Advances in enhanced biological phosphorus removal: from micro to macro scale.

Organic matter must be removed from sewage to protect the quality of the water bodies that it is discharged to. Most current sewage treatment plants are aimed at removing organic matter only. They are energy-inefficient, whereas potentially the organic matter could be regarded as a source of energy. However, organic carbon is not the only pollutant in sewage: Fixed nitrogen such as ammonium (NH4+) and nitrate (NO3−) must be removed to avoid toxic algal blooms in the environment. Conventional wastewater treatment systems for nitrogen removal require a lot of energy to create aerobic conditions for bacterial nitrification, and also use organic carbon to help remove nitrate by bacterial denitrification (see the figure). An alternative approach is the use of anoxic ammonium-oxidizing (anammox) bacteria, which require less energy ( 1 ) but grow relatively slowly. We explore process innovations that can speed up the anammox process and use all organic matter as much as possible for energy generation.

http://science.sciencemag.org/content/sci/328/5979/702.full.pdf

Sewage Treatment with Anammox

http://ntur.lib.ntu.edu.tw/bitstream/246246/90085/1/126.pdf

Aerobic granular sludge: Recent advances

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Wastewater Engineering Treatment Disposal And Reuse

Extracellular polymeric substances (EPS) were quantified in flocculent and aerobic granular sludge developed in two sequencing batch reactors with the same shear force but different settling times. Several EPS extraction methods were compared to investigate how different methods affect EPS chemical characterization, and fluorescent stains were used to visualize EPS in intact samples and 20-mum cryosections. Reactor 1 (operated with a 10-min settle) enriched predominantly flocculent sludge with a sludge volume index (SVI) of 120 +/- 12 ml g(-1), and reactor 2 (2-min settle time) formed compact aerobic granules with an SVI of 50 +/- 2 ml g(-1). EPS extraction by using a cation-exchange resin showed that proteins were more dominant than polysaccharides in all samples, and the protein content was 50% more in granular EPS than flocculent EPS. NaOH and heat extraction produced a higher protein and polysaccharide content from cell lysis. In situ EPS staining of granules showed that cells and polysaccharides were localized to the outer edge of granules, whereas the center was comprised mostly of proteins. These observations confirm the chemical extraction data and indicate that granule formation and stability are dependent on a noncellular, protein core. The comparison of EPS methods explains how significant cell lysis and contamination by dead biomass leads to different and opposing conclusions.

https://kuscholarworks.ku.edu/bitstream/handle/1808/18929/Sturm_polymeric_substances2005.pdf;sequence=1

Composition and Distribution of Extracellular Polymeric Substances in Aerobic Flocs and Granular Sludge

Aerobic granular sludge technology offers a possibility to design compact wastewater treatment plants based on simultaneous chemical oxygen demand (COD), nitrogen and phosphate removal in one sequencing batch reactor. In earlier studies, it was shown that aerobic granules, cultivated with an aerobic pulse-feeding pattern, were not stable at low dissolved oxygen concentrations. Selection for slow-growing organisms such as phosphate-accumulating organisms (PAO) was shown to be a measure for improved granule stability, particularly at low oxygen concentrations. Moreover, this allows long feeding periods needed for economically feasible full-scale applications. Simultaneous nutrient removal was possible, because of heterotrophic growth inside the granules (denitrifying PAO). At low oxygen saturation (20%) high removal efficiencies were obtained; 100% COD removal, 94% phosphate (P-) removal and 94% total nitrogen (N-) removal (with 100% ammonium removal). Experimental results strongly suggest that P-removal occurs partly by (biologically induced) precipitation. Monitoring the laboratory scale reactors for a long period showed that N-removal efficiency highly depends on the diameter of the granules.

Simultaneous COD, nitrogen, and phosphate removal by aerobic granular sludge

Full scale performance of the aerobic granular sludge process for sewage treatment.

Selection of slow growing organisms as a means for improving aerobic granular sludge stability

Aerobic granular sludge - : state of the art

Autotrophic nitrogen removal in the mainstream wastewater treatment process is suggested to be a prerequisite of energy autarkic wastewater treatment plants (WWTP) Whilst the application of anammox-related technologies in the side-stream is at present state of the art, the feasibility of this energy-efficient process at mainstream conditions is still under development Lower operating temperature and ammonium concentration, together with required high nitrogen removal efficiency, represent the main challenges to face in order to reach this appealing new frontier of the wastewater treatment field In this study, we report the evaluation of the process in a plug-flow granular sludge-based pilot-scale reactor (4 m3) continuously fed with the actual effluent of the A-stage of the WWTP of Dokhaven, Rotterdam The one-stage partial nitritation–anammox system was operated for more than 10 months at 19 ± 1°C Observed average N-removal and ammonium conversion rates were comparable or higher than those of convent

M.K. de Kreuk

Papers

Simultaneous COD, nitrogen, and phosphate removal by aerobic granular sludge

Full scale performance of the aerobic granular sludge process for sewage treatment.

Selection of slow growing organisms as a means for improving aerobic granular sludge stability

Aerobic granular sludge - : state of the art

Pilot-scale evaluation of anammox-based mainstream nitrogen removal from municipal wastewater