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WO2011097554A2 - Traitement d'eau résiduaire à faible rejet de phosphore - Google Patents

Traitement d'eau résiduaire à faible rejet de phosphore Download PDF

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Publication number
WO2011097554A2
WO2011097554A2 PCT/US2011/023869 US2011023869W WO2011097554A2 WO 2011097554 A2 WO2011097554 A2 WO 2011097554A2 US 2011023869 W US2011023869 W US 2011023869W WO 2011097554 A2 WO2011097554 A2 WO 2011097554A2
Authority
WO
WIPO (PCT)
Prior art keywords
sample
biosolid
treated
biosolids
wastewater
Prior art date
Application number
PCT/US2011/023869
Other languages
English (en)
Other versions
WO2011097554A3 (fr
Inventor
Frederick P. Mussari
Aaron Zahn
Original Assignee
Bcr Environmental, Llc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bcr Environmental, Llc filed Critical Bcr Environmental, Llc
Publication of WO2011097554A2 publication Critical patent/WO2011097554A2/fr
Publication of WO2011097554A3 publication Critical patent/WO2011097554A3/fr

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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
    • C02F3/02—Aerobic processes
    • C02F3/12—Activated sludge processes
    • C02F3/1205—Particular type of activated sludge processes
    • C02F3/1221—Particular type of activated sludge processes comprising treatment of the recirculated sludge
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C02F11/004—Sludge detoxification
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/76—Treatment of water, waste water, or sewage by oxidation with halogens or compounds of halogens
    • 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
    • C02F3/308—Biological phosphorus removal
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/10—Biological treatment of water, waste water, or sewage

