Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F3/00—Biological treatment of water, waste water, or sewage
  • C02F3/30—Aerobic and anaerobic processes
  • C02F3/302—Nitrification and denitrification treatment

Definitions

• the invention is in the area of waste water treatment and more in particular in the area of denitrifying ammonium oxidation.
• WO-A 8907089 a process of this kind is described, wherein the ammonium ion is used as an electron donor in the denitrification of waste 5 water.
• the ammonium ion and the nitrate are simultaneously fed to a fiuidized bed reactor and reacted therein.
• the said application is specifically directed to specific micro-organisms that are suitable for this process.
• This process is also known as the Anammox process, or the 0 anammox-pathway.
• the reactor in said process is fed with effluent from an anaerobic reactor treating diluted yeast wastewater and the nitrate is supplied from an external sodium nitrate solution.
• ammonium is 5 oxidized with nitrite in stead of nitrate.
• Anammox process Since then most applications of the Anammox process are focused on feeding the Anammox reactor with nitrite produced in an aerobic iiitritification system (e.g. the Sharon- Anammox-process developed by TUD; WO-A 9807664)). Since its discovery the Anammox bacteria have been found on many 0 locations in nature.
• an aerobic iiitritification system e.g. the Sharon- Anammox-process developed by TUD; WO-A 9807664
• the Sharon reactor where nitrite is produced by suspended growing biomass, is placed prior to the Anammox reactor.
• the feeding of the suspended growing biomass from the Sharon reactor (which is essential for this process) into the Anammox reactor may 5 interfere with an appropriate biofilm formation in the Anammox reactor.
• non-attaching microbes are able to hydrolyze the attachment polymers of attaching microbes. This means that this two stage system is characterized by a potential intrinsic instability with respect to attached growing microbes.
• JP-A 2001/104992 a different embodiment of the Sharon process is disclosed, which process differs from the basic process in that part of the waste water bypasses the aerobic reactor in which nitrite is formed.
• the invention is based on the surprising discovery, that the these and other advantages could be overcome by oxidising the ammonia in the nitrifying reactor to nitrate or mainly to nitrate and feeding part of the ammonium ion containing waste water directly into the denitrifying reactor, and the remaining part to the nitrifying reactor.
• the nitrite is not formed in the nitrifying reactor, but in the denitrifying reactor from nitrate.
• the invention concerns a process for biological denitrification of waste water, preferably having a COD/N ratio between 0.5 and 3.5, comprising a nitrifying reactor and a denitrifying reactor, wherein an ammonium ion containing waste water stream is partly fed to the denitrifying reactor and partly to the nitrifying reactor, in which process the ammonium ion is biologically nitrified in the nitrifying reactor to nitrate, which nitrified waste water flow is subsequently fed to the denitrifying reactor, where nitrate is reduced and COD and ammonium are concomitantly oxidised.
• N2O, NO, NO2 volatile nitrogen oxides
• the process of the invention is especially useful for waste water having a COD/N ratio of > 0.5 and ⁇ 3.5.
• the COD/N ratio is bed by weight and determined using the Standard Methods for Examination of Water and Wastewater, 20 th Edition 1998, American Public Health Association, Washington DC. Within these ranges an optimal purification effect is obtained, better than with the Sharon process and the conventional nitrification- denitrification process.
• a COD/N ratio > 3.5-4 is required.
• the COD used is the degradable COD, as defined in the Examples.
• ammonium in the water stream passing the nitrifying system will be nitrified according to the conventional nitrification reactions (1) and (2).
• nitrate in the first, nitrifying, reaction step.
• the reaction goes mainly to nitrate.
• Full nitrification is preferred, although some nitrite in the effluent of the nitrifying reactor (about 5-10% of the influent ammonium concentration) can be tolerated.
• the required nitrite for the ammonium oxidation is produced under denitrifying conditions in the denitrifying reactor from nitrate.
• the nitrate produced in the nitrifying system will be reduced to nitrite according to reaction (3) in which [H] stands for the reduction equivalents originating from sulfide or organic components. This reduction takes place in the biomass in the denitrifying reactor, where a very effective and efficient "interspecies nitrite transfer" occurs.
• the nitrite produced will then be used by the anammox bacteria to oxidize ammonium, which is let directly into the denitrifying reactor, according to reaction (4).
• the induction of nitrite may also proceed through the oxidation of manganese into manganese oxide (Vandenabeele, J. et al, (1995). Influence of nitrate on manganese removing microbial consortia from sand filters. Wat. Res. 29, 579-587).
• Manganese compounds may be present in the effluent of a methane reactor. Also the presence of sulfides or carboxylic acids lead to nitrite formation from nitrate.
• the denitrification reactor is partially fed directly with the ammonium ion containing effluent, for example an anaerobic effluent, such as from a methanogenic pre-treatment.
• the distribution ratio between the nitrifying and the denitrifying reactor is determined by the composition of the wastewater in especially by the concentration of the individual electron donors (sulfide, organic compounds and ammonium) in comparison with the amount of ammonium ion.
• the nitrite production in the denitrifying reactor is preferably controlled and stimulated by a characteristic feeding pattern based on a discontinuous loaded substrate gradient (DLG).
• the discontinuous loaded gradient may be realized by two modes.
