摘要
研究了 2 6种天然黏土矿物凝聚沉降铜绿微囊藻的动力学过程 .在投加量为 0 7g·L- 1时按平衡除藻率和除藻速率将 2 6种黏土分成 3类 .第 1类矿物 (滑石、三氧化二铁、海泡石、四氧化三铁、高岭土等 )的 8h平衡除藻率大于 90 % ,去除 5 0 %藻细胞所需时间t50 <30min ,去除 80 %藻细胞所需时间t80 <2 5h .第 2类黏土 (轻质页岩、陶土、凹凸棒、累托土、伊利土等 7种 )的 8h平衡除藻率为 5 0 %～ 80 % ,t50 <2 5h ,t80 >5h .第 3类黏土(铁矾土 ,云母 ,沸石、浮石、硅藻土、高钾长石和石英等 1 4种 )的 8h平衡除藻率低于 5 0 % ,t50 8h .当投加量逐步降低到 0 2～ 0 1 g·L- 1时 ,2 5种黏土矿物的 8h平衡除藻率均降到 6 0 %以下 ,只有第 1类黏土中的海泡石仍接近 90 % .与黏土相比 ,在 0 0 2～ 0 2 g·L- 1投加量下单独使用聚合氯化铝 (PAC)时的 8h平衡除藻率均低于4 0 % .进一步对海泡石进行电性改性后发现 ,虽然黏土颗粒表面电位的提高 (pH 7 4时 ,Zeta电位由 -2 4 0mV提高到 + 0 4 3mV)可以显著加快海泡石的除藻速率 ,但其平衡除藻率并没有显著提高 .在分析了本研究中的凝聚机理后提出 :架桥网捕作用可能在黏土 藻凝聚过程中发挥了十分关键的作用 。
Twenty-six natural clays were studied for their kinetics of flocculating and removing algal cells of Microcystis aeruginosa. According to the 8 h equilibrium removal efficiencies and removal rates at a clay-loading of 0.7 g·L -1, all the 26 clays were classified into three categories. Type-I clay, which includes talc, ferric oxide, sepiolite, ferroferric oxide, and kaolinite, has an equilibrium removal efficiency greater than 90%, a t 50 (time needed to remove 50% of the algae) of less than 30 min, and a t 80 (time needed to remove 80% of the algae) of less than 2.5 h. Type-Ⅱ clay, which includes argillanceous rocks, attapulgite, rectorite, illite, and argil, etc., has an equilibrium removal efficiency of 50%～80%, a t 50 of less than 2.5 h, and a t 80 of more than 5 h. Type-Ⅲ clay consists of 14 minerals, including laterite, zeolite, mica, clinoptilolite, pumice, tripoli, feldspar and quartz, etc. with the removal efficiency less than 50%, and t 50 8h. When the clay loading was decreased to 0.1～0.2 g·L -1, the 8 h equilibrium removal efficiencies for 25 clays declined to below 60%, except for sepiolite, a Type-I clay, which maintained around 90%. After the sepiolite was modified with Fe 3+ to increase its surface charge (Zeta potential from -24.0 mV to +0.43 mV at pH 7.4), the initial removal rate was increased remarkably although its 8 h equilibrium removal efficiency was not improved substantially. As a comparison, the 8 h equilibrium removal efficiency of PAC was no greater than 40% at loadings of 0.02～0.2 g·L -1. Following the analysis of the flocculation mechanism it was concluded that the effect of bridging and netting may play a key role in the clay-algae flocculation processes, which may be important for selecting and modifying clays to improve significantly the removal efficiency.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2003年第5期1-10,共10页
Environmental Science
基金
国家自然科学基金资助项目 (2 0 1770 2 9)
国家"十五"重大科技专项 (2 0 0 2AA6 0 10 1)
中国科学院"百人计划"项目
关键词
铜绿微囊藻
黏土
水华
絮凝
机理
改性
架桥网捕
电中和
Microcystis aeruginosa
clays
algal blooms
flocculation
mechanism
clay modification
bridging and netting
electrostatic neutralization
