CS239712B1 - A method of biological incorporation of sand filters used to remove suspended matter in drinking water treatment, to remove ammonium ions, nitrites and manganese - Google Patents

Abstract

The purpose of the invention is a method of biological incorporation of sand filters used for the removal of suspended substances in the treatment of drinking water for the removal of ammonium ions, nitrites and manganese. The stated purpose is achieved by treating the sand filter with water containing ammonium ions, nitrites, manganese, chlorine, iron and oxygen in concentrations according to the subject of the invention at a temperature of 4 to 16 C until the water emerging from the filter reaches a concentration of ammonium ions, nitrites and manganese of 0 to 0.1 mg.1, while all the water before reaching the stated concentration goes into the recipient. For a new sand filter, complete biological incorporation takes up to 7 months, for filter sand already used for the filtration of suspended substances in ferric and manganese waters, only a few days are sufficient for incorporation, and the described filtration method can be used for both open and pressure filters up to a filtration speed of 8 m.hour.

Description

BACKGROUND OF THE INVENTION The present invention relates to a method for the biological incorporation of sand filters used up to now for the removal of suspended matter in the treatment of drinking water, for the removal of ammonium ions, nitrites and manganese from the treated water.

Up to now, ozone oxidation has been used to treat water, especially those with a high content of iron, manganese, and ammonium compounds, to ensure removal of iron, manganese, and ammonium compounds from the water using subsequent sand filtration through burel.

This method causes difficulties in operating conditions and is both investment and energy intensive. It is also known to remove ammonia or nitrites using biologically activated carbon or granular activated carbon filters or ion exchange filtration. These methods are transportable and expensive.

The above drawbacks are overcome by the invention, which is based on a method for the biological incorporation of sand filters used to remove suspended solids in the treatment of drinking water also for the removal of ammonium ions, nitrites and manganese by treating the sand filter with water containing ammonium ions. nitrates, manganese, trace amounts of chlorine, iron up to 1.5 mg.I ^- *, saturated with oxygen at a temperature of 4 to 16 ° C until the water leaving the filter reaches the concentration of ammonium ions, nitrites and manganese 0 to 0.1 mg.i &^lt; ^{-1 &gt}; wherein all the water is mixed or mixed with other water before reaching said conaentration.

The advantage of the method of biological treatment of sand filters for removal of ammonium ions, nitrites and manganese according to the invention is a reliable and permanent removal of ammonium ions, nitrites and manganese up to a concentration of 0 to 0.1 mg.I ^- furthermore low operating and investment costs compared to previous methods and a low probability of forming toxic side compounds.

The consumption of chlorine dosed downstream of the filters to treat the treated water is reduced by utilizing the method of the invention by 30% against chlorination upstream of the filters. The free chlorine content of the treated water increases and is more stable in the water network.

Examples

Water with an initial concentration of 30 mg.l -1 iron, 1.4 mg.l -1 manganese and 2.8 mg.l -1 ammonia was pretreated by aeration, coagulation and sedimentation. The lack of oxygen was replaced by the chlorine dosing, but only in the amount necessary to precipitate soluble iron salts into insoluble hydroxide fonts. The pre-treated water reached a pH of 7.8 to 8.1, the ammonium ions contained 2.3 mg.i ", nitrites 0.12 " mg.l ", nitrates 0, manganese 0.25 mg.1 ". iron 1.5 mg.l -1, trace amounts of chlorine, were saturated with oxygen at 9 ° C.

The water of this concentration was applied to sand pressure filters, which were stretched by the unused filter sand until the water leaving the filter reached an ammonium ion concentration of 0 to 0.1 mg.l -1, nitrites 6.2 mg.l ^-1 .

Thereafter, water was added. Further, the nitrite content began to decrease until it reached a concentration of 0.1 and 0 mg.i ^-1 . Then the nitrate content in the filtered water began to increase to a concentration of 6.5 mg.i & quot ^;

This value with minimal fluctuation was maintained for a longer period of time. Simultaneously with increasing nitrate content in filtered water, manganese content began to decrease until it reached a concentration of 0.1 to 0 mg.l -1.

At ammonium concentration of 0 to 0.1 mg.1 ", nitrite 0 to 0.1 mg.l" and manganese 0 mg.i "', a complete biological treatment of the new filter sand was achieved, which was used not only to remove suspended matter but also biologically removed ammonium ions, nitrites and manganese from water at a filtration rate of 8 m.hr ¹ . The incorporation period was 7 months, with water being discharged to the recipients before reaching the indicated concentration.

A similar procedure was followed for the filter sand already used in the de-ironing and de-manganeseing of water, with the inlet concentration of ammonium ions, nitrites and manganese in the water flowing onto the sand filters being the same as in the first example.

The oxidation of the ammonium ions to nitrites to nitrates took place at a considerable rate compared to the first example, so that the biological incorporation of the filter sand already used was achieved in 10 days. The oxidation of ammonium ions to nitrates was so rapid that it was not necessary to remove the treated water for high nitrite content from the recipient.

This biological treatment of sand filters can be advantageously used for both pressure and open filters up to a maximum filtration rate of 8 m.hour ¹ in all treatment plants where the operation of permanent or temporary pollution of treated water with high ammonia and manganese content is endangered the water treatment method used has a high content of nitrites and manganese in the treated water and in the water network. The method according to the invention can be used in water treatment plants with maximum preservation of the existing technological equipment.

Claims (1)

Method for biological treatment of sand filters used for removal of suspended matter in drinking water treatment, for removal of ammonium ions, nitrites and manganese, characterized in that the sand filter is treated with water containing ammonium ions up to 5 mg.i ¹ , nitrites, manganese, maximum trace amount of chlorine, iron up to 1,5 mg.1 ^-1 , which is saturated with oxygen at a temperature of 4 to 16 ° C until the water leaving the filter reaches the concentration for ammonium ions, nitrites and manganese 0 to 0,1 by reaching the stated concentration goes to the recipient. mg.i ' ¹ ', all the water before