DE19734154A1 - Process to choose treatment for municipal or industrial waste - Google Patents

Abstract

A biological process is used to assess the best means of treatment for effluent or waste containing carbon compounds. The process is evaluated by instruments either as an aerobic or as an anaerobic process, or as a combination of both. The reaction targets are continually signaled by detection within a three-chamber oven as: (1) pressure deficit (consumption of oxygen); (2) excess pressure (generation of methane); and (3) absorbed gases (carbon dioxide, change of conductivity, hydrogen sulfide and ammonia). The thermostatic temperature for the anaerobic process is 20 deg C, and 34-39 deg C for the anaerobic process. Plastic hollow rings with appropriate microorganism cultures are placed in the respective oven chambers. Three-way taps allow the selection of the pressure mode, or admit nitrogen for the creation of anaerobic conditions. At the conclusion of the process, the presence of the typical anaerobic poisons hydrogen sulfide and ammonia are registered by photometry. The process may be used to treat municipal or industrial waste water, soil, sludge, sediment and chemicals under both aerobic and anaerobic conditions.

Description

Field of application of the invention

The invention can be applied there if alternatively between the choice aerobic or the increasing importance of anaerobic processes for a certain wastewater to be separated or, based on biological sewage treatment plants with digestion towers, the waste water water for both degradation processes (aerobic with activated sludge formation and subsequent digestion) are evaluating. This invention aims to control an analytical gap between the well process parameters of aerobic degradation processes and the more sensitive, but little through controlled variables of anaerobic processes can be closed.

Characteristic of the known prior art

It is known that aerobic wastewater treatment is scientific and technical today is permeated and in the form of activated sludge technology or carrier-based Biology is used technically in sewage treatment plants. Belonging to control the aerobic processes Devices for determining the chemical oxygen demand, the biological oxygen demand fes, the determination of the dry residue and the loss on ignition, the pH value, deductible substances, the sludge volume and the determination of the oxygen content as standard armament of sewage treatment plants.

According to DIN 29 439, a closed respirometer for aerobic biodegradation organic substances used in aqueous medium, the test substance of microorganism men is consumed and the consumed oxygen, which is produced electrolytically, constantly is delivered later. The carbon dioxide formed is continuously recorded for 28 days the degradation compared to reference substances such as sodium acetate, aniline or sodium benzoate.  

According to DIN / ISO 9408 / EN 29 408, the breakdown of organic substances in the aqueous medium is determined for 28 days by the oxygen requirement, with the soluble or dispersible test substance with approximately 100 mg / l being the only C source in the system. The supplied oxygen is measured in order to maintain a constant pressure or volume. It is compared against a blank value. Similar tried-and-tested methods exist for assessing the organic wastewater pollution using the BOD ₅ method (Warburg) or the newly developed short-term BOD measurements, with oxygen consumption being the basis for these aerobic methods. In the BOD ₃ process, the CO ₂ formed is bound to lye and the resulting negative pressure is measured. Inhibitors such as N-allylthiourea are added to prevent nitrification, which also consumes oxygen.

There are only a few control parameters for the anaerobic processes in the digestion tower. As a rule, organic acids, the pH value, the temperature and the CO ₂ content are determined.

It is known from the literature that anaerobic processes are typical chain reactions and we react considerably more sensitively to disturbances than the aerobic degradation processes. Disorders in the degradation chain (hydrolysis, acetogenic and methanogenic) quickly lead to the nutrient man gel or for the enrichment of intermediates such. B. organic acids. Anaerobic Processes are carried out in the absence of atmospheric oxygen, and malfunctions are suppressed in the carbon dioxide or methane concentration. Hydrogen is derived from acetogenic Bacteria produced, but later immediately reused by methane bacteria. Further Gases that can affect the anaerobic process are hydrogen sulfide (especially acidic area) and ammonia. As a rule, methane formation is the most important indicator kator. If the acetogenic phase is disturbed, the nutrient supply for the subsequent stages drops and methane production decreases. The result is a carbon dioxide content of <30% The pH value drops below 7.0 and instead of digestion there is an acidic fermentation.

