Water purification with the use of granulated activated carbon at the Southern Waterworks

Summary

The results of multi-year studies show that the water quality of the Neva River is deteriorating in relation to organoleptic properties. To ensure high quality drinking water the advanced water treatment technologies including coagulation, sedimentation, oxidation and adsorption were introduced at the K-6 filter block of the Southern Waterworks. Chemviron Carbon granulated activated carbon was used as sorption medium. It is shown that the use of additional carbon medium at the final stage in the sand filters increases significantly the efficiency of treatment. Sampling units were designed, sampling techniques were developed, and samples of the carbon and water from the filtering sorption medium were taken. By analyzing iodine number and sorption activity for methylene blue of activated carbon and permanganate oxidizability of water the life durability of carbon was determined which under the given operation conditions was 3–3.5 years. The perspectivenes of high-temperature carbon reactivation is shown. Herewith the technical-and-economic assessment of the reactivation cost is 50–60% of the new carbon cost.

Key words

sorption , granulated activated carbon , reactivation , sampling unit

Regeneration of the sorption capacity of granulated activated carbon

Summary

The analysis of the Neva River water quality parameters shows the changes in the chemical, biological and physical composition of the water under the environmental impact. Microbial as well as organic chemical pollutants get into the water source. Among all the monitored drinking water quality indicators the customers recognize bad smell at once. Double-layer filter bed (sand and activated carbon) provides for the efficient removal of colloid compounds and finely dispersed particles with low hydraulic size. Herewith the granulated carbon layer traps various organic compounds and water soluble oil products. Owing to the process of chemical compound oxidation (destruction) by ozonation and subsequent treatment with sorbent the chemical substances that flavor water with taste and smell are removed; as well as the color and permanganate value are lowered. When using powdered activated carbon at the filtration facilities achieving the treatment efficiency and estimation of the costs are required because in case chlorine-containing chemical is added to the water immediately after activated carbon is introduced the consumption of disinfection chemicals significantly increases. Thus, it is very important to include a sorption unit with granulated activated carbon to improve the reliability of water treatment. The efficiency of water treatment with granulated activated carbon was tested in K-6 unit at the Southern Waterworks of Saint-Petersburg. The evaluation of the water quality parameters after carbon reactivation was made. Reactivation of Filtrasorb TL 830 activated carbon under the selected process conditions provides for the satisfactory regeneration of the material sorption capacity while preserving its mechanical properties.

Key words

potable water , water treatment , powdery activated carbon , granulated activated carbon , reactivation , sorbent , sorption