral-hydrogel composites’ effectiveness for HAB mitigation in both benchtop cyanobacteria culture and scaled up photobioreactor growth experiments.
Progress Summary:
Based on the synergistic combination of fast-dissolving calcium silicate hydrate (CSH) and CaP mineral seeds, we created and tested mineral-hydrogel composites that combine wollastonite and CaP. We determined that wollastonite’s slower dissolution limits the homogeneous nucleation of CaP particles that may be mobile and releasable to the environment. Wollastonite’s use resulted in excellent heterogeneous P removal performance (from 6.2 mg-P/L to 0.067 mg-P/L in 72 hours) inside the mineral-hydrogel composites and improved their overall P-removal capacity. The demonstrated P-removal performance of the mineral-hydrogel composites will ensure effectively lower P concentrations to mitigate HABs. Meanwhile, the P captured inside the mineral-hydrogel composites can be reused as a slow-release P source/fertilizer for supplying photo-biorefineries.
A conditioning treatment to increase the operating lifespan of the CaP + wollastonite mineral-hydrogel composites was demonstrated. The conditioning treatment was able to restore P-uptake ability after one cycle, supporting multiple cycle reuse of the mineral-hydrogel composites. Furthermore, a salt pretreatment before drying the composites improved their reswelling ability. These advances improve the scalability and applicability of the mineral-hydrogel composites.
We demonstrated the mineral-hydrogel composites’ ability to function when different environmentally abundant cations, anions, dissolved organic matter, or high salt concentrations are present. Furthermore, we applied the mineral-hydrogel composites to complex wastewaters to effectively reduce P. Afterwards, the growth of algal species (including fast growing Synechococcus elongatus, toxin-producing Microcystis aeruginosa, and algal natural consortia from a local pond) was reduced, showing that the mineral-hydrogel composites can restrict algal growth through nutrient removal from complex wastewater matrices.
Furthermore, we found that recovered P and N from hydrogel composites can be released as fertilizers, achieving sustainable nutrient recovery and reuse.
Finally, we have built a multi-substrate and multi-species kinetic model to simulate algal growth and consortia interactions under N- and P-limited conditions. The model can also predict algal growth and toxin productions under different HAB treatment conditions.
Future Activities:
We will further develop the mineral-hydrogel composites’ ability to recover N and P simultaneously from aqueous solutions. We will investigate the effect of N concentrations on algal growths and microcystin (toxin) production. Then, we will systematically evaluate and model the nutrient removal ability of the mineral-hydrogel composites, to support their scaled up application in complex aqueous matrices. Throughout this engineering and scientific process, different algal species will be cultured at bench to large-scale to determine the effect of the mineral-hydrogel composites on algal growth under different environmental and water chemistry conditions. Then, this knowledge will be captured in algal growth models.
Journal Articles:
No journal articles submitted with this report: View all 19 publications for this projectSupplemental Keywords:
Harmful Algal Blooms, Hydrogels, Calcium Phosphate, Nitrogen, Composites, Phosphate, Calcium silicate hydrate, Nitrate, CyanotoxinRelevant Websites:
Dr. Young-Shin Jun’s research group website Exit , Dr. Yinjie Tang’s research group website Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.