KR100721271B1 - Process for the treatment of waste water - Google Patents

Abstract

Provided is a method for treating wastewater which forms active sludge with good sedimentation and good treated water quality and reduces the amount of excess sludge generated.

The activated sludge is contacted with a sarcosine compound.

Activated sludge, sarcosine compounds, wastewater treatment, sedimentation, water quality improvement

Description

Process for the treatment of waste water

The present invention forms a highly compact sludge floc in an industrial wastewater treatment tank or a public wastewater treatment plant, forms an active sludge having excellent sedimentation properties, and also reduces the amount of surplus sludge generated and maintains It relates to an easy method for treating wastewater.

Conventional techniques for forming good activated sludge in wastewater treatment facilities and reducing the amount of excess sludge generated are known by adding agents such as microorganisms or enzymes to activated sludge [e.g. "Reduction and Energy of Sludge in Microbial Treatment." Saving ", again H, energy saving, Vol. 48, No. 7, 1996]. As a method of reducing excess sludge, a method of adding an organic flocculant such as a polymer flocculant or an inorganic flocculant such as polyaluminum chloride or aluminum sulfate has been proposed (e.g., Japanese Patent Application Laid-Open No. 5-253589). . In addition, reduction of sludge can be also achieved by a biofilm method or by installing a digestion tank at the rear of the activated sludge (see "About sludge generation in various active sludge methods", Sakai Yoshio, monthly sewerage, Vo1). .21, No. 2, 1997; "Around Variation and Control," Microbial Ecology Research Group, Microbial Ecology 11, Society Publications Center].

In the treatment method described above, in order to maintain good microbial activity and to reduce the amount of surplus sludge, the addition of a drug such as a microbial agent or an enzyme is attempted, but a satisfactory effect is not necessarily obtained, and there is a problem in terms of economics such as drug cost. In addition, various flocculants such as polymer flocculants have excellent effects in reducing the volume of sludge to increase sedimentation, but can not reduce the amount of sludge generated and do not improve or maintain microbial activity. Further, among the biological treatment methods, the biofilm method is superior in that it does not produce excess sludge compared with the activated sludge method, but it is difficult to adapt to the advanced treatment of wastewater, and there is a difficulty in that the treated water quality is deteriorated by the biofilm peeling.

In addition, although a digestion tank may be installed at the rear end of the aeration tank in order to reduce the excess sludge, the equipment cost is high and the cost of wastewater treatment is increased.

In view of these circumstances, the present invention provides a method for treating wastewater, which forms active sludges with excellent sedimentation and good treated water quality and reduces the amount of excess sludge generated.

As a result of intensive test studies to solve these problems, the present inventors have found that the desired purpose can be achieved by contacting a sarcosine-based compound with an activated sludge, thereby completing the present invention.

Embodiment of the invention

Typical examples of sarcosine compounds suitable for practicing the present invention include, for example, sarcosine, N, N-dimethylglycine or lauroyl sarcosine having a long chain acyl group at the N position, myristoyl sarcosine, palmitoyl sarco Cine, stearoyl sarcosine, oleoyl sarcosine and their alkali metal salts, ammonium salts and inorganic acid salts.

In carrying out the method of the present invention, the amount of sarcosine compound added to the activated sludge is preferably 0.01 to 5% by weight per day based on the sludge solids. If the added amount of the sarcosine compound is higher than 5% by weight, there is a fear of causing biological inhibition. If the added amount is less than 0.01% by weight, the effect of using the drug is not sufficient.

As a method of adding a sarcosine-based compound to the activated sludge, the compound may be added continuously, but may be added intermittently. In this case, the drug may be optionally diluted with water or the like.

The place where the sarcosine compound is added may be any place that can be brought into contact with the activated sludge. However, it is preferable to add the sarcosine compound to the aeration tank or the return line of the sludge in the wastewater before treatment.

[Action]

Sarcosine compounds have bactericidal and antimicrobial properties and are used as additives for dentifrices by preventing the growth of harmful microorganisms in the oral cavity and preventing bad breath. Cow) 62-16927], and is also known to be used to prevent the formation of insect bites (cavities) and tartar (e.g., Japanese Patent Publication No. 5-58403).

In the method of the present invention, by using the bactericidal or antimicrobial activity of such sarcosine-based compounds, specific compounds such as filamentous fungi, which cause the sedimentation of sludge by interfering with the sludge of the sludge, are lysed and killed. The function of the predatory action of active sludge is enhanced by propagating protozoa or epidermis that preys. By obtaining such a benign biological phase, sludge can be reduced and at the same time, sludge which is excellent in sedimentation property is formed, the efficiency of wastewater treatment is improved, and the quality of treated water is considered to be good.

EXAMPLE

Although an Example demonstrates this invention concretely below, this invention is not limited to these.

In addition, the abbreviations and drugs used in the Examples are as follows.

(Abbreviation)

Biochemical 0xygen Demand (BOD): Biochemical Oxygen Demand                     

Chemical 0xygen Demand (COD): chemical oxygen demand

Mixed Liquor Suspended Solids (MLSS): Active sludge concentration in aeration tanks

Sludge Volume Index (SVI): Volume per gram of activated sludge (ml)

SV 30 (S1udge Volume): Settling rate when 1 liter of activated sludge is allowed to stand for 30 minutes

(drugs)

Sarcosine: Sigma Aldrich

Sodium sarcosine: Gurarese

Sarcosine Hydrochloride: Reagents from Sigma Aldrich

Example 1

The sludge reduction test is performed using sarcosine, sodium sarcosine and sarcosine hydrochloride. A continuous activated sludge system equipped with a 10 l aeration tank and a 6 l settling tank was prepared and treated with synthetic sewage wastewater (100 mg / l as BOD) under conditions of 0.2 kg-BOD / kgSS and MLSS 2,000 mg / l BOD sludge load. do.

