DD142870A1 - CLEANING OIL AND FATTY WASTEWATER - Google Patents

Abstract

The method is used for cleaning oil and fatty Waste water, whereby the waste water is an adequate proportion of the fat content of surfactants or soaps for the emulsification of fats or Sodium hydroxide solution for partial saponification is added. The Degradation of the so biodegradable fats takes place in the Intensive biology-driven first biological stage. to Final cleaning is followed by a second biological stage classic surface b.elauturig on. Specially for Animal carcass recycling companies will use the suspended substances Wastewater and the ira purification process formed biomass accumulating Sludge mixture separated, mechanically dehydrated and used for production used by deep-matter flour or feed silage.

Description

Title of the Invention Cleaning of oil and greasy wastewaters.

    Field of application of the invention

The invention relates to a process for the purification of oil and fat Abvjässer, especially from the meat processing industry, and animal carcassing operations.

: Characteristic of the known technical solutions

The biodegradability of organic wastewater substances has been practiced for years. Thus, the classic treatment of this wastewater is based on the digestion. Although these methods enjoy the advantage of high reliability with low manpower, but ornamentation while all substances that can be used as recyclables, · destroyed. * '

The aerobic treatment of wastewater in activated sludge and trickling filter systems has also been carried out for years. These technologies are generally coupled to the previously described digestion, i. All sludge arising in the purification process is treated anaerobically and thus lost for use.

A special case is the combination of the two technological steps according to WP 114 942, in which the anaerobic treatment is preceded by the aerobic. 'In activated sludge plants are due to the high feed concentration and high residence times required, which are reflected in high investment costs and energy requirements. In the case of faults on the fat separator, there may be considerable eett concentration © in the aeration tank, disturbances in the

cause biological degradation, since the microorganisms adsorb as activated sludge floc fat molecules and so diffuses only reduced substrate into the cell. A modern process is the aerobic treatment of the wastewater with technical oxygen after the UKOX .bzw. Although the energy required for the direct fumigation with increased oxygen input decreases, but the production of oxygen represents a technically complex process. These plants work with a minimum accumulation of excess activated sludge. The whole technology .. is very costly because of limited availability. of oxygen. There are also strong corrosion hazards.

Aim of the invention ^; _;

The aim of the invention is to clean these wastewaters despite high fat contents with a relatively simple process biologically within an economically acceptable period. In addition, in the purification of waste water from rendering plants all undissolved organic contaminants contained in the waste water are used together with the organic compounds formed during the cleaning process for recovery in feed production. The method operates without anaerobic pre-treatment of the organic load and without the war'tungsreiche and interference-prone cooling sterilized wastewater fractions with a simultaneous increase of the Betriebssicherheit.- ''''

Explanation of the essence of the invention

- The technical problem that is solved by the invention _: is. , ,

; "The causes of the deficiencies of the already known solutions consist in the fact that due to the encapsulation of the activated sludge flakes by suspended fat particles, the activity

• Microorganisms greatly reduced and a biological treatment of waste water with higher fat content only

at length residence times is possible that a separate treatment of the formed activated sludge and its. Utilization can be done as feed only by very expensive technologies that the organic compounds in Porm of the remaining suspended in the wastewater and the activated sludge formed by anaerobic treatment as recoverable Recyclables are lost and most processes have a significantly higher investment and operating cost, with a higher level of susceptibility to breakdowns »

Features of the Invention

, The essence of the invention for the purification of oil and greasy wastewater is characterized in that the wastewater flows without pre-cleaning and cooling the system and the oil or fat content emulsified by an adequate addition of surfactants or waste soaps or partially saponified by sodium hydroxide and biological easily degradable. In particular

 '<It has been found that a greatly accelerated degradation of emuigierten fats takes place in an intensive stage, since the full biological activity of the individual cells present here is used. The dewatering of sludge separated by sedimentation follows, in particular for rendering plants, which is made possible by the agglomeration of the * colloidal and suspended substances present in the wastewater with the activated sludge formed during the purification process. The dewatered sludge cake is used in the feed production of the farm.

