EP1268352A1 - Traitement des eaux d'egout ou de boues residuaires similaires - Google Patents

Traitement des eaux d'egout ou de boues residuaires similaires

Info

Publication number
EP1268352A1
EP1268352A1 EP01912006A EP01912006A EP1268352A1 EP 1268352 A1 EP1268352 A1 EP 1268352A1 EP 01912006 A EP01912006 A EP 01912006A EP 01912006 A EP01912006 A EP 01912006A EP 1268352 A1 EP1268352 A1 EP 1268352A1
Authority
EP
European Patent Office
Prior art keywords
drying
hours
process according
effected
sludge
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP01912006A
Other languages
German (de)
English (en)
Inventor
Robin Millard
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
R3 Management Ltd
Original Assignee
R3 Management Ltd
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 R3 Management Ltd filed Critical R3 Management Ltd
Publication of EP1268352A1 publication Critical patent/EP1268352A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • C02F11/18—Treatment of sludge; Devices therefor by thermal conditioning
    • C02F11/185—Treatment of sludge; Devices therefor by thermal conditioning by pasteurisation
    • 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
    • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
    • C02F11/13—Treatment of sludge; Devices therefor by de-watering, drying or thickening by heating
    • 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
    • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
    • C02F11/14—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents
    • C02F11/143—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents using inorganic substances
    • C02F11/145—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents using inorganic substances using calcium compounds

