Effects of hydraulic and solids retention times on productivity and settleability of microbial (microalgal-bacterial) biomass grown on primary treated wastewater as a biofuel feedstock

Valigore, J.; Gostomski, Peter; Wareham, David G.; O’Sullivan, Aisling D.

doi:10.1016/j.watres.2012.03.023

Cited by 91 publications

(84 citation statements)

References 32 publications

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“…However, open ponds require a large amount of space, and effluent water quality from such ponds is easily affected by loss of algal biomass because of the poor settleability of microalgae [2]. Therefore, research on algae-based wastewater treatment has recently focus on algal photobioreactors, which are effective, require a small footprint, have high algal biomass production, and can be controlled efficiently [9][10][11]. The coexistence of bacteria and microalgae in algal-bacterial systems improves organic matter and nutrient removal where microalgae deliver the oxygen required for heterotrophic and autotrophic bacteria while consuming the CO 2 released by the bacteria [6,12].…”

mentioning

confidence: 99%

“…The algal-bacterial culture is not ready to completely remove ammonia from wastewater at high loads and short HRTs [17]. Biomass recycling (i.e., algal photo-bioreactor) reduces biomass washout, enables the system to be operated at shorter HRTs, and increases biomass [11].…”

mentioning

confidence: 99%

“…Different studies have tested photo-bioreactors utilizing synthetic wastewater containing high and medium concentrations of nutrients or utilizing primary treated wastewater [9][10][11]. To our knowledge, limited studies have been undertaken on the feasibility of an algal photo-bioreactor as a polishing treatment step for secondary treated wastewater [18].…”

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confidence: 99%

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Using an Algal Photo-Bioreactor as a Polishing Step for Secondary Treated Wastewater

Elawwad¹,

Karam²,

Zaher³

2017

Pol. J. Environ. Stud.

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confidence: 99%

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Using an Algal Photo-Bioreactor as a Polishing Step for Secondary Treated Wastewater

Elawwad¹,

Karam²,

Zaher³

2017

Pol. J. Environ. Stud.

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“…Similarly, effects of return activated sludge conditioning on algal cultures for improved wastewater treatment and settleability have been demonstrated (Valigore et al, 2012;Gutzelt et al, 2005). Related studies have focused on using flocculating cultures of algae as potential sources of bioflocculants, or using activated algae recycle to improve algal species domination and settleability within high rate wastewater ponds (McKinney, 1969;Salim et al, 2011;.…”

Section: Figure 221: Photomicrographs Of Results Observed With Diffementioning

confidence: 99%

“…Another study using the same sequencing batch reactor (SBR) approach was operated in New Zealand to reproduce the Germany study (Valigore et al, 2012). The SBRs were operated with a combination of native microalgae to the wastewater treatment oxidation ponds as well as bacteria fed from primary treated wastewater (Valigore et al, 2012).…”

Section: Section 2533 Addition Of Return Activated Sludge (Ras) Tomentioning

confidence: 99%

Improved Microalgal Biomass Harvesting Using Optimized Environmental Conditions and Bacterial Bioflocculants

Manheim¹

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IMPROVED MICROALGAL BIOMASS HARVESTING USING OPTIMIZED ENVIRONMENTAL CONDITIONS AND BACTERIAL BIOFLOCCULANTS DEREK CONTE MANHEIMThe cost and energy balance of microalgae biofuel production is sensitive to the algae harvesting method, among many other factors. Bioflocculation and settling of suspended microalgae cultures is a harvesting method with potentially low cost and energy input. However, bioflocculation (the spontaneous flocculation of algal cells without chemical addition) has not been a reliable process with cultures grown in ponds. To provide insights to help improve algae settling, factors affecting the settling of algae were investigated in the laboratory using pure cultures of two common microalgae species: Scenedesmus sp. and Chlorella vulgaris.Bioflocculation of these algae was studied with and without the addition of bioflocculants produced by the bacterium, Burkholderia cepacia, to improve settling efficiencies. The bioflocculant produced by this bacterium was used in two different EPS produced by the algae, bacteria, and wastewater organisms was quantified using dialysis separation followed by total organic carbon (TOC) analysis.Wastewater organisms were included because wastewater is a potential growth medium for biofuel algae. Improved settling of both species of algae depended on both the quantity and type of EPS (dissolved or capsular) produced by both the bacterial bioflocculant, and the algae themselves. Scenedesmus settled the best during late growth phases while its own EPS production was high, and combined EPS (capsular and dissolved) from B. cepacia improved settling at a higher dosage of bacterial cells to algae (1:2 B. cepacia cells to algae cells). Since Chlorella settling was not improved at later growth stages when its own EPS production was greatest, vi it appears that Chlorella's settling rate was less affected by the production of its own EPS. For Chlorella, B. cepacia EPS addition (capsular and dissolved) was effective only in low doses (1:6 B. cepacia cells to algae cells).Settling results with the addition of bacterial bioflocculants with the pure algae cultures were compared to settling results of lab experiments with algae pondwater sampled from high--rate algae ponds (HRAPs). These algae samples were used to test the addition of return activated sludge (RAS) to improve settling. RAS addition improved the settling of Chlorella, which was the dominant algae species in the HRAP during the time of this study, at two different doses (a ratio of RAS to algae pond water of 1:3 and 1:6).Nutrient deprivation of B. cepacia cells before use as a bioflucculant was found to improve settling for Scenedesmus, especially during early phases of growth when EPS production of Scenedesmus was low. The EPS produced by the starved bacterial cells was about 30% greater than that produced by cultures which were not nutrient--limited. For the bacterial cultures, EPS production peaked at mid stationary phase for non--starved cultures and during early stationary phase for starved cultures...

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Numerical prediction of algae cell mixing feature in raceway ponds using particle tracing methods

Ali

Cheema

Yoon

et al. 2014

Biotech & Bioengineering

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In the present study, a novel technique, which involves numerical computation of the mixing length of algae particles in raceway ponds, was used to evaluate the mixing process. A value of mixing length that is higher than the maximum streamwise distance (MSD) of algae cells indicates that the cells experienced an adequate turbulent mixing in the pond. A coupling methodology was adapted to map the pulsating effects of a 2D paddle wheel on a 3D raceway pond in this study. The turbulent mixing was examined based on the computations of mixing length, residence time, and algae cell distribution in the pond. The results revealed that the use of particle tracing methodology is an improved approach to define the mixing phenomenon more effectively. Moreover, the algae cell distribution aided in identifying the degree of mixing in terms of mixing length and residence time.

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Effects of hydraulic and solids retention times on productivity and settleability of microbial (microalgal-bacterial) biomass grown on primary treated wastewater as a biofuel feedstock

Cited by 91 publications

References 32 publications

Using an Algal Photo-Bioreactor as a Polishing Step for Secondary Treated Wastewater

Using an Algal Photo-Bioreactor as a Polishing Step for Secondary Treated Wastewater

Improved Microalgal Biomass Harvesting Using Optimized Environmental Conditions and Bacterial Bioflocculants

Numerical prediction of algae cell mixing feature in raceway ponds using particle tracing methods

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