DE2549882A1 - Treating oil contg. industrial wastes - by ultrafiltration and-or reverse osmosis in closed circuit with incinerator - Google Patents

Abstract

Effluents contg. combustible org. impurities (oil) can be treated by thickening through ultrafiltration and/or reverse osmosis, followed by burning the thickened fluid. The filtrate from ultrafiltration or diluted soln. from reverse osmosis is used in a closed circuit to cool or wash the flue gases from the combustion, and to decompose the org. components contained in the filtrate. This system has a very low power consumption, just for recirculation and thickening. The thickened residue requires no auxiliary fuel for combustion. The furnace can be kept small because excess water has been removed, and few waste gases are produced. The absence of active carbon filters saves cost, and the process is a closed circuit, producing no pollution of the drainage system.

Description

Method and device for the treatment of waste water, the combustible organic impurities contained. The invention relates to a method of treatment dilute aqueous solutions which are a by-product of thickening in systems arise in which wastewater, the combustible organic impurities in dissolved, emulsified or suspended form, such as oily wastewater, thickened and then burned as a liquid concentrate.

The invention therefore provides a method for eliminating Wastewater containing combustible organic components by thickening the wastewater by means of ultrafiltration and / or reverse osmosis and burning of the thickened liquid, the is characterized in that one from the ultrafiltration dilute solution (filtrate) obtained or reverse osmosis, if necessary in the circuit, for cooling or scrubbing the exhaust gas from the combustion, for decomposition organic components contained in the filtrate are used.

The invention is explained below with reference to the drawings. 1 and 2 show flow diagrams of the method of the invention and FIG 3 shows a diagram as an explanation of an exemplary embodiment according to the method of FIG Invention.

Am an example that is a description of the incineration process flow this type of thickened liquids is shown below with reference to FIG explained.

The wastewater 10 to be processed is supplied by means of a device 1 according to the ultrafiltration process (hereinafter referred to as the uF process; compare 'lEagaku to Kogyo (Chemistry and Industry) "1973, Vol. 26, No. 8, pp. 94 and 95), and the thickened waste liquid is disposed in a sewage incinerator 3 burned.

The dilute solution (hereinafter referred to as the filtrate) that is used in the thickening occurs, can in some cases depending on the properties of the Solution can be reused or discarded. In most cases, however, it must be subjected to further treatments. In this case the filtrate is in a Device 2 of a reverse osmosis (hereinafter referred to as RVerfabren; compare Kagaku to Kogyo ("Chemistry and Industry") "1973, Vol. 26, No. 8, pp. 94 and 95), and the thickened liquid obtained in this way is combined with the previously in the liquid obtained from the UF stage is incinerated or, in some cases, to the original waste water tank fed back. There are no problems if the filtrate from the RO stage is for reuse is suitable or discarded without further treatment, that is, in the natural Genasser can be headed. In some cases, however, this is because of the high biochemical oxygen demand (BOD) and / or because of the high oxygen demand impossible due to potassium permanganate at 100 ° C (COD; compare JIS K 0102).

There is no convincing method for eliminating the COD.

There are processes such as activated sludge treatment and coagulation precipitation and filtration using activated carbon; however, all of the above procedures require Water treatment equipment on a large scale. In addition, the two are The first method was hardly able to reduce the GOD to a value below the standard suitable for discharge into natural waters, while the latter The method has the disadvantage that you also have a furnace for extraction of activated carbon must install what is reflected in higher costs.

Activated sludge treatment or activated carbon filtration is used to eliminate the BOD followed by an activated sludge treatment. Again, however, there is one Water treatment device required to a considerable extent and, if an activated carbon treatment is carried out, a furnace for the production of activated carbon must be installed. Thus, there are similar problems here as with the elimination of the COD.

On the other hand, the exhaust gases from the combustion device 3 have temperatures from 700 to 1000 00, where it is necessary that Vt this temperature to about 250 0 or below before the exhaust gases enter the dust collector 6, so that adverse effects on the dust collector are avoided. To that end is a smoke (exhaust gas) -Wasch- or Xühlvorrichtung 4 is provided that the temperature of the Reduced exhaust gas, or a waste heat boiler is used for heat recovery or air preheater 5.

That is, the smoke washing or cooling device 4 cools exhaust gas direct contact with water, for example by spraying water into the hot Gas.

