Biochar integrated reactive filtration of wastewater for P removal and recovery, micropollutant catalytic oxidation, and negative CO2e: Process operation and mechanism

• Published in: Water environment research 2023-09, Vol.95 (9), p.n/a
• Main Authors: Yu, Paulo, Baker, Martin C., Crump, Alex R., Vogler, Michael, Strawn, Daniel G., Möller, Gregory
• Format: Article
• Language: English
• Subjects: biochar; Carbon; Carbon footprint; Carbon sequestration; Catalytic oxidation; Charcoal; Climate change; Climate change mitigation; Disinfection; Economic analysis; Ferric oxide; Filtration; Food security; Influents; Iron; Lakes; Life cycle; Life cycle analysis; Life cycle assessment; Life cycles; Micropollutants; Mitigation; Municipal water; nutrient recovery; Nutrient removal; Orthophosphate; Oxidation; Ozonation; Ozone; Ozonization; Phosphorus; Phosphorus removal; pilot‐scale water treatment; Pollutant removal; reactive filtration; Recovery; Removal; Resource recovery; Sand filters; Scale (corrosion); Soil amendment; Technology; Technology assessment; Wastewater; Wastewater treatment; Water consumption; Water quality; Water resources; Water treatment
• ISSN: 1061-4303; 1554-7531
• DOI: 10.1002/wer.10926

Biochar (BC) use in water treatment is a promising approach that can simultaneously help address societal needs of clean water, food security, and climate change mitigation. However, novel BC water treatment technology approaches require operational testing in field pilot‐scale scenarios to advance their technology readiness assessment. Therefore, the objective of this study is to evaluate the system performance of BC integrated into hydrous ferric oxide reactive filtration (Fe‐BC‐RF) with and without catalytic ozonation (CatOx) process in laboratory and field pilot‐scale scenarios. For this investigation, Fe‐BC‐RF and Fe‐CatOx‐BC‐RF pilot‐scale trials were conducted on synthetic lake water variants and at three municipal water resource recovery facilities (WRRFs) at process flows of 0.05 and 0.6 L/s, respectively. Three native and two iron‐modified BCs were used in these studies. The commercially available reactive filtration process (Fe‐RF without BC) had 96%–98% total phosphorus (TP) removal from 0.075‐ and 0.22‐mg/L TP, as orthophosphate process influent in these trials. With BC integration, phosphorus removal yielded 94%–98% with the same process‐influent conditions. In WRRF field pilot‐scale studies, the Fe‐CatOx‐BC‐RF process removed 84%–99% of influent total phosphorus concentrations that varied from 0.12 to 8.1 mg/L. Nutrient analysis on BC showed that the recovered BC used in the pilot‐scale studies had an increase in TP from its native concentration, with the Fe‐amended BC showing better P recovery at 110% than its unmodified state, which was 16%. Lastly, the field WRRF Fe‐CatOx‐BC‐RF process studies showed successful destructive removals at >90% for more than 20 detected micropollutants, thus addressing a critical human health and environmental water quality concern. The research demonstrated that integration of BC into Fe‐CatOx‐RF for micropollutant removal, disinfection, and nutrient recovery is an encouraging tertiary water treatment technology that can address sustainable phosphorus recycling needs and the potential for carbon‐negative operation. Practitioner Points A pilot‐scale hydrous ferric oxide reactive sand filtration process integrating biochar injection typically yields >90% total phosphorus removal to ultralow levels. Biochar, modified with iron, recovers phosphorus from wastewater, creating a P/N nutrient upcycled soil amendment. Addition of ozone to the process stream enables biochar‐iron‐ozone catalytic oxidation demonstrating