Anaerobic processes are very prone to failure. Phenols, chlorinated hydrocarbons and esp heavy metals cause problems with anaerobic treatment. Of all difficult metals come especially from copper (5-100 mg / l), zinc (3-100 mg / l) and lead (8-30 mg / l) toxic effects - i.e. the heavy metals that are used for pipe installation det and are common in wastewater. Also ammonia and especially sulfur hydrogen (<2.3 m g / l) inhibit the methane bacteria.  

Anaerobic processes are becoming increasingly important because, in contrast to aerobic degradation, they convert 95% of the carbon sources into energy-efficient biogas instead of 50% biomass. Especially the sugar industry, starch manufacturers, dairies, vegetable producers, breweries, the meat processing industry, the plastics industry and for the regeneration of biofilters are increasingly using anaerobic processes. Their further application in the chemical, pharmaceutical industry, the photo industry, paint shops, printing plants often fails due to the toxic ingredients. The anaerobic processes offer significant advantages such as

• - Degradation of emulsified aromatic and aliphatic hydrocarbons (DE 41 02 966)
• - Dismantling in a confined space without a large surface to the ambient air
• - Almost complete sales of carbon carriers with low sludge production
• - Preservation of the energy of the degradation substances in the form of methane
• - with high COD exposure up to 106 mg O ₂ / l (DE 39 02 867)
• - Decolorization of dyes sensitive to reduction and good size reduction.

In addition to the well-known digestion towers, there are also fixed bed fluid beds for anaerobic digestion and UASB reactors (upflow anaerobic sludge blanket).

From the prior art it can be seen that the less sensitive aerobic degradation processes are controlled by numerous analytical methods, whereas the much more sensitive anaerobic processes hardly have a prior control such as. B. COD and BSB ₅ are subject. While in the aerobic test methods the metabolic activities are assessed by the consumption of oxygen with simultaneous absorption of carbon dioxide in potassium or sodium hydroxide solution, the anaerobic degradation processes can be assessed by gas formation processes.

However, anaerobic degradation takes longer (20-30 days in the digestion tower) and should be optimized using the following known process parameters:

• - complete exclusion of oxygen and use of nitrogen
• - Temperatures of 30-40 ° C, if possible at 37 ° C
• - maximum pH buffering
• - C / N ratio from 10: 1 to 16: 1  
• - N / P ratio 7: 1
• - Immobilization of microbiology on carrier materials (OS 35 24 896 and OS 33 16 720). Decoupling the substrate and biomass residence times allows higher flow rates
• - Additions of fermentation vinegar foam, sauerkraut brine or fruit vinegar (OS 36 06 917).

A combination of the aerobic and anaerobic subprocesses in one apparatus with little changeover effort would be very useful. The wastewater would first be tested according to the BOD ₅ principle. Based on experience, carbon freight is implemented 45% as carbon dioxide, 50% as excess biomass sludge and 5% residual waste water. This so aerobically modified wastewater sample is subsequently subjected to anaerobic degradation. Here 80% carbon dioxide and methane are formed, only 10% excess sludge and 10% residual wastewater. Furthermore, it would be conceivable to use a triple quiver to control the gas formation, which in addition to carbon dioxide also allows hydrogen sulfide and ammonia to be recorded titrimetrically.

EP 0497414 A1 describes a method and a device for accelerated detection of the Anaerobic biodegradation of a product described by using carbon dioxide and methane as Test gases can be measured.

