SU1008161A1 - Method of purifying waste water - Google Patents

Abstract

ATP; ON CLEANING WASTE WATER containing methionine, sulphate and aliphatic aldehydes, that is, in order to simplify the process with organic impurities, the waste water is acidified with a mineral acid to pH 5 -6 and subjected to electrodialysis at a voltage of 37-43 V, current density O, OO8-O, 023 A / cm, the ratio of the volume of concentrate to wastewater 1 :( 15-21), the flow rate of wastewater and concentrate 16-21 l / h and a purification temperature of 18-26 ° C.

Description

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The invention relates to a method for purifying waste water produced by the production of methionine by an effective feed additive. These waters, in addition to methionine, also contain sodium sulfate and aliphatic aldehydes. The known method of oxidative treatment of wastewater containing various impurities, oxygen in the air at high temperature (250-70 ° C) using a graphite catalyst. The degree of oxidation of 62-99% Cl is achieved. The disadvantages of this method are the use of high temperature during purification, the instability of the catalyst, the degree of wastewater treatment is not high, the consumption of oxygen, the impossibility of reusing the treated wastewater in production. There is also known a method for treating waste water produced by methionine by contacting the vapor-gas mixture with atmospheric oxygen at 1OO-2OO ° C in the presence of fluorinated alumina catalyst. The degree of oxidation of harmful organic substances is 9599% with an air consumption of approximately 30,500 liters per 1 l of wastewater. Before starting the purification, pre-activation of the catalysis is carried out, which consists in calcining the fluorinated acid alu. mini For 2 hours at 4OO-45b ° Ct2j, i The disadvantages of this method are the loss of the valuable and scarce product methionine due to its complete destruction, carrying out the process at high temperature, limited catalyst life, oxygen consumption, pre-activation of the catalyst, obtaining additional waste - sopi (mainly sodium sulfate). The purpose of the invention is to simplify the process while maintaining a high degree of sewage treatment from organic impurities. Uknsann 1 goal is achieved by the fact that the source wastewater (pH 8.0-9, O) containing methionine, sodium sulfate and aliphatic aldehydes is treated with mineral acid to pH 5, O-6, O and subjected to electrodialysis under voltage 37 -43 V, current density 0.0030, 023 A / cm, the ratio of the volume of concentrate to wastewater 1: {15-21), the flow rate of wastewater and concentrate 16-21 l / h and the cleaning temperature of 18-2 ° C. At pH values of less than 5 or greater than 6 (aelectroelectric region for methionine), methionine migrates significantly from the wastewater, which leads to its loss. In the apparatus with a capacity of 1O l, equipped with a mixer, washed with 5 liters of alkaline (pH 8.5) wastewater from the production of methionine and while stirring, gently pour 3 mp of sulfuric acid (s3 1.84 g / cm) to pH 5.5. The wastewater is then sent to the purification unit Rodnik-9. The apparatus is a press-type filter assembly with two electrodes (cathode and anode) made of platinized titanium (the useful area of each electrode is 0.00527 m). Between the electrodes there are 11 cation-exchange membranes MK-4O and 1O of anion-exchange membranes MA-40, which form alternating concentrating (brine) and desalting (diluate) chambers in alternating sequences. A constant current is supplied through an ESA-5 type selenium rectifier. Cleaning conditions: voltage 40 V, current density 0.020 A / cm, temperature. Wastewater (pH 5.5) in the amount of 5 l is pumped at a rate of 18 l / h into the desalting chambers, and a solution containing approximately 1 g / l of sodium sulphate in the amount of 0.5 is fed into the concentration chambers at the same rate. l When the content of sodium sulfate i 1 g / l in the purified waste water (the norm for industrial water produced by methionine,), a new batch of effluent with a pH of 5.5 in an amount of 5 l is supplied for purification. Aliphatic aldehydes (their concentration is conventionally considered to be formaldehyde), present in the wastewater at a concentration of 0.1-0.2 g / l, are completely oxidized, methionine with the initial concentration remains in the treated wastewater and can be returned with desalted water to production. Concentrated sodium sulfate brine containing g / l Na230l. can be sent to the installation of evaporation with obtaining salable sodium sulfate. In tab. shows the dependence of the efficiency of wastewater treatment on voltage, current density, temperature, co-flow of concentrate volumes to wastewater and the flow rate of wastewater and concentrate to the electrodialyzer.

Table i

From the data table. 1 it follows that the pre-: j0 division of voltages 37–43 V is optimal for sewage treatment, since with a voltage less than 37 V the degree of purification from aliphatic is less than 95%, and with a voltage greater than 43 V there is an increase in the temperature of the treated sewage before . This has a negative effect on the structure of ion-exchange membranes, which manifests itself in a change in the pH of the concentrate to a weakly alkaline region. Due to the increased migration of sodium cations from the effluent. At the same time, methionine losses from the purification chambers are observed due to the transfer of the latter to the concentration chambers. According to Table. 2 it follows that the current flow O, OO8-0, O23 A / cm is optimal, since at a current density less than 0, OO8 A / cm the degree of purification from aliphatic aldehydes is less than 95%, and at a current density more Oh, O23 A / cm2, paao-V heating of the effluent to 54 ° C with a single temporary migration of significant quantities of methionine to the concentration chambers. T and l and p and 2 Data tab. 3 show that the range of wastewater treatment temperatures of 18–26 ° C is optimal, since with annepaiype less than 18 ° C, there is a significant loss of sodium sulfate in

From the data table. 4 that the limit is less than 95%, and

The ratio of the volume of concentrate to the base ratio of more than 1:21. Reduced water 1: (15-21) is optimally; the degree of wastewater from sodium sulfate

 as a ratio of less and at the same time there is a significant

1:15 degree of purification from organic migration of methionine from the purification chambers.

Continued table. 2 sediment in the concentration chambers, which leads to disruption of the normal operation of the installation. Cleaning at a temperature more leads to significant losses of methionine from the cleaning chambers. Table3

Tab. 5 it follows that the speed of the hearth; wastewater and water (X centrate in the electrodialyzer, equal to 16-21 l / h, is optimal, since when the feed rate is less than 16 l / h, the degree of purification from organic impurities is less than 95%,

and at a speed of more than 21 l / h, an increase in the migration of methionic molecules from the concentrating chambers is observed. The tloo is explained by an increase in the pH of one hundred. cov in the cells of the camera due to the replacement of the velocity of migration. SO Table 5.

Claims (1)

METHOD FOR CLEANING WASTE WATERS containing methionine, sodium sulfate and aliphatic aldehydes, t and -> characterized in that, in order to simplify the process while maintaining a high degree of purification from _{v of} organic impurities, the wastewater is acidified with mineral acid to pH 5-6 and subjected to electrodialysis at a voltage of 37-43 V, a current density of 0.008-0.023 A / cm ^{2 the} ratio of the volume of concentrate to wastewater 1: (15-21), the flow rate of wastewater and concentrate 16-21 l / h and a treatment temperature of 18-26 ° C. > 1008161 2