Grantee Research Project Results

Final Report: Optimized biochar/hydrochar for disinfection byproduct removal in water

EPA Grant Number: SU840574
Title: Optimized biochar/hydrochar for disinfection byproduct removal in water
Investigators: Marti, Erica , Moon, Jaeyun , Abduraheem, Ismail , Ung-Watson, Kers , Kim, Dong-Yong , Khatamgooya, Ahmadreza , Kalhorizadeh, Tina , Mussio-Marquez, Ashley , Rouhani, Donna , Hatfield, Jesse , Rhoimer-Agdeppa, Rexxor , Nelson, Scarlet
Institution: University of Nevada - Las Vegas
EPA Project Officer: Spatz, Kyle
Phase: I
Project Period: September 1, 2023 through August 31, 2024 (Extended to February 28, 2025)
Project Amount: $24,994
RFA: 19th Annual P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet Request for Applications (RFA) (2022) RFA Text |  Recipients Lists
Research Category: P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources

Objective:

The proposed project is the synthesis, characterization, and optimization of biochar and hydrochar adsorbents produced from agricultural waste biomass. The adsorbents would ultimately be used as a drinking water filter media for disinfection byproduct removal in US households for standard use or during emergency situations or temporary water treatment, which disproportionately affect vulnerable populations. Especially in emergency situations and temporary water treatment systems, disinfection byproducts may exceed the regulated concentrations for drinking water. Removal of disinfection byproducts through a simple and low-cost process, like adsorption, is important because disinfection byproducts are harmful to human health as they are linked to cancer. The research project has three main goals or tasks.

• Task 1: Synthesize and characterize biochar and hydrochar adsorbents from agricultural waste biomass. 
• Task 2: Enhancement of the adsorption properties of BC and HC through modification with physical (i.e., steam) or chemical (i.e., acid, base, thiol) approaches.
• Task 3: Assessment of BC and HC adsorption capacity for removal of regulated and unregulated disinfection byproducts in drinking water. Adsorption batch tests

The project relates to P3 in the following ways: (1) improved drinking water, especially for vulnerable populations, to improve people's health; (2) development of a low- cost adsorbent that any person could afford to use; and (3) use of agricultural waste that would otherwise be discarded and the replacement of fossil fuel derived adsorbents that exacerbate climate change.

Summary/Accomplishments (Outputs/Outcomes):

For task 1, we successfully prepared and characterized biochar and hydrochar under varying conditions. Walnut biochar was created at three temperatures (700, 800 and 900 °C), and 900 °C was selected due to higher surface area and greater hydrophilicity on the biochar surface. Walnut hydrochar was created at three temperatures (200, 230, 250 °C) and at three reaction times (2, 3, 4 hours). 250 °C hydrochar heated for 4 hours was selected due to higher surface area and greater presence of carbon-oxygen bonds. For task 2, we successfully used chemical modification to prepare two biochars: base intercalation with acid exfoliation (BIAE) and sulfur-doped. Characterization showed substantially higher surface area for BIAE modified biochar, as well as sulfur-doped biochar. The bulk of the work was completed under task 3 with adsorption testing and a desorption study. BIAE modified biochar outperformed the unmodified biochar and hydrochar by removing most disinfection byproducts (40-100% removal). Although characterization results suggest that the sulfur-doped biochar would successfully adsorb disinfection byproducts, tests could not be completed. There was not a sufficient supply of biochar available for experiments because the furnace used for biochar production stopped working and could not be repaired. Lastly, adsorbents were tested for desorption of organics from 10 minutes to 7 days. Walnut biochar at 900 °C showed no desorption while  Hydrochar had the least promising result with an increase of 6-7 mg/L organic carbon after 7 days. BIAE modified biochar showed an increase of 2-3 mg/L organic carbon after 7 days. However, the desorption test was repeated after BIAE modified biochar was rinsed thoroughly with deionized water. In this case, there was no significant increase in organic carbon. Thus, the adsorbent should not release organics if it were used in a water filter. 

Conclusions:

Ultimately, the walnut biochar modified through base intercalation with acid exfoliation (BIAE) was superior for adsorption of disinfection byproducts as compared to unmodified walnut biochar or hydrochar. Hydrochar exhibited poor removal for all DBPs and unmodified biochar removed less than half of the tested DBPs. On the other hand, BIAE modified biochar effectively removed most DBPs above 50%. This is presumed to be attributed to chemical modification that increases the surface area. In addition, BIAE modified biochar did not release organic carbon into the water, indicating a low potential to affect water quality as a filtration adsorbent. We met the dissemination objectives through six poster presentations with involvement from multiple graduate and undergraduate students. A manuscript for a peer- reviewed journal is in progress and is expected to be finished during 2025.

Journal Articles:

No journal articles submitted with this report: View all 3 publications for this project

Supplemental Keywords:

Water purification, drinking water, agricultural waste minimization, biochar, hydrochar, adsorption, disinfection byproducts, trihalomethanes, haloacetic acids, haloacetonitriles, nitrosamines, environmental engineering, materials synthesis

Progress and Final Reports:

Original Abstract

2024 Progress Report