P. Krzeminski

Specific energy consumption of membrane bioreactor (MBR) for sewage treatment.

This paper provides an overview of current electric energy consumption of full-scale municipal MBR installations based on literature review and case studies. Energy requirements of several MBRs were linked to operational parameters and reactor performance. Total and specific energy consumption data were analysed on a long-term basis with special attention given to treated flow, design capacity, membrane area and effluent quality. The specific energy consumption of an MBR system is dependent on many factors, such as system design and layout, volume of treated flow, membrane utilization and operational strategy. Operation at optimal flow conditions results in a low specific energy consumption and energy efficient process. Energy consumption of membrane related modules was in the range of 0.5-0.7 kWh/m(3) and specific energy consumption for membrane aeration in flat sheet (FS) was 33-37% higher than in a hollow fibre (HF) system. Aeration is a major energy consumer, often exceeding 50% share of total energy consumption. In consequence, coarse bubble aeration applied for continuous membrane cleaning remains the main target for energy saving actions. Also, a certain potential for energy optimization without immediate danger of affecting the quality of the produced effluent was observed.

Flat sheet or hollow fibre — comparison of full-scale membrane bio-reactor configurations

Abstract Membrane bioreactors (MBRs) are widely used for wastewater treatment and reuse applications. Selection of a membrane configuration is a crucial step in the design process and has a high impact on further plant operations. Despite increasing experience with full-scale applications, practical knowledge concerning the impact of different membrane configurations on process performance and operational costs is still lacking. This paper provides full scale MBR performance data comparing the use of flat sheet and hollow fibre membranes and analyses the consequences on operation, performance and treatment efficiency. Hollow fibre configurations, comparing to the flat sheet, are designed for higher fluxes, operated at lower concentrations, cleaned more often and protected by stricter pre-treatment. Filterability of activated sludge from municipal MBRs is better than from industrial MBRs and does not depend on membrane configuration. The energy consumption depends more on the influent type than on the memb...

Filtration Characterization Method as Tool to Assess Membrane Bioreactor Sludge Filterability—The Delft Experience

Prevention and removal of fouling is often the most energy intensive process in Membrane Bioreactors (MBRs), responsible for 40% to 50% of the total specific energy consumed in submerged MBRs. In the past decade, methods were developed to quantify and qualify fouling, aiming to support optimization in MBR operation. Therefore, there is a need for an evaluation of the lessons learned and how to proceed. In this article, five different methods for measuring MBR activated sludge filterability and critical flux are described, commented and evaluated. Both parameters characterize the fouling potential in full-scale MBRs. The article focuses on the Delft Filtration Characterization method (DFCm) as a convenient tool to characterize sludge properties, namely on data processing, accuracy, reproducibility, reliability, and applicability, defining the boundaries of the DFCm. Significant progress was made concerning fouling measurements in particular by using straight forward approaches focusing on the applicability of the obtained results. Nevertheless, a fouling measurement method is still to be defined which is capable of being unequivocal, concerning the fouling parameters definitions; practical and simple, in terms of set-up and operation; broad and useful, in terms of obtained results. A step forward would be the standardization of the aforementioned method to assess the sludge filtration quality.

MBR performance: Operational problems in industry

A major study undertaken by a number of institutions and a leading engineering consultancy has investigated factors affecting the performance in operation of membrane bioreactors in a variety of different industrial applications. Jose Antonio Gil summarises the findings.