SU1399274A1 - Method of dehydrating sediments of waste water of electroplating shops - Google Patents

Abstract

The invention relates to the dewatering of difficult to filter suspensions, such as hydroxide sewage sludge, and can be used to treat sewage sludge produced in the engineering, chemical and other industries, and improves the productivity of the process. To carry out the process, the sewage sludge from electroplating industry is treated with polyacrylamide twice with intermediate settling. The resulting suspension is subjected to compression nil by filtering with multiple immersion of the filter punch, and compaction is carried out by periodically vibrating the sediment layer above the surface of the filter cartridge with a frequency of 3-49 Hz, which is carried out at the time of the filtration rate decrease after immersion of the filter cartridge by 30-50%. 3 tab. with s

Description

The invention relates to the dewatering of difficult to filter suspensions, such as hydroxide sewage sludge, and can be used to process sewage sludge that forms in industrial, chemical and a number of other industries.

The purpose of the invention is the exploration of the productivity of the process.

Example 1. Sewage sludge of electroplating plants from sedimentation facilities with an initial concentration of the solid phase of 1-1.5% is treated with a solution of polyacrylamide (PAA). Next, the treated PAA precipitate thicken in a thickener with slow stirring to a concentration of the solid phase of 8%. The accumulated sediment is treated with a second dose of the PAA solution and sent to the tank, where it is compressed dehydrated using a filter punch, periodically loaded into the sediment with a force. 0.03 MPa. After the filtration rate drops by 30Z from the beginning of immersion, the upper layers of the precipitate are vibrated at a frequency of 20 Hz for 5 minutes. Then the filter punch is lifted from the sediment and at the same time with the rise the sludge is stirred at a linear speed of 0.5 m / s. Next, the stamp is again lowered into the sediment. The dewatering process is completed after 3 immersion cycles of the filter punch.

The specific productivity is 0.53 hours. The concentration of the solid | phase in the dewatered sludge is 24%. Comparative data on the result; the sludge dewatering offered by iro and the known methods are presented in Table 1.

I Example 2. Similar to Example 1, but the drainage is subjected to a solids concentration with a solids concentration: 7% and vibrations at: the moment when the filtering rate | AI after immersion of the filter punch decreases by 30%. The data are presented in Table 2.

; As follows from the data of Table 2, the maximum performance of the dewatering process is observed at a vibrating frequency of 10 Hz. At smaller values, the pressure value arising from vibration becomes not

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sufficient for separation from the partition of a low-permeable layer of sediment resulting from gravity filtration. As a result, the amount of water flowing under this layer decreases, thus reducing the productivity of the dewatering process.

At a frequency of 10 Hz, the productivity of the process also decreases, due to the fact that the resulting pressure in the suspension leads to its destruction and dispersion. A new layer of sediment with a lower hydraulic permeability than a layer of previously adhered sediment forms on the filter septum. At the same time, the filtration rate decreases sharply, reducing the productivity of the dewatering process, and at a vibration frequency of more than 40 Hz, it becomes lower than in the prototype, i.e., without vibration.

Example 3. Similar to example 1, but the suspension is dewatered with a solids content of 7% and vibrating the upper layers of sediment with a frequency of 10 Hz,

The data on the effect of the moment of immersion of the filter stamp in the sediment are presented in Table. 3

From the data presented in Table 3, it is clear that the purpose of the invention is achieved when the start is carried out, vibrating at a time when the filtration rate after immersion of the filter ptamp decreases by 20-55% (highest at 30-50%). When conducting vibrations, when the filtration rate from the beginning of immersion is less than 30%, the productivity of the dewatering process is reduced. This is due to the fact that in this case the vibration will start to take place at the moment when the filtration under the action of the gravity forces has not finished yet, therefore the destruction and dispersion of the sediment layer on the partition wall by vibration increases its hydraulic resistance, the filtering rate decreases and vibrations. When the filtration rate is lower than 20%, the vibration of the upper layers of the sediment becomes 1 ineffective, and the production of the pump: is less important than the n 1) 1 T (.) Type.

When vibrating is performed when the filtering rate is greater than 50%, the effect of vibrating also starts to decrease due to the increasing difference between the end of the hydrostatic filtering action and the start of the vibrating effect. When the filtration rate decreases by more than 55%, the vibrating effect is zero, and the productivity becomes less than in the prototype.

The results presented in Tables 1–3 show an increase in the productivity of the dewatering process with periodic vibrations of the upper layers of the sludge compared with the known 1.2–1.4 times.

Claims (1)

Invention Formula The method of dewatering sewage sludge from electroplating industries, including double treatment with polyacrylamide with intermediate settling, compression seal by filtering during repeated immersion of the filter punch, characterized in that, with the aim of improving the performance of the process, compaction is carried out during periodic vibration of the sediment layer above the filter surface a whole stamp with a frequency of 3-40 Hz, carried out at the time of the drop in the filtration rate after immersion of the filter stamp by 30-50%. Table 1 The results of the dewatering of sewage sludge from electroplating industry The dependence of the performance of the process on the frequency of vibration of the upper layer of sediment The specific dewatering capacity is 0.33 0.37 0.41 0.42 0.41 0.40 0.36 0.38 0.3 0.27 0.25 0.22 table 2 The effect of the moment of immersion of the filter stamp on the performance of the process Viba start: riro Drop in filtration rate from the beginning of the immersion of the filter stamp,% O T S 20 I 30 1 40 ГЗО 55 60 Specific water flow h 0.05 0.22 0.33 0.40 0.42 0.41 0.33 0.27 .0.12 0.12 0.07 Table 3 60 70 80 90