Sino-Dutch R&D Centre for Future Wastewater Treatment Technologies/Beijing Advanced Innovation Centre of Future Urban Design, Beijing University of Civil Engineering & Architecture, Beijing 100044, PR China.
Sino-Dutch R&D Centre for Future Wastewater Treatment Technologies/Beijing Advanced Innovation Centre of Future Urban Design, Beijing University of Civil Engineering & Architecture, Beijing 100044, PR China.
Sci Total Environ. 2022 Sep 1;837:155673. doi: 10.1016/j.scitotenv.2022.155673. Epub 2022 May 1.
Alginate like extracellular polymers (ALE) recovered from flocculent sludge has been identified as a kind of highly valuable biomaterials. However, the extraction protocols limit the production of biopolymers as ALE extracted from flocculent sludge is at a lower level, around 90-190 mg/g VSS. Under this circumstance, the eco-friendly and effective optimizations for the ALE extraction protocols are expected, and thus surfactants have gained an attention to enhancing the ALE extraction. With this study, different surfactants with different structures and chemical characteristics, such as sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB) and octyl phenyl polyoxyethylene ether (Triton X-100), were experimented to improve the ALE extraction, and in turn the optimal conditions and the associated mechanisms were evaluated and figured out. The experimental results indicated that surfactants could enhance the ALE extraction but also improve the alginate purification of ALE. With the optimal dosage of surfactants, the ALE extraction increased from 124.1 mg/g VSS to about 222.8-281.9 mg/g VSS, and the alginate purify was at around 54%-70%, in which the efficiency of the ALE extraction was improved by 79.5%-127.2%. Among others, Triton X-100 had the best performance on improving the ALE extraction, followed by CTAB and SDS. The mechanisms of surfactants on enhancing the ALE extraction and improving the alginate purify can be attributed to: i) surfactants micelles, which can solubilize flocs and extracellular biopolymers; ii) similar structures of surfactants and ALE, which follows the rule of "like dissolves like"; iii) functional groups adsorption, which facilitates the ALE release from matrixes. In a word, the optimized extraction protocol by using surfactants can be effectively applied to extract ALE from flocculent sludge.
从絮状污泥中回收的藻酸盐样细胞外聚合物 (ALE) 已被确定为一种极具价值的生物材料。然而，由于从絮状污泥中提取的 ALE 水平较低，约为 90-190mg/gVSS，因此提取方案限制了生物聚合物的生产。在这种情况下，需要对 ALE 提取方案进行环保且有效的优化，因此表面活性剂已引起人们对提高 ALE 提取效率的关注。在这项研究中，使用了具有不同结构和化学特性的不同表面活性剂，如十二烷基硫酸钠 (SDS)、十六烷基三甲基溴化铵 (CTAB) 和辛基苯基聚氧乙烯醚 (Triton X-100)，以提高 ALE 提取效率，并评估了最佳条件和相关机制。实验结果表明，表面活性剂可以提高 ALE 提取效率，同时也可以提高 ALE 中的藻酸盐纯度。使用最佳剂量的表面活性剂，ALE 提取量从 124.1mg/gVSS 增加到约 222.8-281.9mg/gVSS，藻酸盐纯度约为 54%-70%，其中 ALE 提取效率提高了 79.5%-127.2%。在所有表面活性剂中，Triton X-100 对提高 ALE 提取效率的效果最好，其次是 CTAB 和 SDS。表面活性剂增强 ALE 提取和提高藻酸盐纯度的机制可以归因于：i）表面活性剂胶束，可以溶解絮状物和细胞外生物聚合物；ii）表面活性剂和 ALE 具有相似的结构，遵循“相似相溶”的原则；iii）功能基团吸附，有利于 ALE 从基质中释放。总之，使用表面活性剂优化的提取方案可以有效地从絮状污泥中提取 ALE。
