HU196043B - Process for the anaerobic biological purification of sewages comprising acetic acid and furfurole and having toxic effect on microorganisms - Google Patents

Abstract

The invention relates to a process for the anaerobic biological purification of acetic acid- and furfural-containing wastewaters (effluents) toxic to microorganisms, in which 1 or more biological substance(s), suitable for maintaining the life functions of microorganisms, containing nitrogen compounds and possibly phosphorus compounds deactivating the reactive aldehyde group of the furfural, is or are added to the wastewaters. The process according to the invention makes it possible to purify acetic acid- and furfural-containing wastewaters using additives which are per se environmentally polluting, valueless or very cheap.

Description

The present invention relates to a process for the anaerobic biological purification of wastewater containing acetic acid and furfural which is toxic to microorganisms in a Jiological reactor.

In recent years, anaerobic biological treatment of high organic matter wastewater has been gaining ground. From an energy point of view, the process is very advantageous as it converts the degraded organic matter into a combustible gas with a high methane content with minimal cellular content. In contrast, earobic biological wastewater treatment produces a large amount of excess sludge (accumulated excess cell) mainly to provide oxygen. The process can be made quite fast if, generally by immobilizing the microbes, a high concentration of cells in the reactor can be achieved.

The process requires the substrate to contain N and P nutrients in addition to the organic carbon compounds. As a general guideline, the desired KQI / N / P nutrient ratio is reported by M. Henze as an average of 1000/7/1 (Water Science and Technology 15, No.8-9, 1-107). [Ratios include concentrations measured in raw sewage, the first of which is the organic oxygen demand (COD).]

The so-called microbes that support the metabolic activity of microbes. the addition of bio-materials improves the efficiency of each bioconversion process. On microbial diets, yeast extract or yeast extract is used as biosubstance in fermentation substrate mixtures. yeast autoMatate is added.

The anaerobic process is particularly easy if the organic material to be decontaminated is a volatile organic acid whose biochemical conversion leads directly to methane production.

There are publications in the literature reporting the results of anaerobic biodegradation of acetic acid. Raw wastewater or synthetic modem material used in similar experiments, derived from the mixing, dilution of compounds containing N and P with acetic acid and bio-material, or naturally occurring wastewater containing additional combiners.

An example of the first variant is L. Baresi et al., Applied and Enviromental Microbiology 36, 186-197 (1987), where the model sewage is composed of calcium acetate, a yeast train and, inter alia, a solution of 5 kinds of mineral salts. The concentration of yeast extract has been varied from 0% to 0.5% to investigate the effect on gas production.

The second variant is exemplified by sugar. wastewater from the starch-spirit industry, where spontaneous acidification occurs while standing. These modest acetic acid wastewaters are generally easy to purify anaerobically since both the nutrient and the natural organic matter are provided from the remainder of the original raw material.

Because of its high acetic acid content, wastewater from furfural production from high pentosan plant parts by high temperature and pressure catalytic hydrolysis would be well suited for anaerobic purification (Hungarian Patent Nos. 155,807 and 164,886). A special advantage here is that the waste water from the manufacturing process is close to 100 ° C, which eliminates the need to heat the wastewater to be fed to an anaerobic reactor operating at temperatures above ambient temperature (usually 35-65 ° C). here are the following three circumstances;

(a) The effluent contains 0 5 to 2 kg / m ^{3 of} furfural and has a lower content of phenols and resins with an acetic acid content of approximately 20 to 30 kg / m ³ . The toxic effect of furfural is generally known. Such an effect is reported by GA Szobcijeva et al. In Damage to the Microbial Dtochrome System (Mikrobiologija42,441-444 / 1973 /). Due to its toxicity, fbrfural is also used as a germicidal agent (The Merck Index, 9th edition, Merck and Co., Rahway, New Jersey, 1976)

b) Does not contain nutrients essential for microbial life (cell synthesis), such as N and P.

c) Nern contains so-called. bio materials.

In conclusion, unlike model water of natural food origin or made from pure materials, wastewater from furfural production is a liquid by-product of the catalytic organic chemical process containing sterile, toxic substances that are nutritionally deficient.

