PROCEDURE AND DEVICE FOR THE DISPOSAL OF CARBON DIOXIDE

Description the invention concerns a procedure as well as a device for the disposal and utilization of carbon dioxide, which results during the cleaning of waste water. Application covers all kinds of the biological 5 waste water purification, thus for example anaerobic procedures just like aerobe procedure and extends equally for example to fixed bed reactors or aeration basins.

In the sewage engineering it is general the goal of transferring as large a part as possible of organic contents materialsof the waste water into mineral final products such as CUe2 and HzO. With the dismantling of organic substances products high-energy and the high-molecular converted during the aerobes water purificationare breathed the organic materials the inorganic final products CUe2 and HÙe mentioned by the aerobes bacteria by metabolic steps up to (oxidized). About 50% of carbon existing in the waste water are converted to CUe2, that as exhaust air result the other half of carbonremain in organic form in the sewage sludge.

Under anaerobic conditions the high-molecular organic substances of the waste water become over-15 weighing fermented and not breathed. Organic materials thereby only up to intermediate products such as acids and alcohols diminished compared with the inorganic final products with aerobes the dismantling is here however not yet sufficient the desired dismantling. Therefore with anaerobic sewage engineerings a large conversion is aimed at to fermentation gas (CH4, CUe2), that from the waste water escapes and the carbon load of the waste water accordingly reduced with the so-called two-stage anaerobic dismantling results as intermediate products acids, alcohols, CUe2 and H2. In a second dismantling step anaerobic methane bacteria convert the acids mainly to methane and CUe2. The dismantling of a complex organic material to methane can take place however only so fast and to the extent, how forthe methanogenen bacteria usable substrates are available.

To convert during the anaerobic water treatment aimed at 90 to 95% of carbon into fermentation gas, 25 during the remainder in the surplus sludge results the fermentation gas contains again approx.. 30% CO2, depending on how the dismantling process is led.

From managing it results that in view of the enormous waste water quantities, which are daily cleaned according to large quantities of CUe2 are delivered into the atmosphere. For the range West Germany thereby over 1,000,000 tons of CCh/Jahr were calculated. CUe2 rnuss however as pollutant to be evaluated to thus limit for its into the atmosphere delivered quantities are.

The available invention is the basis to that extent the task, a disposal-and utilization possibility for the carbon dioxide resulting during the waste water purification to indicate.

The invention is the basis the realization that this can be achieved in surprisingly simple way by the fact that the carbon dioxide (CUe2), withdrawing gaseously from the waste water, is caught and converted into 35 presence by alkali-and/or alkaline-earth oxides and/or-hydroxides to alkali-and/or alkaline-earth carbonates and led back afterwards into the cleaning equipment.

The procedure according to invention is by the characteristics of the requirement 1, which described device by the characteristics of the requirement 3.

Likewise the reaction of Ga (OH) is 2 in presence from CUe2 to CaCOs and HÙe admits thereby can the slaked lime either drying, easily dampened (frequently already 1 Gew is enough.-%surplus humidity) or as lime milk (white milchige suspension) to be used. The use 45 of damp approx. (OH) 2 or lime milk is thereby prefers the reaction kinetics is well controllable. By the waterseparation taking place in each case with the reaction with CUe2 (vaporous or liquid) further humidity becomes free during the reaction. This can be removed for the achievement of a dry finalproduct afterwards by drying process or filtration.

If the carbonating reaction is accomplished using of lime milk, it offers itself, the gaseous CO2 into the appropriate suspension in as fine a distribution as possible to in nozzles. In addition the suspension can be filled into a simple containerand be taken off over a discharge opening again, whereby it along the way between-and and discharge opening as large a quantity of CO2 in finely divided form into the suspension as possible is eingeduest. By obligation agitation of the suspension, for example by agitators, vibrators or ultrasonic mechanisms etc. the conversion of the CO2 with the liquid hydrated lime can be accelerated likewise as by purposeful temperature price increase, like implemented X DE 41 02 685 C2 a special advantage of the procedure according to invention lies above in the fact that afterwards the won inorganic carbonatischematerial, above all calcium carbonate, magnesium carbonate or combinations (dolomite) in the purification plant again to be used to be able.

On the one hand the carbonatische material serves pH-value-for the adjustment (buffering) of the waste water. At the same time in this way in addition, an important and necessary source of substrate can be made available for Nitrifikanten in the waste water 10.

With the nitrification H+ are formed-ions, in accordancewith the following reaction equation: NH4+ + 2 02-* N03-+ H20 + 2 H-by the in such a way formed acids the nitrification handicapped in presence of CaCOs reacts this with the acids under formation of to calcium hydrogencarbonate (approx. (HCOs) 2). Atthe same time takes place according to pH-value-an adjustment via the formed H+-ions. The H+-ions react with the HCOs-ions in the water, whereby again HÙe and CO2 are formed-gas. The CUe2 is taken up of the Nitrifikanten as source of carbon.

The nitrification is favoured thereby crucially by the increase of the concentration of inorganic carbon, which is used by the Nitrifikanten.

Of the inorganic coal materials these autotrophen micro organisms (Nitrifikanten) compose biomass (Cs HjCN), for example according to the following reaction pattern: NH4+ + 1.83 CO2 + 1.98 HCO3->-0.021 C5H7O2N + 0.98 NO2-+ 1.04 HÒ + 1,88H2CO3 approx. as ions in the water can a "cyclic process" is caught solved in this way be developed, with during the waste water purification formed CUe2, into carbonate form converted and afterwards to the process again supplied.

The invention below on the basis a remark example more near described whereby the only figure in strongly schematized representation aerobarbeitende waste water-cleaning equipment describes.

With the reference symbol 10 thereby that becomes waste water-inlet into one altogether marked by the reference symbol 12 represented purification plant the purification plant 12 exhibits a roofing 14.

From the biological stages of the waste water purificationascending carbon dioxide under the roofing 35 14 one catches and one sucks off by a fan 16 and into a lime milk-suspension 18 eingeduest (nozzles 20) whereby the suspension 18 over a supply opening 22 into the reaktionsbehaelter is continuously supplied 24. At the lowerend of the reaktionsbehaelters 24 (with 26) a discharge is intended, over which the suspension is again taken out of the reaktionsbehaelter24. By the reaction of the hydrated lime with that eingedue-sten carbon dioxide-gas comes it in the reaktionsbehaelter to the formation of calcium carbonate and water, which both 40 over the discharge 26 is delivered.

Afterwards the in such a way formed calcium carbonate (if necessary after drying process) can be supplied to a further use (for example than building material) (over the transport equipment 2å);in addition, it is possible to lead back it for example totally or partly for for pH-value-buffering or than source of substrate for Nitrifikanten into the biologically effective stages of the purification plant (over the reconducting mechanism 28b).