Investigation of Membrane Bioreactor Effluent Water Quality and Technology
Joan A. Oppenheimer, MWH
Membrane Bioreactor (MBR) technology has become well established worldwide over the last decade as an activated sludge process option for advanced treatment and recycling of municipal and industrial wastewater. The MBR process utilizes low-pressure membrane filters that are submerged within or adjacent to the conventional activated sludge (CAS) reactor, which eliminates the need for a secondary clarifier or tertiary filters. Although the effluent water quality of MBR processes has been reported to be superior to that of CAS systems, largely attributed to the membrane barrier, the water quality performance of pilot- and full-scale MBR processes indicate varying degrees of performance with respect to microbes, nutrients, aggregate organics, trace organic compounds, and trace metals.
The primary objective of this study is to achieve a better understanding of the effluent quality produced from an MBR system as a function of MBR design and operating conditions and how this quality compares with the effluent produced from CAS treatment systems. The primary objective was met by performing the following set of tasks:
- Comprehensive analysis of MBR effluent quality and operational data collected from a wide variety of sources that included peer-reviewed and grey literature of pilot studies and full-scale plant operations;
- Comprehensive analysis of data obtained through surveys of vendor suppliers and operating full-scale installations; and
- Synthesis of data obtained for aggregate organics and trace organic compounds with the predictions of a mechanistic MBR model developed to simulate different operating scenarios.
In order to address and discuss each of these research objectives, this report is subdivided into chapters:
- Chapter 2 provides a description of the study research approach including literature review, vendor survey, full-scale utility survey, and computational model development. The methodology and data consolidation procedure utilized in each of the previously mentioned tasks are summarized.
- Chapter 3 presents an overview of the MBR technology. The data of this chapter were consolidated from a survey of MBR vendors and a representative group of full-scale MBR plants. The results of the survey are characterized based on the following categories: number of installations, regional distribution, market share by the vendors, drivers for MBR selection, membrane material composition and configuration, and bioreactor operating conditions.
- Chapter 4 summarizes the performance of the MBR system based on the effluent water quality parameters that are categorized into different groups such as aggregate organics, microbial contaminants, particulates, nutrients, trace metals, and trace organic compounds. For each group of parameters, the performance of the MBR processes were evaluated based on removal mechanism and removal observed from available model prediction, literature review, and full-scale operational data survey. This chapter also summarizes the impacts of key operational issues on the effluent water quality performance of the MBR process and describes key differences between MBR and CAS processes.
- Chapter 5 presents and discusses conclusions obtained from this study and recommendations for filling identified knowledge gaps and areas of uncertainty regarding process performance characteristics.
(2012, 119 pages, 06-007-1)
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