Liquid purification or separation – Processes – Treatment by living organism
Reexamination Certificate
2001-10-09
2003-09-09
Prince, Fred (Department: 1724)
Liquid purification or separation
Processes
Treatment by living organism
C210S617000, C210S623000, C210S629000, C210S631000, C210S151000, C210S195300, C210S202000, C210S220000, C210S259000, C210S903000, C210S908000
Reexamination Certificate
active
06616844
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to a method for treating high-concentrated organic wastewater, such as night soil or livestock wastewater, which has high levels of nitrogen and phosphorous. In particular, it is related to a method for treating night soil or livestock wastewater having high levels of nitrogen and phosphorous, comprising an anaerobic ammonium oxidizing (Anammox) step and a biopond step.
BACKGROUND OF THE INVENTION
The treatment of night soil or livestock wastewater has been regarded as a difficult and troublesome problem. No technique has been recognized as being the perfect solution even though many approaches have been taken. Usually, night soil or livestock wastewater is first collected into one place and treated by a locally shared treatment plant because sharing a treatment plant provides the advantage of convenient management and operation. However, such shared treatment plants have never demonstrated any success in removing high levels of organic material and nitrogen, which is generally found in extremely higher concentrations than those expected from an amount of organic material in night soil or livestock wastewater.
Furthermore, another conventional method of treating very highly concentrated night soil or livestock wastewater is dilution. However, the dilution is not efficient in that it requires consumption of an extremely large amount of water. For example, treating livestock wastewater having 15,000 mg/L of BOD by dilution needs 75 times this amount of water. Moreover, the dilution procedure requires a sufficiently large plant to hold this large amount of water. This leads to increase costs in building plants, in aerating the plant, and in fitting complementary equipment.
Other conventional methods for treating night soil or livestock wastewater focus on the removal of organic material and, thus, can not provide an efficient means for removing nitrogen or phosphorous, even though nitrogen and phosphorous are recognized as the main contaminants that causes eutrophication of lakes and marshes.
Studies have been made on various methods for treating night soil or livestock wastewater. In the removal of nitrogen from livestock wastewater, rates of variation in loading have been investigated in Bortone G., Gemeli, S. and Rambaldi, A. “Nitrification, Denitrification and Biological Phosphate Removal in SBR Treating Piggery Wastewater”, Wat, Sci. Tech., Vol, No. 5-6, p 977-985, 1992), which describes a ratio of an average flow rate per day to a maximum flow rate per day as 1.43, and a ratio of a maximum to a minimum of flow rate per hour as being more than 8.
According to Strous, M. et al., it takes about 1 year to make compliant Anammox-causing microorganisms, and such microorganisms have good sedimentation properties and an activity of 0.02 mg NH
4
+
-N/mg biomass/hr (Strous, M., heijnen, J., Kuenen, J., G. and Jetten, M. S. M. “The sequencing batch reactor as a powerful tool for the study of slowly growing anaerobic ammonium-oxidizing microorganisms”, Appl. Microbiol. Biotechnol., Vol. 50, p 589-596, 1998). According to Van de Graff, A. A. et al., Anammox activity is 66 ng NH
4
+
-N/mg VS/hr, and this activity can be affected even by an extremely small amount of O
2
and depends absolutely on NO
3
−
. The amount of microorganisms is directly proportionate to the biomass in the culture bath (Van de Graff, A. A., Mulder, A., de Bruijn, P., Jetten, M. S. M., Robertson, L. A. and Kuenen, J. G., “Anaerobic oxidation of ammonium in a biologically mediated process”, Appl. Environ. Microbiol. Vol. 61, p. 1246-1251, 1995).
A study has been reported to quantify ammonia volatilization from a piggery pond in order to determine its significance as a nitrogen removal mechanism (Andy, S., “Ammonia volatilization from a piggery pond”, Wat. Sci. Tech., Vol. 33, No. 7, p 183-199, 1996). The rate of ammonia volatilization greatly varies within the range of 355 to 1534 mg/m
2
/d, depending on the pH. Upon the volatilization of ammonia, the pH and the COD tend to decrease slowly.
