METHOD FOR DETERMINING THE AMOUNT OF ANAMMOX BACTERIA

Abstract

A method and a kit for determining the amount of anammox bacteria in a bioreactor, comprising the steps of: i) removing a sample from the bioreactor; iii) mixing the sample with alkali; v) heating the samples to at least 60° C.; vi) separating solid components; vii) adding a reducing agent to the liquid phase; viii) measuring the translucence of the liquid phase in a spectrophotometer at three wavelengths ranging from 500 to 600 nm; ix) comparing the measured translucence to a reference spectrum.

Claims

1-13. (canceled)

14. A method of determining the amount of anammox bacteria in a bioreactor, comprising: i) removing a sample from the bioreactor; iii) mixing the sample with alkali; v) heating the sample to at least 60° C.; vi) separating solid components from a liquid phase in the sample; vii) adding a reducing agent to the liquid phase; viii) measuring the translucence of the liquid phase in a spectrophotometer at three wavelengths ranging from 500 to 600 nm; ix) comparing the measured translucence to a reference spectrum.

15. A method according to claim 14, further comprising separating the solid components from liquid components of the sample.

16. A method according to claim 15, further comprising suspending the solid components in an alkaline solution.

17. A method according to claim 14, wherein a wavelength measurement at a first wavelength takes place at 530-540 nm, a second wavelength at 545-555 nm, and a third wavelength at 565-575 m.

18. A method according to claim 15, wherein separating the solid components is effected by centrifugation.

19. A method according to claim 14, wherein the reducing agent is a salt of a dithionous acid.

20. A method according to claim 19, wherein the salt of dithionous acid comprises Na.sub.2S.sub.2O.sub.4.

21. A method according to claim 14, wherein the bioreactor comprises a clarifying basin.

22. A kit comprising a sample vessel, an alkali or alkaline solution, a reducing agent, and a spectrophotometer, which is operable at least at three wavelengths ranging from 500 to 600 nm.

23. A kit according to claim 22, further comprising a heating facility.

24. A kit according to claim 22, further comprising a separating device for solid substances.

25. A kit according to claim 22, further comprising a sample vessel, in which the alkali or alkaline solution is introduced.

26. A kit according to claim 22, further comprising a sample vessel, in which the reducing agent is introduced.

27. A kit according to claim 26, wherein the sample vessel, in which the reducing agent is introduced, comprises a cuvette for the spectrophotometer.

Description

DETAILED DESCRIPTION AND EXAMPLES

[0037] For illustration, reference is made to the figures:

[0038] FIG. 1 shows the non-metric multidimensional scaling of the AC/AnAOB biomass quantification for six types of samples, SL, SL-OF, SL-UF, B, B-OF and B-UF. For the calculation, all six quantitative methods, GA, PT, HQ, AM, qPCR and CC, were included. Samples from the same group (parallels) are connected through lines which reflect the convex enveloping surface of the NM-MDS results.

[0039] FIG. 2 shows the influence of the NaOH concentration on the yield of heme from an anammox biomass (digestion time of 4 min).

[0040] FIG. 3 shows the time course of the heme extraction from an anammox biomass in 1 M NaOH at 100° C.

[0041] FIG. 4 shows the optimization of species, age and concentration of the reducing agent (sodium DT=sodium dithionate).

[0042] FIG. 5 shows the addition of sodium dithionate as a powder or freshly dissolved in 1 M NaOH, respectively, with the final concentration being the same in each case.

[0043] FIG. 6 shows the stability of the haemochrom following a reduction with NaDT.

[0044] FIG. 7 shows an exemplary measurement on the DEMO® reactor of the wastewater treatment plant Tobl/Bruneck and demonstrates the enrichment of the anammox biomass in the cyclone underflow.

COMPARISON OF DIFFERENT METHODS OF DETERMINING THE MASS OR ACTIVITY OF ANAMMOX BACTERIA

[0045] Due to physiological and morphological characteristics which, in part, are very exceptional, the following very diverse examination methods come into consideration: [0046] quantification of functional or phylogenetic genes with molecular-biological techniques [0047] chemical-analytical quantification of characteristic cell ingredients such as membrane components, especially ladderanes [0048] measurement of the characteristic physiological activity, in particular of the conversion of ammonium with nitrite to molecular nitrogen and nitrate [0049] quantification and measurement of the typical granular structures of anammox bacteria.

[0050] Despite the variety of analytical possibilities, today almost only the molecular-biological techniques and the measurement of physiological activity are applied. However, particularly for routine monitoring in a wastewater treatment plant, meaningful, reliable and robust methods, which still can be performed easily on site using standard equipment, are not provided for the control of the anammox population.

