Microbiological aspects of natural underground water deironing and demanganation

Summary

The purpose of the presented work was studying the role of microorganisms that participated in the transformation of iron and manganese compounds in technogenic drinking water purification systems. The studies were carried out at the water treatment facilities of the Novourengoisk gas chemical complex and of Iuzhnyi settlement of Barnaul city. At different stages of water treatment process alongside with studying the composition of bacterial communities and number of different physiological and taxonomical groups of microorganisms performing bidirectional processes of Fe and Mn compounds oxidation and recovery the analysis of physical and chemical parameters of the studied water (concentrations of O₂, CO₂, CH₄, NH₃, soluble forms of Fe²⁺ and Mn²⁺, pH, temperature, oxidability) was carried out with an account of the observation seasonality. It is shown that during the operation of a single-stage water purification system the filters uploaded with inert filtering material are functioning as biofilters, and transformation of Fe and Mn compounds in technogenic water purification systems is provided by the microorganism activity. Precipitated forms of Fe and Mn sludge are represented by exclusively biogeneous (bacterial) structures of iron- and manganese-oxidizing bacteria. Depending on the physical and chemical conditions the latter are presented mostly either by Gallionella species (the Novourengoist water treatment facilities) or by filamentous ferrobacteria Crenothrix and Siderocapsa – Arthrobacter unicells. The efficiency of biological deironing and demanganation of underground water during single-stage purification process is determined by the physical, chemical and microbiological properties of the raw water and depends on the conditions required for microorganism evolution that are provided by the adequate choice of the process equipment and operation modes.

Key words

ground water , single-stage deironing and demanganation , autotrophic ferrobacteria , heterotrophic microorganisms

Special aspects of choosing the methods of single-stage deironing and demanganization of underground waters

Summary

Special aspects of choosing the methods of deironing and demanganization of underground water depending on the physical, chemical and microbiological properties in a single-stage water treatment process are described. The method of removing excessive concentrations of iron and manganese shall be chosen in the process of studies at the pre-project phase of front-end engineering and design. For underground water containing apart from manganese also iron mainly as oxides, the physical and chemical methods that combine pretreatment of raw water with a strong oxidant (sodium hypochlorite, ozone etc.) and subsequent filtration through chemically active material are most acceptable. Biological method of water deironing and demanganization is conditioned by the presence of microbiocenosis with the life cycle associated with the processes of iron and manganese oxidation in the ecosystem of the treatment facilities. The procedures of filter media inoculation with Crenothrix and Siderocapsa – Arthrobacter bacterial cultures are described. Based on the experience of operating «Vostochnyi-2» facilities for underground drainage water deironing and demanganization with a capacity of 25,000 m3/day in Krasnodar the use of the physical and chemical method of water treatment was justified. The results of operating a water treatment plant in «Yuzhnyi» settlement of Barnaul city show the efficiency of the biological method of underground water deironing and demanganization conditioned by the presence of microbiocenosis with the life cycle associated with the processes of iron and manganese oxidation in the ecosystem of the treatment facilities.

Key words

ground water , iron , manganese , iron bacteria , single-stage deironing and demanganation , catalytically active filtering material