Continuous flow aerobic granular sludge reactor for dairy wastewater treatment

Abstract

The focus of this study was to assess the treatment performance and granule progression over time within a continuous flow reactor. A continuous flow airlift reactor was seeded with aerobic granules from a laboratory scale sequencing batch reactor (SBR) and fed with dairy wastewater. Stereomicroscopic investigations showed that the granules maintained their integrity during the experimental period. Laser diffraction investigation showed proof of new granules formation with 100-500 μm diameter after only 2 weeks of operation. The treatment performances were satisfactory and more or less similar to the ones obtained from the SBR. Thus, removal efficiencies of 81-93% and 85-94% were observed for chemical oxygen demand and biological oxygen demand, respectively. The N-NH(+)(4) was nitrified with removal efficiencies of 83-99% while the nitrate produced was simultaneously denitrified - highest nitrate concentration determined in the effluent was 4.2 mg/L. The removal efficiency of total nitrogen was between 52 and 80% depending on influent nitrogen load (39.3-76.2 mg/L). Phosphate removal efficiencies ranged between 65 and above 99% depending on the influent phosphate concentration, which varied between 11.2 and 28.3 mg/L.

Continuous flow reactors for cultivating aerobic granular sludge: configuration innovation, principle and research prospect

“…When applying the same H/D selection pressure, the size of granules cultured in CFRs are smaller than those cultured in SBRs (Fig. 9), 17,40,71 which might be attributed to two main reasons. First, under continuous flow conditions, the substrate concentration is low, resulting in their low diffusion.…”

“…Moreover, the polysaccharides (PS) in the EPS secreted by the microorganisms can hinder the oxygen and organic matter transfer into the granules to a certain extent 72 . As a result, granules with large diameters collapse due to the lack of organic matter inside 12,28,71,73 . Second, due to the constant HSF in the CFR, the unsteady collision between aggregates and granules can strip off the fast‐growing filamentous bacteria from their surfaces 9,74 .…”

“…72 As a result, granules with large diameters collapse due to the lack of organic matter inside. 12,28,71,73 Second, due to the constant HSF in the CFR, the unsteady collision between aggregates and granules can strip off the fast-growing filamentous bacteria from their surfaces. 9,74 Although the smallsize granules in CFR were observed to have good stability and biological activity owing to their special structure, however, these granules contain dead as well as living cells evenly distributed inside and outside of granules.…”

The effects of carbon/phosphorus ratio on polyphosphate- and glycogen-accumulating organisms in aerobic granular sludge

“…This technology provides excellent settleability, high biomass concentration, retention of slow-growing microorganisms and resistance to loading and toxic shocks. Therefore, it can be successfully used not only for nitrogen and phosphorus removal Wei et al 2014), but also for industrial wastewater treatment (Bumbac et al 2015) and toxic organic compound degradation (Zhu et al 2014). Community structure in aerobic granules is one of the most interesting topics for researchers (de Kreuk and van Loosdrecht 2004;de Kreuk et al 2007;Lee et al 2010;Weissbrodt et al 2013).…”

Kinetical Parameters Evaluation for Microalgae-Bacteria Granules used for Waste Water Treatment

“…Compared to conventional activated sludge systems, algae based biological wastewater treatment solutions have the advantages of lower costs (due to the lack of aeration need), but the drawback of difficulties in solids separation from the effluent [8]. A solution to this drawback was identified in using granular structures of mixed microalgae and bacteria [9], the granules being obtained by a methodology similar to the one used for activated sludge granules [10,11]. The advantage of this microalgae-bacteria system has been represented by a better harvesting and less expensive aeration (reducing by 60% the energy costs) [12].…”