[0051] Samples from the wastewater treatment plant Strass im Zillertal (AT) were examined by six different methods, the results were statistically evaluated, and the characteristics of the methods, in particular their advantages and disadvantages, were compared to:

[0052] 1. gravimetric analysis of anammox granules (GA)

[0053] 2. quantification of the heme content (HQ)

[0054] 3. counting and measuring the granules with a Coulter Counter (CC)

[0055] 4. counting and measuring the granules using image analysis (PT)

[0056] 5. DNA extraction and quantitative polymerase chain reaction (qPCR)

[0057] 6. physiological activity measurement (AM)

Material and Methods

Samples, Sampling and Sample Pretreatment

[0058] In line with this invention, samples from the wastewater treatment plant Strass im Zillertal were examined. The samples come from different plant sections and therefore differ significantly with respect to their sample matrix: [0059] a) DEMON® reactor, treats digested-sludge press water highly loaded with nitrogen, contains large amounts of anammox bacteria [0060] b) aeration basin in the main stream which has been doped with anammox biomass from the DEMON® reactor since 2011. Municipal wastewater with a relatively low nitrogen load is treated there, the anammox bacteria have a far lower concentration in comparison to other populations of bacteria.

[0061] In addition, at each plant, three different fractions were taken from the respective installed hydrocyclone: i) cyclone inflow (=reactor contents), ii) cyclone underflow (=enriched anammox fraction which is recycled to the reactor), iii) cyclone overflow (=depleted anammox fraction, withdrawn excess sludge).

TABLE-US-00001 TABLE 1 sample designations sample Plant fraction designation DEMON ® basin SL cyclone overflow SL-OF cyclone underflow SL-UF main stream aeration basin B cyclone overflow B-OF cyclone underflow B-UF

[0062] From each sample, 3 parallels of 1 L each were taken representatively. The further sample division for the various analyses was performed in a thoroughly mixed stirrer vessel in order to prevent especially the rapid sedimentation of the granular biomass (vessel with baffles, Rushton stirrer). Depending on the method, the subsamples were deep-frozen until the examination (qPCR), stored at 4° C. (GA, CC, PT) or examined immediately on the same day (AM, HQ).

Gravimetric Analysis (GA)

[0063] The mass of substances capable of being filtered off was determined by filtration through glass fiber filters (Macherey & Nagel GF5) and drying overnight at 105° C. The loss on ignition as a measure of the organic portion was analyzed after 3 h at 550° C. In the samples from the DEMON® reactor, the anammox granules were sieved in the wet state through an analysis sieve with a mesh size of 0.125 mm, dried and weighed. For the main stream samples, this was not possible because of the slimy biomass.

Quantification of the Heme Content (HQ)

[0064] 1.5 mL each of the samples were centrifuged in 2 mL micro reaction vessels for 3 min at 5000 g. The supernatant was discarded and replaced by 1 M NaOH. The pellet was resuspended, the vessels were placed in boiling water for 2 minutes and subsequently allowed to cool for 10 min, while occasionally being shaken up. Residual particles were centrifuged at 5000 g for 3 min, and 1 mL of a clear supernatant was transferred to semi-micro photometer cuvettes. For the reduction of the extracted heme, 100 μL of a freshly prepared solution of sodium dithionite (200 g/L in 1 M NaOH) was mixed in.

[0065] After 5 minutes, the extinctions were measured at 535, 550 and 570 nm with a spectrophotometer. The peak at 550 nm was related to the baseline, which is defined by the extinctions at 535 and 570 nm.

[0066] The analysis was calibrated with cytochrome c from the heart of a horse (contains 1 heme per molecule; Sigma C-2506). Calculation of the peak height at 550 nm:

[00001]$\mathrm{Peak}.Math..Math.\mathrm{height}\left(\mathrm{AU}\right)=E_{\mathrm{bb}.Math..Math.0}-E_{b.Math..Math.35}-\frac{E_{570}-E_{535}}{570.Math..Math.\mathrm{nm}-535.Math..Math.\mathrm{nm}}*\left(550.Math..Math.\mathrm{nm}-535.Math..Math.\mathrm{nm}\right)$

[0067] E.sub.535, E.sub.550, E.sub.570 . . . measured extinctions (AU) at the respective wavelength

Counting and Measuring the Granules Using the Image Analysis Method “Particle Tracking” (PT)

[0068] Samples of 15 mL each were filled into petri dishes, and those were recorded against a homogeneous white background with a flatbed scanner at a resolution of 600 dpi. The samples were diluted to such an extent that no superpositions of particles appeared in the image.

