Grantee Research Project Results
Optimizing biochar adsorbent production through semi-gasification
EPA Grant Number: SU840404Title: Optimizing biochar adsorbent production through semi-gasification
Investigators: Shimabuku, Kyle
Institution: Gonzaga University
EPA Project Officer: Spatz, Kyle
Phase: I
Project Period: July 1, 2022 through June 30, 2023 (Extended to June 30, 2024)
Project Amount: $24,982
RFA: 18th Annual P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet (2021) RFA Text | Recipients Lists
Research Category: P3 Awards , Water
Description:
Per- and poly-fluoroalkyl substances (PFAS) can pose a health risk to rural, small, and/or disadvantaged communities. For example, elevated PFAS levels have been found in private and municipal wells and community members’ blood in the West Plains of Spokane County, WA. Point-of-use (POU) treatment can empower these communities with the ability to reduce their exposure to PFAS from drinking water. Granular activated carbon (GAC) adsorbers are arguably the most sustainable POU filters widely used to control PFAS and other organic contaminants (OCs). However, it has shortcomings with respect to the P3 approach that could be addressed by biochar, which is an emerging OC adsorbent. For example, GAC is often made from coal using an energy intensive activation process whereas biochar can be a byproduct of energy production by pyrolyzing or gasifying excess biomass (e.g., forestry and agricultural residuals). Biochar could increase disadvantaged communities’ access to POU PFAS treatment as it can be purchased at fraction of the cost of GAC. Todate, however, biochar adsorbents have shown poorer OC (e.g., PFAS) removal efficiencies compared to GAC, which would make it less appealing to end users as it would need to be replaced more frequently than GAC. To ensure biochar is adopted in POU filters to sustainably remove PFASs, it should be designed to achieve PFAS removal efficiencies that rival or exceed that of GAC.
Objective:
We recently showed biochar produced in top-lit drum (TLUD) semi-gasification systems exhibited OC adsorption capacities approaching that of a commercial GAC and 10-times greater than that of biochar produced in a kiln, which most studies use to make biochar for OC treatment. These were promising findings because efficient OC adsorbents were produced even though the TLUDs examined had limited control over production conditions. It is hypothesized, herein, that TLUD production conditions can be optimized to produce biochar with PFAS adsorption efficiencies that rival or exceed that of GAC.
We propose using a modular TLUD, which we used previously to identify optimal conditions to limit combustion emissions, because it allows for production parameters to be fine-tuned that may influence adsorption efficiency (e.g., primary air content and flow rate). Thus, this project will use an innovative, interdisciplinary approach combining water quality and combustion engineering as well as a custom-designed experimental apparatus to design efficient, low-cost, and sustainable biochar adsorbents.
Approach:
This project seeks to develop biochar adsorbents with PFAS removal efficiencies that rival or exceed that of established adsorbents (e.g., GAC) while addressing sustainability issues associated with widely-used POU technologies. Phase I will identify TLUD operational conditions that produce biochar optimized for PFAS adsorption. Around 30 biochars made in the modular TLUD will be evaluated in benchscale batch and column adsorption tests using PFAS contaminated water collected from the West Plains. Phase I will inform in Phase II the design of a high-throughput biochar production system prototype and operational conditions for a project partner’s full-scale semi-gasification system. These biochars will be examined in pilot tests.
For POU PFAS removal technologies to be adopted it is essential that their utility is communicated to end users. We will engage local K-12 schools that have been directly impacted by PFAS contamination with hands-on learning modules on PFAS treatment. They will also be stakeholders in this research as PFAS contaminated groundwater will be collected from such schools and used in experiments performed at GU. The project’s P3 approach, results, and outcomes will also be shared through GU engineering, chemistry, and environmental studies courses; the broader community through GU research symposia and office of sustainability media; and water quality and biochar professional communities through conference presentations and journal publications. Developing biochar adsorbents to support their adoption could be a catalyst for integrated P3 benefits since many aspects of biochar that make it environmentally friendly (e.g., managing excess biomass) also make it affordable. Because TLUDs can be inexpensive systems that use locally available biomass, biochar can be manufactured by rural, remote, and/or disadvantaged communities. Thus, developing biochar adsorbents to efficiently remove PFASs could empower such communities with the ability to improve their health, environment, and economy. Through collaborations between the project team and partners, this project can model how communities can overcome environmental challenges by leveraging partnerships between local universities, public health agencies, environmental nonprofits, and businesses.
Expected Results:
Outputs include (i) identification of optimal production conditions such as peak temperature, primary air flow rate, and inert gas and steam levels; (ii) models that predict biochar adsorbent performance based on its characteristics (e.g., surface area); (iii) specification of biochar POU filter design criteria including empty bed contact times and biochar replacement frequencies; and (iv) hands-on learning modules for K-12 students to explore watershed pollution, climate change, and sustainable engineering solutions following the P3 approach. These outputs will be measured and tracked by the number and quality of peer-reviewed journals, continued interest in the project from project partners and stakeholders, and engagement of GU students in this research.
Anticipated outcomes could include: (i) improving and maintaining the health and wellbeing of end users by increasing access to POU PFAS removal technologies in rural, small, and/or disadvantaged communities; (ii) advancing the economic competitiveness of biochar manufactures in communities impacted by PFAS contamination by specifying production conditions that generate efficient biochar adsorbents for PFASs and other OCs; and (iii) preserving the environment by producing biochar that can be used in various environmental remediation applications while simultaneously valorizing excess biomass, producing energy, and sequestering carbon. These outcomes could be tracked by surveying the extent to which biochar is produced to control PFASs in POU filters and changes in PFAS-levels in human blood.
Supplemental Keywords:
Water purification technologies, resource recovery, organicsProgress and Final Reports:
The 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.