CN109294921B

CN109294921B - Issatchenkia orientalis strain ZT-C2 and application thereof

Info

Publication number: CN109294921B
Application number: CN201810822897.4A
Authority: CN
Inventors: 钟增涛; 曹亚君; 江高飞; 马东燕; 尹显燕
Original assignee: Zhangjiagang Hongyi Aquaculture Co ltd; Nanjing Agricultural University
Current assignee: Zhangjiagang Hongyi Aquaculture Co ltd; Nanjing Agricultural University
Priority date: 2018-07-25
Filing date: 2018-07-25
Publication date: 2021-08-10
Anticipated expiration: 2038-07-25
Also published as: CN109294921A

Abstract

The invention discloses an Issatchenkia orientalis strain ZT-C2 and application thereof, wherein a denitrogenation sulfur ZT-C2 is preserved in the common microorganism center of China Committee for culture Collection of microorganisms in 6 months and 25 days in 2018, the preservation number of the strain is CGMCC NO.16008, and the classification and the designation are as follows: issatchenkia orientalis (Issatchenkia orientalis) with address: west road No.1, north west of the republic of kyo, yang, institute of microbiology, academy of sciences of china, zip code: 100101. through tests, the removal rate of hydrogen sulfide in water after the strain is inoculated into sewage in 12 hours reaches more than 60%, the removal rate of hydrogen sulfide in water in 24 hours reaches more than 80%, the removal rate of ammonia in sewage reaches about 60% after 20 days, and the removal rate of ammonia in wastewater approaches 70% after 23 days, further explaining that the strain is high in activity, strong in adaptability and high in sulfur and nitrogen removal efficiency.

Description

Issatchenkia orientalis strain ZT-C2 and application thereof

Technical Field

The invention belongs to the field of environmental microorganisms, and particularly relates to an Issatchenkia orientalis strain ZT-C2 with sulfur and nitrogen removal capability and application thereof in sulfur and nitrogen removal in wastewater.

Background

Along with the continuous development of economy and the continuous promotion of urbanization process, the living standard of people is continuously improved, municipal treatment facilities such as sewage treatment plants, sewage lifting stations, garbage transfer stations and garbage landfills are closer and closer to living areas of people, and black and odorous sewage generated in the operation process of the facilities becomes an important factor influencing the normal life of people. The eutrophication is mainly caused by the overhigh ammonia nitrogen content in the black and odorous sewage, so that the content of organic matters in the water body is increased. The organic matter mainly comprises sulfur-containing compounds, nitrogen-containing compounds, halogen and derivatives thereof, hydrocarbons, oxygen-containing organic and organic acids and the like.

The high ammonia nitrogen content and the high hydrogen sulfide content in the sewage generate unpleasant odor, and the hydrogen sulfide and the ammonia gas have low odor threshold values due to the particularity of the hydrogen sulfide and the ammonia gas, so that the treated water body does not smell the odor from the air. The sewage needs to be thoroughly removed.

Biological sulfur and nitrogen removal processes generally involve three steps:

(1) the odor molecules in the wastewater enter a liquid phase from a gas phase and are dissolved in a liquid film on the surface of the biological film.

(2) The odor molecules dissolved into the water further diffuse to the biofilm surface and are then metabolically decomposed by the microorganisms.

(3) The odor molecules entering the microbial cells are metabolized and decomposed to remove inorganic small molecular substances, ions and the like, thereby purifying the air.

The biological desulfurization and denitrification is to perform desulfurization and denitrification by using a microbial method. The microorganisms for removing nitrogen and hydrogen sulfide include thiobacillus thioparus (Thiobacillus thioparu), thiobacillus thiooxidans (Thiobacillus thiooxidans) and thiobacillus denitrificans (Thiobacillus thiooxidans), and the strains for removing ammonia mainly include Pseudomonas.

The yeast has the characteristics of bacteria, such as existence in a unicellular form, fast growth and reproduction and capability of forming better flocs, so that the yeast is suitable for various bioreactors; meanwhile, the yeast has the characteristics of filamentous fungi, larger cells and vigorous metabolism, has various advantages compared with microorganisms for removing hydrogen sulfide in sulfur and nitrogen removal gas found in the prior art, such as high treatment efficiency, small required field, low treatment cost and the like, but the application of the yeast in sewage or waste gas in the prior art is mostly used for treating organic matters, and the current situation and the progress of the application of the yeast in waste water treatment such as Cao Wen level have reported that the yeast only has strong treatment effect on organic pollutants, but has strong treatment effect on some organic pollutantsContaminants (e.g. SO)₄ ^2-And NH₄ ⁺) The treatment effect is not good because the yeast is a chemoheterotrophic microorganism ". Due to the report, no report related to the removal of hydrogen sulfide and ammonia gas by yeast is known at present.