[0069] The images were processed with an image analysis program (Fiji) such that the anammox granules could be detected separately because of their color difference to the background and to other particles. The identified granules were counted and the cross-sectional area of each granule was calculated. The number of granules and the sum of the cross-sectional areas were related to the employed sample volume and used as a measure of the anammox biomass.

Counting and Measuring the Granules with a Coulter Counter (CC)

[0070] As an alternative to the image evaluation, a particle analyzer was also used according to the Coulter principle (Coulter 1956). The particles are thereby sucked through a measuring opening and the increase in the electrical resistance of the opening, which occurs as a result of the narrowing of the cross-section, is measured and evaluated. In contrast to the image analysis, the Coulter Counter detects only that volume of a particle which is electrically isolated from the surrounding electrolyte. Bacterial slimes and cavities of anammox granules are not detected in this way, but rather the sum of intact cells.

[0071] In a sample-isotonic saline solution, the samples were diluted to such an extent that always only individual particles get sucked through the opening. The measurements were carried out using a Multisizer II (Coulter Beckman Inc.) having a measuring tube with a measuring opening of 1000 μm.

[0072] Size calibration was effected with spherical styrene-divinylbenzene particles having a modal diameter of 320 μm.

[0073] DNA Extraction and Quantitative Polymerase Chain Reaction (qPCR)

[0074] The quantitative polymerase chain reaction (qPCR) was used for determining the number of 16 S rRNA gene copies. Beforehand, the DNA was extracted by means of the DNeasy® Blood & Tissue Kit according to the “Pretreatment for Gram-Positive Bacteria” protocol (QIAGEN; manual 07/2006). In order to increase the total DNA yield, three freeze-thaw cycles (liquid nitrogen/65° C. water bath; 5 minutes each) were also conducted at the beginning. A mechanical digestion was additionally included after the chemical lysis according to the manufacturer's instructions (20 mg/mL lysozyme and proteinase K), wherein the sample was transferred into PowerBead vessels (MO BIO Laboratories., Inc.) and was shaken in a horizontal shaker at 60 Hz for 4 minutes. Subsequently, the sample was centrifuged at 8000 g for 3 minutes and the protocol was continued. The final elution occurred in 100 μL AE buffer (heated to 60° C.) in two consecutive steps (2×50 μL).

Physiological Activity Measurement (AM)

[0075] The metabolic activity of anammox bacteria was quantified as a conversion rate of the sum of the three essential dissolved nitrogen species ammonium, nitrite and nitrate, for which the following reaction equation is applicable if conditions are undisturbed:

NH.sub.4.sup.++1.32 NO.sub.2.sup.−0.132 HCO.sub.3.sup.−+0.512 H.sup.+1.02 N.sub.2+0.26 NO.sub.3.sup.−+0.132 CH.sub.2O.sub.0.5N.sub.0.15+2.19 H.sub.2O

[0076] The samples to be examined were adjusted to sufficient initial concentrations of the substrates (NH.sub.4: 100 mg N/L with NH.sub.4HCO.sub.3, NO.sub.2, 70 mg N/L with NaNO.sub.2), and the pH was adjusted to 7.2. 100 mL were each filled into 100 mL Erlenmeyer flasks, which were sealable in a gas-tight manner, and the dissolved oxygen was driven out by the injection of nitrogen gas. The vessels were sealed and incubated at 30° C. while being shaken. 1 mL samples were taken over a total of 4 h at intervals of 30 min, they were centrifuged, and the concentrations of nitrite, nitrate and ammonium were measured in the supernatant (in each case with Nanocolor Kits from Macherey & Nagel). The concentrations were added up per measuring point (in mg N/L), and, from the linear area of the temporal concentration gradient, the slope was calculated which was used as a measure of the activity (volumetric N-conversion rate in mg N/(L.h.)). In addition, the specific N-conversion rate was calculated with reference to the biomass dry matter contained in the sample (mg N/(L.h.g. TS)).

Statistical Analyses

[0077] All statistical analyses were performed with the software PAST (Version 2.17) (Hammer et al. 2001). The separation of the various sample types using all the examined methods was illustrated with reference to a non-metric multidimensional scaling. For this purpose, the data were log-transformed, and the Bray-Curtis index was used. The correlation between the different methods was illustrated by a MANTEL permutation analysis, based on Bray-Curtis distance matrices, for each method and for all sample types. In order to check the reproducibility of the heme method, the coefficient of variation (CV(%)) was determined, and the mean values were calculated for every sample matrix and compared to each other.

