Jaap H. J. M. van der Graaf

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.

Sustainability criteria as a tool in the development of new sewage treatment methods

In The Netherlands a research project is presently conducted, which has the objective to identify new, more sustainable sewage treatment scenarios which are based on physical-chemical pretreatment. After collecting possible treatment scenarios by means of literature research and contacts with international experts the identified scenarios are evaluated on sustainability and costs. For evaluating the sustainability, the following sustainability criteria (derived from the Life Cycle Assessment methodology) are used: energy balance, final sludge production, effluent quality, the use of chemicals and space requirement (footprint). Within this paper the use of these criteria is illustrated and discussed by means of two example scenarios and a reference scenario. The calculation results for the two example scenarios show that physical-chemical pretreatment leads to energy saving when biological post treatment is applied. Besides, more energy can be generated through sludge digestion, due to an increased sludge production. However, the increased particle removal also leads to an increased final sludge production after digestion which will have to be disposed of and to a relatively high consumption of chemicals.

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...

Practical Performance of Various Systems for Small-Scale Waste Water Treatment during a Two-Year Field Test

Diffuse pollution, caused by direct discharges from individual houses or groups of houses for which connection to central waste ;/ater treatment systems is not feasible, may be significantly reduced by on-site treatment. The performances of 14 different systems for on-site treatment in the range of 5-200 population equivalents (p.e.) in the Netherlands were tested over a two-year period of field research. Treatment results showed reasonably comparable removal percentages in relation to large systems, the effluent quality however may not be as good due to higher influent concentrations. Significant differences in treatment, operation and maintenance aspects were recorded, causing some systems to be preferred to others. A further evaluation involving costs is currently being carried out. The feasibility of wide-spread application of small treatment plants may depend more on financial, management and organizational aspects than on technological aspects.

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.

Handbook on particle separation processes.

Contents: Introduction A. van Nieuwenhuijzen and J. van der Graaf Characterization of Aquatic Particles M. Boller and R. Kaegi Characterization Profiling of NOM- as a Basis for Treatment Process Selection and Performance Monitoring G. Amy, S. Sharma, S. Salinas Rodriguez, S. Baghoth and S. Maeng Technologies for the removal of natural organic matter H. Odegaard, S. Osterhus, E. Melin and B. Eikebrokk Advanced Physical Chemical Treatment by Flocculation Y. Watanabe Dissolved Air Flotation M.Y. Han Characterising the Membrane Filtration Process of Wastewater J. van der Graaf, S. Geilvoet and J. Roorda Enhanced Flocculation/ Sedimentation Process by a Jet-Mixed Separator Y. Watanabe Particle Behaviour and Removal in a Rainwater Storage Tank and Suggestions for Operation J.S. Mun and M.Y. Han Direct Membrane Filtration of Wastewater A. Ravazinni, A.F. van Nieuwenhuijzen and J.H.J.M. van der Graaf

New developments in upgrading waste-water treatment plant effluent using ultrafiltration

Abstract In the Netherlands interest in advanced treatment is increasing now that almost all waste-water treatment plants apply full biological treatment and nutrient removal. Membrane filtration, especially ultrafiltration, of waste-water treatment plant effluent appears to be a very promising method. However, many experiments show a rapid decrease in flux, which means that frequent and intensive cleaning is required. Various methods for the development, as this article shows. Further research will lead to a new understanding of the filtration and fouling processes, and will finally result in highly efficient and cost-effective ultrafiltration plants.