Disclosure of Invention

The invention aims to provide a novel yeast, belonging to the family of Saccharomyces, and aiming at solving the problem that odor gas generated by hydrogen sulfide and ammonia gas in the existing wastewater brings troubles to the life of people.

The invention provides a yeast strain, which is named as denitrogenation ZT-C2, is preserved in China general microbiological culture Collection center in 2018, 6 months and 25 days, has the strain preservation number of CGMCC No.16008 and is named in classification as follows: issatchenkia orientalis (Issatchenkia orientalis) with address: west road No.1, north west of the republic of kyo, yang, institute of microbiology, academy of sciences of china, zip code: 100101.

the bacterial strain presents a typical colony shape of Issatchenkia orientalis, the colony is large and thick, the surface of the colony is smooth, the wetting bulge is sticky, the colony is easy to pick up, the texture of the colony is uniform, the edge is neat, and the colony is milky white.

The Issatchenkia orientalis strain ZT-C2 provided by the invention has the function of removing sulfur and ammonia in environmental wastewater.

The Issatchenkia orientalis strain ZT-C2 provided by the invention can grow to the maximum concentration on a PDA culture medium after 12 hours, can normally grow under the conditions of 25-40 ℃ and pH5-9, has high strain activity and strong adaptability, and can be widely used in the biological treatment process of various sewage.

The invention also provides application of the Issatchenkia orientalis strain ZT-C2 in environmental sewage treatment, in particular application in sewage rich in hydrogen sulfide or/and ammonia.

The invention also provides a microbial inoculum containing the Issatchenkia orientalis strain ZT-C2.

The microbial inoculum provided by the invention has a purification effect on sewage.

The purifying agent provided by the invention contains the Issatchenkia orientalis strain ZT-C2.

The purifying agent of the present invention has total viable bacteria concentration of 1 × 10⁶～1×10¹⁰CFU/ml, preferably 1X 10⁷～1×10⁹CFU/ml, more preferably 1X 10⁸CFU/ml。

The invention also provides the application of the purifying agent in environmental sewage treatment, in particular to the application in sewage rich in hydrogen sulfide or/and ammonia.

The invention has the beneficial effects that:

1. the research shows that the Issatchenkia orientalis strain ZT-C2 with the advantages of separating and screening different products to efficiently remove hydrogen sulfide and ammonia gas can grow to the maximum concentration on a PDA culture medium after 12 hours, and can normally grow under the conditions of 25-40 ℃ and pH5-9, and the Issatchenkia orientalis strain provided by the invention has high activity and strong adaptability, and can be widely applied to various biological sewage treatment processes.

2. The bacterial strain for purifying sewage obtained by screening is domesticated into a high-efficiency and stable bacterial strain, and through tests, the bacterial strain is inoculated into the sewage, the removal rate of hydrogen sulfide in the sewage in 12 hours reaches more than 60%, the removal rate of hydrogen sulfide in the sewage in 24 hours reaches more than 80%, the removal rate of ammonia in the sewage after 20 days reaches about 60%, and the removal rate of ammonia in the sewage after 23 days approaches 70%.

Drawings

FIG. 1 is a colony morphology of a denitrogenation strain ZT-C2 provided by the present invention;

FIG. 2 the 36 hour growth curve of the strain S.thiodenitrificans ZT-C2 in PDA;

FIG. 3 optimal culture temperature of the strain ZT-C2;

FIG. 4 optimum culture pH of Strain ZT-C2;

FIG. 5 shows the removal rate of ammonia gas in sewage by the bacterial strain ZT-C2;

FIG. 6 shows the removal rate of hydrogen sulfide in sewage by the bacterial strain ZT-C2.

Detailed Description

The present invention is further illustrated by the following examples, in which experimental procedures not specifically identified are generally performed according to methods known in the art or according to manufacturer's recommendations.

The removal rate of the bacterial strain to hydrogen sulfide and ammonia gas is used as an evaluation standard in the research.