Definitions

  • This invention relates to treating sewage sludge or similar organic sludge, such as that obtained from industrial sites such as waste water treatment plants.
  • EP 0 283 153 Bl discloses a method of treating wastewater sludge to provide a fertiliser for agricultural lands which can be applied directly to the land.
  • the method involves mixing the sludge with alkaline material of specified fineness to raise the pH of the mixture to at least 12 for at least a day and to effect pasteurisation, and then drying the mixture. Drying is done either a) by aeration and maintaining the pH above 12 for at least seven days until the solids levels reach and maintain a minimum of 65% bulk solids, or b) by aeration and heating to a temperature of at least 50 °C and so that the solids levels reach and maintain a minimum of 50% solids. In b) the temperature should not be so high as to destroy all non-pathogenic organisms.
  • the elevation of the pH and the drying are effected so as to reduce odour and undesirable viruses, bacteria, parasites and vector (e.g. flies) attraction to the sludge and prevent significant pathogen regrowth while not eliminating beneficial non-pathogenic microorganisms. At least some of the temperature rise is due to the exothermic reaction with the alkali.
  • the product is allowed to air cure for about 10 days after achieving the desired solids content. Drying and curing may be effected by windrowing, turn-over or other forced air methods, and curing or aeration time is dependent on the aeration procedure and other factors and clearly need to be determined, for any particular circumstances, experimentally to see that the required end point has been reached. This involves taking samples to measure the solids content, testing for :
  • the minimum recommended time for maintaining the temperature at least 50 °C is at least 12 hours and the heat treated alkaline stabilised dewatered sludge cake is then air dried (while the pH remains above 12 for at least 3 days) through intermittent turning of windrows until a minimum of 50% solids content is achieved.
  • GB 2 276 876 A which refers to EP 0 283 153, describes treatment of sewage sludge having a solids content of at least 15% by weight with an alkaline material containing free lime, and storing and/or drying and/or composting the resultant mixture, adding sufficient lime to the mixture to achieve a pH of at least 10.
  • Higher pH values, even higher than 12, are not ruled out, but it is suggested that excellent reduction in pathogens can be achieved at pH levels below 12 with reduced evolution of ammonia, which renders the treated sludge and its surroundings less unpleasant and means that the treated material retains more nitrogen increasing its value as a fertiliser.
  • the method of GB 2276 876 involves dewateringthe sludge, e.g. in a press, and measuring it using a weigh hopper into a mixer into which is delivered alkaline material in the appropriate amount, the mixed material being delivered to a skip to deliver it to a windrowing area where it is turned periodically, normally for a period up to seven days. It is suggested also that provided the amount of calcium oxide that has been introduced is sufficient to raise the pH to a value greater than 12, and sufficient, indeed, to ensure that it stays above 12 for at least 2 hours, then it is possible to store the mix for not less than two hours, but then apply it directly to the land. However, GB 2 276 876 notes that such a product is not sterile.
  • WO 98/29348 discloses a different approach to the treatment of sewage sludge to those disclosed in EP 0 283 153 and GB 2 276 876.
  • drying is effected solely by heating caused by exothermic reaction with an alkaline admixture.
  • the approach of WO 98/29348 has the considerable advantage that the time and space consuming step of aeration is not required. This results in improvements in processing speeds - near continuous or continuous operation is possible.
  • the present invention overcomes the aforementioned problems and disadvantages, and overturns the received wisdom in the art regarding the nature of the pasteurisation step. Further the present invention does not utilise time and space aeration techniques.
  • a process for treating sewage sludge or similar organic sludge in which dewatered sludge cake and an alkaline admixture are mixed and then dried under pasteurisation conditions utilising heat from the exothermic reaction with the alkali; in which drying is effected by extraction of moisture evaporated from the mixture by the exothermic heat;
  • the pasteurisation conditions comprise maintaining a pasteurising temperature for less than 10 hours at a pH of at least 12, the pH of the mixture being maintained at 12 or above for less than a day.
  • the processing time required in order to treat the sludge is reduced.
  • the pasteurising temperature is maintained for less than 8 hours, more preferably less than 6 hours, most preferably for about 4 hours.
  • the time during which the mixture is at 12 or above is, necessarily, longer than the time spent at the pasteurising temperature. However, it is desirable that the mixture is at 12 or above for as short a period of time as possible.
  • the drying may be effected to dry the product to at least 50%, preferably at least 55%, dry solids content.
  • the drying may be effected to dry the product to between 50 and 65%, preferably between 55 and 60% dry solids content.
  • the drying product may pass two or more times through a drying hopper. Drying may be assisted by an air flow, which may be fan generated. Gases given off during drying may be passed through an ammonia scrubber.