Definitions

  • the decomposition of the algae by bacteria uses up so much of oxygen in the water that most or all of the animals die, which creates more organic matter for the bacteria to decompose. In addition to causing deoxygenation, some algal species produce toxins that contaminate drinking water supplies.
  • FIG. 1 shows a schematic diagram of an embodiment of the present invention.
  • the wastewater treatment process consists of a number of sequential steps.
  • wastewater enters a wastewater treatment plant at the headworks.
  • the headworks acts as a primary grit and foreign matter removal system for a wastewater treatment plant.
  • wastewater is transferred to a form of biological treatment unit (“BTU") (i.e. an oxidation ditch, sequential batch reactor, member bioreactor, etc.).
  • BTU biological treatment unit
  • Nutrients are removed from the wastewater.
  • Nitrification itself is a two-step aerobic process, each step facilitated by a different type of bacteria.
  • the oxidation of ammonia (NH 3 ) to nitrite (NO 2 " ) is most often facilitated by Nitrosomonas spp. (nitroso referring to the formation of a nitroso functional group).
  • Nitrite oxidation to nitrate ( ⁇ ' ) though traditionally believed to be facilitated by Nitrobacter spp. (nitro referring the formation of a nitro functional group), is now known to be facilitated in the environment almost exclusively by Nitrospira spp.
  • Denitrification requires anoxic conditions to encourage the appropriate biological communities to form. It is facilitated by a wide diversity of bacteria. Sand filters, lagooning and reed beds can all be used to reduce nitrogen, but the activated sludge process (if designed well) can do the job the most easily. Since denitrification is the reduction of nitrate to dinitrogen gas, an electron donor is needed. This can be, depending on the wastewater, organic matter (from faeces), sulfide, or an added donor like methanol. Many sewage treatment plants use axial flow pumps to transfer the nitrified mixed liquor from the aeration zone to the anoxic zone for denitrification. These pumps are often referred to as Internal Mixed Liquor Recycle pumps (IMLR pumps).
  • IMLR pumps Internal Mixed Liquor Recycle pumps
  • Phosphorus removal is important as it is a limiting nutrient for algae growth in many fresh water systems. It is also particularly important for water reuse systems where high phosphorus concentrations may lead to fouling of downstream equipment such as reverse osmosis.
  • Phosphorus can be removed biologically in a process called enhanced biological phosphorus removal.
  • specific bacteria called polyphosphate accumulating organisms (PAOs)
  • PAOs polyphosphate accumulating organisms
  • Phosphorus removal can also be achieved by chemical precipitation, usually with salts of iron (e.g. ferric chloride), aluminum (e.g. alum), or lime. This may lead to excessive sludge productions as hydroxides precipitates and the added chemicals can be expensive. Chemical phosphorus removal requires significantly smaller equipment footprint than biological removal, is easier to operate and is often more reliable than biological phosphorus removal.
  • the wastewater and accumulated organic matter is sent to a clarification process. Clarification is where the water, or effluent, is separated from the solids, or organic matter known as wastewater sludge. Sludge that is generated by a process of biological nutrient removal, as described above, is referred to as waste-activated sludge, or 'WAS'. From this point, the WAS typically is subjected to some type of digestion. Following digestion, or other treatment to disinfect, dry or in some way further treat the material, it is referred to as municipal biosolids ("Biosolids"). Digestion
  • the solids or sludge accumulated in a wastewater treatment process must be treated and disposed of in a safe and effective manner.
  • the purpose of digestion is to reduce the amount of organic matter and the number of disease-causing microorganisms present in the solids.
  • the most common treatment options include anaerobic digestion and aerobic digestion.
  • Anaerobic digestion is a bacterial process that is carried out in the absence of oxygen.
  • the process can either be thermophilic digestion, in which sludge is fermented in tanks at a temperature of 55°C, or mesophiiic, at a temperature of around 36°C. Though allowing shorter retention time (and thus smaller tanks), thermophilic digestion is more expensive in terms of energy consumption for heating the sludge.
  • Anaerobic Digestion is the most common (mesophiiic) treatment of Domestic Sewage in Septic Tanks, which normally retain the sewage for a number of days or weeks, reducing the B.O.D. by about 35 to 40%. This reduction can be increased by a combination of anaerobic and aerobic by installing 'Aerobic Treatment Units' (ATUs) in the Septic Tank.
  • ATUs 'Aerobic Treatment Units'
  • Aerobic digestion is a bacterial process occurring in the presence of oxygen. Under aerobic conditions, bacteria rapidly consume organic matter and convert it into carbon dioxide. The operating costs used to be characteristically much greater for aerobic digestion because of the energy used by the blowers, pumps and motors needed to add oxygen to the process.
  • Biosolids can be transported away from the wastewater plant and dispersed on the ground or be safely disposed of.
  • the inventors have realized that during the course of digesting waste activated sludge, the Nutrient Loading resulting from digestion process itself contains a substantial amount of nitrogen and phosphorus.
  • the inventors have devised a new biosolid treatment process that can be used in conjunction with any wastewater treatment that avoids digestion and the resulting Nutrient Loading, yet still meets the regulatory required pathogen reduction requirements.
  • the invention enhances the Nutrient removal of a wastewater treatment plant and meets regulatory standards for Biosolids disposition without the use of Digestion.
  • the present invention relates to a wastewater treatment system that reduces the production of Nutrient Loading.
  • the process includes obtaining a solids containing wastewater sample following any type of nutrient filtration or biological nutrient removal; subjecting the sample to a separator to produce a first effluent and an untreated WAS sample; subjecting the untreated WAS sample to an on-site generated chlorine dioxide treatment to produce a treated Biosolid sample and a second effluent, wherein said treated Biosolid sample is reduced in pathogen content (fecal coliform bacteria) down to less than 2,000,000 cfu/gm dry weight solids without being subjected to digestion and wherein said second effluent has a reduced Nutrient content.
  • pathogen content fecal coliform bacteria
