CS196133B1 - Method of biological regeneration of sorption materials - Google Patents

Abstract

When treating wastewater using known biological methods, the concentration gradient decreases with increasing residence time of wastewater in the treatment plant. Similarly, when applying physicochemical methods, such as clarification, to wastewater, we reach a certain limit state, which cannot be further influenced by the addition of a clarifier. In both cases, we reach a certain limit value of residual pollution, which can no longer be reduced by the used cleaning process.

Description

When treating wastewater using known biological methods, the concentration gradient decreases with increasing residence time of wastewater in the treatment plant. Similarly, when applying physicochemical methods, such as clarification, to wastewater, we reach a certain limit state, which cannot be further influenced by the addition of a clarifier. In both cases, we reach a certain limit value of residual pollution, which can no longer be reduced by the cleaning process used.

Due to the increasing demands on the quality of water leaving the treatment plant, i.e. increasing the resulting cleaning effect, a number of additional cleaning processes have been developed.

One of the most commonly used methods is the use of sorption on active materials, the most undeveloped of which is sorption on activated carbon. Individual types of sorption materials differ significantly in their ability to remove organic pollution, expressed by the global indicator of chemical oxygen demand /COD/. Given the high prices of sorption materials, which for activated carbon range from 20 to 56 CZK/kg, the technical application of these methods depends on the possibility of regenerating the spent activated carbon. Assuming a sorbent with an area of 1,000 m ² /lg of active material, we can calculate that the capture of pollution expressed as COD will be 10% of the mass of the used active material, i.e., that 1 g of activated carbon will capture approximately 0.1 g of COD. Then, the spent activated carbon must be regenerated.

Regeneration is carried out by high-temperature or low-temperature regeneration of the active surface, which is essentially the oxidation of the captured impurities with subsequent activation of the surface centers of the activated carbon. During this thermal regeneration of activated carbon, there is approximately a ten percent loss of the regenerated material, and therefore after 10 times regeneration, approximately 30% of the original amount of sorption material remains. If less valuable materials that are not regenerated are used for sorption, one must expect both worse output parameters, i.e. worse cleaning effect, and the fact that the exhausted material must be disposed of, whether by landfilling, incineration or other methods.

The mentioned shortcomings, namely the extension of the residence time of the wastewater in the treatment plant beyond the economically acceptable limit on the one hand and the economically unacceptable losses of the sorption material on the other hand, are solved by the method according to the invention.

The method of biological regeneration of sorption materials in the process of biological wastewater treatment, according to the invention, consists in activating the sorption material by pouring a biological suspension, after which biologically pre-treated wastewater is introduced onto it at a rate determined by the relationship

G . S _K “ A . aBSK ₅ ' where

Q is the amount of wastewater in l/fiod,

G is the weight of the sorbent material in g,

S _K coefficient expressing the single sorption capacity of the material used ABSK^ difference between BOD5 of the inlet and outlet water in g/1 and

And the residence time of the captured organic substances on the sorbent material reaches values of 1 to 300 hours, preferably 120 hours, and after the sorption capacity is exhausted, manifested by an increase in filtration resistance, the sorbent material is left in a wet state for 24 to 700 hours, preferably 360 hours, after which it is washed for 10 minutes with water or a mixture of water and air.

The principle of the invention is based on the fact that the rate of removal of organic substances by microorganisms is, within certain limits, dependent on the concentration of organic substances and that as organic substances decrease over time, the rate of their removal also decreases, which can be described, with certain limitations, by a general equation for the reaction rate in the overall expression of the concentration of individual components /The case when n * 0 is not considered/, where

S _t is the concentration of the reacting component, t is the time, k is the reaction constant, and n is the exponent expressing the order of the reaction, and furthermore, that during sorption processes, organic substances are captured on the sorption material, i.e., they are concentrated due to the influence of physicochemical forces.

If we combine these two principles into one technological unit, that is, if we feed wastewater of a certain concentration to the active material, or water with pollution that has been reduced to a limit by previous methods, where further reduction of this pollution would, due to the low concentration gradient, require an excessive increase in residence times in the treatment plant, organic substances will be concentrated on the active material, which again, under certain conditions, will cause an increase in the rate of removal of organic substances due to an increase in their concentration in the system.

