基于高效磷捕获剂的饮用水“磷断粮”生物稳定性研究

The control of microbiological contamination in drinking water constitutes one of the greatest topics facing drinking water security, especially for water quality in pipe network. Conventional solutions (e.g. by enhancing residual chlorine or removing AOC) are suffering from some challenges, which drived us to pay attention to phosphorus-starvation to secure drinking water. However, most of current phosphorus-removal measures were short of pertinency to drinking water treatment, additionally, they cannot provide satisfactory low levels of phosphorus after treatment to suppress microbial growth. In our recent work, we found that suitable adsorbents or adsorption technology could provide a powerful platform to construct stringent phosphorus deficient condition to keep bio-stablity. Thus the project is proposed as follows: (i) We study the relationship between the concentration of bio-available phosphate and bio-stability, and consequently clarify the threshold of phosphate for microbiological regrowth. (ii) Rationally design and fabricate highly efficient, green and safe scavengers for low concentration phosphorus by appropriate synthesis, encapsulation or loading methods, and specify the interaction mechanism between the solid surfaces of adsorbents and the targets. (iii) Systematically estimate the phosphorus-removal performance and investigate the effects of water quality and features of the as-prepared materials,which would give an insight of the phosphorus-starvation efficiency on the control of microbiological contamination. (iv) Explore the use forms and running behavior of the adsorbents and other fundamental questions, which serves as an important support for the bio-stability of phosphate-starvation in drink water.

控制饮用水微生物污染，保证供水特别是管网水质安全是一个重要课题。鉴于通过增加余氯和控制可同化有机碳等方法存在一些关键问题难以避免或突破。我们将目光投向“磷断粮”的水质稳定方法。然而目前除磷的方法缺乏对给水中超低浓度磷的针对性，而且很难达到磷浓度限值。我们前期工作发现适当的吸附技术可为饮用水严格缺磷环境的创造提供重要手段。因此提出本项目：首先通过建立磷—生物稳定性的关系，掌握不同水质水力条件下磷营养与微生物生长的定量规律，确立所需磷阈值；根据需求，通过适当纳米制备技术和封装、负载技术，得到适宜饮用水的高效、绿色安全低浓度磷去除剂，并明晰固体界面与目标物的微观作用机制；系统评价除磷吸附效能，考量水质和材料参数对性能的影响，检测“磷断粮”环境对微生物生长的控制，建立吸附—除磷—生物稳定联动机制；并研究吸附剂的不同使用方法和作用规律等应用基础问题，最终为饮用水“磷断粮”生物稳定性方法提供重要支撑。

本项目通过考察 AOC、磷酸盐与细菌总数之间的关系，明确了 AOC 和磷酸盐对细菌生长繁殖的促进能力，并给出了实现水质生物稳定的 AOC 含量、磷含量和水龄的建议值。结果发现磷酸盐比 AOC 更容易促进细菌的生长繁殖，去除磷比去除 AOC 更容易实现水质生物稳定；为了实现水质生物稳定，需将磷含量控制在至少 3 μg P/L 以下；此外，还初步探讨了腐殖酸对细菌生长的促进作用，结果表明腐殖酸可直接作为营养源被细菌利用进行生长繁殖，当磷酸盐和腐殖酸共存时，细菌生长繁殖的能力大大增加。针对饮用水中低浓度磷营养的特点，利用静电纺丝技术，水热合成，共沉淀等方法，设计开发了多种绿色高效的磷吸附剂，包括镧基非负载粉末态吸附剂（如LaO2CO3），高分子负载型镧基吸附剂（La2O3/PAN纤维，La(OH)3/PAN纤维），碳负载型镧基吸附剂（嵌镧碳纤维，LaO2CO3/碳核壳吸附剂）；以及基于价态调控的Ce基高容量吸附剂等；可将水中几十μg P/L的磷迅速降低到几μg P/L一下的水平，且具有良好的生物安全性。并对相应吸附剂除磷时，药剂用量，pH，磷初始浓度，共存离子等影响进行系统研究，揭示配位键与反馈配位键共强化磷吸附机制。针对应用基础问题，将镧吸附剂制备成纳米纤维亚微滤膜（120 nm左右的孔尺寸），对已存在细菌进行快速滤除，并通过“磷断粮”的方式达到水质生物稳定的目的，实现快速滤菌和长效控菌的有机耦合；并利用镧/碳复合吸附剂，同步实现磷与腐殖酸等有机营养的去除，达到更严格的“低营养”水质稳定的目的；此外制备磁性磷吸附剂并研究了磁性填料和反应器的效能。基于本项目发表SCI论文6篇，申请或授权发明专利5项，培养4名博士研究生毕业，2名硕士研究生毕业。