Problematic algae in the sedimentation and filtration process of water treatment plants

Joh, Gyeongje; Choi, Yang Soon; Shin, Jae-Ki; Lee, Ji-Young

doi:10.2166/aqua.2011.035

Cited by 43 publications

(21 citation statements)

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“…The efficiency of this settling rate is likely to be at least partly dependent on the shape of the diatom. One report documented that elongated pennate diatoms were problematic in a water treatment facility because they did not settle well in the facility's sedimentation tanks, causing clogs in the downstream sand filters [143]. However, diatom cell walls are covered with organic material having properties similar to other algal cell walls, and respond well to both cationic and anionic chemical flocculation treatments [144].…”

Section: Settling Rates Flocculation Harvesting and Shear Stressmentioning

confidence: 99%

The place of diatoms in the biofuels industry

et al. 2012

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Section: Settling Rates Flocculation Harvesting and Shear Stressmentioning

confidence: 99%

The place of diatoms in the biofuels industry

et al. 2012

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“…Aside from esthetic problems, algal assemblages can clog the filter media, increase the head loss, shorten the run times of sand filters, and increase the requirements for backwashing (Lyons et al 2007). Normally, sand filters are backwashed every 2-3 days, but with algal clogging, backwashing can be required every few hours (Jun et al 2001;Joh et al 2011). Accumulated algal scums in the surface water of FBs have to be eliminated more frequently during the spring and autumn, when periphyton biomass is greatest.…”

Section: Discussionmentioning

confidence: 99%

Cyanobacterial biofilms on sedimentation basins in a water treatment plant in South Korea

Joh

Lee

2011

J Appl Phycol

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We studied periphytic algal biofilms that formed in the sedimentation basins (SBs) of a water treatment plant (WTP) in South Korea. The submerged cement wall of the basin was heavily coated by mats of algal filaments, which resembled a small sheet of carpet. These biofilms were more common in the dry season (spring and autumn), than the rainy season (summer) and winter. Oscillatoria and Phormidium (Cyanobacteria) were predominant in the biofilm of the SB walls, where the water was stagnant. Lyngbya (Cyanobacteria) and Oedogonium (Chlorophyta) were dominant on the walls of overflow weirs and troughs of the SB, where there was a substantial current. As the biofilm matured, the assemblages were detached from the walls and floated as "scum" on the water, causing contamination. Many factors control the development of cyanobacterial biofilms on the walls of WTPs, including the nutrient levels of the raw water, and interstitial or pore water of biofilm assemblages, temperature, and irradiance. We isolated and grew unialgal cultures of the five most important cyanobacteria of the WTP biofilm. Oscillatoria splendida strongly produced the musty odor from the cultures. We suggest implementation of antifouling strategies to reduce the formation of biofilm on the wall and contamination of water supplies.

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“…Because the density of the algae is too low to be effectively settled in the sedimentation process, the burden on the operation of the filtration unit in water treatment plants (WTPs) is significantly increased. Furthermore, the algae may clog the filter and consequently slow down or stop the filtration process [1]. While preoxidation prior to coagulation-sedimentation process is commonly adopted to remove algae from raw water, it is difficult to effectively remove strip or needle algae before it enters the deep-bed filter in the WTPs, because the setting rate of these algae is rather poor [2].…”

Section: Introductionmentioning

confidence: 99%

“…While preoxidation prior to coagulation-sedimentation process is commonly adopted to remove algae from raw water, it is difficult to effectively remove strip or needle algae before it enters the deep-bed filter in the WTPs, because the setting rate of these algae is rather poor [2]. As a result, the deep-bed filter is easily clogged with these algae, which significantly impedes its operation, resulting in an increased frequency of backwashing [1]. Therefore, optimum pretreatment, such as oxidation and coagulation, is a crucial step in reducing algal interference in the operation of WTPs.…”

Section: Introductionmentioning

confidence: 99%