Enrichment of activated sludge in a sequencing batch reactor for polyhydroxyalkanoate production

Majone, Mauro; Beccari, M.; Gregorio, Simona Di; Dionisi, Davide; Vallini, Giovanni

doi:10.2166/wst.2006.379

Cited by 27 publications

(11 citation statements)

References 17 publications

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“…The obtained yields of polymer on substrate consumed were fallen in the same range with those obtained by Majone et al [6] (0.37-0.41 g COD PHA g -1 COD S), Dionisi et al [3] (0.32-0.66 g COD PHA g -1 COD S), Serafim et al [8] (0.37-0.83 g COD PHA g -1 COD S), and were slightly higher than those observed by Bengtsson et al [9] (0.08-0.27 g COD PHA g -1 COD S). Increase in storage yield for increased acetate concentrations were observed before [8].…”

Section: Effect Of Substrate Loading On Polymer Accumulationsupporting

confidence: 87%

“…Under transient conditions, such as feast/famine or anaerobic/aerobic, growth becomes unbalanced and PHA accumulating ability of mixed cultures increase. A three-step process is proposed by many researchers [3,6,7] for PHA production, of which first step was production of organic acids. The second step of the process was enrichment and production of biomass with high storage ability.…”

Section: Introductionmentioning

confidence: 99%

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Effect of nitrogen limitation on enrichment of activated sludge for PHA production

Başak

İnce

Artan

et al. 2011

Bioprocess Biosyst Eng

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Polyhydroxyalkanoates (PHA) are good candidates to plastics because of their material properties similar to conventional plastics and complete biodegradability. The use of activated sludge can be a cheaper alternative to pure cultures for PHA production. In this study, effect of nitrogen limitation during acclimatization period of biomass on production of polyhydroxyalkanoate was investigated. Activated sludge was selected in two sequencing batch reactors operated with and without nitrogen limitation. Batch tests were performed to examine polymer productions of activated sludges acclimatized to different nitrogen regimes. Responses of biomass to different organic loading rates, organic acids, and carbon to nitrogen (C/N) ratios were studied by determining specific polymer storage rate, polymer storage yield, and sludge polymer content of biomasses. Results obtained from batch experiments showed that concentrations of polymer accumulated by two different sludges increased directly with initial substrate concentration. Observed highest polymer yields for the biomasses enriched with and without nitrogen deficiency were 0.69 g COD PHA g(-1) COD S and 0.51 g COD PHA g(-1) COD S, and corresponding polymer contents of biomasses were 43.3% (g COD PHA g(-1) COD X) and 38.3% (g COD PHA g(-1) COD X), respectively. Polymer yields for both biomasses decreased with substrate shift however, biomass enriched with nitrogen deficiency adapted well to acetate-propionate mixture. The results presented in this study showed that polymer storage ability of biomass was improved more under dynamic conditions with nitrogen deficiency when compared to that without nitrogen deficiency. Limiting ammonia availability during batch experiments also caused higher polymer production by suppressing growth, as well as during enrichment of biomass.

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Section: Effect Of Substrate Loading On Polymer Accumulationsupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Effect of nitrogen limitation on enrichment of activated sludge for PHA production

Başak

İnce

Artan

et al. 2011

Bioprocess Biosyst Eng

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“…However, on operational day 271 Meganema decreased to 4.95–6.93% of the population, while Zoogloea was the only genus >10% (and only in reactor AE-12). Though Meganema has been observed in other ADF enrichment SBRs wherein PHA was synthesized in excess (Hanson et al 2016, Majone et al 2006), including with fermented dairy manure as a substrate (Hanson et al 2016), the high abundance of Meganema was in contrast to other ADF studies that reported dominant genera including Thauera (Albuquerque et al 2013, Carvalho et al 2014, Lemos et al 2008), Azoarcus (Bengtsson et al 2010a, Bengtsson et al 2010b, Waller et al 2012), or Plasticicumulans (Jiang et al 2011, Jiang et al 2012, Marang et al 2013). Additionally, most of the genera identified in this study present at >1% (e.g., Leadbetterella , Haliscomenobacter, Aquabacterium, Luteimonas, Hydrogenophaga, Thermomonas, Mycobacterium, Filomicrobium, Dokdonella, Hylemonella, Pseudofulvimonas, Mesorhizobium, Hyphomicrobium, Parvibaculum, Brevundimonas, Novosphingobium, Sphingomonas, Altererythrobacter, Xanthobacter, Gp6, and Gp4 ) have not been reported in other ADF investigations; Amaricoccus and Paracoccus have only been nominally present in ADF systems (Lemos et al 2008, Queirós et al 2014).…”

