SU842058A1 - Method of treatment of active silt excess - Google Patents

Description

The invention relates to the biological treatment of wastewater and the treatment of the resulting activated sludge with the possibility of recycling it as a feed additive or for fertilizer and can be used in the treatment of highly concentrated wastewater, for example, wastewater from livestock farms. Biochemical treatment of highly concentrated wastewater produces a large amount of excess activated sludge. For example, in pig breeding industrial complexes, the volume of activated sludge with a moisture content of 99.2% is about 20% of the daily volume of wastewater. There are known methods for processing surplus activated sludge which, with the aim of recycling inclusive. the next {cue operation; compaction, digestion, dehydration and thermal drying. An important technological operation in this case is the seal I provide. A general decrease in the total volume of sludge before aerobic or anaerobic squeezing. The degree of sludge compaction is the main factor in determining the performance of sludge digestion facilities, as well as apparatus for dewatering. In this method of treating excess activated sludge, the compaction is carried out by settling in an ice packer for 5-10 hours. The settling reduces the moisture of the sludge to 95-97% or reduces its volume by 4-6 times 1. The disadvantage of this method is longer compaction process, the implementation of which requires large volumes of structures. In addition, during prolonged compaction, the quality of the activated sludge deteriorates, which makes its utilization difficult. There is also known a method for treating activated sludge, in which, in order to compact sludge, it is acidified to pH 2 and heated to 66-90 ° C. 21. The disadvantage of this method is the large operating cost of treating sludge and the impossibility of using sludge as a feed additive. The closest in technical essence and the achieved result to the proposed method is the treatment of activated sludge, including sequentially compaction of sludge by means of sedimentation, digestion, introduction of active chlorine into fermented sludge, compaction of fermented sludge and dehydration. The essence of the method consists in the chemical oxidation of the surface layer of hydrophilic particles of the solid phase of the precipitated sediment with active chlorine. Active chlorine is introduced into the fermented sediment (100–3000 mg / l), Compaction of the active sludge is carried out for 6–8 h. The introduction of active chlorine into the fermented sediment allows decreasing the specific resistance of the sediment, increasing the productivity of the apparatus for dewatering the fermented sediment 3 However, this method has a longer compaction time, as a result of which the sludge swells and its quality deteriorates. Saturation of the solid phase of the precipitate with chlorides of more than 3% when it is oxidized with chlorine also leads to a significant deterioration in the quality of the precipitate as fertilizer and its unsuitability for the preparation of the feed additive, since the content of chlorides in the feed should not exceed 1%. The high consumption of chlorine and high humidity of compacted sludge entering the fermentation process imposes considerable costs on the construction and operation of the fermentation and chemical reagent facilities. The purpose of the invention is to intensify the compaction process and improve the quality of the treated sludge. The goal is to achieve that active chlorine is introduced before compaction in the form of an aqueous solution with a concentration of 560-600 mg / l in a ratio of 1: 20-1: 25. Compaction is carried out within 3-3.5 hours. With suggested values of chlorine concentration and volume ratio of aqueous solution of chlorine and activated sludge, the respiratory enzymatic apparatus of microorganisms of active sludge is inactivated and the gas release in zoogluous flakes of sludge is inhibited during metabolic processes that prevent their precipitation. . This makes it possible to improve the sedimentation properties of the sludge and thereby increase the efficiency and speed up the compaction process. The introduction of chlorine into the sludge in the form of an aqueous solution ensures a uniform distribution of chlorine ions throughout the sludge volume and increases its utilization. The method is carried out as follows. Excessive activated sludge from biological sewage treatment facilities and an aqueous solution of chlorine with a concentration of 560-600 mg / l are fed into a vortex mixer in the ratio of 20: 125: 1, where they are intensively remapped. From the mixer, activated sludge flows by gravity into a vertical silt compactor, in which it is settled for 3-3.5 hours. The compacted sludge is fed for digestion and then disposed of for fertilizer. If treated sludge is used for feed additive, it is sent for thermal drying. Sludge water is fed into the head of biological sewage treatment facilities. An example. Excess activated sludge with a moisture content of 98.5-99.2%, resulting from the biological treatment of highly concentrated wastewater, is mixed under laboratory conditions with an aqueous solution of chlorine with a concentration of 510-1320 kg / l in ratios of 15: 1, 20: 1, 25 : 1, 30: 1 and defend within 2-4.5 hours. The results of laboratory tests of the proposed method are presented in tables 1, 2, 3 in comparison with the known method. Table 1

Volume of compacted sludge500 340 80 75 ka, ml Concentration of chlorine in the sludge water after compaction, mg / l Efficiency 15 80 81.3 compaction,% 1.8 g, 8 72 8.3 9.6 82 82

Investigated parameter

Volume of excess

The volume of compacted sludge from a mixture of excess activated sludge and chlorine water, ml

The compaction efficiency of the proposed method,%

The volume of compacted cage at settling without introduction. bleach water (by a known method), ml

The effectiveness of compaction without treatment with chlorine water (by a known method),%

From tab. 1, it follows that the most effective concentration of chlorine in the aqueous solution is in the range. 560-600 mg / l. A further increase in concentration does not lead to an increase in the efficiency of compaction and significantly increases the content of free chlorine in water.

The data table. 2 show that the optimal ratio of volumes of chlorine water and activated sludge is in

table 2

Ratio of volumes of chlorine water and systolic active sludge

I 1:20 1 1:25 1 1:

thirty

1:15

Table

75

315 ao

66 66

21.7 80

85

85 85

480 475

500 500

500

the interval lj20-J: 25, since it corresponds to the highest compaction efficiency, or, while the 1:15 ratio is not taken into account, since with equal efficiency

Completion In this case, a significant consumption of bleach water is required.

Out of that bl. C, it barely blows, then the formation of a precipitate, its compaction with the introduction of chlorine-bonft into silt Bonft, ends in 3-3.5 hours. Increase in time

settling does not lead to an increase in the effectiveness of compaction. When compaction of sludge without the introduction of chlorine water after 3 hours of settling, the sludge swells, reaching a compaction efficiency of 5%.

The advantage of the proposed method before known is confirmed by checking it under production conditions for livestock waste water. The results of the production tests of the proposed method are presented in table. four.

Table 4

Continued table. four

Effects

Claims (1)

Claim Volume of compacted sediment, m \ Humidity of compacted sediment,% VNIIIPI Order 98.5 4970/22 A method of treating excess activated sludge, including compaction, fermentation and the introduction of active chlorine, characterized in that, in order to intensify the compaction process and improve the quality of the processed sludge, activated chlorine is introduced into the excess activated sludge before it is compacted in the form of an aqueous solution with a concentration of 560- 600 mg / l in the ratio of 1: 20-1: 25 and compaction is carried out for 3-3.5 hours.