Study of the factors effecting the intensive growth of microalgae in the Don River

Summary

The factors enhancing the growth and evolution of the microalgae species composition in the Don River were studied. The effect of phosphorus on the phytoplankton growth rate was proved. The sources of nutrients incoming to the water bodies were analyzed. The factors of anthropogenic eutrophication of water bodies are presented: dyke construction facilitating the reduction of the river flow rate; decay of the vegetation on the lands immersed during the construction of water reservoirs and canals; intensive development of industrial production, agricultural activities, cattle breeding; increase of household and industrial use of synthetic detergents. The strategy of controlling water source bloom is proposed: bloom suppression during its development directly in the water body; the use of biological treatment methods (rehabilitation of the natural biocenosis by seeding certain microalgae species – different Chlorella strains and some species of herbivorous fish, e.g. silver carp; elimination of household and industrial use of phosphorus-containing detergents and their replacement with phosphate free detergents; strengthening of control of nitrogen and phosphorus fertilizer use in agriculture; construction and stepwise reconstruction or upgrade of wastewater treatment facilities that provide for enhanced removal of nitrogen and phosphorous compounds.

Key words

water supply , odor , nitrogen , phosphorous , phytoplankton , microalgae , geosmin , odor components , surface water source

Microalgae as a factor affecting the organoleptic properties of the Don River water

Summary

Stringent hygienic requirements are set to the drinking water quality: epidemiologic, radiation and chemical safety, favorable organoleptic properties. The applicable regulatory documents control a number of parameters; however, other factors exist that affect the water safety and potability. In particular, among these are the amount and species composition of microalgae in water. Massive microphyte growth in surface water sources during water bloom raises serious difficulties in the process of water treatment and severely affects such regulated parameters as color and taste. The laboratory workers at «Rostovvodokanal» JSC have made observations of the microphyte growth in the Don water for 34 years. During this period the evolution of the species composition of microalgae in the Don River has been investigated. It was proved that certain cyanobacteria species affect the organoleptic properties of water. The efficiency of different water treatment methods of odor strength reduction is considered. For the operating water treatment plants the method of water odor strength reduction with the use of rapid gravity filter by natural aeration is suggested.

Key words

water supply , surface water source , water treatment , odor , phytoplankton , microalgae , geosmin , odor components