丝状产嗅蓝藻光响应机制与水源水库中原位控制策略研究

The off-flavour problems caused by filamentous cyanobacteria in source water reservoirs have been frequently recorded in China, some of these cyanobacterial strains are able to produce 2-Methylisoborneol (2-MIB), an earthy/musty odorant. 2-MIB, with an extremely low odor threshold can not be effectively removed by conventional water treatment process, and thus threatens water supply safety. This project explores the growth and odor characteristics of typical filamentous odor-producing cyanobacteria under different light conditions at different intensity level and spectrum distribution, as well as the competition with bloom forming cyanobacteria. By combining the results from lab culture studies and on-site simulation experiments, the light thresholds for restricting cyanobacterial growth was determined. Based on these results, hydraulic regulating strategy is expected to be developed to control underwater light conditions for different type of reservoirs, and a hydraulic model can be construct according to boundary conditions of targeting reservoirs. This hydraulic model can be subsequently used to simulate various scenes with different hydraulic measures and to compute the distribution of underwater light climate, which can be used to elect the best feasible hydraulic measure according to light thresholds of different strains. The research consists of light response mechanism exploration for various typical odorous filamentous cyanobacteria, and hydraulic measures development for different types of reservoirs with different turbidity level, herein two case studies for the low turbid Miyun Reservoir and high turbid Qingcaosha Reservoir will be performed for developing respective control strategies.

我国水源水库中由于丝状蓝藻生长代谢产生致嗅物质2-甲基异莰醇导致饮用水呈现土霉味的现象层出不穷。由于2-甲基异莰醇嗅阈值低，常规工艺无法处理，威胁供水安全。本项目通过考察不同光照强度与光谱分布光源条件下典型丝状产嗅蓝藻的生长与产嗅特征，以及与表层水华型蓝藻之间的竞争生长关系，结合实验室培养实验与原位模拟验证实验确定抑制产嗅藻生长的光阈值条件，在此基础上针对不同类型水库研究丝状产嗅蓝藻的调控机理，通过水力学模型模拟不同水力调控模式下水下光照条件分布情况，并根据不同产嗅藻的光阈值条件优选出最佳可行水力调控模式。项目研究内容主要包括丝状产嗅蓝藻的光响应机制及其与表层水华型蓝藻之间的光竞争机制，并分别以“低浊度”密云水库和“高浊度”青草沙水库为研究对象开发相应的水力调控策略。

我国近一半水源水库存在由丝状蓝藻代谢产生2-甲基异莰醇（MIB）导致饮用水嗅味问题，是供水行业面临的最主要问题之一。为此，该致嗅物质MIB已新增列入《国家生活饮用水卫生标准》（GB5749-2022）。然而，由于该物质嗅阈值低（10 ng/L），难以采用常规水处理方法去除，因此需研究产嗅藻在水源水库中的竞争生长机制，开发针对性原位控制技术。本项目选择北京、上海、珠海等城市水源水库，通过开展野外调查、实验室模拟、原位验证及模型构建等手段明确了产嗅藻在水源中生长的关键机制，揭示水下光照是藻类种群竞争演替的主要驱动因子，打破了产嗅藻生长由营养盐驱动的传统认识；发现丝状产嗅藻受光面积大，具有喜好在水体亚表层生长的生态位特征，据此构建以物理调光为核心的绿色抑藻控嗅技术；构建水位-风险模型确定北京密云水库抑制产嗅藻生长的安全水位为146 m，利用南水北调补水契机证实物理调光抑藻技术可原位解决密云水库固有土霉味问题，规避了国际上采用化学法除藻带来的生态风险，国际同行评价技术“简单经济、绿色无害”。上海青草沙水库实施该技术后，已连续3年成功解决该水库季节性嗅味问题，节省活性炭等除嗅成本超1000万元/年；成果还成功应用于珠海、宁波等地的多座水源水库，显著提升了我国在水源嗅味方面的管理水平。项目成果发表SCI论文10篇，中文核心论文2篇，专著1部，申请/授权专利4项，软件著作权2项，编制行业指南1份，获中国科学院杰出科技成就奖、住建部华夏建设科学技术奖二等奖、中国供排水协会科学技术奖特等奖及北京市水利协会科学技术一等奖。