Optimising design, operation and energy consumption of biological aerated filters (BAF) for nitrogen removal of municipal wastewater

Abstract

The Biofiltration process in wastewater treatment combines filtration and biological processes in one reactor. In Europe it is meanwhile an accepted technology in advanced wastewater treatment, whenever space is scarce and a virtually suspended solids-free effluent is demanded. Although more than 500 plants are in operation world-wide there is still a lack of published operational experiences to help planners and operators to identify potentials for optimisation, e.g. energy consumption or the vulnerability against peakloads. Examples from pilot trials are given how the nitrification and denitrification can be optimised. Nitrification can be quickly increased by adjusting DO content of the water. Furthermore carrier materials like zeolites can store surplus ammonia during peak loads and release afterwards. Pre-denitrification in biofilters is normally limited by the amount of easily degradable organic substrate, resulting in relatively high requirements for external carbon. The combination of pre-DN, N and post-DN filters is much more advisable for most municipal wastewaters, because the recycle rate can be reduced and external carbon can be saved. Exemplarily it is shown for a full scale preanoxic-DN/N/postanoxic-DN plant of 130,000 p.e. how 15% energy could be saved by optimising internal recycling and some control strategies.

Effect of the Aeration Strategy on NOB Suppression in Activated Sludge and Biofilm in a Hybrid Reactor with Nitrification/Denitrification

“…Limiting the effect of this factor in the treated medium requires the maintenance of high dissolved oxygen concentration. According to Rother and Cornel [23] and Pal et al [24], the provision of highly efficient nitrification in pure moving-bed technology requires the maintenance of DO concentration at least at a level of 5 mg O 2 /L. Oxygen diffusion does not play such an important role in the case of activated sludge flocs, although in order to maintain identical conditions in test reactors, the same oxygen concentration as for tests with biofilm was also adopted for this form of biomass.…”

Adopting Primary Plastic Trickling Filters as a Solution for Enhanced Nitrification

“…When considering robustness, option 1 is already discounted, yet remains a viable option to offload organic carbon if space is available (Pearce and Foster, 1999;Pearce, 2004). The pre-stage aerated process 7 could be adopted for partial BOD removal with reduced aeration rates (Rother and Cornel, 2004). However, one of the fundamental disadvantages of secondary stage mechanically aerated process is the increased risk of media clogging without consistent prior solids removal (Albuquerque et al, 2012).…”

Field experiment on biological contact oxidation process to treat polluted river water in the Dianchi Lake watershed

“…The Daqing River acts as an extension of the sewer. To consider the removal of nitrogen and phosphorus from the river water, configuration of a step feeding flow [20,21] and an internal recycling [22] were designed to modify the processes into a step-feed biological contact oxidation process (SBCOP) and an inter-recycle biological contact oxidation process (IBCOP). Through long-term operation of the facility, the treatment efficiencies and process parameters of the two units were compared.…”