Results

General Comparison Between the Six Employed Methods

[0078] Table 2 summarizes all analytical findings and additional data regarding the individual sample types (dry matter (TS), organic dry matter (oTS), number of granules). The deeply reddened AC granules (Anammox Consortium: AnAOB, AerAOB and other potential microbial groups which may also be aggregated in the granules, such as NOB and Chloroflexi) from the wastewater treatment plant Strass exhibit a relatively heterogeneous structure. Cryotome sections show that the interior of those granules consists largely of cavities (data not shown).

[0079] Due to the sample selection and the density fractionation using hydrocyclones in the plants, the following basic sequence of the samples in terms of the anammox biomass may be assumed: SL-UF>SL>SL-OF>B-UF>B>B-OF (anammox is much more active in the DEMON® reactor (SL) than in the main stream (B), and, in each case, there is an anammox accumulation in the cyclone underflow). This hypothesis had to be confirmed with the employed methods.

[0080] All six methods were capable of distinguishing between the different sample matrices and hydrocyclone fractions (non-metric multidimensional scaling (NM-MDS), FIG. 1). A lower stress value of <0.02 indicated a realistic depiction of the original data in the NM-MDS. The R.sup.2 values were 0.99 (coordinate 1) and, respectively, 0.00007 (coordinate 2). It became evident that the SL samples could be distinguished from each other better than, for example, the samples B and B-OF, for which an overlap occurred along the x-axis (R.sup.2=0.99). All in all, samples which, in general, contained more anammox biomass (SL matrix) could be separated better.

[0081] Looking individually at the results of all six methods, it became apparent that all were able to categorize the SL samples correctly, whereas, for the B matrix, this was possible only by means of qPCR and HQ (Table 3). The quantification by means of CC was carried out only for the SL matrix, since the separation of the granules from the activated sludge turned out to be very complex for B samples. In order to check the reproducibility and, respectively, the variance of the heme method, the coefficient of variation was determined. Thereby, it was shown that the average CV was roughly the same for both sample matrices, namely 4.45 (SL) and, respectively, 5.20 (B), and therefore this method yielded data of similar reproducibility in substantially different sample matrices.

[0082] Looking at all the methods in terms of their suitability for quantifying only AnAOB biomass, it becomes apparent that the qPCR approach aimed at the 16 S rRNA of Planctomycetales is the most accurate method. However, should one wish to determine the AC biomass, HQ, PT and CC are similarly suitable. In comparison to the CC approach, the PT method has the advantage of an additional color selection and, hence, a better identification of AC granules, whereby this method is also suitable for more complex matrices, e.g., activated sludge with embedded granules. In addition to the quantification of the AC biomass, both methods provide an additional qualitative evaluation of the size distribution of the granules. Based on three false classifications of the samples, the GA was classified as the least precise method (see Table 3).

[0083] Table 4 summarizes the most important advantages and disadvantages of each method and provides further information on the average duration of the measurements, detection limits, and the price per analysis.

[0084] In Tables 5, 6 and 7, the results of the correlation analyses between all methods are shown, which can be summarized as follows: the highest correlation was achieved for the SL matrix, with significant Pearson correlation coefficients for all methods >0.71. Excluding the qPCR method, even values >0.96 are obtained. Looking at both sample matrices jointly, significantly positive correlations are still obtained, albeit with a somewhat lower Pearson coefficient (0.30-0.96). The highest correlation was obtained between GA and PT, the lowest values with AM. The analysis of the B matrix provided significantly high positive correlations (all >0.94; CC not examined) for GA, PT and HQ and significantly reduced, but positive correlations for qPCR (0.41-0.47). For the AM, no positive correlation was achieved in the B matrix, a fact which is examined more closely in the chapter “Physiological Activity”.

[0085] In sum, the correlation analysis is supposed to serve as a guideline to understand which methods group the examined samples in a similar way. However, this does not imply the correctness of the results. Nevertheless, HQ and qPCR were the only methods which were able to divide the sample set as expected (see Table 3), and both methods achieved a correlation coefficient of 0.81. Therefore, a high correlation of a different method with those two methods also suggests a higher accuracy of the results.