It is an object of the present invention to provide a process which enables anaerobic treatment of wastewater from fur oil production under economically and technically realistic conditions.

The present invention is based on the discovery that reactive aldehyde groups that produce toxic effects of furfural can be rendered harmless to microbial conditions by reacting with Wos materials containing nitrogen and phosphorus compounds to form amine aldehyde condensate.

Accordingly, the present invention provides a process for the anaerobic biological purification of toxic to microorganisms of wastewater containing acetic acid and furfural in a biological reactor characterized in that the reactive aldehyde group of furfural is chemically deactivated with nitrogen or phosphorus compounds, manure or slurry from milk processing or whey from milk processing is added at such a rate that the temperature in the reactor is adjusted to between 30 ° C and 60 ° C.

The preferred inexpensive bio-material for use in the process of the present invention is animal manure, known per se, for the disposal and utilization of fertilizers by anaerobic bioconversion, which first comprises organic acids formed from some of the more complex compounds of higher molecular weight. The pig manure of the original 4 in mesophilic anaerobic acidification (usually at 35 ° C), characterized by typically 40/4/1 COD / N / P ratio of about 7-8 kg / m ³ of an organic acid containing 5% solids materials , a product of a heritable composition is formed as a result of a residence time of 2.5-4 days. Not only does the pre-treated fertilizer additive not only neutralize the toxic effect, but its volatile organic acid content increases the methane production of the anaerobic process. The additive is based on approximately the same COD value of crude impurity and generally COD / N / P of 40/4/1; The addition of 15 parts by weight to the wastewater already satisfies the ΌΟΟ / 7 / L COD / N / P ratio mentioned above. It should be noted that four times less N and P than this optimal nutrient ratio

196,043 cleaning process.

In the process of the invention, the anaerobic reactor has a neutral, ca. It is advisable to maintain a pH of 7. The original sewage has a pH of 2 to 2 because of its high acid content. Therefore, it is advisable to use lime hydrate to neutralize it before adding the bio additive. It is sufficient to neutralize the pH of the effluent to be fed to about 5.5. The average pH in the reactor is solved by recycling some of the purified effluent, reducing the need for neutralizing chemicals. A further advantage of recirculation is that the high acetic acid content alone is toxic and / or toxic. eliminates the inhibitory effect of the process. The effluent content of the effluent can be kept below 1 kg / m ³ by approximately diluting the effluent. This reduces the acidity of the mixture fed to the reactor to below 4 kg / m ^3, which is considered critical. The biogas produced by the anaerobic decomposition of acetic acid has a methane content of more than 50% that can be calculated theoretically, since acetate removed from calcium acetate allows the capture of a significant part of the CO ₂ produced as calcium carbonate.

Additional viral materials which may be advantageously used in the process of the invention;

- Excessive activated sludge from municipal sewage treatment plants, or its volatile organic acid product, already partially digested following anaerobic acidification similar to fertilizer. Its COD / N / P ratio is typically 70/6/1. Based on this, mixing the wastewater in a ratio of about 1:25 by weight provides the best N and P nutrient requirement for the process. The activated sludge may be wholly or partly derived from excess sludge production from anaerobic biological post-treatment.

- Slurries formed during the production of alcohol during the rectification process. A particularly advantageous feature of this is that it is a product rich in bio-materials and proteins, which has a COD content of between 10 and 100 kg / m ³ , depending on the raw material and technology processed. The dosage is preferably in a ratio of 1: 4 to 1:40 relative to the waste water.

- In the dairy industry, cheese and cheese. Whey from curd, with a COD between 60 and 120 kg / m ³ , contains three-quarters of its dry matter content as lactose and lactic acid and one quarter as protein. Mixing with wastewater in a ratio of 1: 20 to 1: 200 is advisable.

After the anaerobic pre-acidification of manure and activated sludge, the other two substances have a significant organic acid content and low pH even in their original state.

