Fixed film phosphorus removal – flexible enough?

Abstract

While biological phosphorus removal (BPR) has been practised for 30 years, up to recently it has been restricted mainly to activated sludge processes, with the corresponding need for large basin volumes. Yet, research with biofilm reactors showed that the principle of alternate anaerobic and aerated conditions was applicable to fixed bacteria by changing the conditions in time rather than in space. Attached growth enhanced biological phosphorus removal (EBPR) systems are attractive because of their compactness and capability to retain high biomass levels. However, the phosphorus extraction depends on backwashes to enhance the phosphorus-rich attached biomass, and correct control of unsteady effluent quality created by frequently modified process conditions. Accordingly, EBPR remains a challenging task in terms of combining nitrogen and phosphorus removal using attached growth systems. Nevertheless, a combination of activated sludge and biofilm carriers, in the integrated fixed-film activated sludge system, provides treatment opportunities not readily available using suspended growth systems. Current practice is only at the beginning of exploiting the full potential of this combination, but the first full-scale results show that compact tankage and low nutrient results based on biological principles are possible.

Enhanced biological nitrogen and phosphorus removal using sequencing batch membrane-aerated biofilm reactor

“…During the anaerobic stage (DO under 0.2 mg/L), a large number of organic carbon sources were aggregated and stored by PAOs, and the phosphorus contained in the biomass was released as soluble phosphate. During the aerobic stage, PAOs degraded the intracellular organic matter as energy sources to excessive uptake of phosphorus from the wastewater and replenished as their internal poly-P-storage (Rogalla et al, 2006). And then, the P-rich biomass was removed by periodic backwashing.…”

Simultaneous nutrients and carbon removal from low-strength domestic wastewater with an immobilised-microorganism biological aerated filter

“…It is better than the activated sludge systems in terms of system stability and compactness, because high concentration of active biomass can be maintained and suspended solids in the influent can be captured physically. Moreover, by reason of the gradient of dissolved oxygen (DO) from the interior to the exterior of the carrier, it is effective in removing carbon and nitrogen concurrently (Lemoine et al 2006;Rogalla et al 2006). In particular, phosphorus removal can be achieved in BAF systems operated under alternated anaerobic/aerobic conditions (Shanableh et al 1997;Zheng & Long, 2008).…”

Decoupling and Optimization of Both P and N Removal in an Advanced IFAS-EBPR-MBR System

“…At a same COD/P ratio, (Hesselmann et al 1999) obtained effluent P level below 0.5 mg-P/L with a lab-scale SBR-EBPR system. The first full-scale IFAS operation with biofilm career (K1) in Broomfield which studied mainly the nitrification capacity of the system has shown to produce effluent with a stable P level at 0.5 mg-P/L and total P of 1.25 mg-P/L with a COD/TP ratio ranging from 15-30 (Rogalla et al 2006;Rutt K. 2006). (Sriwiriyarat and Randall 2005b) has shown in the evaluation of a pilot-scale IFAS system with accuweb media that it was capable of producing effluent with P level at 10.2±3 mg-P/L corresponding to 70% removal efficiency at a COD/TP of 20 and the efficiency was reduced to 50% at a COD/TP of 52 and these efficiencies were not significantly higher than their control without IFAS, mainly hypothesized due to higher release of P in the anoxic zone without subsequent uptake in following aerobic zone.…”

“…These make the simultaneous N and P removal in fixed film system more challenging and requiring biofilm processes to be separated in both space and time (Gieseke et al 2002;Gieseke et al 2001;Helness and Odegaard 1999;Pastorelli et al 1999). However, some studies with full scale plants have demonstrated that IFAS has the potential to reach low effluent P-level requiring proper reactor configuration and operational conditions (Onnis-Hayden 2008; Rogalla et al 2006). But detailed kinetic analysis for varying conditions and configurations is not yet available.…”