Bioflocculation for Control of Wastewater Pond Microalgae

Frost, Daniel Thomas

doi:10.15368/theses.2008.39

Cited by 4 publications

(10 citation statements)

References 51 publications

(162 reference statements)

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“…Your expertise, availability, and friendship will always be cherished. (Frost 2008). Pond systems are usually comprised of a series of ponds that are 1-4 m deep and mixed only by wind or influent flow momentum.…”

Section: Acknowledgmentsmentioning

confidence: 99%

“…Although pond systems offer several advantages, many municipalities upgrade existing pond systems with mechanical technologies, such as activated sludge, because activated sludge systems tend to have more consistent treatment performance than ponds, while occupying less land area (Frost 2008). The most basic need for improvement in pond systems is controlling effluent suspended solids concentrations, which are often higher than desired discharge limits.…”

Section: List Of Tablesmentioning

confidence: 99%

“…The addition of RAS in high-rate ponds has been explored in past Cal Poly master's thesis projects (Frost 2008, Podevin 2011). The addition of RAS has been hypothesized to encourage bioflocculation of algae and bacteria.…”

Section: List Of Tablesmentioning

confidence: 99%

“…In addition to lower energy use, properly designed natural systems are also considered more aesthetically pleasing than activated sludge facilities. Since algae cannot produce oxygen levels comparable to those in continuously aerated basins, the land requirements in pond systems often range from 50-500 times that of activated sludge aeration (Frost 2008). …”

Section: Natural Biological Treatment Systemsmentioning

confidence: 99%

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Bioflocculation and CO2 Supplementation in Wastewater Treatment by Algal High-Rate Ponds

Ward¹

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Section: Acknowledgmentsmentioning

confidence: 99%

Section: List Of Tablesmentioning

confidence: 99%

Section: List Of Tablesmentioning

confidence: 99%

Section: Natural Biological Treatment Systemsmentioning

confidence: 99%

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Bioflocculation and CO2 Supplementation in Wastewater Treatment by Algal High-Rate Ponds

Ward¹

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“…Traditionally in wastewater treatment plants, produced biomass is settled out of water through gravity-operated clarifiers. However one of the key factors required for effective settling of biomass is flocculation (Frost, 2008).…”

Section: Algal Harvestingmentioning

confidence: 99%

Production and Harvest of Microalgae in Wastewater Raceways with Resource Recycling

Roberts¹

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Microalgae can be grown on municipal wastewater media to both treat the wastewater and produce feedstock for algae biofuel production. However the reliability of treatment must be demonstrated, as well as high areal algae productivity on recycled wastewater media and efficient sedimentation harvesting. This processes was studied at pilot scale in the present research.A pilot facility was operated with nine CO 2 -supplemented raceway ponds, each with a 33-m 2 surface area and a 0.3-m depth, continuously from March 6, 2013 through September 24, 2014.The ponds were operated as three sets of triplicates with two sets continuously fed primaryclarified municipal wastewater at either a 2-day or 3-day hydraulic residence time (HRT), and one set fed the clarified effluent of the 3-day pond set. This second pond-in-series was operated with a 3-day HRT.Areal biomass productivity is reported as gross and net, the former based only on biomass in the pond effluents and the latter subtracting the volatile suspended solids in the influent from those in the effluent. An estimate was also made of autotrophic biomass productivity, as differentiated from heterotrophic growth.v Over a year, net productivity averaged 83 metric tons per hectare per year (MT/ha-yr) for the 2-day HRT ponds, 52 MT/ha-yr for the 3-day HRT ponds, and 44 MT/ha-yr for the 3-day HRT ponds receiving clarified effluent of the first set of 3-day HRT ponds (i.e., recycled water). The lower net productivity of the pond receiving water recycling was attributed to two factors. First, the relatively high influent suspended solids concentrations were subtracted from the effluent suspended solids concentrations before net productivity was calculated. Second, the recycled water contained less soluble organic matter than the primary-clarified wastewater leading to less heterotrophic biomass production. The accumulation of inhibitory allelochemicals is a possible third cause of lower productivity, but no specific information was collected on allelopathy.Algae were harvested from pond effluent by sedimentation, with harvest efficiency most affected by the extent of natural bioflocculation occurring in the ponds. Some forms of bioflocculation are thought to be mediated by bacteria, which often make-up a substantial fraction of the settled flocs. Pond samples settled in 1-L Imhoff cones averaged <20 mg/L total suspended solids after 24 hours of settling; but all ponds fell short of meeting an averaged <30 mg/L total suspended solids after a 2 hour interval which would be ideally achieved for wastewater effluent. No relationship was seen between settling performance and the bacterial content of flocs.Soluble carbonaceous biochemical oxygen demand (scBOD 5 ) removal by the raceway ponds was sufficient to meet wastewater treatment requirements year around. Influent scBOD 5 concentrations averaged 83 mg/L, and the effluent averaged 5.1 mg/L and 4.2 mg/L for the 2-day and 3-day HRT pond sets, respectively.The variable with the greatest influence on productivity in all pond sets, ...

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Settling and bioflocculation of two species of algae used in wastewater treatment and algae biomass production

Manheim

Nelson

2013

Env Prog and Sustain Energy

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The settling and bioflocculation of two strains of algae were investigated in the laboratory to provide insights to help improve algae settling in large-scale, algae-based wastewater treatment systems with simultaneous algae biofuel production. Energy-efficient algae harvesting methods are needed for cost-competitive production of biofuels from algae. The use of bacterially derived exudates (bioflocculation) is promising, but its use in high-rate algae pond (HRAP) wastewater systems has not yielded consistently reliable settling. The settling of the algae species Scenedesmus sp. and Chlorella vulgaris was investigated in the laboratory with and without cultures of the bacterium Burkholderia cepacia to investigate environmental effects on the settling of pure algal cultures and to examine possible bioflocculation by bacteria and bacterial exudates. Scenedesmus sp. and C. vulgaris responded in opposite ways to changes in operating conditions such as culture age and bioflocculation. Scenedesmus sp. settled better in later stationary growth stages, while C. vulgaris settled better in its early exponential growth phase. Scenedesmus sp. settling was improved by bioflocculation during early exponential and late stationary growth stages, but not during early stationary growth. Scenedesmus sp. responded better to B. cepacia cells plus filtrate (filtered bacterial broth) than to filtrate addition alone. In contrast, C. vulgaris settling was not improved via bioflocculation with neither the addition of B. cepacia cells nor filtrate at any growth stage. Longer contact time between the algae cells and bioflocculants improved the settling of Scenedesmus sp., but not the settling of C. vulgaris. Observed differences in settling and bioflocculation of the two algae species were attributed to differences in algal cell size and shape, culture density, and exudate type (i.e., capsular versus dissolved EPS). The widely different settling behavior of the two species of algae used in this research may explain the often varied results observed with mixed cultures in algae wastewater ponds. V C 2013 American Institute of Chemical Engineers Environ Prog, 32: 946-954, 2013

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Bioflocculation for Control of Wastewater Pond Microalgae

Cited by 4 publications

References 51 publications

Bioflocculation and CO2 Supplementation in Wastewater Treatment by Algal High-Rate Ponds

Bioflocculation and CO2 Supplementation in Wastewater Treatment by Algal High-Rate Ponds

Production and Harvest of Microalgae in Wastewater Raceways with Resource Recycling

Settling and bioflocculation of two species of algae used in wastewater treatment and algae biomass production

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