In the case of the requirement for increased fat production, the pH can be lowered by the addition of chemicals before the first biological stage so that the suspended fat particles can float and be separated, whereby

.: in which sedimented sludge is also used as animal feed «,

Embodiment.

"Example 1:

The method is discussed at a rendering plant with an annual capacity of 15 kt of raw material:

Wastewater attack. 300 nrvd. ; , BOD ₅ (daily average) 3000 mg 0 ₂ / d .. fat (daily average) 1000 mg / 1 ''

The resulting wastewater is conveyed via sand trap, and grease, in a closed expansion tank. From there, the waste water flows continuously into the intensive biology, which works according to the submersible jet method. To ensure the biodegradation of the high fat content, about 20 to 100 g / m.sup.3 surfactants or waste soap ^: metered in. The same effect is also possible with the addition of approx. 50% laundry wastewater (approx. 150 m Yd), if that corresponds to the territorial conditions. The residence time in this stage is about six hours.

The subsequently obtained by sedimentation (intermediate clarification) mixture of settleable substances (meat, bone residues, etc.) and the activated sludge formed in the first stage is combined with that after the second biological stage, the classic activation stage with surface aerators and about 15 hours Residence time, mixed by sedimentation (Hachklärung) separated excess activated sludge and thickened. The sludge mixture, the solids content of which amounts to approx. 30 kg of dry matter per annum, is added by means of a decanter to a solids content of approx ^. 250 kg of dry matter per m- 'dewatered and used for the production of animal meal.'

Both biological stages work with added sludge return ^; tion. . · ^'·:;.'

The clear phase of the second clarification flows directly into the receiving waters. , ''

Example 2:

The effluent from the same operation is continuously fed to the expansion tank by metering in sulfur;

acid lowered to a pH of about 2. By means of a mechanical grease separation approx. 50 % of the fat recovered «The sedimented mixture of pesticides is fed into the feed silage production.

Subsequently, the clear phase is neutralized and then about 10 to 50 g / nr surfactants or soap are added. The biological treatment corresponds to that already described. , , , The separated and thickened sludge mixture is treated with a physiologically acceptable flocculant, e.g. approx. 1 kg · lime per m, mixed, dewatered by machine and fed to animal body meal production «

Example 3: '' .. '

For operation to produce edible oils and margarine, the process is modified as follows:

Wastewater (oil-contaminated wastewater) 600 irr / d

, BOD ₅ (daily average) · 10 000 mg / l

Fat (by the mean of the day). '' 1 500 mg / 1

The wastewater is pumped through rake, sand trap and grease separator into a surge tank.

The feed to the first biological stage, about 30 to 150 g / m surfactants or soap are added. 'The biodegradation is ^% as described in Example 1';

If there is no use of the resulting sludge mixture, "this can be subjected to anaerobic treatment together with the municipal wastewater".

Claims (3)

- 6 - £ invention claims 1. Purification of oily and greasy wastewater by aerobic biological processes, by a classical intensive stage; is followed by the activated sludge stage, characterized in that surfactants, waste soaps and / or .Natronlauge be added to the non-prepurified and uncooled wastewater in the intensive stage. · _: 2 · Cleaning of oil and greasy wastewater according to point 1, characterized in that preferably for animal body recycling plants after the first stage by sedimenta-, ·· tion separated and concentrated by thickening to ca, 3 % pesticide content activated sludge mixture together with the After the second stage separated and thickened excess activated sludge - dehydrated with or without the addition of phy¬siologically harmless chemicals for flocculation to a pesticide content of about 25 % and processed into animal meal or feed silage. 3. cleaning oil and greasy waste water according to item 1 and 2, characterized in that - preferably for rendering plants - before the first stage, the pH is lowered by the addition of chemicals so far that after the emulsion splitting an additional recovery of fats possible and the sedimented pesticides are separated and either separated or dewatered after mixing with the other sludges and recycled. -. :