Example 1 screening and identification of Denitrification Strain ZT-C2

PDA culture medium: potato dextrose agar medium (PDA): 20.0g of glucose, 200.0g of potato (cooked and filtered, the filtrate is needed), 15.0g of agar powder, 1000mL of distilled water, natural pH and sterilization for 30min at 115 ℃.

Ammonia-containing enrichment medium: sucrose 5.0g, peptone 2.0g, potassium dihydrogen phosphate (KH)₂PO₄)2.0g, magnesium sulfate (MgSO)₄·7H₂0.5g of O), 2.0g of sodium chloride (NaCl), and zinc sulfate (ZnSO)₄)0.05g, ferrous sulfate (FeSO)₄)0.04g, 5.0mL ammonia water (filter sterilization, sterilization after adding), coating, when purification adding agar powder 15.0g, adding distilled water to 1000mL, pH 7.0, 121 degrees C sterilization for 20 min.

Sulfur-containing enrichment medium: ammonium chloride (NH)₄Cl)2.0g, magnesium chloride (MgCl)₂)0.5g of dipotassium hydrogen phosphate (K)₂HPO₄·3H₂O)3.0g, sodium sulfide (Na)₂S·9H₂O)10.0g (added after filtration sterilization and sterilization), calcium chloride (CaCl)₂·6H₂O)0.2g, agar powder 15.0g, distilled water to 1000mL, pH 6.1 ± 0.1, and sterilization at 121 ℃ for 20 min.

Sulfur-containing purification medium: ammonium chloride (NH)₄Cl)2.0g, magnesium chloride (MgCl)₂)0.5g of dipotassium hydrogen phosphate (K)₂HPO₄·3H₂O)3.0g, sodium thiosulfate (Na)₂S₂O₃·5H₂O)10.0g, calcium chloride (CaCl)₂·6H₂O)0.2g, agar powder 15.0g, distilled water to 1000mL, pH 6.1 ± 0.1, and sterilization at 121 ℃ for 20 min.

Citrate medium: dipotassium hydrogen phosphate (K)₂HPO₄·3H₂O)1.0g, sodium chloride (NaCl)5.0g, dihydrogen phosphateAmmonium ((NH)₄)H₂PO₄)1.0g, sodium citrate 2.0g, magnesium sulfate (MgSO)₄·7H₂O)0.2g, and distilled water was added to 1000mL, and the above solutes were dissolved by heating and stirring at pH 7.0, 121 ℃, 20 min.

1. Primary screen for deamination functional bacteria

Weighing 10mL of distilled water into a 250mL triangular flask, adding 10-20 glass beads, sterilizing at 121 ℃ for 20min, and cooling to room temperature. Weighing 10mL of self-brewing white wine, adding the self-brewing white wine into sterile water, smashing and uniformly mixing the self-brewing white wine in a constant temperature oscillator at 30 ℃ and 180r/min for 1-2h to enable the bacteria to be dissociated, taking 5mL of a wine-water mixture, transferring the wine-water mixture into 100mL of PDA culture medium, adding 1% of ammonia water subjected to filtration sterilization into the PDA culture medium, culturing in a constant temperature oscillator at 30 ℃ and 180r/min, transferring the mixture into the PDA culture medium added with the ammonia water again according to the inoculation amount of 5% when uniform turbidity is observed in the culture medium, separating and removing sulfur and nitrogen removal bacteria by a dilution plating method after transferring the mixture three times, shaking the culture medium, taking 1mL of liquid into sterile EP tubes for three times, diluting the liquid by using a vortex oscillator and the sterile water respectively, taking 100 mu L of bacteria and adding the bacteria into the EP tubes containing 900 mu L of sterile water, namely diluting the bacteria by 10 times, sequentially diluting the bacteria to 10-6 gradients, taking 10, 10-6 gradient of 100 μ L of bacteria-containing water are spread on PDA culture medium containing 0.5% ammonia water, and the plate is cultured in 30 deg.C constant temperature incubator. After the bacterial colonies grow out on the solid culture medium, selecting single bacterial colonies with different forms, respectively carrying out streaking on three regions on corresponding solid culture media for purification, and carrying out transfer for at least 3 times to obtain primarily purified bacterial strains.

