SU833582A1 - Method of waste water purification - Google Patents

Description

one

The invention relates to the physicochemical and biological treatment of highly concentrated wastewater containing toxic impurities in quantities exceeding the maximum allowable concentrations for biological treatment, and can be used to clean wastewater from enterprises such as the leather industry.

The known method of wastewater treatment is that the wastewater after the grids and sand traps come to the 1st settler, then to the pre-aerator, where it simultaneously drains the excess activated sludge and the final sediment, then the wastewater is directed to flotation, while as a reagent А 1 (504)), then into aeration tanks, a settling tank (2nd, biofilter and again to the settling tank DJ

The disadvantages of this method are the high consumption of reagents for the physical treatment of untreated wastewater; insufficient effect of wastewater treatment, corresponding to the quality indicators of biologically treated wastewater.

Indicators of water quality after the tertiary stop: a suspension of 19 g / m, biological oxygen consumption (BOD) 16.5 g Og / M; chemical oxygen consumption (COD 80 g ammonium nitrogen 7.5 g / m; nitrate nitrogen 19.0 g / m nitrite nitrogen 3.5 g / m; ether-soluble substances 13.0 chromium 0.35 g / m

The purpose of the invention is to increase the degree of wastewater treatment.

The goal is achieved by the fact that, in a method including settling, pre-aeration with hydrated active sludge, reagent injection, flotation, two-step biological cleaning in aeration tank and a biofilter with settling, after the final step and returning the final sludge water after the biofilter, and the final precipitate is fed to the flotation.

The method is carried out as follows.

Untreated sewage passes through 5 mechanical cleaning on grids, in sand traps and septic tanks and enters the pre-aerator ,. where excess activated sludge and air are supplied. In the pre-aerator, a decrease in the concentration of contamination occurs due to oorption by their active sludge. Then a mixture of water with activated sludge enters the flotation cell. Clarified in the floater, water. Enters the 1st stage of biological treatment - aeration tank mixer. separation of activated sludge from water is carried out in a secondary clarifier. Excessive active sludge is fed into the pre-aerator, and circulating activated sludge is returned to the aeration tank after regeneration. I

Sewage water after the 1st stage of biological treatment enters the biofilter, where full biological treatment takes place. After the bio filter, waste water is mixed with reagents and fed to a tertiary settling tank.

Entering the reagent before the tertiary septic tank allows for further purification of wastewater that has undergone complete biological treatment, and feeding the flotation sludge formed in the tertiary septic tank consisting of biofilm and reagent improves the efficiency of the primary physicochemical treatment.

PRI me R. The installation includes: primary settling tank, pre-rattor, flotation device, aerotank-mixer activated sludge regenerator, secondary settling tank, high-loading biofilter with a loading height of 2 m, mortar and consumable reagent tanks, a tertiary settling tank. To the installation of the hearth: water cTO4iiyTO, taken from the averager of the existing sewage treatment plants and treated on the gratings and in the sand trap

Deposition of larger particles occurs in the primary clarifier for 0.5 h, after which the water enters the pre-aerator, where it is mixed with excess active sludge at a rate of 0.15-0.20 g of sludge per 1 liter of vda. Duration of pre-aeration

20 minutes. Then the mixture of waste water and activated sludge is clarified by pressure flotation with a process time of 0.33 hours. The working fluid for the flotation process is prepared by filling the recirculation water with air at an excess pressure of 0.35 MPa using an ejector installed on the bridge between the suction and pressure a recirculation pump nozzle. For a more complete dissolution of air, water is held under pressure in the pressure tank for 3 min. Recycling water is taken from the sedimentary part of the tertiary clarifier together with biofilm and sediment resulting from the use of a reagent (aluminum sulphate). The recirculation coefficient is 0, 5.

Sewage water, after flotation purification, is fed to the 1st stage of biological treatment - aeration tank-mixer. The duration of aeration of sewage is 3.6 hours. The separation of activated sludge from the treated water is carried out in a secondary settling tank for 1.5 hours. Circulating activated sludge after regeneration for 3.3 hours returns to the aeration tank, and excess sludge is sent to the pre-aerator .

After the secondary sedimentation tank, the treated wastewater is fed to the second stage of biological treatment - a highly-charged biofilter with a hydraulic load of 10.5 m day. Biofilter loading height 2.0 m, loading size 50-70 mm. In the mixer, located at the outlet of the biofilter serves a 7% solution of aluminum sulphate at the rate of 80 g / m anhydrous salt. The separation of water and sediment occurs in a vertical tertiary clarifier at a flow rate of 0.6 mm / s. The waste water according to the treatment stages is characterized by the indicators presented in the table.

Suspended substances, g / m

BOD, g

COD, g

one

Nitrogen ammonium-yngy, g / m

 nitrates, g / m

Nitrite Nitrogen, g / m Zephyry soluble substances., Chromium (Cr)

101 53

6.0 7

48

96

four

15

2.8

47

four

8 0.3

0.7

Claims (1)

1. The patent of France No. 2380990, cl. C 02 C 5/10, 1978,