The invention aims at the decomposition and evaporation of organic substances Components (impurities) that are the cause of the COD or BOD Using the RO filtrate, and in some cases the UF filtrate, as water for the smoke-scrubbing or -kUbi'uug If you have sewage, that is generally a few percent Contains combustible organic components to ten times the concentration and then burns, the gas produced during the combustion has a temperature of about 1000 ° C. If this exhaust gas is cooled by the aforementioned filtrate, it falls the temperature of the exhaust gas to about 500 to 200 when all of the filtrate evaporates and gets lost. This will break down most of the COD or BOD elements. If the COD or BOD elements are not completely decomposed by this procedure but organic constituents still remain in the filtrate, this will Filtrate used in the circuit as water for smoke washing or cooling. That Filtrate that has been thickened as a result of use in the cycle can be the Combustion can be subjected to an incinerator, thereby creating herein contained COD or BOD elements are finally decomposed apply with reference to Figure 1. Depending on the properties of the original wastewater, the use of a method according to FIG. 2 is also possible.

Figure 2 shows an example where the aforementioned treatment method on a filtrate is applied, which after thickening by means of the UF process alone or the RO process alone If, for example, for the Case that the contaminants in the original sewage by the UF process are covered in such a way that the filtrate is only slightly contaminated, and, moreover, the filtrate does not contain any heavy metals, the UF filtrate can as Cooling water or smoke-washing water can be used as before set out above.

On the other hand, there is wastewater, for example from food production arises from cases where the RO thickening can be applied directly while thickening by the UP process is not very successful. Even in these cases the RO filtrate can be used as cooling water or smoke washing water, such as set out above.

Below is a preferred embodiment of the method of FIG The invention is described with reference to FIG.

The starting material is one in rolling with the use of lubricants accumulating wastewater. The oil is present in an emulsified form and it is extraordinary difficult to treat this wastewater by a conventional method so that it can be discarded, i.e. discharged into the natural fountain.

The original wastewater (oil content 3.5 percent: COD 95,000 ppm) in one A quantity of 1690 kg / hour is thickened using the UF method. Here one obtains 200 kg / hour thickened liquid (oil content 30 percent) and 1490 kg / hour filtrate (Oil content 15 ppm, COD 14,000 ppm). This filtrate in an amount of 1490 kg / hour is still subjected to the RO process, with 50 kg / hour thickening Liquid (oil content 450 ppm: COD 370,000 ppm) and 1,440 kg / hour filtrate (oil content not more than 1 ppm: COD 1400 ppm). The thickened liquid after the UF- and RQ method (oil content 24 percent) is incinerated using 40 kg / hour of heating oil A serve to support combustion. The resulting 1440 kg / hour of the RO filtrate are sprayed onto the 1050 0C hot exhaust gases and evaporated.

The entire filtrate evaporates, which reduces the temperature of the Exhaust gas drops to 235 0C.

The analysis of this exhaust gas shows that there are no unburned organic niches Substances are present.

The invention can not only apply to the treatment of oily wastewater, as described above, but also to the treatment of pulp mill accruing water, lactam wastewater and other wastewater are applied to the Contain combustible organic components.

The invention is particularly suitable for those cases where the oily Wastewater wastewater from emulsified oil represents, since one here the advantages of the UF process can be used to the full as set out below.

1. There is currently no convincing method for treatment of oily wastewater from emulsified oil. According to experts, there is the only way to burn the whole lot.

2. If the oil is not in emulsified form, it is more advantageous to to separate the oil using the different specific gravity.

3. If the oil is not in emulsified form, it may become clogged the UF membrane come with an oil film.

The range of oil content in the liquid to be treated according to the method of the invention is from about 1000 ppm to about 50 percent. (A direct e Activated carbon treatment is sufficient for a dilute solution of about 1000 ppm, while it is more beneficial to incinerate the sewage as it is when it is Contains 50 percent or more combustible components.) Application of the invention however, it is not limited to the range mentioned. The method of the invention is particularly suitable for sewage that contains a few percent to 10 percent oil or something about it contains.

In the case of oily wastewater, this itself is flammable, and you does not require any additional fuel, whoever is up to it a concentration is thickened by about 40 percent oil content or more. This is particularly dated Economical stanipoint from advantageous.

Using the method of the invention, COD values are about 1000 ppm or less and BOD values of about 1900 pum or less are preferred Areas for using the filtrate as cooling water or smoke wash water; the However, the method of the invention is not limited to the areas mentioned.

The disposal of oily wastewater that contains emulsified oil, is a serious problem for the following reasons.

If you take great adversity, it is possible to adjust the oil content (n-hexane extract) to 5 ppm or below. flo at the same time of the COD is however activated carbon filtration is the only way to reduce this to a few 10 to reach several 100 ppm or below. Recently, in numerous Cases for the discharge of waste water into natural waters 5 ppm or less n-hexane extract and 20 ppm or less <XH) are required, and it is almost impossible to achieve these values only through water treatment methods. The view of Rather, experts go to the point that there is a satisfactory elimination of the COD elements can only be achieved by burning. In fact, there are quite a few of cases in which oily wastewater, the oil content of which does not exceed a few percent, have been burned in their entirety.

