RU2023684C1 - Method of biochemical sewage treatment from zinc ions - Google Patents

Abstract

FIELD: chemical industry. SUBSTANCE: water is filtered by descending flow through nonaerated biodiaphragm with opened surface of grain loading. Upper layer of the latter (height is 25-50 cm) contains activated carbon as 150-200 g coal per 1 m³ of total filter loading. Filtration is carried out at the loading value by water 2,5-3,5 m³ per 1 m³ loading for 24 h. Method ensures to increase the rate of treatment process from zinc ions by 2.7-2.8 times and provides quality of treated water according with standards for treated water disposal to the superficial ponds. EFFECT: improved method of sewage treatment. 2 cl, 1 tbl

Description

 The invention relates to the field of water treatment and can be used in the chemical industry and municipal services for the treatment of wastewater containing zinc ions and hardly oxidizable organic compounds.

 A known method of biochemical wastewater treatment from zinc ions. The purification is carried out under anaerobic conditions in loading reactors. The method allows you to completely purify water from zinc ions, but the speed of the purification process is low, in addition, it does not provide purification from difficultly oxidized organic compounds, for example, synthetic surface-active substances (SAS), to standards allowing the discharge of treated wastewater into surface water bodies.

The purpose of the invention is to increase the speed of the cleaning process and to ensure the removal of difficultly oxidized organic compounds from water. Compared with the prototype, in which wastewater containing Zn ^{2+ ions} in an amount of 4.5-5.0 mg / l is purified at a rate of 0.200-0.225 mg / l ˙ h, in the proposed method - 0.56-0, 6 mg / l ˙h.

 Using the proposed method allows to increase the speed of the process of purification of zinc ions from 2.7 to 2.8 times and to ensure the removal of hardly oxidizable organic compounds from water to standards allowing the discharge of purified water into surface water bodies.

To implement the method, wastewater containing zinc ions and organic compounds is filtered downward through a non-aerated biofilter with an open surface of a granular charge, the upper layer of which contains powdered activated carbon (PAH) based on 150-200 g of coal per 1 m ^{3 of the} total filtrate charge.

Filtration of purified water is carried out at a water load of 2.5-3.5 m ³ / m ³ load per day.

 The upper layers of the boot containing PAHs are in satisfactory oxygen conditions. Microorganisms are immobilized with a thin layer on the surface of PAH particles, forming a secondary biofilm on which biosorption of difficultly oxidized organic compounds takes place, as well as extracellular enzymes and oxygen adsorption, which increase the oxidation state of poorly adsorbed substances and metabolic products. The interaction of the secondary biofilm and PAHs provides a synergy of biosorption and biooxidation processes.

 Thus, the presence of PAHs in the upper layers of the biofilter increases the bioactivity of microorganisms. The high surface area of PAHs allows for the simultaneous regeneration of coal to continue the processes of biosorption and oxidation of difficultly oxidized organic substances and cork products of metabolism. Due to the additional sorption of oxygen on the PAH particles in the upper layers of the biofilter under aerobic conditions, the wastewater is deeply purified from difficultly oxidized organic substances to bring their residual amount to the MPC norms.

 Anaerobic sulfate reduction processes occur in the lower layers of the biofiltrate. The product of the metabolism of sulfate reducers of the genera Desulfovibrio, Desulfotomaculum and others is hydrogen sulfide. At pH greater than 7.2, hydrogen sulfide is present in the medium in the form of hydrosulfides, which react with zinc ions to form insoluble metal sulfide, carried out by the water stream from the biofilter load together with the dead biofilm and deposited in settlers. After settling and subsequent filtration, zinc is absent in purified water. Excess biofilm contains metal sulfide and therefore its additional processing is not required.

The application of PAHs in an amount of less than 150 g / m ^{3 of} loading does not provide for deep removal of difficultly oxidized organic compounds from water.

The introduction of PAHs in excess of 200 g / m ³ leads to a decrease in the speed of the cleaning process by increasing the filter loading density.

Filtration with a water load of less than 2.5 m ³ / m ³ reduces the speed of the cleaning process due to siltation of the filters.

With an increase in the load value of more than 3.5 m ³ / m ^{3, the} speed of the cleaning process decreases with a decrease in the quality of water treatment for hardly oxidizable organic compounds and zinc.

PRI me R. The waste water of the chemical fiber plant is subjected to purification, having the following characteristics, mg / l: Zn ²⁺ 4-5; COD 400-600; SPAS 26-30; BOD _p 280-350; SO ₄ ^2-6-7 ; NH ₄ ⁺ = 15-25.

According to the conditions of discharge into fishery reservoirs, the concentration of pollution should not exceed the relevant MPC standards, mg / l: Zn ²⁺ 0.01; SPAS 0.1; BOD _p 3; NH ₄ ⁺ 0.5.

Wastewater with a flow rate of 25,000 m ³ / day is passed through a non-aerated biofilter with a granular charge with a grain size of 20-30 mm. Loading height 2 m.

The required volume of the filter load with a water load of 3 m ³ / m ³ per day is:
V _zagr. = 25000: 3 = 8333 m ³ .

The amount of PAHs for application to the upper layers of the biofilter with a specific landing of 200 g PAH / m ³ load is:
8333 x 0.2 x 10 ^-3 = 1.67
Repeated application of PAHs is carried out after 3 months. Thus, the need for PAHs is about 7 tons / year.

 The water after the biofilter is settled and filtered through a quartz filter.

 The table presents data on the effectiveness of water treatment plant chemical fiber.

Claims (2)

 1. METHOD FOR BIOCHEMICAL WASTE WATER TREATMENT FROM ZINC IONS, including treatment with microorganisms under anaerobic conditions followed by sedimentation of purified water, characterized in that the treatment is carried out by filtering water in a downward flow through a non-aerated biofilter with an open surface of a granular charge, the upper layer of which contains powder powder from the calculation of 150 - 200 g of coal per 1 m of biofilter load.  2. The method according to claim 1, characterized in that the filtration is carried out at a load of 2.5 - 3.5 m of water per 1 m of load per day.

Images