At the start of the process of the invention, the reactor is suitably seeded with digested activated sludge rich in active methanogenic microflora. Adaptation of the microflora to the disintegrate is performed in two stages. Initially, only the additive is fed, and for a longer period of time, preferably 1-2 months, we increase the rate of the wastewater feed and reduce the feed of the additive wastewater! weight ratio up to the 1000/7/1 KOJ / N / P ratio described above.

The most important advantage of the process according to the invention is that it enables advantageous anaerobic biological purification of waste water containing furfural having a toxic effect on microbes. To eliminate the toxic effect, additives containing biodegradable components, ie no secondary contamination or only a minor cause, are used. The listed materials are worthless or very cheap by-products, which are waste in themselves and pollute the environment. Purified water leaving the reactor. Recirculation has increased protection against the high acid concentration of the wastewater, while reducing the amount of alkaline chemical used to neutralize the wastewater.

The following examples illustrate the process of the invention in more detail.

EXAMPLE 1 0.7 m ^{3 of a} furfural plant in a m ³ spherical, heat insulated reactor treated with 80-90 ° C waste water with an acetic acid content of 25 kg / m, a furfural content of 1.2 kg / m ³ , and a COD 19 kg / m ³ , pri and 2.2. The effluent was neutralized with 12 kg of lime hydrate per pH ^{3 to} pH 5.5 prior to feeding.

Subsequently, 0.1 m ^{3 of} 30 kg / m ^{3 of} digested activated sludge from a municipal wastewater treatment plant is added to the reactor. In another temperature controlled reactor at 35 ° C, anaerobic acidification of 0.1 m ^{3 of} 45 kg / m ³ dry slurry of pigs with an organic acid content of 7.5 kg / m ³ was carried out for 3.5 days. The temperature of the wastewater treatment reactor, without separate heating, is set at the optimum temperature of thermophilic microorganisms: 50 ° C. The feed! the speed is chosen so that the organic acid content of the effluent is less than 1 kg / m ³ .

The recirculation rate is set to 60 at start-up and is continuously reduced to 8. (Recirculation ratio is the ratio of the volume flow from the effluent to the additive effluent flow.)

The reactor will reach its rated capacity in 2.5 months. At this time, the residence time of the wastewater is 2.1 days and the gas production is 3.2 g / m ³ reactor volume days. The gas contains 75% methane and 25% carbon dioxide. The concentration of organic acids in the effluent is 0 9 kg / m ³ (measured by gas chromatography), it contains only traces of furfural and the COD is 1.8 kg / m ³ .

Example 2

The furfural plant wastewater of the composition shown in Example 1 was treated in the same embodiment except that 45 kg / m ^{3 of} dry matter containing distillation residue (slurry) and 25 kg / m ^{3 of} dry slurry mixed with manure were added to the wastewater treatment reactor. The system was acidified to pH 5.5 by anaerobic fermentation in a system of 0 ° C. The wastewater treatment reactor operates at 55 ° C. The method of circulation is the same as that of Example 1, except that the wastewater is neutralized to pH 6.5 with NaOri instead of lime broth. The effluent discharged does not contain furfural and has a COD of 1 6 kg / m.

Example 3

All proceed as in Example 2 with the exception that the furfural plant wastewater

Instead of 196.043, 20 kg / m ³ stalk is replaced with whey and scavenging mixture of milk and high protein and carbohydrate obtained during milk processing instead of 20 kg / m ^{3 of} stalk instead of spirits slurry and pig slurry. The mixture is added to 0.7 m ^{3 of} wastewater in an amount of 0 035 m ³ , i.e. 20: 1. .

The organic acid concentration of the treated effluent is <0.05 kg / m ³ and the COD value is 1.2 kg / m ³ .

Claims (1)

PATENT CLAIMS A process for the anaerobic biological purification of wastewater containing toxic effects on microorganisms containing acetic acid and furfural in a lithological reactor, characterized in , slurry from alcohol production or whey / S whey from milk processing is added at a rate such that the temperature in the reactor is adjusted to between 30 ° C and 60 ° C. 2. The method of claim 1, wherein a portion of the effluent stream leaving the reactor is continuously recycled to the reactor feed. place.