  • the chlorine dioxide treatment is dosed to achieve a fecal coliform bacteria content of between 1 ,000-2,000,000 cfu/gm. In a more specific embodiment, the chlorine dioxide is dosed to acheive a fecal coliform bacterial content of between 10,000- 2,000,000 cfu/gm, and in an even more particular emboidment, 100,000-2,000,000 cfu/gm.
  • the process may further include transporting the treated Biosolid sample subsequent to the subjecting step so as to make the treated Biosolid sample available for land dispersal.
  • the term "reduced phosphorus content" with respect to effluent refers to an amount of phosphorus that is lower than that produced from an equivalent mass of biosolids treated by digestion.
  • the capacity of the wastewater treatment plants is limited by the ability of the biological treatment steps in removing Nutrients such as nitrogen and phosphorus As commonly practiced, the biological nutrient removal step is followed by some form of digestion, which releases nutrients which have been taken up in the biological nutrient removal step.
  • the present invention allows wastewater treatment facilities a method of reducing pathogen content of the biosolids without increasing the loading of nitrogen and phosphorus, thus decreasing the capacity of the facility.
  • the amount of phosphorous that is present in the effluent from a dewatered, treated Biosolids sample is less than 100, 90, 80, 70, 60, 50, 40, 30, 20, 15 or 12 mg/kg.
  • the amount of nitrogen in the effluent is less than 50, 40, 30, 20, or 18 mg/kg of effluent.
  • Biosolids Once Biosolids are treated they may be applied as fertilizer to improve and maintain productive soils and stimulate plant growth. Biosolids also are used to fertilize gardens and parks and reclaim mining sites. Biosolids are carefully monitored and must be used in accordance with regulatory requirements.
  • biosolids are dewatered before they are beneficially reused. Following secondary clarification, municipal biosolids are often just 1-5 percent solids, so removal of the water from the material is essential to reducing weight and the cost of further treatment or disposal or reuse.
  • a variety of technologies are employed to dewater biosolids—including belt presses, centrifuges, and other devices. The inventors have surprising found that the use of chlorine dioxide alters the microflocculation characteristics of the sludge by altering the ionic characteristics of the material, greatly reducing the amount of polymer needed for dewatering.
  • the invention pertains to a method of producing a pathogen-reduced, dewatered Biosolids sample, that has a 20% total solids content with polymer consumption of less than 30, 28, or 25 lbs per ton dry weight of the Biosolids sample.
  • the treatment systems and method embodiments of the present invention dramatically improve the capacity of wastewater treatment.
  • the inventors have discovered that the under conventional prior art methods, the wastewater treatment is being overloaded with Nutrients, such as phosphorus, that is actually produced by the feedback from its own treatment, Digestion.
  • the inventors have discovered that there are biosolid-associated Nutrients and biosolid-dissociated Nutrients.
  • the biosolid-dissociated Nutrients present in nascent influent are removed via the biological treatment steps.
  • Biosolid-associated Nutrients are released from the biosolids under prior art methods and, in turn, returned back to the headworks, which overloads the system and decreases nutrient removal capacity.
  • Certain embodiments of the present invention avoid this problem because the Biosolid- associated Nutrients remain associated with the biosolid and can be discarded, as opposed to feeding back to the headworks. Furthermore, the embodiments of the present invention provide the additional advantage of achieving pathogen-reduction down to set regulatory standard ("Class B standard), which serves as an economic advantage since the biosolids can be land dispersed.
  • Class B standard set regulatory standard
  • the embodiments of the present invention provide enhancements to common dewatering methods of Biosolids.
  • the inventors have surprising found that much less polymer (e.g. polyacrylamide cationic polymer, Percol 402, Percol 406, Alkafix 357, all manufactured by Allied Colloids, Inc., of Suffolk, Va.
  • polyacrylamide cationic polymer e.g. polyacrylamide cationic polymer, Percol 402, Percol 406, Alkafix 357, all manufactured by Allied Colloids, Inc., of Suffolk, Va.
  • the high molecular weight polymers are Percol 757, Percol 455, and Percol 710, all of which are also manufactured by Allied Colloids, Inc., of Suffolk, Va.
  • This ability of the biosolid sample delivered to the dewatering station having an improved ability to have water removed with less polymer, vs. biosolids produced according to a different method, is referred to herein as "improved dewatering characteristics.”
  • FIG. 1 A specific example of a wastewater treatment system for producing a Class B Biosolid sample with low phosphorus loading is shown in FIG. 1.
  • wastewater 108 containing Biosolid-associated and Biosolid-dissociated Nutrients first enters the headworks 110 and then is transferred to a biological treatment station 115.
  • the biological treatment station functions primarily to remove Biosolid-dissociated Nutrients (and a low percentage of Biosolid-associated Nutrients) in the wastewater to produce a Nutrient-reduced wastewater sample 116.
  • the Nutrient-reduced wastewater sample 116 is transferred to a clarifier 120, where the Nutrient-reduced wastewater sample 116 is separated into an effluent component 121 and a WAS component 122.
  • the effluent component 121 is either returned to the headworks 110 or is discarded.
  • the WAS component 122 is then subjected to a chlorine dioxide treatment zone 125 that is fed by an on-site chlorine dioxide generator 127 in fluid communication with the chlorine dioxide treatment zone 125.
  • the water content of the WAS component 122 can be adjusted as needed to optimize the flow rate through, and/or dose time, of the WAS component 122 at the chlorine dioxide treatment zone 125.
  • the subjecting of theWAS component 122 to the chlorine dioxide is conducted at an appropriate dose and exposure time sufficient to reduce the fecal coliform content of the Biosolids component 122 to less than 2,000,000 cfu/gm, thereby producing a pathogen-reduced (treated) Biosolid component 130.
  • the pathogen-reduced Biosolid component is not subjected to a digester prior to being dewatered at a dewatering station 140.
  • the release of Biosolid-associated Nutrients is minimized and the dewatering station 140 produces a phophorus-reduced water component (Filtrate or centrate depending on mode of dewatering, or generally referred to as the effluent component 150) that can be sent back to the headworks or discarded on the plant site.
  • the Biosolids achieved following the dewatering station 140 have reduced pathogen content and can be classified as Class B by set regulatory standards.