If wastewater of a given concentration is fed to the active material at such a rate that the organic substances captured on the material are degraded biologically before the sorption capacity of this material is exhausted, in addition to filling the active centers of the sorption material physically, their release biologically will also occur continuously, which will significantly prolong or completely eliminate the need for thermal or other regeneration of these materials.

If the wastewater is brought into contact with the active material at a rate such that

BOD5 is the biochemical oxygen demand for the oxidation of biodegradable organic substances in 5 days /g/1/

Q is the amount of wastewater fed into the device /1/h/ and while maintaining the contact time of the sorbent material with the wastewater of at least 6 minutes, the period between individual regeneration cycles will be significantly extended.

Design examples

Example 1

Glass column with a diameter of 0.03 m, area

7.1O"4 _{is added to the} column at a _rate of 7.10^ of activated carbon weighing 0.33 kg. 1,000 cm^ of biological suspension β is poured through the device thus modified, followed by feeding biologically pre-treated wastewater from the bottom into the column. Biologically pre-treated water with the composition given in Table 1 is fed into the column in an amount of 7.103.h"

Table 1

100 X COD /mg/1/ 55 10.2 bsk ₅ /mg/1/ 13.2 14.3

During the operation of the device, which lasted 170 days, the water passing through the device had the following average composition: /Table 2/

Table 2

X -S- . 100 X 7. net effect COD /mg/1/ 7.3 17.3 86.7 BOD ₅ /mg/1/ 1.2 22.5 90.9

Due to the increase in the filtration resistance of the column during long-term operation of the device, the column was washed once every 24 hours with a mixture of filtered water and air.

In the monitored period, 342 g of BOD^ were removed from the column packing without any deterioration in the sorption capacity of the activated carbon. Example 2

Wastewater ^>0 sand filtration showed the following average composition /tab. 3/

Table 3

X COD /mg/1/ 1 23 BOD _S /mg/1/ 64

π g of activated carbon ^{Q =} c . u . 24 . 5 ' where the amount of captured dissolved _organic substances_ ^c weight of active material input pollution in BODj-output _pollution in BOD5_ input pollution in BOD5

This water, after a short (3 minutes) intensive aeration (40 m^/m^ H2O), is fed from above under pressure to a column with a diameter of 0.125 m and a height of 2 m, which was filled with 24 kg of activated carbon.

Similar to Example 1, the column is activated before starting operation by pouring 15 l of biological suspension through it.

Wastewater with the composition given in Table 3 is fed to this column in the amount of 6.4.10"2,.h"1 for a period of 620 days. During this period, the column is washed from the bottom once every 12 hours with a mixture of pressurized water and air. During the monitored period, the water passed through the purification device has the following average composition: /Table 4/

Table 4

7 net effect COD /mg/1/ 29 76 bsk ₅ /mg/1/ 1 1 83

Since the cleaning effect was deteriorating towards the end of the monitored period, the operation was stopped, the column was left for 30 days without wastewater supply, and then intensively washed with a mixture of water and air for 2 hours. Wastewater with the composition given in Table 3 was again fed to the thus modified column in the amount of 6.4./h for another 120 days, during which the same average cleaning effect was achieved as given in Table 4.

Claims (1)

SUBJECT V Method for biological regeneration of sorption materials in a biological process of wastewater treatment, characterized in that the sorption material is activated by pouring the biological suspension, followed by the introduction of biologically pre-treated waste water at a rate determined by the formula _Q · G ·. ·? Κ_, And .ABSKj 'where Q is the amount of waste water in 1 / h G weight of sorption material in g, Sj, the coefficient expressing the one-time sorption of the material used in g captured BOD5 per g of material used, ŮBSK5 difference between BOD5 inlet and outlet water in g / l And the residence time on the sorption material captured by org. % of substances having a value of 1 to 300 hours, preferably 120 hours. and after exhaustion of the sorption capacity resulting in an increase in filtration resistance, the sorption material is left in a wet state for 24 to 720 hours, preferably 360 hours, and then washed for 10 minutes with water or a mixture of water and air. Srverognfia. n. p .. rivod 7. Moel FIXED DESCRIPTION OF THE INVENTION TO THE COPYRIGHT CERTIFICATE. 196 133/51 / Int. Cl. ³ - C 02 F 1/28 In the description of the invention for the author's certificate no. 196 133 the name of the author is wrongly stated: