Bio-clogging mitigation in vertical subsurface flow constructed wetlands using rhamnolipids-citric acid compound
Bio-clogging mitigation in vertical subsurface flow constructed wetlands using rhamnolipids-citric acid compound
复制标题
DOI：
10.1016/j.cej.2021.131278
复制
发表时间：
2021-12
影响因子：
15.1
通讯作者：
Yuan Cao;Yue Li;L. Ren;Meng Sha;Dongqing Lv;Sen Wang;Fanlong Kong
中科院分区：
文献类型：
--
作者：
Yuan Cao;Yue Li;L. Ren;Meng Sha;Dongqing Lv;Sen Wang;Fanlong Kong
由于细胞外聚合物（EPS）在基质间隙的过度聚集导致生物堵塞，人工湿地（CWs）的可持续运行面临挑战。本研究首次采用鼠李糖脂（RLs）和柠檬酸（CA）作为原位增溶剂，缓解了水化液中的生物堵塞。为了验证CA-RLs的效率，设置了四个具有垂直地下流的实验室规模的CWs。经CA-RLs增溶处理后，有效孔隙率恢复到初始孔隙率的83.0%左右。RLs可以溶解和分散堵塞，CA通过破坏EPS的稳定结构进一步促进作用。CA-RLs处理后，表面接触角增大，疏水EPS的zeta电位绝对值增大，这是由于疏水EPS的增溶作用。CA-RLs抑制细胞表面粘附，使EPS解离成小颗粒，降低EPS的聚集能力。EEM-PARAFAC分析显示，增溶处理增加了废水中色氨酸样或蛋白质样成分。此外，CA-RLs增溶处理后的恢复孔隙为反硝化菌（特别是rhodopseudomonas和rubrivivax）的生长提供了适宜的条件，有利于恢复CWs的性能。缓解生物堵塞后，水化液对NH4+-N（25-30%）和COD（50-55%）的去除率分别逐渐恢复到55-70%和70-75%。这些发现有助于更好地了解生物堵塞特性，有助于减轻生物堵塞。
Sustainable operation of constructed wetlands (CWs) is challenging due to bio-clogging caused by the excessive aggregation of extracellular polymeric substances (EPS) in substrate interspaces. In this study, rhamnolipids (RLs) and citric acid (CA) were used as solubilizers in situ with the influent to mitigate bio-clogging in CWs for the first time. Four lab-scale CWs with vertical subsurface flow were set to validate the efficiency of CA-RLs. After solubilization treatment with CA-RLs, the effective porosity of CWs restored to about 83.0% of the initial. RLs could solubilize and disperse blockage, and CA further promote the effects by destroying the stable structure of EPS. The surface contact angle became larger after CA-RLs treatment, as did the absolute zeta potential of EPS, attributed to the solubilization of hydrophobic EPS. CA-RLs inhibited the surface adhesion of cells and dissociated EPS into small particles, reduced the aggregation ability of EPS. The EEM-PARAFAC analysis showed solubilization treatment increased the tryptophan-like or protein-like components in effluent. Furthermore, the rehabilitative porosity after CA-RLs solubilization treatment provided suitable conditions for the growth of denitrifiers (especiallyRhodopseudomonasandRubrivivax),conducive to recover the performance of CWs. After bio-clogging mitigation, the removal rates of NH4+-N (25–30%) and COD (50–55%) in CWs gradually recovered to 55–70% and 70–75%, respectively. These findings provided a better understanding of the bio-clogging characteristics, which were helpful to mitigate bio-clogging in CWs.