Department of Civil Engineering, University of Minnesota, 500 Pillsbury Dr. SE, Minneapolis, MN 55455-0116, USA.
Water Res. 2010 Feb;44(3):769-80. doi: 10.1016/j.watres.2009.10.018. Epub 2009 Nov 10.
Saint Paul Regional Water Services (SPRWS) in Saint Paul, MN experiences annual taste and odor episodes during the warm summer months. These episodes are attributed primarily to geosmin that is produced by cyanobacteria growing in the chain of lakes used to convey and store the source water pumped from the Mississippi River. Batch experiments, pilot-scale experiments, and model simulations were performed to determine the geosmin removal performance and bed life of a granular activated carbon (GAC) filter-sorber. Using batch adsorption isotherm parameters, the estimated bed life for the GAC filter-sorber ranged from 920 to 1241 days when challenged with a constant concentration of 100 ng/L of geosmin. The estimated bed life obtained using the AdDesignS model and the actual pilot-plant loading history was 594 days. Based on the pilot-scale GAC column data, the actual bed life (>714 days) was much longer than the simulated values because bed life was extended by biological degradation of geosmin. The continuous feeding of high concentrations of geosmin (100-400 ng/L) in the pilot-scale experiments enriched for a robust geosmin-degrading culture that was sustained when the geosmin feed was turned off for 40 days. It is unclear, however, whether a geosmin-degrading culture can be established in a full-scale filter that experiences taste and odor episodes for only 1 or 2 months per year. The results of this research indicate that care must be exercised in the design and interpretation of pilot-scale experiments and model simulations for predicting taste and odor removal in full-scale GAC filter-sorbers. Adsorption and the potential for biological degradation must be considered to estimate GAC bed life for the conditions of intermittent geosmin loading typically experienced by full-scale systems.
圣保罗地区水资源服务（SPRWS）在明尼苏达州圣保罗市每年夏季温暖月份都会经历口感和气味事件。这些事件主要归因于蓝藻产生的土臭素，这些蓝藻在用于输送和储存从密西西比河抽取的水源的湖泊链中生长。进行了批处理实验、中试规模实验和模型模拟，以确定颗粒活性炭（GAC）过滤器-吸附剂的土臭素去除性能和床寿命。使用批量吸附等温线参数，当受到 100ng/L 恒定浓度的土臭素挑战时，GAC 过滤器-吸附剂的估计床寿命范围为 920 至 1241 天。使用 AdDesignS 模型获得的估计床寿命和实际中试工厂加载历史为 594 天。基于中试规模 GAC 柱数据，实际床寿命（>714 天）比模拟值长得多，因为土臭素的生物降解延长了床寿命。在中试规模实验中连续进料高浓度的土臭素（100-400ng/L），富集了一种强大的土臭素降解培养物，当土臭素进料关闭 40 天时，该培养物得以维持。然而，尚不清楚在每年仅经历 1 或 2 个月口感和气味事件的全规模过滤器中是否可以建立土臭素降解培养物。这项研究的结果表明，在设计和解释预测全规模 GAC 过滤器-吸附剂中去除口感和气味的中试规模实验和模型模拟时，必须谨慎行事。必须考虑吸附和生物降解的潜力，以估算在全规模系统通常经历的间歇式土臭素加载条件下的 GAC 床寿命。