The removal efficiency rate of total nitrogen (TK) from piggery wastewater was 86% when a reactor was operated with mixed liquor suspended solids (MLSS) being 17,000 mg/L during an intermittent aeration process. (José R. Bicudo and Ivo F. Svoboda, “Intermittent aeration of pig slurry—farm scale experiments for carbon and nitrogen removal,” Wat. Sci. Tech., Vol 32 No 12 pp 83-90, 1995)
SUMMARY OF THE INVENTION
The objective of this invention is to provide a method for the treatment of wastewater having high concentrations of nitrogen and phosphorus, such as night soil or livestock, and an apparatus used therefor.
In order to achieve the above objective, we, the applicants, provide a novel method for the treatment of wastewater that includes an Anammox step and a biopond step. This method adopts solid-liquid separation instead of dilution with water.
In particular, this method comprises the following steps:
(a) equalizing a flow rate and an amount of concentrated wastewater having at least 10,000 mg/L of BOD in an equalization tank,
(b) carrying out solid-liquid separation of the equalized wastewater from step (a) by adding an aggregating agent thereto so that the concentrations of organic material and nitrogen can be adjusted to desired levels,
(c) stripping ammonia selectively from the wastewater with the concentration of organic material unchanged,
(d) fermenting non-degradable organic material in the wastewater from step (c) by using an anaerobic microorganism, whereby the material can be converted into forms that can be easily fed to aerobic microorganisms in subsequent steps; and, also, fermenting the sludge that is returned from step (i) below to produce organic acids,
(e) carrying out Anammox reaction of ammonia in the wastewater with NO
2
—N in the sludge, which underwent the anaerobic fermentation in step (d) after being returned from step (i),
(f) activating soil microorganisms that are contained as a solid form in a biopond,
(g) feeding the activated microorganisms into a denitrification-inducing aeration tank, which then contributes both to the degradation of organic material and to the nitrification from ammonia nitrogen in the wastewater from step (e) to NO
3
—N in cooperation with aerobic microorganisms, which already exist in the aeration tank, and mixing to induce denitrification,
(h) denitrificating the wastewater from step (g) by reducing nitrates in the wastewater to nitrogen through endogeneous respiration of the microorganisms under a condition in which oxygen does not exist and external carbon sources are not introduced,
(i) carrying out a solid-liquid separation of the wastewater from the microorganisms and returning a part of the precipitated sludge to step (d) above, and
(j) removing any residue from the supernatant from step (i) by aggregating them and effluenting the finally treated wastewater.
The method of the invention can be carried out by using an apparatus comprising the following elements:
(a) an equalization tank for equalizing the flow rate and concentration of the wastewater that has originated from the source,
(b) a chemical solid-liquid separator for adjusting the concentration of the organic material and nitrogen,
(c) a stripping tank for selectively removing ammonia nitrogen while leaving the concentration of organic material in the wastewater unchanged,
(d) an anaerobic fermenter for both fermenting non-degradable organic material in the wastewater by using an anaerobic microorganism, whereby said organic material can be converted into forms that can be easily fed to aerobic microorganisms in subsequent steps; and for fermenting the sludge that is returned from the sedimentation tank below to produce organic acids;
(e) an Anammox tank for reacting ammonia in the wastewater with NO
2
—N in said sludge to generate nitrogen gases;
(f) a biopond to contain solidified soil microorganisms and to activate and feed them into a denitrification-inducing aeration tank;
(g) a denitrification-inducing aeration tank for both the d
Jung Hun
Kim Tae Hyung
Lee Chang Ju
Park Wan Cheol
Korea Institute of Science and Technology
Pennie & Edmonds LLP
Prince Fred
LandOfFree
Method for treating high-concentrated organic wastewater... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for treating high-concentrated organic wastewater..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for treating high-concentrated organic wastewater... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3080968