BIOCHAR IN AN AIR DUCT UNIT FOR THE FILTRATION OF HAZE PARTICLES GENERATED FROM FOREST FIRES

Abstract

Despite tightening measures in recent times, haze remains a relatively common occurrence with such a significant impact such that it cannot simply be ignored. Though measures such as increased bilateral cooperation, assistance and enforcement has helped to mitigate the frequency of haze in recent years, it cannot simply be ignored every time it strikes the country. Biochar is a carbon-rich material with vast uses in agriculture that has potential for use in air filtration due to its unique sorption capabilities. Past studies have demonstrated its CO2-sorping capacities, however, due to the unique physical and chemical makeup of biochar, there is potential for it to be used as an instrument supplementary to traditional air handling unit filters. This study looks to investigate the Particulate Matter-sorption capabilities of biochar and its potential use in a built environment. This is done by reproducing the occurrence of haze in an air chamber that simulates the air handling system in a building. Biochar is coated onto a finned filter and is placed in the middle air chamber, which is also fitted with a fan that induces air flow through it. The fins of the filter can be rotated to manipulate the opening angle and space in order to investigate the 2 topics of interest – the resultant air velocity through the air chamber system, and the percentage of Particulate Matter (PM) that has been successfully filtrated.

By placing aerosol spectrometers before and after the filters, the difference in the percentage reduction of PM through the different opening angles of the finned filters can be seen, and generally, the smaller opening angle resulted in greater filtration of PM. The porous nature of biochar is theorized to provide it with such PM-filtration capabilities, and results showed that there is an average filtration of around 75% across PM10, PM2.5 and PM1.0 particles for different opening angles. By placing a flowmeter at different points of the air chamber and taking air-velocity readings, the resultant air velocities of the different opening angles were also tested. Analyses showed that a smaller opening angle resulted in a smaller air flow through the system. There as an air velocity reduction of 35.7%, 38.9% and 13.9% for opening angles of 0, 45 and 90 degrees respectively.

The results of this study proved to be supportive of the hypothesis that biochar has PM-filtration capabilities in an air duct system, however, for this topic of interest to have greater weight and relevance in real life application, there has to be further study in the durability of the filter system, its effectiveness in a real haze episode, as well as the actual cost-benefits with regards to balancing the filter effectiveness and cost.