Development of a High-Throughput Fiber-Optic-Based Closed Bottle System for Evaluating the Ready Biodegradability of Water-Soluble Polymers

Water-soluble polymers are widely used in various applications. However, a large portion of them may end up in natural environments after use and may pose a risk if they do not decompose naturally, especially through biodegradation. Existing methods for evaluating the ready biodegradability of water-soluble polymers are generally costly, low throughput, and labor-intensive. To overcome such limitations, this study developed a high-throughput method using a fiber-optic dissolved oxygen measurement approach based on a modified OECD 301D method. The new method was first compared with traditional methods and showed similar biodegradation results. PolySeed was then evaluated as an alternative inoculum to secondary effluent, and a strong correlation was observed between the inoculum types, especially for highly biodegradable substances (>60% of degradation). The investigation on the effect of inoculum dosage suggested little difference among the three dosage levels (0.05, 0.5, and 5 mL/L) within the recommended range by OECD 301D. Compared to smaller reactors (20 and 40 mL), only reactors with volumes of 300 mL resulted in reasonable biodegradation. The further evaluation of this new method on over 40 natural, synthetic, and graft polymers indicated that it could be reliably applied for testing the ready biodegradability of diverse water-soluble polymers.水溶性聚合物（water-soluble polymers）在诸多领域应用广泛。然而，该类材料在使用后有相当比例会进入自然环境，若无法自然降解——尤其是无法通过生物降解途径完成分解，则可能引发环境风险。当前用于评估水溶性聚合物快速生物降解性（ready biodegradability）的现有方法普遍存在成本高昂、检测通量偏低且人力投入繁重的弊端。为克服上述局限，本研究基于改良的OECD 301D标准方法，开发了一种采用光纤溶解氧检测技术的高通量测试方案。首先将该新方法与传统检测方法进行对照实验，结果显示二者的生物降解结果具有良好一致性。随后以PolySeed作为替代接种物（inoculum），与传统的二级出水（secondary effluent）接种物开展对比评估，结果发现两种接种物的检测结果呈现较强相关性，在高生物降解性物质（降解率＞60%）的测试中这一相关性尤为突出。针对接种物投加量影响的探究表明，在OECD 301D标准推荐的投加范围内，0.05、0.5与5 mL/L这三个投加梯度下的检测结果无显著差异。相较于体积更小的反应器（20 mL与40 mL），仅300 mL体积的反应器可获得合理可靠的生物降解检测结果。针对40余种天然聚合物、合成聚合物及接枝聚合物（graft polymers）开展的进一步评估结果证实，该方法可可靠地用于检测各类水溶性聚合物的快速生物降解性。