With the Degramat test system, wastewater as well as commercial products can be tested on their anae robe biodegradability are examined (Niepötter Labortechnik). The develop Recognized analytical methods for anaerobic degradation are still in the early stages. A test substance is mixed with a prescribed mineral salt solution containing 1 liter Bottle evacuated several times and filled with nitrogen, sewage sludge added as vaccine and thermostated at 35 ° C. The formation of biogas creates an overpressure that is the sum of Represents methane and carbon dioxide. By injecting caustic soda through a septum at the end of the test, the residual pressure only corresponds to the methane formed. From the CSB Value can be max. Mole number methane = COD / 64 for substances unknown anaerobic biodegradability can be determined in comparison.

There is also a Schott anaerobic test unit, in which one is on Siran-Raschigringen aerobic mixed population was settled and the hydroquinone and halogen aromatics were full constantly break down to carbon dioxide and methane at a high turnover rate. For the anaerobic Degradation are given a simple culture vessel, a stirring vessel or a bioreactor where  pH control is provided for the last two types. Here too the organic gas measured according to its two basic components.

Instead of the wastewater z. B. current and potential soil breathing without eluate dung aerobic or anaerobic to determine the correct utilization of the soil decide (agricultural utilization or only shipment under sealed areas) Chen) or the extent of contamination can be recognized as an inhibition of breathing become. In the same sense, carbon-containing chemicals, sediments, sludges or Waste are assessed. For soils and sediments, the initial weight should be at least 150 g lie. Waste can, for example, be assessed according to its compostability. A circular shaker must be used instead of the magnetic stirrer.

Aim of the invention

While well-functioning analytical methods are used to check aerobic activated sludge biology or carrier-supported biology, there is a need to catch up for the anaerobic methods, which are significantly sensitive to interference. The idea of combining both mic robiological methods is completely new. The activated sludge of the aerobic degradation level, which contains the pollutants adapted, is subjected to a second degradation process under anaerobic conditions. With this double assessment, the degradation of carbon-containing waste water can be viewed analogously to the degradation of biological sewage treatment plants with digestion towers. However, it is also possible to carry out separate measurements for aerobic degradation (BOD ₅ ) or anaerobic degradation.

There are fundamental differences between the two microbiological processes, which must be observed separately:

• - Vacuum formation in aerobic processes when the carbon dioxide formed absorbs becomes
• - Formation of overpressure in anaerobic processes, due to the absorption of carbon dioxide Alkali the methane component can be determined as the difference
• - Different temperatures of 20 ° C or 35-37 ° C  
• - Different nutrient additions to minimize the breakdown time
• - Ultimate handling for oxygen-free anaerobic processes
• - Detection of the reduced degradation performance in the more sensitive anaerobic processes due to the formation of hydrogen sulfide and ammonia.

The measuring principle works as follows:

• 1. Determination of the chemical oxygen demand M ₀
• 2. determination of the BOD ₅ with simultaneous titration of the CO ₂ bound to the alkali (5 days),
  aerobic mineralization rate M ₁ = CO ₂ / COD (with lye)
• 3. Determination of the anaerobic mineralization quotient
  Anaerobic partial mineralization rate M ₂ = CO ₂ / COD (with lye)
  Anaerobic partial mineralization rate M ₃ = (CH ₄ + CO ₂ ) / COD (without alkali).

M ₂ corresponds to the gas volume of methane formed, the carbon dioxide being removed from the gas by absorption in alkali. M ₃ is the total volume of carbon dioxide and Me than. The two values M ₁ and M ₃ indicate how much chemically bound carbon waste water can be mineralized aerobically or anaerobically. In particular, the aerobically formed excess sludge is checked for anaerobic mineralization. In the literature there is a connection between COD (g / l) and methane formation
Max. Mole number of methane = COD / 64.

The regulation for the determination of mineral carbon dioxide is known.

