Removal of Emerging Contaminants in Drinking Water Treatment

饮用水处理中新兴污染物的去除

• 批准号: RGPIN-2017-06078
• 负责人: Andrews, Robert
• 金额: $ 2.99万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=712038
• 关键词: Removal; Emerging; Contaminants; Drinking; Water

Biofiltration is a drinking water treatment process which relies on naturally occurring microorganisms that have formed a biofilm on filter media. Biofilters have been shown to effectively remove a wide variety of compounds including micropollutants, taste and odor causing compounds and inorganics. N-nitrosodimethylamine (NDMA) is a disinfection by-product (DBP) that is suspected of carcinogenic activity. A growing number of drinking water treatment plants that use chloramines for secondary disinfection have reported NDMA in finished water due to the reaction of chloramines with small nitrogen-containing molecules such as dimethylamine (DMA) that serve as NDMA precursors. With respect to NDMA precursors, it is hypothesized that biofiltration is able to reduce some of the precursors, but may contribute others. These may include bacterial and soluble microbial products (SMP) which are comprised of compounds released from the biofilm as waste, or sheared off of the media. It is expected that the release of biofilter derived precursors is dependent on biofilter operational conditions including filter design and pre-treatment. Many different NDMA precursors have been shown to be derived from anthropogenic sources. Of particular interest are pharmaceutically active compounds that have high molar conversions to NDMA upon chloramination. A number of PhACs that readily convert to NDMA are found in wastewater, but their presence in drinking water plant influents will depend on potential wastewater impacts. Pilot testing will concurrently evaluate the impact of flowrate, media type and pre-treatment for the removal of precursor compounds by biofiltration. Pilot- and full-scale studies will evaluate a range of EBCT ranging from 5 to 30 minutes to examine the formation of biomass and the removal or formation of NDMA precursors. Although it is expected that longer EBCT will provide better removals of NDMA precursors, and biodegradable organics, it is unclear whether increased biomass density will result in the formation of NDMA precursors in the filter effluent. Careful consideration may be required to optimize the removal of organics without generating excess biomass which may result in increased NDMA precursor formation. Confirmation of NDMA precursor removal efficiencies will provide valuable information to other researchers. This will also be of importance to utilities that already have biofiltration as well as those contemplating implementation in lieu of conventional granular filters. In addition, benefits will be realized by consultants who are involved in the water treatment industry, membrane and carbon producers, and regulatory setting agencies such as Health Canada and provincial environment ministries.

生物过滤是一种饮用水处理过程，依赖于在过滤介质上形成生物膜的天然微生物。生物过滤器已被证明可以有效去除多种化合物，包括微污染物、引起味道和气味的化合物和无机物。 N-亚硝基二甲胺 (NDMA) 是一种消毒副产物 (DBP)，疑似具有致癌活性。越来越多使用氯胺进行二次消毒的饮用水处理厂报告称，由于氯胺与作为 NDMA 前体的二甲胺 (DMA) 等含氮小分子发生反应，成品水中含有 NDMA。对于 NDMA 前体，假设生物过滤能够减少一些前体，但可能会增加其他前体。这些可能包括细菌和可溶性微生物产物（SMP），它们由生物膜作为废物释放或从介质上剪下的化合物组成。预计生物过滤器衍生前体的释放取决于生物过滤器的操作条件，包括过滤器设计和预处理。 许多不同的 NDMA 前体已被证明源自人为来源。特别令人感兴趣的是在氯胺化后具有高摩尔转化率的药物活性化合物。废水中发现了许多易于转化为 NDMA 的 PhAC，但它们在饮用水厂进水中的存在将取决于潜在的废水影响。中试将同时评估流量、介质类型和预处理对生物过滤去除前体化合物的影响。中试和全面研究将评估一系列 EBCT（5 至 30 分钟），以检查生物质的形成以及 NDMA 前体的去除或形成。尽管预计较长的 EBCT 将更好地去除 NDMA 前体和可生物降解的有机物，但尚不清楚增加的生物质密度是否会导致过滤器流出物中 NDMA 前体的形成。可能需要仔细考虑以优化有机物的去除而不产生过量的生物质，这可能导致 NDMA 前体形成增加。 NDMA 前体去除效率的确认将为其他研究人员提供有价值的信息。这对于已经拥有生物过滤的公用事业以及那些考虑实施代替传统颗粒过滤器的公用事业也很重要。此外，参与水处理行业的顾问、膜和碳生产商以及加拿大卫生部和省环境部等监管机构也将受益。