Purification of domestic wastewater with a sand filter from biogenic elements

Wastewater after biological wastewater treatment very often exceeds the natural ability of reservoirs and watercourses to self-purify. Increasing requirements for the environmental safety of wastewater discharge into natural water bodies determines the particular relevance of improving technological methods and wastewater treatment facilities. In the world practice of post-treatment, preliminary filtration and filtration are rightfully considered one of the most effective methods. At the same time, one of the most common devices used in post-treatment of wastewater are sand filters with granular filter material, the effectiveness of which is often overestimated. The problems of post-treatment of wastewater by filtration using sand filters with a granular filter load are considered, the main problems that arise when using such devices are considered without taking into account the features of post-treatment processes in the presence of organic matter in highly dispersed colloidal forms. Substantiated are additional requirements for reducing the concentration of toxic substances when discharging wastewater into natural water bodies and minimizing changes in the conditions for the development of the biocenosis of these objects. The reasons for the insufficient efficiency of wastewater post-treatment on sand filters, including the reasons for the increase in the content of organic substances in the filtrate after post-treatment, are determined. The main criteria for the effective use of filtering devices in wastewater treatment systems are formulated.