2. Separation and primary screening of desulfurization functional bacteria

Similar to the primary screening of the deamination functional bacteria, an enrichment method is adopted. Measuring 25mL of distilled water into a 250mL triangular flask, adding 10 glass beads, sterilizing at 121 ℃ for 20min under high pressure, cooling to room temperature, adding 10mL of self-brewing white wine, placing the triangular flask in a constant-temperature shaking table at 28 ℃ and 180r/min for shake culture, crushing and uniformly mixing for 1-2h to free bacteria in the wine, taking 5mL of shake culture solution by using a liquid transfer gun, transferring the shake culture solution into 100mL of PDA (PDA) culture medium containing 1% of hydrogen sulfide (filtration sterilization), placing the triangular flask in a constant-temperature shaking table at 28 ℃ and 180r/min for shake culture again, and when the culture medium is turbid, then using the liquid transfer gun to perform shake cultureTaking 5mL of a pipette from a clean bench, transferring the pipette into the same PDA culture medium rich in sulfur, separating functional bacteria on an agar plate by a dilution plating method after transferring for three times, taking 100 mu L of culture solution, adding the culture solution into 900 mu L of sterile water, equivalently diluting by 10 times, and so on, respectively diluting to 10 times^-4、10^-5、10^-6100 mu L of the three dilutions with gradient concentration are uniformly spread on agar plates containing sulfur purification medium, and the plates are placed in a constant temperature incubator at 28 ℃. And after the bacterial colony grows out, selecting a single bacterial colony with different shapes, sizes and appearances, scribing three areas on the agar plate of the sulfur-containing purified PDA culture medium again, after the bacterial colony grows out, scribing the single bacterial colony with the three areas scribed on the agar plate of the sulfur-containing purified culture medium again, and repeating the steps for three times to obtain the purified bacterial strain.

3. The re-screening of deamination strain is to screen the strain with strong deamination capacity by using a Nassler reagent colorimetric method

The bacterial strain to be tested is a purified bacterial strain enriched and separated from an ammonia-containing enrichment culture medium, a single bacterial colony of each bacterial strain is picked from a solid agar plate and transferred to a PDA culture medium, the bacterial strain is placed in a constant temperature shaking table for overnight culture under the culture condition of 28 ℃ and 180r/min to obtain fresh seed liquid, the seed liquid is taken by a liquid transfer gun and transferred to the PDA culture medium according to the inoculation amount of 5 percent, the PDA culture medium is placed in the constant temperature shaking table for culture at 180r/min and 28 ℃ for 24 hours, bacterial liquid is taken at intervals, the bacterial liquid is centrifuged at 12000r/min for 2min, the supernatant is taken and is subjected to colorimetric method by a Nashin reagent, then a spectrophotometer is used for measuring the content of ammonia nitrogen in the solution under the wavelength of 420nm, meanwhile, the content of ammonia nitrogen in CK is measured by taking a culture medium (CK) without adding bacteria as a control under the same condition, and the removal rate of the ammonia.

When a sample is measured, respectively taking a proper amount of supernatant after the bacterial liquid is centrifuged, adding ammonia-free water to complement to a marked line, firstly adding 0.2mL of potassium sodium tartrate solution, and uniformly mixing on an oscillator. Then 0.3mL of Nashi reagent solution is added and mixed on the shaker. After standing for 10min, the absorbance was measured at a wavelength of 420nm using a 10mm optical path cuvette with no ammonia as a reference. And subtracting the absorbance of the zero-concentration blank tube from the measured absorbance to obtain a calibration absorbance value, and drawing a standard curve of ammonia nitrogen content (mg) to the corrected absorbance. And meanwhile, replacing a water sample with ammonia-free water, performing blank measurement, and calibrating the light absorption value of the sample. And subtracting the absorbance of the blank control from the measured absorbance of the sample, searching the ammonia nitrogen amount (mg) from a standard curve, calculating the ammonia nitrogen amount in the culture medium according to the sampling volume, comparing the ammonia nitrogen amount in each bacterial liquid and the ammonia nitrogen amount in the control CK, and calculating the ammonia removal rate in the culture medium, so as to compare the deamination capacity of each bacterial strain, and selecting the bacterial strain with good deamination effect for the next experiment.