In general, there are the following methods for Disposal of waste water that contains purified oil A. Procedure using water treatment methods (a) salting out, coagulation method After having made the emulsion by heating with addition of sulfuric acid, magnesium sulfate or the like has broken, the oil is taking advantage of its specific Weight separated.

While adding a coagulant to the lower water layer, the remaining oil is separated by precipitation or floating under pressure.

(b) Electrolytic process The emulsion is made by electrolysis decomposed, and there is a separation by piotizing by means of that by electrolysis bubbles generated, or the usual coagulation method is used at.

(c) Activated Carbon Filtration Process This process is not based Applicable to wastewater with high concentration. It is accordingly in nature a post-treatment, for example a treatment to remove n-hexane extract and COD elements remaining in the water layer that are treated according to the treatment (a) or (b) has been subjected.

B. Ultrafiltration. Reverse osmosis Even with ultrafiltration and reverse osmosis can be carried out, as already stated, the COD of the filtrate in some Cases are not reduced to the required value.

The only way to overcome the difficulties involved has hitherto consisted of subjecting the filtrate water to activated carbon filtration.

G, total incineration method. All waste water is burnt under Use of auxiliary fuels.

However, the aforementioned methods A to a have the following specified disadvantages.

With reference to A: A- (a) 1. In most cases it will be sulfuric acid used so that the procedure is dangerous.

2. The liquid containing sulfuric acid is increased to 70 to 80 o0 heated. This is dangerous and energy consuming.

3. The results of the treatment are variable.

4. Some 10 to some 100 ppm remain in the treatment water n-hexane extract and some 10 to some 100 ppm COD, so another treatment is required.

A- (b) 1. Electrical power is expensive.

2. The maintenance and monitoring of the electrodes and tanks is a hard work.

3. What was said under A- (a) 4 applies here.

A- (c) 1. The cost is high.

2. You need a furnace to produce activated carbon.

In addition, in practice it is necessary to A- (a) or A- (b) and A- (c) combine so that both installation and running costs are high.

With reference to B: As this process combines with activated carbon filtration is, the cost is high.

With or on C: 1. Since the evaporation of water at high temperature occurs, there is a high fuel consumption.

2. For this reason, the furnace must be made large. There too The amount of exhaust gas is large, the system as a whole must be large and therefore expensive, in contrast to do this, the method of the invention has to follow.

de advantages: 1. You only have to pay the energy costs for the circulating pump turn off; thickening requires little energy.

2. Since it is possible to thicken the liquid to a degree, in which it is almost self-flammable, you either do not need any or very little auxiliary fuel.

3. Since excess water is removed by thickening, the Combustion device can be kept very small.

4. The amount of exhaust gas is therefore also low.

5. As it does not require a water treatment, for example using activated carbon filtration to eliminate the COD is the cost for COD elimination from the filtrate almost zero, so that the cost of reduce the overall treatment considerably.

6. There is no water, so the natural waters do not (the procedure can be carried out as a closed system).

Patent claims

Claims (3)

P a t e n t a n s p r ü c h e 9 experience on the disposal of wastewater, that contains combustible organic pollutants by thickening the wastewater by means of ultrafiltration and / or reverse osmosis and burning of the thickened liquid, d a d u r c h e k e n n n z e i c h n e t that one from ultrafiltration or Reverse osmosis obtained dilute solution (filtrate), if necessary in the circuit, for cooling or scrubbing the exhaust gas from the combustion, for decomposition organic component contained in the filtrate is used. 2. The method according to claim 1, characterized in that the Filtrate in the circuit for cooling or washing the combustion product Used exhaust gas, and the filtrate thickened as a result of the circulation Incineration, to decompose the organic components contained in the filtrate, feeds. 3. Device for disposal of waste water, the combustible organic Contains impurities, characterized by a storage tank for the combustible Waste water containing organic contaminants, an ultrafiltration and / or Reverse osmosis device, a combustion device, a smoke cooling or washing device, a chimney and optionally a dust collector, the combustible organic Waste water containing impurities from the storage tank of the ultrafiltration device or is supplied from the storage tank of the reverse osmosis device, or from the Storage tank is fed to the ultrafiltration device, from which the filtrate is fed to the reverse osmosis device, the thickened liquid (concentrate), that of the ultrafiltration device and / or the reverse osmosis device originates, the combustion device is supplied, the exhaust gas from the combustion device fed to the smoke cooling or washing device, the cooled or washed exhaust gas the chimney, if necessary after ate a dust collector supplied, and the filtrate, that is, from the ultrafiltration device and / or Reverse osmosis device obtained dilute solution of the smoke cooling or washing device is fed. Blank page