  • the drying may be effected in a first in first out (FIFO) hopper.
  • FIFO first in first out
  • Drying may be effected in a cycling operation until a predetermined moisture content is detected, then the dried material is discharged.
  • the dried material may be tested for moisture (or dry solids content) by a sensor the output of which determines whether the product is recycled or delivered to another location, e.g. a stockpile.
  • the dried mixture may be tested by an infra-red moisture measuring transducer.
  • the dewatered sludge may be measured for water content and the measure used to control the alkaline admixture - the dewatered sludge may pass beneath an infra-red moisture measuring transducer.
  • the dewatered sludge cake may be fed to a storage bin from where it is delivered to a mixing arrangement with the alkaline admixture.
  • the storage bin may have a level sensor controlling the supply of sludge cake to the storage bin and/or delivery of sludge cake to the mixing arrangement.
  • the delivery of sludge cake to the mixing arrangement may be measured and the measurement used to control the supply of alkaline admixture to the mixing arrangement. Delivery of sludge cake to the mixing arrangement may be effected by a weigh belt.
  • the moisture content of the mixed dewatered sludge cake and alkaline admixture may be measured and the measurement may be used to control the addition of said admixture to said sludge cake.
  • the moisture content of the mixed dewatered sludge cake and alkaline admixture may be measured before drying and the measurement used to control the drying process.
  • Dewatered sludge cake may be fed directly from a dewatering arrangement such for example comprising a belt press arrangement.
  • the belt press arrangement may comprise primary and secondary high pressure belt press arrangements.
  • the output from the infra-red moisture measuring transducer may be used to control sludge cake throughout via adjustment of the operation of the belt process arrangement.
  • the process may be controlled by a microprocessor.
  • Feedback loops may be used to control operational parameters (such as feed rates, alkaline admixture mixing ratios and polyelectrolyte dosing).
  • the feedback loops may comprise proportional integral differential loops.
  • the steps of mixing, filing, drying and discharging the product may be performed within 24 hours.
  • the step of filling comprises filling a pasteurisation unit, such as a FIFO hopper.
  • the mixing and filling may be performed in less than 8 hours, drying in less than 5 hours and discharging in less than 3 hours.
  • Figure 1 is a plan view of a sludge cake-alkali mixing apparatus
  • Figure 2 is a schematic diagram of apparatus for introducing sludge cake to the mixing apparatus
  • the invention comprises a process for treating sewage sludge and similar organic sludge in which dewatered sludge cake and an alkaline admixture are mixed and then dried under pasteurisation conditions utilising heat from the exothermic reaction with the alkali, in which drying is effected by extraction of moisture evaporated from the mixture by the exothermic heat. Apparatus for performing the process are depicted in Figures 1 and 2.
  • Pasteurisation and drying by aeration, is effected in a first in first out (FIFO) hopper 10 such as a 100% live capacity Samson hopper fitted with full width discharger 10a.
  • the drying is effected in a cycling operation until a predetermined moisture content is detected, then the dried material is discharged via outloading belt conveyor 12, and take away belt conveyor 26.
  • FIFO first in first out
  • the drying is effected to dry the product to between 50 and 65%, preferably between 55 and 60%, dry solids content.
  • the drying product passes two or more times through the drying hopper 10, carried by an inclined belt conveyor 14, reversing belt conveyor 16, screw feeder discharger 18 and recycling belt conveyor 20. Drying is assisted by an air flow which may be fan generated by an extraction fan (not shown). The air flow is distributed across the cross section and length of the hopper 10.
  • Gases given off during drying are passed through an ammonia scrubber 24.
  • discharges to atmosphere are treated, and do not present a health risk either to the process operators or to the general public.
  • Residual material from the ammonia scrubber 24 may be mixed with the final dried product to eliminate a waste stream and to enhance the nutrient value of the final product.
  • the product is held for a maximum of 10 hours at pasteurisation temperature, which is monitored by temperature probes (not shown).
  • the pasteurisation temperature is in the range 50-55 °C, although the use of higher temperatures still is not ruled out.
  • the present invention can effect complete or near complete destruction of harmful pathogens, in particular E.coli 157 and Ascaris species. Ascaris species are regarded as being particularly difficult to destroy-see, for example, EP 0 283 153.
  • the pH of the mixture is maintained for less than a day, preferably less than 12 hours. This can be ensured by providing an alkaline admixture which comprises (CaO) and one or more further addivitives, such as fly ash.
  • the amount of lime used is enough - but just enough - to obtain the required rise in temperature.
  • the fly ash (which is at a pH of ca. 9.5) provides granularity and bulk in the final product.