[0086] Additional observations made on samples from other wastewater treatment plants are indicated hereinbelow. These results are indicative of a high applicability of the employed methods to other sample matrices: i) samples from a DEMON® basin of a different wastewater treatment plant contained red and black anammox granules; these could be divided into two fractions based on their different densities and were analyzed by means of AM and HQ. Both methods indicated a high activity and heme concentration in the red fraction and drastically reduced values in the black fraction. This suggests that, due to the color selection, HQ and PT can be used not only for the quantification, but also for the activity measurement. ii) In a further wastewater treatment plant, which also carries out sidestream deammonification using DEMON® technology and, in addition, features two completely separate biological sludge lines, an anammox biomass was enriched in one of those lines, and the second line was left untreated as a control. In the control line, only few anammox granules could be detected by PT (less than 0.1%-1%, as compared to the results of the B samples (this study), whereas anammox granules were clearly detected in the bio-augmented line. iii) Heme proteins are ubiquitous in nature (Gumiero et al. 2011), but the measured HQ values in samples from wastewater treatment plants not operating an additional deammonification process were still below the detection limit. This indicates a reduced risk of false positive results with this method.

TABLE-US-00002 TABLE 3 summary of the sample division by the six employed methods, as compared to the expected sample sequence; differences in this sequence are marked grey; expected Sample AC/AnAOB designation abundance* GA PT HQ AM qPCR CC SL 2 2 2 2 2 2 2 SL-OF 3 3 3 3 3 3 3 SL-UF 1 1 1 1 1 1 1 B 5 5 6 5 6 5 n.a. B-OF 6 5 5 6 5 6 n.a. B-UF 4 3 4 4 4 4 n.a. AnAOB accuracy for 6 3 2 5 1 4 specifity exclusive AnAOB measurement * figures reflect the ranked, expected AC/AnAOB abundance, with 1 representing the highest and 6 the lowest abundance; figures in the lowermost line are ranked from 1 (best suited method) to 6 (least suited method), n.a. . . . not analyzed;

TABLE-US-00003 TABLE 2 sample characterization by means of TSS, VSS; granular SS (particles >0.125 mm diameter), PT.sub.tot cross-sectional area (entire sample), PT.sub.sieved cross-sectional area (particles >0.125 mm and <1 mm diameter), PT.sub.tot (particle count entire sample), PT.sub.sieved (particle count >0.125 mm and <1 mm diameter), CC (AC volume of granules sieved samples >0.125 mm and <1 mm diameter), HQ, qPCR, AM (total nitrogen conversion), rate of NH.sub.4—N, NO.sub.2—N and NO.sub.3—N formation; mean values (bold) and standard deviation; n = 3 (for CC n = 9 (3 technical parallels)), n.a. = not analyzed; PT.sub.sieved PT.sub.tot cross- GA cross- sectional qPCR NH.sub.4 NO.sub.2 NO.sub.3 granular sectional area PT.sub.tot PT.sub.sieved HQ [gene AM [mg [mg [mg SS VSS r-SS area [mm.sup.2 L.sup.−1] [particle [particle CC [mL [mAU copies [mg N NH.sub.4—N NO.sub.2—N NO.sub.3—N [g L.sup.−1] [g L-1] [g L.sup.−1]* [mm.sup.2 L.sup.−1] sieved L.sup.−1] L.sup.−1] L.sup.−1] L.sup.−1] L.sup.−1] L.sup.−1*h.sup.−1] L.sup.−1 h.sup.−1] L.sup.−1 h.sup.−1] L.sup.−1 h.sup.−1] SL 2.95 2.32 0.79 283 280 326267 297600 40 164 9.32E+11 −36.1 −17.2 −22.7 3.72 0.09 0.07 0.12 35.6 33.2 36116 32822 0.94 12.2 7.50E+11 4.51 4.27 0.77 0.24 SL-OF 2.19 1.77 0.44 131 129 184400 160933 35.8 86.4 7.01E+11 −23.1 −10.8 −14.6 2.22 0.06 0.05 0.00 11.3 11.2 9165 8259 1.61 7.03 2.48E+11 2.20 1.39 1.15 0.24 SL-UF 8.95 6.59 4.69 4985 4965 4249333 3958667 113 1143 3.72E+12 −115 −71.3 54.7 10.9 0.51 0.32 0.19 984 997 691449 490067 3.00 8.68 1.19E+12 2.33 2.95 1.93 0.52 B 4.25 3.05 0.07 3.62 3.46 8533 6000 N.a. 12.3 4.00E+09 −0.45 3.65 −4.11 0.01 0.61 0.44 0.01 0.55 0.66 462 2227 0.33 1.27E+08 2.83 2.53 0.31 0.01 B-OF 4.20 3.03 0.07 5.97 4.21 47333 13600 N.a. 11.6 2.70E+09 −1.20 2.57 −3.78 0.01 0.09 0.07 0.01 0.94 0.82 3585 1600 0.51 4.03E+08 2.43 2.64 0.55 0.01 B-UF 6.71 4.53 0.79 32.3 50.1 113200 76000 N.a. 25.1 2.88E+10 −3.23 4.00 −7.22 −0.01 0.11 0.06 0.10 16.6 16.4 22087 18543 2.14 4.45E+10 2.77 1.18 1.70 0.02