The apparatus consists of an overpressure / underpressure sensor ( 1 ), which is connected to the two sockets ( 3 , 4 ) of the 500-1000 ml brown dismantling bottle ( 5 ) with pressure-stable air hoses ( 2 ). A conductivity electrode ( 6 ) extends into the triple quiver ( 7 ) in order to continuously detect the carbon dioxide formed, bound to the alkali. From special sorption solutions in the small quivers ( 8 , 9 ), the anaerobic poisons hydrogen sulfide and ammonia are detected at the end of the experiment. The continuous recording of CO ₂ production, aerobic as well as anaerobic, is a decisive advantage for the evaluation of the mineralization. The magnetic stirrer ( 10 ) is only of importance for aerobic degradation in order to constantly stir the oxygen from the air cushion of the apparatus. He rests for the anaerobic processes. The Raschig rings ( 11 ) are used to colonize the microbial population. The three-way cocks ne ( 12 ) and ( 13 ) have the task, depending on the position, either to connect the negative pole of the pressure sensor with simultaneous blocking of the positive pole (aerobic) or to measure the pressure build-up (anaerobic) by reversing the position and at the same time measuring the To shut off the negative pole. If both taps are in the position so that both measuring sockets are sealed off, a nitrogen purge can be carried out to prepare the anaerobic degradation processes. The feed pipe ( 14 ) is connected to a nitrogen pressure bottle and the department pipe ( 15 ) to the environment.

The measuring principle is described for the complicated case of the combined measurement aerobic / anaerobic degradation. First, at least 500 ml of the wastewater is poured into the brown glass bottle 5 , mixed with about 10 ml of a buffered nutrient solution (accelerated microbiological degradation), 6 ml of a vaccine solution from the aeration tank (3 ml) and the digestion tower (3 ml), 25 Raschig rings ( 11 ) for the construction of the microbiological lawn, the triple quiver ( 7-9 ) with the potassium hydroxide solution, lead acetate and dilute hydrochloric acid is inserted and the airtight seal 16 with the conductivity electrode 6 is used. After thermostatting at 20 ° C, the positive pole is stopped by the three-way valve 13 , while the other three-way valve 12 establishes a direct connection with the negative pole.

With aerobic degradation, oxygen consumption now occurs when the magnetic stirrer 10 is switched on , which is continuously displayed as negative pressure development. At the same time the gebil Dete carbon dioxide is bound to the alkali in the stove and detected by the conductivity electrode 6 . In the system, a population of facultative aerobes / anaerobes settle on the Raschig rings and at the same time activated sludge is produced as in a sewage treatment plant, which is now to be assessed for anaerobic degradation.

When aerobic degradation is complete, the system is preferably heated to 37 ° C and thermostated to this optimal temperature. The residual oxygen is now displaced when the negative and positive poles of the sensor are stopped by the position of the three-way cocks 12 and 13 by the inflow of nitrogen from the feed line 14 (about 1 min).

Then the minus pole is shielded by the three-way valve 12 and the valve 13 is brought into position so that the system is only connected to the positive pressure pole (+). The activated sludge formed is broken down by the optional microorganisms and the anaerobic degradation processes are now assessed by a new change in conductivity (carbon dioxide) and by an overpressure formation (methane). At the end of the test, a possible inhibitory effect by hydrogen sulfide or ammonia or by a fermentation process using contents 8 and 9 or a final pH measurement can be determined.

The process and the apparatus offer the following advantages:

• - It detects aerobic or anaerobic processes individually.
• - It can combine both processes, i. H. the activated sludge formed with the sorbed pollutants again evaluated anaerobically. The combination thus corresponds Course of a biological sewage treatment plant with digestion tower.
• - A double evaluation is always carried out. In the aerobic area it is Oxygen consumption (negative pressure) and carbon dioxide formation (conductivity) and in The anaerobic area shows the overpressure methane and the conductivity again the Carbon dioxide formation.
• - Any degradation inhibitions are at the end of the experiment by a pH measurement or Detection of hydrogen sulfide and ammonia detectable.

With the invention it is possible for the first time, the complicated process of a biological Wastewater treatment plant in the complex (activated sludge formation and digestion process) as a preventive measure to consider.  