4. The re-screening of desulfurization bacterial strain is to screen the bacterial strain with strong desulfurization capacity by methylene blue colorimetric method

Similar to the determination of deamination function, the bacterial strain to be detected is a purified bacterial strain enriched and separated from a sulfur-containing enrichment culture medium, a single bacterial colony of each bacterial strain is picked from a solid agar plate and transferred to a PDA culture medium, the PDA culture medium is placed in a constant-temperature shaking table for overnight culture under the culture condition of 28 ℃ and 180r/min to obtain a fresh seed solution, the seed solution is taken by a liquid transfer gun and transferred to the PDA culture medium containing hydrogen sulfide according to the inoculation amount of 5 percent, the PDA culture medium is placed in the constant-temperature shaking table for culturing for 24 hours at 180r/min and 28 ℃, the bacterial solution is taken at intervals, the bacterial solution is centrifuged at 12000r/min for 2 minutes, the supernatant is taken and is subjected to color development by a methylene blue colorimetric method, the content of sulfide in the solution is determined at the wavelength of 665nm, and 3 times are set for each treatment. Measuring the content of sulfide in the culture supernatant, placing the culture supernatant in a 10mL colorimetric tube, adding carbon dioxide-free water to 8mL, adding 1mL of p-aminodimethylaniline solution, covering tightly, turning upside down once, and slightly mixing. And (3) not oscillating violently, then adding 200 mu L of ammonium ferric sulfate solution, immediately oscillating and uniformly mixing on an oscillator, standing for 10min, measuring the light absorption value at 665nm by taking water as a reference, and correcting by taking a blank tube without carbon dioxide water as a comparison.

Taking a proper amount of supernatant fluid in a colorimetric tube, adding water to dilute the supernatant fluid to 8mL, developing according to a standard curve developing method, adding 1mL of p-aminodimethylaniline solution, covering tightly, turning upside down once, and slightly mixing the mixture. And (3) not oscillating violently, then adding 200 mu L of ammonium ferric sulfate solution, immediately oscillating and uniformly mixing on an oscillator, standing for 10min, measuring the light absorption value at 665nm by taking water as a reference, and correcting by taking a blank tube without carbon dioxide water as a comparison. And calculating the content of sulfide from the standard curve, comparing the experimental sample with a blank control sample, and removing the sulfide value of the blank control sample to obtain the amount of the sulfide catabolized by the desulfurization strain. And screening and comparing the strains according to the removal capacity to obtain the strains with stronger desulfurization rate. Finally obtaining the bacterial strain ZT-C2 with strong desulfurization and denitrification capability.

The biochemical properties of the isolated strains were determined by the methods of Bergey's Manual of bacteria, and the results are shown in Table 1 and FIG. 1.

TABLE 1 Biochemical Properties of the isolated Strain ZT-C2

Table 1 shows that the physiological and biochemical results of the bacterial strain ZT-C2 conform to the genus Saccharomyces, belong to Issatchenkia orientalis, are preserved in the common microorganism center of China general microbiological culture Collection center (CCCGNO: 16008) in 2018, 6 months and 25 days, and have the classification name of: issatchenkia orientalis (Issatchenkia orientalis) with address: west road No.1, north west of the republic of kyo, yang, institute of microbiology, academy of sciences of china, zip code: 100101.

example 2 growth curves of Issatchenkia orientalis ZT-C2

The single colony shown in FIG. 1 was picked up and cultured in PDA liquid medium with shaking at 28 ℃ for 12 hours to obtain a fresh seed solution. Taking 6 50ml Erlenmeyer flasks of 20ml liquid PDA culture medium, with the reference numbers of 01, 02, 03, ZT-C2-1, ZT-C2-2, and ZT-C2-3. ZT-C2-1, ZT-C2-2, ZT-C2-3 are experimental groups, and 100 μ L of seed liquid is inoculated into the experimental group according to 1% of inoculation amount to a triangular flask. The blank was then filled with the same volume of sterile water, and one set was taken as three replicates. From 0h onwards, the absorbance A at 560nm was measured every hour with a spectrophotometer. Blank groups were used as blank controls. A36-hour growth curve of the denitrogenation strain ZT-C2 in PDA was obtained. As shown in fig. 2, the optimum value has been reached in 12 hours.

Example 3 determination of optimum pH and optimum temperature of Strain ZT-C2

The single colony shown in FIG. 1 was picked up and cultured in PDA liquid medium with shaking at 28 ℃ for 12 hours to obtain a fresh seed solution. 24 tubes of 5ml liquid PDA medium were taken and pH adjusted with a pH meter, with a repeat pH range of 4-10 for one pH in each three tubes. Medium at normal pH served as control. The experimental group was inoculated with 100. mu.L of seed solution into a flask at 1% inoculum size. The blank was added with the same volume of sterile water. After 8 hours the absorbance at OD560 was determined and the blank was used as a blank control. The optimum pH. of the denitrogenated strain ZT-C2 at pH 4-10 was obtained as shown in fig. 3. The optimum pH of the bacterial strain ZT-C2 is 5-9.

