Effect of calcium addition on the formation and maintenance of aerobic granular sludge (AGS) in simultaneous fill/draw mode sequencing batch reactors (SBRs)

Simultaneous nitrogen and phosphorus removal from domestic wastewater in an aerobic granulation system operated at different anaerobic–aerobic durations

“…In most of the previous studies, Ca 2+ is always the focus, as it is deemed to have the most vital role in the granulation process. 64,65 Several advantages such as the improvement of sludge settleability and formation of aerobic granules have been reported after the addition of Ca 2+ . 65,66 However, the higher concentration of Mg 2+ and Fe 3+ measured in all the granular sludge samples during M1, M2 and M3 disprove the previous findings.…”

“…64,65 Several advantages such as the improvement of sludge settleability and formation of aerobic granules have been reported after the addition of Ca 2+ . 65,66 However, the higher concentration of Mg 2+ and Fe 3+ measured in all the granular sludge samples during M1, M2 and M3 disprove the previous findings. Instead of Ca 2+ alone, Mg 2+ and Fe 3+ seemed to play a significant role in granulation as well.…”

Effects of wastewater type on stability and operating conditions control strategy in relation to the formation of aerobic granular sludge – a review

“…To overcome the problems with filamentous bacteria, the growth rate of aerobic granules was controlled by a deliberate increase in the N/COD ratio (Hamza et al 2018). In addition, positive recovery of aerobic granules after exposure to external carbon sources, toxic shock loading, breakage, drying and storage has ascertained its stability (Rollemberg et al 2019;Barros et al 2020). Storage can be performed at low temperatures with the aim of minimizing bacterial growth rates and further enhancing the stability of granules (Chen et al 2019).…”

Removal and recovery of nutrients and value-added products from wastewater: technological options and practical perspective

“…In some previous reports, PHA production has been optimized and demonstrated in full-scale systems. Some examples of such bioprocesses are mentioned as follows: (i) at the Brussels North wastewater treatment plant (WWTP), municipal wastewater was treated for 22 months using a feast-famine strategy, and the biomass accumulated PHA (0.4 g PHA/ gVSS) from volatile fatty acid (VFA) rich fermented sludge at 42 °C, resulting in 70% COD, 60% COD sol , 24% nitrogen, and 46% phosphorus removal [103], (ii) batch fermentation of WWTP sludge at different temperatures of 35, 42, and 55 °C produced VFA in the range of 6.0-9.4 g COD VFA/L and 0.39 g PHA/g VSS, and optimal performance was achieved at 42 °C [104], (iii) maximum PHA content (~ 0.76 g PHA/g VSS) was achieved using fermented wastewater containing ethanol and Plasticicumulans acidovorans was observed as the dominant PHA producing microorganism in an anaerobic bioreactor [105], (iv) in anaerobic fermenters and under alternating anaerobic-aerobic conditions in sequencing batch reactors, VFA (0.64 g COD/g COD), ethanol (022 g COD/g COD) and nitrogen were treated in cycles of 12 h, at an SRT of 24 h, under feast and famine conditions to produce PHAs [106,107], and (v) in another study, two different carbon sources (acetate and wastewater from a soft drinks company) was treated in a bioreactor with carbon/ nitrogen feeding regimes and higher PHA accumulation was observed using acetate (79% mg PHA/mg TSS) compared to soft drink wastewater (25% mg PHA/mg TSS) [108].…”

“…In that study, during PHA production, high COD reduction (75%) was achieved based on phylogenetic profile analysis using 16S rRNA. The authors reported that Firmicutes (71.4%) and Proteobacteria (28.5%) were dominant during PHA accumulation and wastewater treatment [105,107]. Thauera species with aerobic dynamic feeding steps are the dominating microbial species during PHA accumulation (65% DCW) in continuously operated bioreactors [113].…”