  • the dried material is tested for moisture (or dry solids content) by a sensor (not shown), the output of which determines whether the product is recycled or delivered to another location, e.g. a stockpile, via the reversing belt conveyor 16 and take away belt conveyor 26.
  • the dried material may be tested by an infra-red moisture measuring transducer. The process achieves total exhaustion of free calcium oxide with the water in the drying product. Additionally, when the product is ready to be discharged, a reduction in temperature to around 25 °C is achieved.
  • Figure 2 depicts apparatus used at earlier stages of the process.
  • the dewatered sludge is measured for water content and the measurement used to control the alkaline admixture. This is achieved by passing the dewatered sludge beneath an infra-red moisture measuring transducer 30, and subsequently controlling certain operations in a manner described more fully below.
  • the dewatered sludge cake is fed - via a belt conveyor 32 - to a storage bin 34 from where it is delivered to a mixing arrangement 36 with the alkaline admixture.
  • the storage bin 34 has an ultrasonic level sensor 38 controlling the supply of sludge cake to the storage bin 34 and/or delivery of sludge cake to the mixing arrangement 36.
  • the delivery of sludge cake to the mixing arrangement 36 is measured and the measurement used to control the supply of alkaline admixture to the mixing arrangement 36.
  • Delivery of sludge cake (exiting the storage bin 34 via a sliding frame discharger 34a and screw feeder 34b) to the mixing arrangement is effected by a weigh belt feeder 40, which permits the measurement of sludge cake delivery by monitoring the weight of sludge cake fed.
  • the mixing arrangement 36 provides complete and intimate contact between the sludge cake and the alkaline admixtures without breaking the structure of the sludge cake (which would result in a "plasticised", paste-like material).
  • Alkaline admixture is supplied from two silos 42, 44 via screw conveyors 46, 48. Further silos may be employed. Additionally, a lime silo 52 is provided. The purpose of the lime silo 52 is to provide small, controlled additions of CaO or a material having a high free CaO content (for example, lime kiln dust) in the event that the other alkaline admixtures do not achieve the required temperature rise and hold criteria.
  • the mixed dewatered sludge cake and alkaline admixture is transferred via a swivel belt conveyor 49 to the inclined belt conveyor 14 which supplies the hopper 10.
  • the moisture content of the mixed sludge cake and alkaline admixture is measured before drying and the measurement used to control the drying process.
  • the measurement is made by an infra-red moisture measuring transducer 50, the output of which may also be used to adjust the feed rates of the alkaline admixture. This is used to achieve the desired mixed product moisture setting, typically 50%.
  • the dewatered sludge cake may be fed directly from a dewatering arrangement, which comprises a belt press arrangement (not shown).
  • the belt press arrangement involves both primary and secondary belt pressing operations.
  • Such an arrangement results in a number of advantages, such as an increase in dry solids content from a norm of ca. 25% to a norm of ca. 33 to 38%.
  • substantial reductions in sludge cake tonnage feed, alkaline admixture, mixed product and overall plant size are found to occur.
  • the process is controlled by an industrial process controller (PLC) with PC based data acquisition.
  • PLC provides automatic control of material handling, mixing, and the pasteurisation/aeration process.
  • the control and automation system incorporates proportional integral differential (PID) feedback loop controls to optimise process economy (e.g. admixture consumption and polyelectrolyte useage during dewatering) within the constraints of the required operating parameters.
  • PID proportional integral differential
  • Inputs from the moisture sensors and tachometers fitted to the feed screws (which provide indications of speeds and thus feed rates) are used in the control loops, although the master control is provided by the weight indication given by the weigh belt feeder 40.
  • Variables such as polyelectrolyte dosing, and belt process speed and throughput are also under microprocessor control.
  • the output from infra-red moisture measuring transducer 30 may be used to control sludge cake throughput via adjustment of the operation of belt press arrangement, in particular to optimise dry solids output with respect to polyelectrolyte additions.
  • the system software provides both visual and hard copy on line, reporting on all of the process steps described above. Daily production reports, heat pulse temperature graphs, and sludge, mixed and final product dry solids reports can be made available. Additionally, a "help line" service from the operating site to Head Office is provided via a modem link, with a remote management reporting facility.
  • twin pasteuriser arrangement a continuous operational cycle can be employed whilst enjoying 100% back-up capacity.
  • an extra hopper might be provided to the set-up shown in Figure 1, swivel belt 49 alternating between the two hoppers.
  • both pasteurisers can be used in tandem.
  • the advantages of the continuous treatment include reduced plant requirements, a reduced plant footprint, increased processing throughput and reduced operating labour and power costs per tonne of sludge processed, since most of the plant operations are carried out when the site is unmanned.