• the process of the invention may be based on any biological nitrification and denitrification system using micro-organisms, such as suspended sludge systems and is preferably based on systems using a biofilm in granules (e.g. EGSB or UASB) or on a supporting matrix (filter or fluidized bed systems).
• the ammonium oxidation under denitrifying conditions is operates optimal by a consortium of microbes in a biofilm where the intermediate nitrite concentration is kept surprisingly low. This shows that the process proceeds through a very effective and efficient interspecies nitrite transfer in the granules.
• FIG. 1 A typical flow diagram with the process of the invention is given in Figure 1.
• the methane treatment (1) UASB-reactor
• biodegradable organic components are largely removed and the effluent contains only residual organic components and sulfide (when the influent contains sulfate).
• the effluent of the methane reactor is divided over the nitrifying treatment (2) and the denitrifying treatment (3). This division is preferably discontinuous (see Figure 2) and the ratio is determined by the composition of the wastewater, especially by the concentration of the reduction equivalents and nitrogen. It is to be noted that it is also possible to use more than one reactor for both the nitrifying and the denitrifying step, either parallel or subsequent.
• the separate streams are combined in the denitrification reactor through separated feeding lines in order to create the intended substrate gradient in the reactor.
• the separate inlet and the discontinuous division will realize the required discontinuous loaded substrate gradient which triggers and control the denitrifying ammonium oxidation.
• the denitrification process is appropriate for treatment of nitrogen (i.e. ammonium) containing wastewater which contains a too low concentration of electron donors for conventional denitrification (anaerobic treated yeast wastewater, leachate etc.).
• any conventional system can be applied: 1) activated sludge (SBR etc) and 2) trickling filter.
• the preferred technology for the denitrifying- reactor (DE AMOX-re actor) is UASB or EGSB.
• activated sludge from nitrifying / denitrifying treatment plant can be used.
• the reactor is generally filled nearly completely, unwanted sludge will be washed out and under denitrifying conditions granulating sludge will develop gradually. If no anaerobic pre-treatment is used, for example in case of leachate, it can be seeded with a small fraction methanogenic sludge (10%). After start-up the system can be seeded with acclimatized denitrification -sludge.
• the invention is now elucidated on by the following example, which is intended as elucidation and not as limitation.
• waste water having the following composition: total COD 4.53 g/1, COD after centrifugation 3.86 g/1 and sulfate 135 mg S-SO4/I was fed to reactor (1) wherein an anaerobic treatment took place.
• the effluent of the anaerobic reactor had the following composition: total COD 1.2 g/1, COD after centrifugation 0.98 g/1, sulfate 0 mg S-SO4/I and N-NH 4 382 mg N/1.
• the COD/N ratio in the effluent based on biodegradable COD was 1.2 (Table 1).
• the hydraulic retention time in the anaerobic reactor was 28 h and the COD loading rate was 3.92 g COD totai/1/d. 50% of the said effluent was fed to the nitrification reactor (2) and the remaining 50% bypassed the said reactor (2) and was fed to denitrification reactor (3).
• the effluent of the nitrification reactor (2) had the following composition: total COD 0.94 g/1, COD after centrifugation 0.78 g/1, sulfate 77 mg S-SO4/I, N-NH 4 31 mg N/1, N-NO 2 5 mg N/1 and N-NO 3 194 mg/1, and was also fed to the denitrification reactor (3)
• the total flow through the anaerobic reactor and Deamox reactor was constant, however the actual distribution of the flow through the nitrifying system and the flow from the methane reactor direct to the Deamox reactor was discontinuous (see Fig. 2).
• the influent of the Deamox reactor (3) had the following composition: total COD 1.07 g/1 COD after centrifugation 0.87 g/1, sulfate 39 mg S-SO 4 /1, N- NH 4 197 mg N/1, N-NO 2 2 mg N/1 and N-NO 3 102 mg/1.
• the final effluent of reactor (3) had the composition: total COD 0.75 g/1 COD after centrifugation 0.73 g/1, sulfate 62 mg S-SO 4 Zl 5 N-NH 4 93 mg N/1, N-NO 2 0 mg N/1 and N-NO 3 55 mg/1.
• the effluent of the nitrification reactor (2) had the following composition: total COD 0.78 g/1, sulfate 135 mg S-SO 4 A, N-NH 4 0 mg N/1, N-NO 2 12 mg N/1 and N-NO3 200 mg/1, and was also fed to the denitrification reactor (3)
• the total flow through the anaerobic reactor and Deamox reactor was constant, however the actual distribution of the flow through the nitrifying system and the flow from the methane reactor direct to the Deamox reactor was discontinuous (see Fig. 2).
• the influent of the Deamox reactor (3) had the following composition: total COD 1.03 g/1, sulfide 71 mg S-H 2 S/1, sulfate 78 mg S-SO4/I, N-NH 4 99 mg N/1, N-NO 2 12 mg N/1 and N-NO 3 112 mg/1.
• the final effluent of reactor (3) had the composition: total COD 0.64 g/1, sulfide 0 mg S/l, sulfate 138 mg S-SO4/I, N-NH 4 17 mg N/1, N-NO 2 0 mg NA and N-NO 3 4 mgA.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Biodiversity & Conservation Biology (AREA)
• Microbiology (AREA)
• Hydrology & Water Resources (AREA)
• Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)

Priority Applications (1)

Applications Claiming Priority (3)

Publications (1)

Family

ID=34928476

Family Applications (2)

Family Applications Before (1)

Country Status (2)

Families Citing this family (11)

Family Cites Families (4)

• 2004
  • 2004-08-23 EP EP04077415A patent/EP1630139A1/de not_active Withdrawn
• 2005
  • 2005-08-22 EP EP05774782A patent/EP1805110A1/de not_active Withdrawn
  • 2005-08-22 WO PCT/NL2005/000606 patent/WO2006022539A1/en not_active Ceased

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events