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

Abstract

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.

The Impact of Extreme Weather Events on Bacterial Communities and Opportunistic Pathogens in a Drinking Water Treatment Plant

“…There was a clear increase in the percentage of Cyanobacteria in finished water samples during the typhoon event (Figure 2). It has previously been reported that Cyanobacteria can survive in drinking water treatment systems due to their filamentous morphology [54]. In addition, Cyanobacteria have been demonstrated to be prevalent in the reaches of the Yangtze River [55].…”

Physico‐Chemical Processes

“…Among the studied treatment technologies, sedimentation showed the highest health risks of both emission rates and cancer and non-cancer risks to the workers. According to Joh et al (2012), the submerged cement wall of the sedimentation basin in water treatment plant was heavily coated by algal filaments. The matured biofilm could detach from the walls and contaminate the water supplies.…”

Substratum‐Associated Microbiota

“…A strain of the cyanobacterium Synechococcus showed different removal efficiencies of five different sources of nitrogen relevant to wastewaters (Deng et al, 2012). Joh and Lee (2012) recommended the use of antifouling strategies to prevent contamination of water supplies after finding that the algal biofilms found on sedimentation basins in a wastewater treatment plant contained undesirable taxa. A constructed wetland with duckweed and immobilized algae improved water quality and was approved for use in tertiary wastewater treatment (Bouali et al, 2012).…”