Blackburn Emma A J, Dickson-Anderson Sarah E, Anderson William B, Emelko Monica B
Water Science, Technology & Policy Group, Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
Department of Civil Engineering, McMaster University, Hamilton, Ontario L8S 4L8, Canada.
ACS ES T Water. 2023 Feb 24;3(3):639-649. doi: 10.1021/acsestwater.2c00209. eCollection 2023 Mar 10.
Elevated/altered levels of dissolved organic matter (DOM) in water can be challenging to treat after wildfire. Biologically mediated treatment removes some DOM; here, its ability to remove elevated/altered postfire dissolved organic carbon (DOC) resulting from wildfire ash was investigated for the first time. Treatment of wildfire ash-amended (low, moderate, high) source waters by bench-scale biofilters was evaluated in duplicate. Turbidity and DOC were typically well-removed (effluent turbidity ≤0.3 NTU; average DOC removal ∼20%) in all biofilters during periods of stable source water quality. Daily DOC removal across all biofilters (ash-amended and controls) was generally consistent, suggesting that (i) the biofilter DOC biodegradation capacity was not deleteriously impacted by the ash and (ii) the biofilters buffered the ash-associated increases in water extractable organic matter. DOM fractionation indicates this was because the biodegradable low molecular weight neutral fractions of DOM, which increased with ash addition, were reduced by biofiltration while humic substances were largely recalcitrant. Thus, biological filtration was resilient to wildfire ash-associated DOM threats to drinking water treatment, but operational resilience may be compromised if the balance between readily removed and recalcitrant fractions of DOM change, as was observed during brief periods herein.
野火过后，水中溶解有机物（DOM）含量升高或发生变化，其处理颇具挑战性。生物介导处理可去除部分DOM；本文首次研究了其去除因野火灰导致的火灾后溶解有机碳（DOC）含量升高或变化的能力。采用小型生物滤池对添加了野火灰（低、中、高剂量）的原水进行处理，并重复评估两次。在原水水质稳定期间，所有生物滤池的浊度和DOC通常都能得到良好去除（出水浊度≤0.3 NTU；平均DOC去除率约为20%）。所有生物滤池（添加灰分的和对照的）的每日DOC去除情况总体一致，这表明：（i）生物滤池对DOC的生物降解能力未受到灰分的不利影响；（ii）生物滤池缓冲了与灰分相关的可水提取有机物的增加。DOM分级表明，这是因为随着灰分添加而增加的DOM中可生物降解的低分子量中性组分通过生物过滤减少了，而腐殖质在很大程度上具有顽固性。因此，生物过滤对野火灰相关的DOM对饮用水处理的威胁具有弹性，但如果DOM中易去除组分和顽固性组分之间的平衡发生变化（如本文在此期间短暂观察到的情况），运营弹性可能会受到影响。
