Effect of dispersion characteristics of suspended solids
on the parameters of surface runoff treatment

Summary

Quantitative and dispersion characteristics of insoluble pollutants in rainfall and snow-melt water and its effect on the parameters of removing pollutants from water by sedimentation, chemical free and chemical filtration are considered. It is shown that the concentration of suspended solids in surface runoff multiply exceeds the concentration of oil products whereupon these pollutants are present in the form of two-component particles. In the particles oil products or inorganic admixtures can be adsorbed components, and during sedimentation of surface runoff suspended solids and oil products are being removed synchronically. The concentration and kinetic consistency of suspended solids from residential areas are lower than those from highways; which reduces the sedimentation time in the storage settling tank and concentration of pollutants in settled water. During 1–3 days of settling tank empting monotonic reduction of suspended solids concentration in settled water before filtration occurs. Fluctuation range depends on the sedimentation time in the settling tank, initial suspended solids concentration and tank empting time. The use of coagulants before filtration of settled surface runoff from highways provides for improving the treatment efficiency and obtaining sustained quality of filtered water.

Key words

settling , suspended substances , oil products , hydraulic size , surface runoff , filtration , kinetic consistency , coagulants , storage settling tank

Principal directions for improving process flow schemes and designs of units for surface runoff treatment

Summary

The issues of surface runoff treatment from the territories of communities of various functional purposes are considered, in particular, the improvement of process flow schemes and designs of low-capacity local treatment facilities of flow-through or storage type, that discharge the effluents into the public wastewater disposal systems and water bodies. The features of the organization of systems for the surface runoff disposal and treatment, as well as the provisions of the water and environmental legislation of the Russian Federation and design code that have come into force over the past 2 years are given. It is noted that in the context of the transition of the federal regulation of wastewater discharge to technological regulation based on the best available technologies, the scope of small-capacity facilities of flow-through and storage type tends to expand. This is due to the fact that the customers are allowed to use them while discharging surface runoff into the public wastewater disposal systems of the communities, provided the quality of effluents received by these systems comply with the regulatory requirements. Principal schemes of the flow-through and storage type facilities for surface runoff treatment in combination with tertiary treatment plants are given. Casings of underground tanks and vessels, including improved flow-through units for the primary mechanical treatment of surface runoff, are made of fiberglass pipes of increased ring stiffness and durability.

Key words

mechanical treatment , thin layer sedimentation , surface runoff , wastewater management systems , storage settling tank , treatment facilities of flow-through and storage type , filtration-sorption tertiary treatment , open hydraulic cyclone , fiberglass pipes

Engineering and economical comparison of the surface runoff disposal options

Summary

The results of an engineering and economical comparison of two surface runoff disposal options are presented. Option 1 involves the use of treatment facilities discharging the effluent into a water body; option 2 involves the use of a storage tank followed by the discharge of surface runoff into a public sewer. The comparison was based on life-cycle costs over a 25-year operational period for new construction of treatment facilities with a capacity of 250 m³/h and storage tanks with a capacity of 6,000 m³. Option 2 involving surface runoff discharge into a public sewer, was determined to be the most cost-effective, with an economic efficiency of 214.75 mln rubles. This 46.59% economic efficiency is achieved by reducing capital expenditures. Furthermore, one of the main expenditure items is the sewer user fee that virtually offsets the difference in operating costs.

Key words

surface runoff , treatment facilities , life cycle cost , storage settling tank , domestic wastewater disposal system