SU1039897A1 - Method for biochemical purification of effluents - Google Patents

Description

The invention relates to the treatment of wastewater and mo: rt to be used for the biochemical treatment of industrial wastewater, requiring the addition of a biogenic element (nitrogen-ammonium compounds). A known method of wastewater treatment with activated sludge in the presence of air and with the addition of biogenic elements (nitrogen and phosphorus) l. As a result of the consumption of micro (by nutritious nutrients cracked in the wastewater, the process of oxidation of organic substances and the synthesis of new cells, the so-called increase in activated sludge, which in turn is a contaminant, presented in a new form and requires significant costs its removal and treatment. An important feature of the process of biological wastewater treatment, unlike other types of microbiological industrial activity, is not oxidizing the biomass synthesis (i.e., activated sludge) microorganisms capable of providing sufficient depth and purification efficiency with minimal biomass accumulation. There is also known a method for reducing the increase in activated sludge in a process of biochemical wastewater treatment by using pure oxygen instead of air with a concentration of 4 mg / l. 2.2. Also known is the method of wastewater treatment by conducting a purification process with the addition of bactericidal preparations (phenol in bactericidal doses, toluene at the rate of 1 mg / l, 2 -2 dimethylphenol-5 m g / l, КСN-2 mg / l, acetatetriphenyltin - 50 mg / l), which prevents the synthesis of new cells and the decrease in sludge growth by 20-25%. A purification method is also known by adding thiourea to wastewater at a rate of 0.1-10 mg / l, which helps to slow down the process of nitrification and that {development of nitrifying bacteria 4. However, many of the added elements are too expensive and scarce, their use does not provide a minimal increase in sludge activity, besides overdosing of these substances leads to the suppression of the biochemical purification process itself and other adverse events. 972 The closest to the proposed technical solution is the biochemical method sewage treatment in aerotanks with separate regeneration of return sludge. Industrial wastewater after adding certain nutrient elements (nitrogen and phosphorus compounds) to certain concentrations is fed to the aeration tank, where the absorption and mineralization of organic matter takes place. Then, in the settling tanks, the sludge mixture is separated into purified water and activated sludge. Part of the activated sludge (excess sludge) is then sent for treatment and disposal, and another part (return sludge) is recycled to the regenerators, where its oxidative properties are restored. When treating municipal wastewater, the required amount of nitrogen added to wastewater is determined by the ratio of BOD complete: N 1OO: 5. In the treatment of industrial effluents, this ratio is determined in each case experimentally by g | . The biochemical purification process with the addition of nitrogen compounds in front of the aeration tanks has the following disadvantages: a large increase in activated sludge, which requires significant costs for its treatment and disposal; high consumption of reagents (razlizk1n 1x salts containing nitrogen and ammonium); additional consumption of oxygen for the nitrification process; incomplete imposition. nitrogen, which requires additional measures for its removal from wastewater before going into the reservoir. The purpose of the invention is to reduce the amount of excess sludge, increase the degree of wastewater treatment, reduce the cost of the process. This goal is achieved by the fact that the cleaning process in aerotanks is carried out by non-growing microorganisms, and the nutrient element containing nitrogen is added and return sludge to the regenerator, preferably at the rate of 102O mg per 1 g of sludge per day. The biochemical purification method is carried out as follows. During the start-up of the sewage treatment plant and their output at the design capacity, the supply of biogenic elements (nitrogen and phosphorus) into the waste water entering the aeration tank is carried out according to: existing standards. Then stop. ammonium nitrogen is added, which leads to a slowdown in the proliferation of microorganisms of activated sludge in the aeration tank and an increase in the lifespan of existing microorganisms. Returnable activated sludge is directed to the regenerator, where ammonium nitrogen solution is applied at the rate of mg N per 1 g of the ash-free part of activated sludge per day. In the regenerator, the cell's reserve substances are dissipated (dissimilated) and the simultaneous use of ammonia nitrogen for the synthesis of new kp currents. The active sludge from the regenerator is fed to the aeration tank to carry out the cleaning process. PRI m e-p. Cleaning is subjected to synthetically prepared water (glucose, phenol, etc.), as well as the waste water production of epoxy resins. The experiments were carried out in laboratory models of aerotanks-mixers with separate regeneration of active sludge of the VNIIVODEO system. The control over the biochemical purification process was carried out by chemical and hydrobiological analysis. Serving as experimental data, obtained during the purification of wastewater containing biogenic elements (nitrogen and phosphorus). The results of the experiments are presented in table. 1 and 2, and in tab. 1 - biochemical oxidation of glucose, in table. 2 - phenol. As can be seen from the above data, the limitation of nitrogen in wastewater entering the JB aerotank leads to a decrease in the increase in activated sludge (by 60% in average). Some increase in the biomass of activated sludge is not due to the proliferation of microorganisms, but is the result of the accumulation of reserve substances and chemicals. This is confirmed by an increase in the COD of activated sludge (from 1.2-1.4 to 1.81 mgO / mg) and a decrease in ash content. During the period of aeration (10-24 hours), the nitrogen content in the biomass of activated sludge decreases by 10-12%. The addition of ammonium nitrogen to the regenerator makes it possible to increase the nitrogen content and, thus, to maintain it at the same level in the aeration-regenerator system. It was established that in order to preserve the nitrogen content in the biomass of activated sludge in an amount of 80-1OO - mg / g sludge (8–10%), it is necessary to add 1 744 ammonium salts of mg / g ashless sludge per day. The results of determining the optimal concentration of ammonium nitrogen supplied to the regenerator are shown in Table. 3. An increase in the ammonium nitrogen content in the solution fed to the regenerator does not increase the nitrogen concentration in the biomass of activated sludge, but leads to its accumulation in the sludge mixture. In the regenerator, microorganisms, using cell storage as a carbon source and added ammonium nitrogen, multiply. The total amount of biomass of microorganisms of activated sludge, usually determined as the ash-free part of the dry matter, remains practically unchanged. The COD of activated sludge is reduced to the original values (1.3-1.4 mgO / mg sludge). Determination of the dehydrogenase activity of activated sludge selected from aeration tanks shows that the oxidative activity of bacteria is higher when limiting them with nitrogen than under conditions favoring reproduction. The results of experiments on the intensity of the process of oxidation of organic substances from wastewater in the presence of ammonium nitrogen and activated sludge, pretreated in the conditions of the regenerator with the addition of nitrogen (ammonium, are presented in Table 4. From the data presented, it is clear that under conditions of difficult synthesis cells, increases the oxidative activity of microorganisms. This is evidenced by an increase of 10-15% in oxygen consumption by microorganisms. The cost of maintaining life without reproduction increases, t. E. The life of microorganisms under unfavorable conditions for multiplication is more expensive Example 2. The diluted waste water is subjected to purification of the production of epoxy resins in aerotanks with a regenerator. During the period of start-up and exit of the structures to the design capacity, the purification is carried out by the classical method with the addition of biogenic elements from the calculation of BCPL: P 100: 4: O, 6. Then the wastewater is supplied to the secondary oi stoker, where part of the excess sludge is removed for further processing, and another part (return sludge) is sent to the regenerator, where ayut air and reduced oxidizing properties. From the regenerator, the activated sludge enters the aerotank. After obtaining stable results, the wastewater treatment process is changed for this purpose, only the phosphorus salts in the above proportions are introduced into the wastewater, and ammonium nitrogen (at the rate of 10-20 mgN / g sludge per day) is added to the regulator. From the regenerator, activated sludge enters the aerotank, where: it produces the actual biochemical treatment of wastewater. The main purification indicators and technological parameters of the process are presented in Table. . Technological parameters of the process are presented in Table. 6. 1 976 Considering that the treatment of 1 ton of activated sludge on sludge grounds according to VNIIVODGEO costs 39.8 r, and 1 ton of ammonium sulfate - 53.7 p., The annual economic effect for a sewage treatment plant with a capacity of 5OOO m / day due to reduction of operating costs will amount to 19.179 rubles. without taking into account the costs associated with a decrease in the volume of facilities, a decrease in air consumption and the removal of residual ammonium nitrogen from treated wastewater, the pepper discharges them into a body of water. The proposed method allows to reduce the cost of reagents, purification and after-treatment of wastewater, treatment of excess sludge and increase purification. Table 1