TABLE-US-00004 TABLE 4 summary of the employed methods and their suitability for AC/AnAOB quantification suitability for time additional price per granular and required demand for sample methodical non-granular per laboratory (material Method background advantages disadvantages detection limit biomass sample* equipment cost) GA mass determination of fast, cheap, not applicable to the not defined only granular 5-10 min analysis sieves, <0.50  granular biomass small demand smallest fraction biomass drying balance >0.125 mm diameter; for equipment (<0.125 mm); or drying imprecise; sieve chamber clogging due to (slimy) main stream sludge PT particle count/ exact granular red*** colour of with only granular  10 min flatbed scanner, <0.50  determination of AC abundance granules necessary conventional biomass image analysis cross-sectional area and biomass for activated sludge flatbed scanner software by image analysis; area/volume**; matrix; particle size distribution diameter of of granules; approx. 50 μm; small demand for equipment HQ extraction and relatively fast; none are known protocol was arbitrary 5-10 min standard   1-2  colorimetric exact; cheap; adapted such centrifuge, determination of the measures esp. that water bath or haemochrom AnAOB; small measurements heating block, demand for were possible photometer equipment in both sample matrices AM sum of NO.sub.2, NO.sub.3, measures distortion due to not defined; arbitrary   6 h  specific approx. 50  H.sub.4—N activity, not presence of incubation time equipment for (with wastage/production only presence; denitrifying bacteria can be commercial commercial rates; and ammonification prolonged if kits kits) (B); rates are low (photometer) or alternative analysis equipment qPCR 16S rRNA gene AnAOB extraction bias; 1.2 10.sup.4 gene arbitrary, but 8-10 h/3 molecular- approx. quantification; specific; if specific equipment copies per L; suitable h**** biological 10-15  based on RNA, required; extraction laboratory suitable also as protocol is equipment, an activity important PCR cycler, parameter qPCR cycler CC determination of exact granular specific equipment ideal size of only granular 30-45 min Coulter   <1  particle count/volume; AC abundance required; dependent granules 2%- Counter granules are assigned and volume**; on sample matrix; 60% of the to size channels; size distribution measuring of granules; opening (here diameter of 1000 μm); *approximate time required for one sample; dependent on the employed method, the total time required for several samples is usually less than a multiple of this specified time. **the Coulter Counter provides the net biomass volume, whereas Particle Tracking provides the gross volume; ***here, the red colour is the discriminating factor, but other colours or grey scales (darker, denser granules as compared to activated sludge) may also be used as a factor, and the protocol can be modified accordingly; ****the first time also includes the generation of the standards and the DNA extraction, the second only the qPCR run;

TABLE-US-00005 TABLE 5 correlation of the AC/AnAOB quantification results between all the examined methods for all six sample types (both sample matrices); Pearson correlation coefficients are indicated along with the respective significance levels (exponent); exponents defined as follows: a (p < 0.01), b (p < 0.001) and c (p < 0.0005); GA PT sieved PT total HQ qPCR AM GA — 0.95.sup.c 0.94.sup.c 0.71.sup.c 0.54.sup.b 0.37.sup.b PT sieved 0.95.sup.c — 0.99.sup.c 0.78.sup.c 0.69.sup.c 0.49.sup.c PT total 0.94.sup.c 0.99.sup.c — 0.78.sup.c 0.68.sup.c 0.53.sup.c HQ 0.71.sup.c 0.78.sup.c 0.78.sup.c — 0.81.sup.c 0.30.sup.a qPCR 0.54.sup.b 0.69.sup.c 0.68.sup.c 0.81.sup.c — 0.38.sup.c AM 0.37.sup.b 0.49.sup.c 0.53.sup.c 0.30.sup.a 0.38.sup.c —

