10 Years of Experiences of an MBBR Process for Post-Denitrification

Abstract

Problems with eutrophication and algae blooms initiated the need for enhanced nutrient removal at European wastewater treatment plants in the end of the eighties. When upgrading the two WWTPs in Malmö, site specific upgrading concepts had to be considered because of the existing plant structures. As phosphorus removal already was implemented, the upgrading was focused on enhanced nitrogen removal. The key element in the upgrading procedure was the retrofit with an appropriate post-denitrification process. A newly developed concept with a moving bed biological reactor process was found to be cost-effective. Pilot plant tests with an MBBR process for post-denitrification were performed for demonstration purpose and to get some ideas for proper design criteria. The later experiences from the full-scale plant operation showed good agreement with the selected design criteria from the pilot plant data. The future effluent standards could be met by the upgrading of the plants. The pilot plant tests as well as the experiences from full-scale operation pointed out the need for a control system for external carbon dosage. The control action was based on the instantaneous nitrate load calculated from on-line measurements of nitrate and wastewater flow. The need for an active control of the phosphorus concentration in the MBBR process was also stressed by the experiences.

Experiences from MBBR Post-Denitrification Process in Long-term Operation at two WWTPs

“…al., 1994). This has been experienced at Sjölunda WWTP (Aspegren et al, 1998;Hanner et al, 2003;Täljemark et al, 2004). Low phosphate concentrations in the influent to the MBBR at Sjölunda have resulted in higher effluent nitrate concentrations and an increase in effluent BOD 7 concentration as a result of non-consumed carbon source (Hanner et al, 2003;Täljemark et al, 2004).…”

Evaluation of alternative electron donors for denitrifying moving bed biofilm reactors (MBBRs)

“…For plants that already have tertiary filters and in cases where those filters cannot be costeffectively converted to denitrifying filters, a high-rate MBBR process located after the final clarifiers, but before the tertiary filter, could be an effective technology for polishing effluent nitrate. Since being developed in Norway in the late 1980's/early 1990's, MBBRs have been constructed in a number of full-scale applications for this purpose (Taljemark et al 2004;Odegaard 2006).…”

Biological Treatment of Industrial Wastewaters and Other Contaminated Aqueous Streams: Selection of Bioreactor Alternatives

“…The surface area potentially available for biofilm growth per unit of reactor volume in GAC based FBRs and PBRs, will be more than 10 times greater than in most MBBRs, when media size and reactor fill fraction values are considered. It has been confirmed at the commercial scale level this difference in surface area does translate to a significant volumetric efficiency advantage for FBRs and PBRs versus the MBBR in the application to remove nitrate (i.e., denitrification) from municipal wastewaters following an ammonia oxidation (i.e., nitrification) step (Bratby et al, 2003;Taljemark et al, 2004). If hydraulic conditions within the bioreactor (e.g., short-circuiting and bypass feed flow) limit the surface area available for biofilm growth, the volumetric efficiency will not directly correlate to the media surface area.…”