Embodiment 1 (aerobic degradation)

500 ml of wastewater from a municipality is placed in the amber glass bottle, with 10 ml Nutrient solution and 6 ml of a vaccine culture from activated sludge and digestion biology are added, 25 Raschig rings added, the quiver with the three special solutions inserted and the fla screwed to the conductivity electrode and the closure and at 20 ° C thermosta animals. After a short lag phase, oxygen consumption starts when the magnetic stirrer is moving which is displayed as negative pressure. The mineralized carbon is called carbon dioxide bound to alkali and displayed as a change in conductivity. The dismantling will be double rated tet, on the one hand as oxygen consumption (negative pressure) and on the other hand as a change in conductivity (Carbon dioxide formation).

Embodiment 2 (anaerobic degradation)

50 ml of industrial sludge are introduced into the amber glass bottle, with 10 ml of nutrient solution solution and 6 ml of a vaccine culture from activated sludge and digestion biology were added, the oxygen is replaced by a nitrogen supply, the quiver with the special solutions set and the bottle with the conductivity electrode screwed airtight. The Magnetetrüh rer rests and the system is tempered at 37 ° C. The positive pole of the sensor shows the content of methane and the conductivity electrode the content of carbon dioxide. Through the At the end of the experiment, two lower half-shells on the quiver can contain the septic acid hydrogen and ammonia are recognized.

Embodiment 3 (combination of 1 and 2)

500 ml of industrial waste water with a COD value <10,000 mg O ₂ / l are introduced into the amber glass bottle, 10 ml of nutrient solution are added, 6 ml of inoculation sludge according to Example 1, 25 Raschig rings and the quiver with the three special solutions are used. The apparatus is thermostatted at 20 ° C, the magnetic stirrer switched on and the oxygen consumption determined as a vacuum measurement. The mineralized carbon from the organic wastewater pollution is determined via the conductivity measuring electrode. At the end of aerobic degradation after 3-5 days, a nitrogen purge is carried out via the two three-way cocks and the temperature adjusted to 37 ° C. The apparatus is switched to the positive pole and the gas development in the anaerobic area is determined as methane (overpressure) or via the conductivity electrode (carbon dioxide) as a second measurement. At the end of the test series, in the event of an inhibition of degradation, the pH or the content of hydrogen sulfide or ammonia can be determined by colorimetric measurements.

Embodiment 4

150 g of soil are sieved to 2 mm and a with 50% of the maximum water holding capacity posed. 100 ml of the nutrient solution are previously added to the added water. in the In the dark, oxygen consumption and carbon dioxide evolution are measured where with the rotary shaker with 100 rpm for a slight ground movement. By the Zu potential breathability can be determined by adding 1.5 g glucose. The breathable Activity is depleted of oxygen per 100 g of soil per hour specified.

Claims (5)

1. The method and device for biodegrading carbon-containing wastewater, characterized in that the degradation is assessed either aerobically or anaerobically or as a combination of both processes and the reaction products continuously as measurement signals in the form of a negative pressure (oxygen depletion) or an excess pressure (methane) or as sorbed gases (carbon dioxide due to changes in conductivity, hydrogen sulfide and ammonia) are recorded in a triple quiver. 2. The method and device according to claim 1, characterized in that a thermostat at 20 ° C for aerobic degradation and 34 ° -39 ° C for anaerobic Dismantling can be made and plastic hollow rings to the settlement area of the Microorganisms are added. 3. The method and apparatus according to claim 1, in which by different positions of two three-way valves either on the negative or positive pressure pole of a sensor switch or the reaction bottle with an stick to create anaerobic conditions fabric can be filled. 4. The method and apparatus according to claim 1, after the typical anaerobic poisons Schwe hydrogen sulfide and ammonia are recorded photometrically at the end of the experiment. 5. The method and device according to claim 1, characterized in that instead of the Ab water soils, sludges, sediments and chemicals aerobic and anaerobic in the degradation can be voted.