Biochar Water Treatment for Control of Organic Micropollutants with UVA Surrogate Monitoring

Abstract

Biochar adsorbent can be produced in low-resource settings using local materials and simple pyrolysis technology, and it has shown promise for uptake of micropollutants (MPs) such as pesticides, pharmaceuticals, industrial compounds, and chemicals released from consumer goods present in water at ng/L to lg/L levels. Accordingly, the use of biochar in water treatment applications where granular activated carbon (GAC) is economically or logistically infeasible is gaining interest. Monitoring treatment systems for individual MPs require laboratory analytical techniques that are typically cost-prohibitive and impractical for low-resource settings. Therefore, identification of surrogate parameters(s) for adsorbent bed life that can be measured inexpensively and in the field is a high priority. Background dissolved organic matter (DOM) is ubiquitous in natural and anthropogenic waters at concentrations typically 1,000 to 100,000 that of MPs. Some constituents of DOM foul the adsorbent and reduce bed life for removal of target contaminants. Aromatic DOM foulants absorb ultraviolet light at a wavelength of 254 nm (UVA 254 ). Because DOM fouling directly affects MP adsorption capacity and DOM is a bulk water parameter that can be quantified using relatively inexpensive and portable instruments, it could be exploited as a surrogate for monitoring biochar adsorber bed life under field conditions. The objective of this study was to quantify removal of MPs from waters containing different types and concentrations of background DOM (surface water, wastewater, dump leachate) and thus exhibiting different UVA 254 breakthrough profiles in bench-scale column experiments. Breakthrough profiles of weakly to moderately adsorbing MPs, including herbicides, pharmaceuticals and personal care products, and perfluoroalkyl acids, were collected using biochars generated under different pyrolysis conditions and a commercial GAC as a performance benchmark. Optimal conditions for biochar water treatment include using biochar produced from wood at ‡850°C under slightly aerobic conditions, empty bed contact times of ‡30 min, and upstream treatment processes to reduce DOM. Relative UVA 254 breakthrough (C/C 0 ) up to 0.6-0.9 corresponded to ‡90% MP removal for most MP-water combinations studied.

Integrated Water Resource Management: Rethinking the Contribution of Rainwater Harvesting

“…As cities continually grew, more water was needed and distant water sources were sought and large-scale infrastructures were built [3,5]. Local water sources, including rainwater, were progressively abandoned and scientifically justified to the extent that today, there are efforts to pipe distant waters for centralized water supply in scattered small communities (non-densely populated) [14][15][16]. It is in this effort that decentralized safe water management arose as a novelty, mostly using so-called low-technology solutions.…”

“…However, while special skills are required to transform all kinds of energetic raw materials (e.g., coal, sun, water) to electricity, water is available everywhere and sometimes already of drinking quality [33,39]. Moreover, affordable safe drinking water technologies (e.g., filtration on biochar and metallic iron) have been developed and used for decades [12,[14][15][16]40,41]. Interested readers are referred to Kearns et al [14,16] or Yang et al [15], who give an excellent overview on the state-ofthe-art knowledge on treating natural water using biochar and metallic iron, respectively.…”

“…The present communication is focused on rainwater harvesting (RWH). It is considered that by using available water treatment technologies, and adsorption in particular, water and wastewater can be effectively treated everywhere and in an affordable decentralized manner [11][12][13][14][15][16]. Such affordable technologies for safe drinking water provision include filtration on beds filled with biochar [14,15] and metallic iron [16].…”

“…It is considered that by using available water treatment technologies, and adsorption in particular, water and wastewater can be effectively treated everywhere and in an affordable decentralized manner [11][12][13][14][15][16]. Such affordable technologies for safe drinking water provision include filtration on beds filled with biochar [14,15] and metallic iron [16]. This implies that RWH should be regarded as a stand-alone technology for water supply, including safe drinking water provision.…”

Global Environmental Engineering for and with Historically Marginalized Communities

“…Kearns et al ( 2021 ) examined strategies for improving the efficacy of biochar adsorbents to remove organic chemical pollutants from water. They devised simple measurements that would make it easy to quantify the treatment capacity of biochar by measuring dissolved organic matter using ultraviolet light detection.…”