500

63 87.5% 13.8

344% 96.0

0.4

20.4

Tracks 4.2

0.3

31 93.8 7.4 97.8

0.23

0.2

24.4

14

OD

2.9

2.9

Ash content of sludge,%

Ashless part of sludge, g / l

Nitrogen in silt, mg / g

Silt incex

Sludge growth, mg / l fasting, vots

COD percentage of water

COD of activated sludge, mgO / mg

The load on the sludge nitrogen, MrV / r sludge / day: in the aeration tank

in the regenerator

12

2.56 83

52 70 14 1.8

table 2

19.34

10.2

Phosphorus content, mg / n

The dose of activated sludge in the aeration tank, g / l

Ash content of sludge,%

Ashless part, g / l

NITROGEN in silt, Mg / l silt

Silt index,

.Growth shh mg / l

COD percentage

1039897

10 Continued table.

0.2

3.0 8

2.7. 78 47 57

1О39897

eleven

5000 O8.3

810162

79.7

60O15

97.5

.

241.4

Traces;

3.8

3,60,8

12 Table 4

Table 5

5000

Tracks 0, 320,38

0.2

3.6

Dose of activated sludge in the aerotank, .g / l

Ash content of sludge,% Dose of sludge in regener, g / l

Nitrogen content in activated sludge, mg / g:

in the aero tank

in the regenerator Silt index, cm

COD content of activated sludge, mgO / mg:

Continued table. five

3.0

9 8

93 94

85 93

63

43

Claims (2)

1. WAY OF BIOCHEMICAL WASTE WATER TREATMENT in aerotanks with separate regeneration of activated sludge in regenerators and introduction of biogenic elements into wastewater, characterized in that, in order to reduce the amount of excess sludge, increase the degree of purification and cheapen the process, * purification process in aeration tanks: · they are carried out by non-growing microorganisms, and a biogenic element containing nitrogen is introduced into the return sludge into the regenerator. • 2. The method according to π. 1, with the fact that the biogenic element containing nitrogen is administered in an amount of 10-g 20 mg of nitrogen per 1 g of sludge per day. SU ... 1039897