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

Abstract

L'invention porte sur des procédés de production de biosolides déshydratés à teneur réduite en pathogènes qui réduisent la quantité de phosphore rejeté dans l'environnement. L'invention porte également sur un nouveau système de traitement d'eau résiduaire et des procédés correspondants qui produisent un échantillon de biosolides traités présentant des caractéristiques de déshydratation améliorées et qui réduisent de manière spectaculaire la quantité de polymère nécessaire pendant la déshydratation.
PCT/US2011/023869 2010-02-05 2011-02-07 Traitement d'eau résiduaire à faible rejet de phosphore WO2011097554A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US30189410P 2010-02-05 2010-02-05
US61/301,894 2010-02-05

Publications (2)

Publication Number Publication Date
WO2011097554A2 true WO2011097554A2 (fr) 2011-08-11
WO2011097554A3 WO2011097554A3 (fr) 2011-12-29

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5976375A (en) * 1998-04-03 1999-11-02 Pulp And Paper Research Institute Of Canada Process for reducing production of biomass during activated sludge treatment of pulp and paper mill effluents
US20020148780A1 (en) * 2001-04-13 2002-10-17 Tiemeyer Eric B. Method of enhancing biological activated sludge treatment of waste water, and a fuel product resulting therefrom
US20060151400A1 (en) * 2004-12-03 2006-07-13 Biochem Resources Biosolids stabilization process
US20080116130A1 (en) * 2005-01-31 2008-05-22 Ashbrook Simon-Hartley Operations, Lp Methods and apparatus for treating wastewater employing a high rate clarifier and a membrane

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5976375A (en) * 1998-04-03 1999-11-02 Pulp And Paper Research Institute Of Canada Process for reducing production of biomass during activated sludge treatment of pulp and paper mill effluents
US20020148780A1 (en) * 2001-04-13 2002-10-17 Tiemeyer Eric B. Method of enhancing biological activated sludge treatment of waste water, and a fuel product resulting therefrom
US20060151400A1 (en) * 2004-12-03 2006-07-13 Biochem Resources Biosolids stabilization process
US20080116130A1 (en) * 2005-01-31 2008-05-22 Ashbrook Simon-Hartley Operations, Lp Methods and apparatus for treating wastewater employing a high rate clarifier and a membrane

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Publication number Publication date
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