RU2001025C1 - Method for waste water purification - Google Patents

Abstract

Usage: wastewater treatment of the food industry. Essence: pre-matured microalgae culture in the nitrogen starvation mode is additionally treated with ultrasound for 4-6 minutes with a frequency of 880 - 1000 kGtsiintensity of 0.6 x 10-4-0.8 x 104 W / m 2

Description

The invention relates to the biological treatment of wastewater from food industry enterprises

A known method of treating wastewater with organic impurities is that the wastewater subjected to treatment by fermentation, biological nitrification and deazotization. mixed with excess activated sludge. High molecular weight cationic coagulant is added to the mixture and the resulting sludge and water are separated. The separated water is subjected to secondary treatment with a coagulant containing inorganic components, followed by separation of water and sludge.

The disadvantage of this method is that it includes six consecutive steps and the total cleaning time is at least 3-4 days

A known method of using microalgae for the post-treatment of liquid waste from poultry farms is as follows. that poultry farm waste was pretreated with methanogen bacteria, then it was autoclaved to kill pathogens and kept in air-aerated reactors, which was then used to grow chlorella. Growing chlorella for two weeks improved the organoleptic characteristics of the waste being cleaned: the unpleasant odor disappeared, liquid clarification occurred, especially intense during pretreatment of waste with bacteria methanogens

The disadvantage of this method is the very long cleaning period of a total of at least 16-17 days

Closest to the proposed technical essence and the achieved result is a method for biological treatment of wastewater from nitrogen, which consists in introducing Chlorella microalgae into the treated sludges. concentration of 3 10 g / l, maintained in the fasting mode for 4-10 hours; Duration of cleaning 2-8 hours, while the degree of purification from nitrogen is 97 98%

The disadvantage of this method is that when the nitrogen concentration in the effluent is increased to 500 mg / l, the effectiveness of this method decreases sharply and the duration increases to 40-55 hours. In addition, the current treatment facilities of industrial plants are not always it is possible to provide effective lighting when cultivating microalgae up to 300,000 l

The aim of the invention is to reduce the time of biological wastewater treatment

The goal is achieved by

waste water (CB) is introduced (nitrogen concentration 50-400 mg / l) of Chlorella microalgae (concentration in the tank for cleaning 0.6-15 g / l depending on the nitrogen content in the treated CB), aged

starvation for 4-10 hours and treated with high-frequency (880-1000 kHz) ultrasound of low intensity (0.6 x 104 - 0.8 x 10) for 4-6 minutes, the cleaning time was 5 et 2-8 hours at illumination 200 lux.

During the cleaning process, a part (80%) of the microalgae biomass is simultaneously gravitationally precipitated, which is then removed and concentrated to a concentration

0 60-100 g / l, incubated under nitrogen starvation, sonicated and re-fed to a container for cleaning.

When implementing the proposed method, the illumination intensity is not significant

Purified water with a part of the biomass (20%) is fed to the coagulator, where, in order to completely separate the biomass and suspended solids, iron (III) chloride is added in the form of a 1% solution so that the mass fraction of FeCIa in the wastewater is 0.01-0.015% This is 1.5-2 times less than in known methods.

Next, water is fed to a separator for

5 purification from coagulum, and then discharged into a pond. Purified water contains 1-5 mg / l of nitrogen and MIC 3-6 mg l.

Chlorella pre-ultrasound treatment promotes intensive

0 the formation of the metabolic fund of oxygen, which goes to the photooxidation of organic substances. In this case, first of all, non-molecular organic compounds are actively oxidized.

5 A drawback of coagulation wastewater treatment methods is that low molecular weight nitrogenous substances are not involved in the treatment. In addition, the Chlorella cell qi population is used as

0 natural flocculant, which allows to reduce the dose of coagulant administered by 1.5-2.0 times in comparison with known methods

Ultrasonic processing allows

5 to reduce the necessary illumination during biomass cultivation by 150 times.

Example 1. Wastewater with a nitrogen concentration of 200 mg / l is fed into the reaction tank-settler, there is also served passed for 4 hours the stage of starvation

and sonicated (with a frequency of 880 kHz, intensity 0.6 10 W / m for 4 min), the condensed microalgae biomass with a concentration of 15 g / l of the Chlorella mlg strain DARG-15, the concentration of microalgae in the reaction tank-settler 5 g / l.

The mixture of wastewater with microalgae was incubated for 8 hours at an illumination of 200 lux. From the settling reaction chamber, purified water with a part of the biomass is fed to the coagulator, where it is mixed with a 1% solution of iron (III) chloride so that the mass fraction of FeCb in the treated effluents with biomass residues is 0.015%. The settled biomass is pumped out and fed to a separation, where it is concentrated to 30 g / l, and then fed to a regeneration chamber for holding under starvation conditions for 4 hours and sonication,

Purified water contains 5 mg / l of nitrogen; BOD is 16 mg of l.

Example 2. Purification is subjected to wastewater with a nitrogen content of 400 mg / L. The process is carried out analogously to example 1. but using a strain of Chlorella kessleri.

The concentration of microalgae in the reaction vessel is maintained at

not 6 g / l. The duration of pre-fasting is 10 hours; scoring is performed by ultrasound at a frequency of 1000 kHz. intensity of 0.5 104 for 5 minutes Duration of cleaning is 8 hours at illumination of 200 lux.

Purified water contains 2 mg L of nitrogen; BP ' 5 is 9 mg / L.

Example 3. Cleaning is subjected to wastewater with a nitrogen content of 50 mg / L. The process is carried out analogously to example 2. The concentration of microalgae in the reaction vessel is maintained at 0.6 g / l. The duration of pre-fasting is 7 hours, scoring is performed by ultrasound at a frequency of 880 kHz, intensity 0.4 104 W / cm 2 for 6 minutes. The cleaning time is 2 hours at 200 lx illumination.

Purified water contains 1 mg / L of nitrogen; BOD5 is 3 mg / L.

(56) Japanese Patent Application 62-44996, cl. C 02 F9 / 00, 1987.

The use of microalgae for the post-treatment of liquid waste from poultry farms. Myslovich V.O. et al. Editorial Board of the Hydrobiological Journal, Kiev, 1987.

USSR Copyright Certificate No. 998390, cl. C 02 F 3/34, 1980.

Claims (1)

SUMMARY OF THE INVENTION A WASTE WATER TREATMENT METHOD, which comprises introducing into the wastewater cultures of Chlorella microalgae, kept under nitrogen fasting for 4-10 hours, characterized in that that previously, before introducing into the wastewater, the microalgae culture 35 is further treated for 4 minutes with ultrasound at a frequency of 880 - 1000 kHz and an intensity of 0.6 10 - 0.8 104,