Some aspects of mathematical modelling of physical, chemical and biological processes in natural leachate treatment systems

Abstract

The problem of natural ecosystems protection against pollution by waste water is very actual
in many countries, including Russia. Yearly water consumption by industry and agriculture of
Russia is about 75 - 80 billion cubic meters. Only 3 - 4 % of total volume of the industrial
and municipal waste water is purified to establish norms. However basic quantity of waste
water is discharged without treatment in natural reservoirs. The most dangerous pollutants of
water are pesticides, nitrates, sulfates, phosphoric substances and salts of heavy metals[!].
The methods of waste water treatment can be divided on two groups: a) the methods of
treatment in artificial plants (for example, aerated lagoons; biological filters and etc.); b) the
methods of treatment in natural systems (for example, fields of irrigation; filtration fields;
wetlands and etc.). The choice of the treatment depends on composition and concentration of
waste substances in leachate and economical expediency.
During projecting and building of any water protection constructions, it is necessary to
develop the theoretical basis. However, the exact calculations of hydrodynamic processes of
convective - diffusive transfer in space and in time and physical-chemical transformation of
non-conservative substances are impossible because of extreme complicity in most cases [2].
Moreover, using of exact analytical models is non-effective because of considerable
inexactitude of initial information. The investigations of processes of the convective -
diffusive transfer and transformation of substance in natural conditions are very complex and
expensive task. Therefore, the methods of mathematical modeling are the most favorable in
this case