Water Engineering: Membrane fouling for low energy advanced wastewater treatment

水工程：低能耗高级废水处理的膜污染

• 批准号: EP/K010360/1
• 负责人: Ewan McAdam
• 金额: $ 12.52万
• 依托单位: CRANFIELD UNIVERSITY
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FK010360%2F1
• 关键词: Water; Engineering; Membrane; fouling; low

The UK water industry treats over 3 billion m3 of sewage every day and so plays a major role in safe-guarding water sources for the protection of wildlife and human health through wastewater treatment. Within the EU, member states are required to meet a number of new, stricter sanitary determinant targets by 2015 which have been set out within the Water Framework Directive (WFD). Sewage treatment is currently predominantly facilitated by biological treatment systems, typically designed as activated sludge processes (ASPs). Whilst effective for treatment to existing standards, both operating utilities and the industry regulator, the Environment Agency, have raised concerns that the proposed WFD standards cannot be met by existing ASP assets. Membrane bioreactors (MBRs) are an advanced wastewater treatment process that couples membrane separation with the activated sludge process. The membrane units are typically comprised of pores with a nominal diameter in the range of 0.1 to 0.01 micrometres and thus enhance the separation of particles versus conventional ASP. Furthermore, the enhanced retention of active microbes enables more robust nitrification to be achieved and have therefore demonstrated a capability to exceed the proposed effluent compliance set out in the WFD.Consequently, MBRs represent the fastest growing advanced wastewater treatment technology with a global annual market value of around $1 Bn. However, the energy required to operate the membrane in the MBR process results in a markedly higher process energy demand than for conventional ASP technology. This constraint has therefore limited the uptake of this technology for municipal sewage treatment as it is in conflict with current regulatory and utility drivers which are seeking to, "Transform wastewater treatment to reduce carbon emissions" (Environment Agency Report, 2009), and in the long term move toward carbon neutral wastewater treatment. Nevertheless, the demand to meet stricter wastewater consents is imminent and is further exacerbated by the increased demand on scarce water resources. MBRs are an integral technology to fulfilling these challenges. This proposal therefore seeks to radically reduce the specific energy demand associated with membrane operation in MBR to enable uptake of this critical technology. During membrane filtration, particles accumulate at the membrane surface forming concentrated fouling layers at the membrane surface. This fouling layer gradually compresses with time, restricting flow further. The membrane energy demand arises from the air injection required to limit the accumulation of the concentrated particulate fouling layers. Recent studies at Cranfield have shown that by manipulating the hydrodynamics imposed by air injection, it is possible to restructure the particles within the foulant layer to make it more easy to remove, reducing the energy demand by up to ten times. Critical to understanding the scientific mechanism behind this relationship is in establishing the role of small particles (<1 micron) in these fouling layers as it is argued that small particles represent the critical fouling fraction. Whilst methodologies are available to measure foulant layers in such dynamic conditions, they are not sufficiently sensitive to detect particles in the sub-micron size range. Consequently, a novel Reflected Light Fluorescence Direct Observation method is proposed that will enable measurement of this critical group of particles. Once established, this method will provide quantitative evidence of particle distribution and particle transport within these complex fouling structures. The resultant evidence will be used to engineer highly reversible fouling layers within MBR, eliminating the critical energy barrier and enabling MBR utilisation as a reduced carbon technology option for advanced protection of the environment.

英国水务行业每天处理超过30亿立方米的污水，因此通过污水处理在保护水源、保护野生动物和人类健康方面发挥着重要作用。在欧盟内部，要求成员国在2015年之前达到《水框架指令》（WFD）中规定的一些新的、更严格的卫生决定因素目标。污水处理目前主要通过生物处理系统来促进，通常设计为活性污泥法（ASP）。虽然对现有标准的处理有效，但运营公用事业和行业监管机构环境局都提出了对现有ASP资产无法满足拟议WFD标准的担忧。膜生物反应器（MBR）是一种先进的废水处理工艺，它将膜分离与活性污泥法相结合。膜单元通常由标称直径在0.1至0.01微米范围内的孔组成，因此与常规ASP相比增强了颗粒的分离。此外，活性微生物的增强保留能够实现更稳健的硝化，因此证明了超过WFD中规定的拟议污水合规性的能力。因此，MBR代表了增长最快的先进污水处理技术，全球年市场价值约为10亿美元。然而，在MBR工艺中操作膜所需的能量导致比常规ASP技术显著更高的工艺能量需求。因此，这种限制限制了该技术在城市污水处理中的应用，因为它与当前的监管和公用事业驱动因素相冲突，这些驱动因素正在寻求“改造废水处理以减少碳排放”（环境署报告，2009年），并在长期内朝着碳中性废水处理发展。然而，满足更严格的废水同意的需求迫在眉睫，并且由于对稀缺水资源的需求增加而进一步加剧。MBR是应对这些挑战的必要技术。因此，该提案旨在从根本上减少与MBR中的膜操作相关的特定能量需求，以实现这一关键技术的吸收。在膜过滤期间，颗粒在膜表面处积聚，从而在膜表面处形成浓缩的污染层。该污垢层随着时间逐渐压缩，进一步限制流动。膜能量需求来自限制浓缩颗粒污垢层的积累所需的空气注入。克兰菲尔德最近的研究表明，通过操纵空气注入所施加的流体动力学，有可能重组污垢层内的颗粒，使其更容易去除，从而将能源需求减少多达十倍。理解这种关系背后的科学机制的关键是确定小颗粒（<1微米）在这些结垢层中的作用，因为有人认为小颗粒代表临界结垢分数。虽然方法可用于在这种动态条件下测量污垢层，但它们对于检测亚微米尺寸范围内的颗粒不够灵敏。因此，提出了一种新的反射光荧光直接观察方法，将使这一关键组粒子的测量。一旦建立，该方法将提供这些复杂的污垢结构内的颗粒分布和颗粒传输的定量证据。由此产生的证据将用于设计MBR内高度可逆的污垢层，消除关键的能量障碍，并使MBR作为一种先进的环境保护低碳技术选择。

项目成果

Investigating the significance of coagulation kinetics on maintaining membrane permeability in an MBR following reactive coagulant dosing

• DOI: 10.1016/j.memsci.2016.06.008
• 发表时间: 2016-10-15
• 期刊: JOURNAL OF MEMBRANE SCIENCE
• 影响因子: 9.5
• 作者: Autin, O.;Hai, F.;McAdam, E. J.
• 通讯作者: McAdam, E. J.

Fluorescence enabled direct visual observation for diagnosis of ultrafiltration membrane fouling by bi-disperse submicron particle suspensions

荧光可以直接目视观察双分散亚微米颗粒悬浮液对超滤膜污染的诊断

• DOI: 10.1111/wej.12349
• 发表时间: 2018
• 期刊: Water and Environment Journal
• 影响因子: 2
• 作者: Autin O

Direct observation of sub-micron biopolymers during crossflow filtration using a new reflected light fluorescent methodology

使用新的反射光荧光方法在错流过滤过程中直接观察亚微米生物聚合物

• 作者: Ewan McAdam (Co-Author)