Production of drinking water from raw water containing cyanobacteria—pilot plant studies for assessing the risk of microcystin breakthrough

Abstract

Toxins in cyanobacteria are a recognized risk in the treatment of drinking-water treatment. Cyanotoxins can occur in two modifications: cell bound and dissolved in water. The process of toxin release may occur naturally, but it also may be induced through the processes of drinking-water treatment. Both causes of release are relevant to the safety of drinking water. This study investigated cyanotoxin release and elimination through different treatment trains in systematic pilot-scale studies with water from the Weida Reservoir, in Thuringia, Germany. The Weida Reservoir is a dimictic mesoeutrophic reservoir typical for a number of mountainous areas in Europe, with Planktothrix rubescens as the dominant phytoplankton species, and shows a characteristic seasonal pattern of population development and microcystin occurrence. To assess the risk of microcystin breakthrough, the pilot-scale results as well as results of laboratory-scale experiments were used for developing a kinetic model of toxin release in relation to elimination. By calculating removal efficiency of total microcystins (cell bound and dissolved) for different treatment trains, raw water quality was related to the quality targets for finished water, and breakthrough risks could be calculated for given treatment trains and varying cyanobacterial population densities in the reservoir.

Simultaneous removal of multiple odorants from source water suffering from septic and musty odors: Verification in a full-scale water treatment plant with ozonation

“…Organic particles including algal cells are trapped in flocs during coagulation, and then settle down in the bottom of settlers until the discharge of sludge. Algal cells trapped in sludge may rupture when the sludge residence time in the sedimentation tank was long enough (sludge was removed once a day from the sedimentation tank) or the sedimentation sludge removal was incomplete, releasing the intracellular odorants (Schmidt et al, 2002(Schmidt et al, , 2009Kommineni et al, 2009;Ho et al, 2012;Li et al, 2012aLi et al, , 2012bZamyadi et al, 2012Zamyadi et al, , 2013Zamyadi et al, , 2014Ho et al, 2013). On the other hand, anaerobic digestion could easily take place in sedimentation sludge because of the presence of algal cells and other organic materials.…”

Occurrence and elimination of cyanobacterial toxins in drinking water treatment plants

“…The value of 0.1 Ag/l was originally used for pesticides, but nowadays it is applied as a provisional value for other toxins whose character is unknown or as a quality target designed to be well below the concentration derived from health criteria (Schmidt et al, 2002). step, i.e., the slow sand filter, also functions as a substrate for bacteria, which detoxify and clean the treated water similarly to natural water cleaning conditions.…”

Assessment of the Water Treatment Process’s Empirical Model Predictions for the Management of Aesthetic and Health Risks Associated with Cyanobacteria

“…Concentrations in the raw water can reach over 200 ng/L, with the concentration of dissolved geosmin less than 50% of the total. The ratio of dissolved and intracellular metabolites plays an important role in the performance of treatment processes [22][23][24][25][26][27]. Treated water geosmin concentrations rarely exceed the 10 ng/L goal; however, during the summer of 2016/2017, high concentrations of geosmin were breaking through the plant at times.…”