Abstract

L'invention concerne un procédé de traitement des boues résiduaires ou boues organiques similaires, consistant à mélanger un gâteau de boue essorée et un produit d'addition alcalin puis à sécher ce mélange dans des conditions de pasteurisation en utilisant la chaleur de la réaction exothermique avec l'alcali. Le séchage s'effectue par extraction de l'humidité qui s'évapore du mélange via la chaleur exothermique.
EP01912006A 2000-03-25 2001-03-22 Traitement des eaux d'egout ou de boues residuaires similaires Withdrawn EP1268352A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB0007246A GB2363116A (en) 2000-03-25 2000-03-25 Treating sewage or like sludge
GB0007246 2000-03-25
PCT/GB2001/001239 WO2001072646A1 (fr) 2000-03-25 2001-03-22 Traitement des eaux d'egout ou de boues residuaires similaires

Publications (1)

Publication Number Publication Date
EP1268352A1 true EP1268352A1 (fr) 2003-01-02

Family

ID=9888400

Family Applications (1)

Application Number Title Priority Date Filing Date
EP01912006A Withdrawn EP1268352A1 (fr) 2000-03-25 2001-03-22 Traitement des eaux d'egout ou de boues residuaires similaires

Country Status (9)

Country Link
EP (1) EP1268352A1 (fr)
JP (1) JP2003528715A (fr)
AU (1) AU2001240924A1 (fr)
CA (1) CA2402728A1 (fr)
GB (1) GB2363116A (fr)
MX (1) MXPA02009394A (fr)
PL (1) PL358805A1 (fr)
WO (1) WO2001072646A1 (fr)
ZA (1) ZA200207565B (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102014118618A1 (de) * 2014-12-15 2016-06-16 Endress + Hauser Conducta Gesellschaft für Mess- und Regeltechnik mbH + Co. KG Verfahren zur Regelung einer Prozessgröße

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3128673C2 (de) * 1980-07-29 1986-06-19 Gustav 3030 Walsrode Richard Verfahren zur Herstellung eines Bodenverbesserungsmittels aus Klärschlamm
US5013458A (en) * 1990-04-06 1991-05-07 Rdp Company Process and apparatus for pathogen reduction in waste
US5135664A (en) * 1990-11-30 1992-08-04 N-Viro Energy Systems Ltd. Method for treating wastewater sludge
US5277826A (en) * 1991-11-01 1994-01-11 Browning Ferris Industries Lime and fly ash stabilization of wastewater treatment sludge
US5435923A (en) * 1992-03-20 1995-07-25 Bio Gro Systems, Inc. Method for the treatment of sewage sludge and the like
US5385673A (en) * 1992-09-08 1995-01-31 Hazen And Sawyer, P.C. Method of treating wastewater biosolids
US5554279A (en) * 1994-09-26 1996-09-10 Rdp Company Apparatus for treatment of sewage sludge
US5679262A (en) * 1995-02-13 1997-10-21 Bio Gro Systems, Inc. Method for alkaline treatment of sewage sludge for beneficial use
SG73986A1 (en) * 1995-08-30 2000-07-18 Ohio Med College Method for treating bioorganic and wastewater sludges
GB9700015D0 (en) * 1997-01-02 1997-02-19 R3 Management Limited Treating sewage or like sludge

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0172646A1 *

Also Published As

Publication number Publication date
CA2402728A1 (fr) 2001-10-04
AU2001240924A1 (en) 2001-10-08
GB0007246D0 (en) 2000-05-17
WO2001072646A1 (fr) 2001-10-04
MXPA02009394A (es) 2004-05-17
PL358805A1 (en) 2004-08-23
JP2003528715A (ja) 2003-09-30
ZA200207565B (en) 2003-05-08
GB2363116A (en) 2001-12-12

Similar Documents

Publication Publication Date Title
EP0950030B1 (fr) Traitement de boues d'epuration ou de boues similaires
CA2199382C (fr) Procede et dispositif de traitement de boues residuaires
US6623650B2 (en) Processes and apparatus for treating sewage or like sludge
US6387281B2 (en) Processes and apparatus for treating sewage or like sludge
JP2016022468A (ja) 亜臨界水処理方法及び装置
CA2410814A1 (fr) Methode de traitement de boues organiques et de boues d'epuration
US20010023850A1 (en) Treating sewage or like sludge
WO2001072646A1 (fr) Traitement des eaux d'egout ou de boues residuaires similaires
KR20210072597A (ko) 퇴비제조장치 및 방법
CA2403554A1 (fr) Procede et appareil de traitement des eaux usees ou de boues similaires
CZ9902288A3 (cs) Úprava splaškového nebo podobného kalu
KR100508976B1 (ko) 음식물쓰레기의 연속처리시스템
CA2425717A1 (fr) Procedes et appareil ameliores destines au traitement de boues d'eaux usees ou du meme type
JPH11116369A (ja) 堆肥化装置
KR200182396Y1 (ko) 식품쓰레기의 사료 및 퇴비화 처리장치
RU2116714C1 (ru) Линия для получения гранулированного удобрения из птичьего помета
ZA200303034B (en) Improved processes and apparatus for treating sewage or like sludge.
ZA200207566B (en) Process and apparatus for treating sewage or like sludge.
US20100000277A1 (en) Granulated plant nutrient
SK812004A3 (sk) Zariadenie na úpravu čistiarenských kalov

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20020918

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR

AX Request for extension of the european patent

Free format text: AL;LT;LV;MK;RO;SI

17Q First examination report despatched

Effective date: 20040227

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20040709