The reduction rate of surplus sludge in the aeration tank, the sedimentation of sludge represented by the indicator of SVI, and the BOD after the operation for one month by adding the sarcosine or salt thereof to the wastewater at a ratio of 0.1 wt% per day to the sludge weight of the aeration tank. The removal rate is measured to investigate the impact on the treatment capacity of the waste water.

These test results are shown in Table 1, and the surplus sludge is drastically reduced by adding sarcosine or a salt thereof. In addition, although the sedimentation properties of sludge are improved and the BOD removal rate is maintained at a high level, inhibition of wastewater treatment function is not confirmed.

additive % Reduction of surplus sludge SVI (ml / g) BOD removal rate (%) Sarcosine 35 152 97 Sarcosine Sodium 33 155 98 Sarcosine Hydrochloride 28 150 98 No addition - 161 97

Example 2

Table 2 shows the test results when the concentration of sodium sarcosin is added to the wastewater in Example 1 at a ratio of 0.01% by weight, 1% by weight and 5% by weight, respectively, based on the sludge weight of the aeration tank.

According to these test results, it is confirmed that the excess sludge only slightly decreases when the concentration of addition is 0.01% by weight, while the addition effect cannot be expected when the concentration of addition is less than 0.01% by weight.

On the other hand, in the addition amount of 5% by weight, a significant sludge reduction effect is confirmed, but the BOD removal rate is slightly lowered. Therefore, when the added amount is more than 5% by weight, the wastewater treatment function is lowered, which is not preferable.

% Added % Reduction of surplus sludge SVI (ml / g) BOD removal rate (%) 0.01 3 160 97 One 33 155 98 5 42 150 90 0 - 161 97

Example 3

Excess sludge reduction tests are carried out in food factories. Operating conditions in the processing facilities of the plant the quantity (水量) 1,000m ³ / day, an aeration tank capacity 1,000m ^3, settling tank 600m ^3, and MLSS 5,000mg / ℓ, BOD sludge load was 0.20 to 0.25kg-BOD / kg- SS. The test period is 4 months, and during the first two months, the treatment status when no sodium sarcosine is added is examined, and during the second two months, sarcosine sodium is aerated at a rate once per week. 30 kg of weight percent is added to the aeration tank to compare the treatment of the wastewater before and after introduction.

These test results are shown in Table 3, and the amount of dehydrated cake is reduced to 27% after the addition. In addition, a marked improvement in treatment ability such as BOD removal and sedimentation of sludge is found.

Analysis item Before medication (2 months) After medication injection (2 months) Influent Treated water Removal rate Influent Treated water Removal rate pH 7.3 7.4 7.3 7.3 BOD (mg / l) 940 26 97.2 950 15 98.4 COD (mg / L) 320 25 92.2 380 19 95 MLSS (mg / l) 5200 5100 SV30 (%) 98 88 SVI (ml / g) 188 173 Dehydrated Cakes (kg / day) 4800 3500 (27.1% reduction) Dehydrated Cake Water Content (%) 87.8 85.5 Dehydrated Cake Solids (kg / day) 586 508 BOD sludge change rate (%) 62.3 53.4 BOD sludge change rate (%): BOC of dehydrated cake solids / influent

Example 4

Inflow water 8,0Om ³ / day, aeration tank volume 3,000m ³ , MLSS 2,000mg / ℓ, BOD sludge load 0.2kg-BOD / kg-SS in the sewage treatment plant operated 0.1% per day Continuous injection into the return line of sludge using a metering pump at a percentage by weight.

Table 4 shows the results of comparing the wastewater treatment conditions for each of two months before and after adding sodium sarcosine.

According to the obtained test result, the reducing effect of surplus sludge is remarkably confirmed.

In addition, as a result of observing the activated sludge image before and after the injection of the drug, filamentous bacteria and actinomycetes are reduced after the injection, whereas positive welfare animals and protozoa such as pyridina or Baltisera proliferate. In other words, it is confirmed that the addition of sodium sarcosine promotes high-level microorganisms useful for wastewater treatment, thereby increasing the predatory action of activated sludge, thereby promoting the reduction of excess sludge.

Analysis item Before medication (2 months) After medication injection (2 months) Influent Treated water Removal rate Influent Treated water Removal rate pH 6.8 7 6.8 7 BOD (mg / l) 150 5 96.7 165 4 97.6 COD (mg / L) 125 4 96.8 133 4 97 MLSS (mg / l) 2000 1900 SV30 (%) 26 24 SVI (ml / g) 130 126 Dehydrated Cakes (kg / day) 5210 3880 (25.5% reduction) Dehydrated Cake Water Content (%) 79.5 78.1 Dehydrated Cake Solids (kg / day) 1068 850 (20.4% reduction) Firodina - ++ Baltisera + ++ Episdirus + +++ Actinomycetes (Nogarudia) + - Filamentous Bacteria (021N) + - (Note)-: none at all, +: less, ++: more, ***: very much

According to the method of the present invention, by contacting the sarcosin-based compound to the activated sludge to increase the predation action of the activated sludge, it is possible to increase the wastewater treatment capacity and to drastically reduce the amount of excess sludge generated and to easily maintain the wastewater treatment facility. In addition, maintenance costs can be significantly reduced.

Claims (1)

A method for treating wastewater, characterized by contacting a activated sludge with a sarcosine compound.