TABLE-US-00006 TABLE 6 correlation of the AC/AnAOB quantification results between all the examined methods for the SL sample matrix; Pearson correlation coefficients are indicated along with the respective significance levels (exponent); exponents defined as follows: a (p < 0.01), b (p < 0.001) and c (p < 0.0005); GA PT sieved PT total HQ qPCR AM CC GA — 0.99.sup.c 0.99.sup.c 0.99.sup.c 0.75.sup.b 0.99.sup.c 0.96.sup.c PT sieved 0.99.sup.c — 1.sup.c 1.sup.c 0.73.sup.b 0.99.sup.c 0.98.sup.c PT total 0.99.sup.c 1.sup.c — 0.99.sup.c 0.73.sup.b 0.99.sup.c 0.98.sup.c HQ 0.99.sup.c 1.sup.c 0.99.sup.c — 0.71.sup.b 0.99.sup.c 0.97.sup.c qPCR 0.75.sup.b 0.73.sup.b 0.73.sup.b 0.71.sup.b — 0.75.sup.b 0.72.sup.b AM 0.99.sup.c 0.99.sup.c 0.99.sup.c 0.99 0.75.sup.b — 0.96.sup.c CC 0.96.sup.c 0.98.sup.c 0.98.sup.c 0.97.sup.c 0.72.sup.b 0.96.sup.c —

TABLE-US-00007 TABLE 7 correlation of the AC/AnAOB quantification results between all the examined methods for the B sample matrix; Pearson correlation coefficients are indicated along with the respective significance levels (exponent); exponents defined as follows: a (p < 0.05), b (p < 0.001) and c (p < 0.0005); GA PT sieved PT total HQ qPCR AM GA — 0.99.sup.b 0.97.sup.b 0.99.sup.b 0.44.sup.a −0.15 PT sieved 0.99.sup.b — 1.sup.c 0.96.sup.a 0.47.sup.a −0.12 PT total 0.97.sup.b 1.sup.c — 0.94.sup.a 0.45.sup.a −0.06 HQ 0.99.sup.b 0.96.sup.a 0.94.sup.a — 0.41.sup.a −0.17 qPCR 0.44.sup.a 0.47.sup.a 0.45.sup.a 0.41.sup.a — −0.20 AM −0.15 −0.12 −0.06 −0.17 −0.20 —

Gravimetric Analysis of Anammox Granules (GA)

[0087] If anammox granules are present in a high density, the biomass is not too slimy and the amount of particulate impurities in the ratio is low, this simple determination (sieving, washing, drying, weighing) can be used for monitoring. Depending on the size distribution of the granules and the impurities, the mesh size of the sieve can be adjusted. In the case examined herein, the different fractions could be distinguished correctly with a 0.125 mm sieve in the DEMON® basin (SL samples) and correlated with the anammox activity.

Quantification of the Heme Content (HQ)

[0088] Hemes act as prosthetic groups of many enzymes in all life forms (Gumiero et al. 2011). Particularly high heme contents cause reddening of the cells, such as in case of red blood cells and anammox bacteria. Within the latter, they are an essential component of the metabolic pathway of the anaerobic ammonium oxidation, the enzymes of which can constitute up to 20% of the total protein content of those cells (Jetten et al., 2009), while the heme content in other microorganisms is almost negligible by way of contrast. Thus, the heme content of the biomass of a wastewater treatment plant is a specific parameter for the indirect determination of the content of anammox bacteria and, respectively, their relevant enzymes. The determination of heme for the analysis of medical samples such as, e.g., feces or tissue has been known for quite some time (Sinclair et al. 2001), but had to be optimized to be applied to bacteria.

[0089] A correlation between an optically visible reddening of the anammox biomass and its metabolic activity has already been observed on several occasions (separate studies and (Ali et al. 2013)), in particular that very brightly coloured granules as well as granules dyed dark including black show a significantly reduced performance. In combination with optical methods (PT), the analysis of the heme content of the biomass is a simple but safe method of monitoring the abundance and vitality of the anammox population on site.

Counting and Measuring the Granules with a Coulter Counter (CC) and Using Image Analysis (PT)

[0090] Those two methods differ from all others in that, in addition to the quantification parameters for the anammox biomass, namely number of granules (CC and PT), total cross-sectional area of granules (PT) and total volume of granules (CC and PT), also size distributions of the particles are detected. This information is relevant, for example, if the growth and composition of the biomass is to be assessed (Nielsen et al. 2005, Volcke et al. 2010, Winkler et al. 2011) or the mode of operation of the hydrocyclones is to be examined in detail.