Section: Resultsmentioning

confidence: 81%

Polyhydroxyalkanoate synthesis by mixed microbial consortia cultured on fermented dairy manure: Effect of aeration on process rates/yields and the associated microbial ecology

2016

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Polyhydroxyalkanoates (PHAs) are biodegradable polymers that can substitute for petroleum-based plastics in a variety of applications. One avenue to commercial PHA production involves coupling waste-based synthesis with the use of mixed microbial consortia (MMC). In this regard, production requires maximizing the enrichment of a MMC capable of feast-famine PHA synthesis, with the metabolic response induced through imposition of aerobic-dynamic feeding (ADF) conditions. However, the concept of PHA production in complex matrices remains unrefined; process operational improvements are needed, along with an enhanced understanding of the MMC. Research presented herein investigated the effect of aeration on feast-famine PHA synthesis, with four independent aeration state systems studied; MMC were fed volatile fatty acid (VFA)-rich fermented dairy manure. Regardless of the aeration state, all MMC exhibited a feast-famine response based on observed carbon cycling. Moreover, there was no statistical difference in PHA synthesis rates, with qPHA ranging from 0.10–0.19 CmmolPHA gVSS−1 min−1; VFA uptake rates exhibited similar statistical indifferences. PHA production assessments on the enriched MMC resulted in maximum intracellular concentrations ranging from 22.5–90.7% (mgPHA mgVSS−1); at maximum concentration, the mean hydroxyvalerate mol content was 73±0.6%. While a typical feast-famine dissolved oxygen (DO) pattern was observed at maximum aeration, less resolution was observed at decreasing aeration rates, suggesting that DO may not be an optimal process monitoring parameter. At lower aeration states, nitrogen cycling patterns, supported by molecular investigations targeting AOBs and NOBs, indicate that NO2 and NO3 sustained feast-famine PHA synthesis. Next-generation sequencing analysis of the respective MMC revealed numerous and diverse genera exhibiting the potential to achieve PHA synthesis, suggesting functional redundancy embedded in the diverse MMC. Ultimately, results demonstrate that aeration can be controlled in waste-based ADF systems to sustain PHA production potential, while enriching for a diverse MMC that exhibits potential functional redundancy. Reduced aeration could also enhance cost competitiveness of waste-based PHA production, with potential further benefits associated with nitrogen treatment.

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“…(30,31) were found able to store PHA in axenic cultures. In relation to FlaVobacterium sp., it has been isolated from activated sludge (32) and has been detected, by this research group, in a different mixed culture showing PHA storage response under feast and famine regime (27). The Cytophaga-FlaVobacterium group has been studied in relation to PHA production under anaerobic/aerobic conditions (33).…”

Section: Effect Of Length Of Cycle On Storage Versus Growthmentioning

confidence: 96%

Effect of the Length of the Cycle on Biodegradable Polymer Production and Microbial Community Selection in a Sequencing Batch Reactor

et al. 2007

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The effect of the length of the cycle on the enrichment and selection of mixed cultures in sequencing batch reactors (SBRs) has been studied, with the aim of biodegradable polymers (namely, polyhydroxyalkanoates (PHAs)) production from organic wastes. At a fixed feed concentration (20 gCOD/L) and organic loading rate (20 gCOD/L/day), the SBR was operated at different lengths of the cycle, in the range 1-8 h. Process performance was measured by considering the rates and yields of polymer storage and of the competing phenomenon of growth. The selected biomass was enriched with microorganisms that were able to store PHAs at high rates and yields only when the length of the cycle was 2 or 4 h, even though in these conditions the process was unstable. On the other hand, when the length of the cycle was 1 or 8 h, the dynamic response of the selected microorganisms was dominated by growth. The best process performance was characterized by storage rates in the range 500-600 mgCOD/gCOD/h and storage yields of 0.45-0.55 COD/COD. The corresponding productivity of the process was in the range 0.25-0.30 gPHA/L/h, the highest values obtained until now for mixed cultures. The microbial composition of the selected biomasses was analyzed through denaturing gradient gel electrophoresis (DGGE) and reverse-transcriptase denaturing gradient gel electrophoresis (RT-DGGE). The instability of the runs characterized by high storage rate was associated with a higher microbial heterogeneity compared to the runs with a stable growth response.

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Enrichment of activated sludge in a sequencing batch reactor for polyhydroxyalkanoate production

Cited by 27 publications

References 17 publications

Effect of nitrogen limitation on enrichment of activated sludge for PHA production

Effect of nitrogen limitation on enrichment of activated sludge for PHA production

Polyhydroxyalkanoate synthesis by mixed microbial consortia cultured on fermented dairy manure: Effect of aeration on process rates/yields and the associated microbial ecology

Effect of the Length of the Cycle on Biodegradable Polymer Production and Microbial Community Selection in a Sequencing Batch Reactor

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