The single colony shown in FIG. 2 was picked up and cultured in PDA broth at 28 ℃ for 12 hours to obtain a fresh seed solution. 15 test tubes of 5ml liquid PDA medium were taken, and each three test tubes were replicated in one group for 5 groups. Placing into shaking tables at 20 deg.C, 30 deg.C, 40 deg.C and 50 deg.C, respectively, and performing shake culture. After 8 hours the absorbance at OD560 was determined and the blank was used as a blank control. The optimum growth temperature of the denitrogenation bacterial strain ZT-C2 between 20 ℃ and 50 ℃ is obtained. As shown in fig. 4. The optimal temperature of the bacterial strain ZT-C2 is 25-40 ℃.

Example 4 Total Process desulfurization and Denitrification of Strain ZT-C2

The sulfur and nitrogen removal waste gas sample is untreated sewage of a city north city sewage treatment plant in Nanjing, the main components of the sewage are ammonia and hydrogen sulfide, and the ammonia and the hydrogen sulfide are mainly obtained by decomposing and metabolizing organic matters by microorganisms under an anaerobic condition, so the experimental condition is that the sulfur and nitrogen removal strain ZT-C2 is added and inoculated into the standing sewage, the contents of the ammonia and the hydrogen sulfide in the sewage are measured at different times, and the removal rate is calculated.

(1) Adding the ZT-C2 bacterial liquid cultured for 12h into the sewage, stirring uniformly, adding the culture medium without bacteria into the sewage according to the same inoculation amount in the control group, and repeating three groups.

(2) Taking the sewage at 0h, 2h, 4h, 6h, 8h, 12h, 24h and 36h to measure the content of the hydrogen sulfide in the sewage, and calculating the removal rate.

(3) And taking the sewage every day to measure the content of ammonia nitrogen in the sewage, measuring the ammonia nitrogen value for 23 days in total, and calculating the removal rate.

The results show that:

(1) the hydrogen sulfide removal rate of the hydrogen sulfide in water after being inoculated into the sewage in 12 hours reaches more than 60 percent, and the hydrogen sulfide removal rate of the hydrogen sulfide in water in 24 hours reaches more than 80 percent.

(2) The bacteria are inoculated into the sewage to remove the ammonia nitrogen by 60 percent at 20 days and 70 percent at 23 days.

(3) The removal rate of hydrogen sulfide reaches 100% after 4 days, and the removal rate of ammonia nitrogen is more than 70% after 23 days. The removal effect is obvious, which shows that the microbial inoculum can well remove the contents of ammonia nitrogen and hydrogen sulfide in sewage, and the application of biological desulfurization and denitrification is realized.

Claims

1. A yeast strain ZT-C2 is classified and named as Issatchenkia orientalis (Issatchenkia orientalis) with the collection number of CGMCC NO. 16008.

2. Use of the strain ZT-C2 according to claim 1 in environmental sewage treatment.

3. Use of the strain ZT-C2 according to claim 1 for treatment of hydrogen sulfide or/and ammonia rich sewage.

4. A microbial inoculum comprising the strain ZT-C2 of claim 1.

5. Use of the bacterial agent of claim 4 in environmental sewage treatment.

6. Use of the bacterial agent according to claim 4 in the treatment of wastewater enriched with hydrogen sulphide or/and ammonia.

7. A scavenger comprising the strain ZT-C2 of claim 1.

8. The purifying agent as claimed in claim 7, whereinThe total concentration of viable bacteria in the purifying agent is 1 × 10⁶～1×10¹⁰CFU/ml。

9. The purifying agent as claimed in claim 8, wherein the total concentration of viable bacteria in the purifying agent is 1 x 10⁷～1×10⁹CFU/ml。

10. The purifying agent according to claim 9, wherein the total concentration of viable bacteria in the purifying agent is 1 x 10⁸ CFU/ml。

11. Use of a depurative according to any of claims 7 to 9 in environmental sewage treatment.

12. Use of the scavenger according to any one of claims 7 to 9 in the treatment of hydrogen sulphide-or/and ammonia-rich effluent.