Quantitative PCR (qPCR)

[0091] The fact that all previously known anammox bacteria belong to the same monophyletic order Planctomycetales facilitates their molecular-biological quantification via specific 16 S rRNA primers (Kuenen 2008, Li and Gu 2011). The method provides, on the one hand, the highest possible specificity and therefore essentially the highest correctness for the biomass determination, but involves also some potential sources of error, in addition to the large expenditure. In particular the standard protocol for DNA extraction from gram-positive bacterial cells had to be modified significantly and supplemented with mechanical cell lysis steps in order to achieve a sufficient stable DNA yield from the granular biomass.

Physiological Activity Measurement (AM)

[0092] The conversion rates of the essential dissolved nitrogen species ammonium, nitrite and nitrate are often used for evaluating the physiological activity of anammox bacteria, regardless of their growth form. In this connection, it could be shown that this method is very well suited for sewage sludges with high contents of anammox, as they are common in the DEMON® reactor. In samples with a high amount of other microorganisms, such as in the examined anammox-enriched main stream basin, the measurements are often hard to interpret due to the superposition by other metabolic processes. In particular denitrification and ammonification (Wett et al. 2013) have the most disturbing effect there, often cause the anammox activity to be underestimated strongly, and, so far, it has not been possible to selectively inhibit them to a sufficient degree. Especially in the cyclone overflow, the ratio of depleted anammox biomass to any other biomass is very inconvenient and renders an activity measurement virtually impossible.

Conclusions

[0093] Using all methods which have been examined herein for the assessment of the anammox biomass or its nitrogen conversion performance, the three different samples from the DEMON® reactor (basin, cyclone overflow and underflow) could be distinguished and ranked correctly. Heme determination and PCR were best suited for examining the samples from both reactors (DEMON® and main stream).

[0094] By means of the methods qPCR and Coulter Counter, which involve more material costs and are reserved for research laboratories, the results and the reliability of the less demanding techniques Particle Tracking and heme determination, which are feasible in every routine laboratory, could be confirmed. Basically all methods were positively correlated, in particular the sample with the highest anammox content yielded the highest values in all methods.

[0095] In summary, the following monitoring strategy is proposed for wastewater treatment plants with anammox technology: Regular heme determination and Particle Tracking perfectly complement the abundance and vitality control of anammox bacteria. Occasionally, activity tests should also be performed.

Optimization of the Heme Extraction and Determination from Anammox Bacteria

[0096] The optimization of the heme extraction was performed with an anammox biomass from the DEMON® reactor Strass im Zillertal and tested at several other facilities. From the test series with regard to liquor strength (FIG. 2) and digestion time (FIG. 3), the optimal combination of degree of digestion and time insensitivity was determined with a NaOH concentration of 1 mol/L and a digestion time of 2 min at 100° C. in a 1.5 mL micro reaction vessel in boiling water. For varying volumes and, respectively, heating techniques (e.g., thermoblock), the optimal digestion time has to be redetermined.

[0097] FIG. 4 shows the significance of the addition of a freshly prepared sodium dithionite solution (old=older than 24 hours; fresh=younger than 2 hours). Ascorbic acid is unsuitable as a reducing agent. Instead of a NaDT solution in 1 M NaOH, the reagent may also be added as a powder (FIGS. 4-5).

[0098] After extraction and reduction, the red dye remains stable for about 20 min and can be measured photometrically during that time without any significant change (FIG. 6). The peak of the reduced haemochrom at 550 nm can be determined optimally by measuring at 3 wavelengths. Via the measuring points at 535 and 570 nm, the baseline is established and the peak height at 550 nm is based thereupon (3-wavelengths calibration of every modern photometer).

[0099] FIG. 7 exemplifies the results from samples of the cyclone inflow (=reactor), underflow and overflow of the DEMON® reactor of the wastewater treatment plant Tobl/Bruneck (the purpose of the hydrocyclone is to keep the anammox biomass in the reactor via the cyclone underflow and to remove the surplus amount of less dense, faster growing nitrifying and heterotrophic bacterial biomass from the reactor via the cyclone overflow.)

[0100] An example of the implementation looked like this, for instance:

[0101] Step 1: sampling

[0102] Step 2: filling approx. 8-10 mL of the sample into a small tube from the kit in which approx. 200 mg sodium dithionite is submitted in the dry state

[0103] Step 3: adding approx. 1 mL caustic soda from the kit (concentration approx. 10-11 mol/L) so that the final concentration in the mixture is 1 mol/L

[0104] Step 4: heating the sealed tubes to 70° for 10 min

[0105] Step 5: allowing cooling to room temperature

[0106] Step 6: filtering and mixing in empty cuvettes (in the kit round cuvettes made of glass such as in other Nanocolor tests)

[0107] Step 7: measuring the filtrate in the spectrophotometer.

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