CA1229807A - Process for biological conversion of substrates - Google Patents
Process for biological conversion of substratesInfo
- Publication number
- CA1229807A CA1229807A CA000458126A CA458126A CA1229807A CA 1229807 A CA1229807 A CA 1229807A CA 000458126 A CA000458126 A CA 000458126A CA 458126 A CA458126 A CA 458126A CA 1229807 A CA1229807 A CA 1229807A
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- electric field
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- 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
- C02F1/24—Treatment of water, waste water, or sewage by flotation
-
- 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
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
- C02F1/465—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electroflotation
-
- 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
- C02F1/48—Treatment of water, waste water, or sewage with magnetic or electric fields
-
- 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
-
- 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
- C02F3/1215—Combinations of activated sludge treatment with precipitation, flocculation, coagulation and separation of phosphates
-
- 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
- C02F3/34—Biological treatment of water, waste water, or sewage characterised by the microorganisms used
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
- C12N13/00—Treatment of microorganisms or enzymes with electrical or wave energy, e.g. magnetism, sonic waves
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- 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
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- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Microbiology (AREA)
- Biodiversity & Conservation Biology (AREA)
- Zoology (AREA)
- Genetics & Genomics (AREA)
- Bioinformatics & Cheminformatics (AREA)
- Health & Medical Sciences (AREA)
- Wood Science & Technology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Biotechnology (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Engineering & Computer Science (AREA)
- General Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Breeding Of Plants And Reproduction By Means Of Culturing (AREA)
- Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
- Medicines Containing Plant Substances (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
- Water Treatment By Electricity Or Magnetism (AREA)
- Treatment Of Sludge (AREA)
- Immobilizing And Processing Of Enzymes And Microorganisms (AREA)
- Preparation Of Compounds By Using Micro-Organisms (AREA)
- Processing Of Solid Wastes (AREA)
- Activated Sludge Processes (AREA)
Abstract
For the biological conversion of substrates, particularly the sewage water purification, charging of the microbial material with the substrate is improved by applying an electric field during the charging and/or a flotation using pulsating direct current. By applying this electric field only during the charging and/or the flotation the actual biological conversion can take place in an aerobic or anaerobic process according to optional values.
Description
Tne invelltioll relates to a m e; hod for the biological con\~ersion of sub-strates in ~hich substrate and microbial material are mLYed, it^ neces~ary aifter preliminary purification of the substrate, and the thus obtained ,nicrobial syste m is kept under reaction conilitions.
In the following bacteria, yeasts and the li'i;e, mixed with a corresponding substrate, are understood by microbial systems. Such ;nicrobial s)stems are often designated as biomass which effects a biological reaction as a self-contained system. In particular, microbial systems are acti~,ated or cligested sludge. Equally, tile microbial biocoenoses as are present in the acetic or lO alcoholic fermentation shaIL be classed under the concept of microbial systems.
Such microbial systems take in the s~lbstance usuall~ by absorption to the cell membrane. ~Yithin the ran8e oE the ceLl membralle first degradation reac--tions take place. The absorption rate of the substrate -~s determirled among other ti~ings by tlle concelltration of the primclry metabolites in the c~ll plasm.
15 Depending on the t~,pe of the employed microorgal~isms such a microbial system is able to effect a certa n biological reaction or to convert certain substancescontained in the sul~strate.
For im provirlg the charging of the microorganisms ~:ith the subs~rate to be converted polyelectrolytes are added ~ ich ob~iously e:cert an in1uence 20 upon ttle transport processes througil the cell m e m l-rane. The additioll or`
greater amounts of polyelectrolytes StlOWS oEten negative inEluences upon the activ-ity of Lil(' microbes w;~ich can be e~pLIined b~ the fact that the transport proce~-se.s througrl the ceL1 m e m brane are blocl~ed~ nu m ber of microbial systems are e:cceedingly dit'~icult to float and tne separatior, of ~5 the substrates to be convertecl i5 succe~sslil orLl.y to an unsatisfdctory e:~terlt.
The additiorl of greater arnounts oE polyelectrol)tea has lisadvantaca~eous efL'ects on the se~.!age load. Furtller m ore, a nu m ber of bio1O~,ical reactions in such microbial systems go on very s1OI~1ly becal;se a fast abs~rp~ioll of t'-ne substrdte to be degrcl~late~l by the microbes is not pos~ible.
The invention aims .at increasing the chargillg rat~ of micro'ui,l1 ma;eri.~l a~
by the substrate, at ~liminishing dramaticaLly the amoun~: oE polyelectrolytes to be adcied, and at irnpro~,ing the floatability of the charged biomass. In order to solve this proble m the invention con ~ists essentially in applying an electric field in the miYing space and/or :in a ~otation de~ice after mi.~ing 5 the substrate ~ith the microbial m aterial using pulsating direct current, and in effecting a biolog:ical reaction subsequently without appl~ing an electric field. Ilerein it turned out to be essential that puL~ating direct current is used for build-up of the electric field. Such a pulsating direct current can a]so be a swe:lling current which starting ~rom a minimum value has hr-llf-lO waves of only one single polarity. By using such an electric field after mi.~ingthe substrate with the microbial m aterial it has been surprisingly found that the substrate is absorbed to an increasLng extent by the microbes, wherein the concentrations of the prim ary m etabol:ites to be e~;pected ob~iously clo not exert an influer-ce wort:ll rnentioning upon tile substIate resorption rate.
15 It is alrea(ly l~no~r-l to subject sewage ~aters to elect~-olysis bec'ore biological purificatioll. Until now, ho~lever, there was a prej~lcLice of the eYperts agaiJlst subjecting the bio m ass to the influence of an electrLc f-ield. The surpri~iing etfects oE the inf1uence ot an elecLric ielrl built up with p~lsatulg d:irect current upon the t-iorna~ss can be pos-~ibly eY~pk~ ed by the fact that the charge 20 dist~ibution :in the ce~l m e m brane is changed by the il~1uerlce of the electric ~ie:ld, by ~hich the transport processes throuc,h the ce11 men.lbrane are e.ssell-tially acceLerrlted. 'L`he superiority of using p~Llsating d~rect currellt in corn-par-Lsorl ~ ith smoc)th direct currellt could be proved b~ e.~;pe!imen~, althuu~h an e:~act e~;plallation coukl not be found. 'I`he super~orit.y .owar-ds the use _5 of alterllatillO curr-erlt s~ith posLtive and negative halL-.~avc?s r~ be indicated by the fact that inver-sioll of pol~rit y of such half~ ves in zero crossover d:isturbs a~ain Lhe activation of the cell rn e n~ b~-alles. ~ pplying such an electric l~iekl an a~l~iitiona1 absorption of subs;rate by Lhe mic.robes coul~l be observe(l an(l in isolated cases it could e~ t?n be i. bsr r ~ ed that the alicrobes 30 absorb substclnces t hey usuaLl-. do not co~ erL. 'I`hl s~ .'or e~:a m ple în : he t71 species Saccharom~!ces cere~ iae (b~ewer's yeast) it was observed that apart ~ro m the he.~;oses usuaUy converted by tl~is species it absorbs also pentoses in the electric l~ieLd uncler anaerobic conditions. Subsequently, it was obser-ved that under the influence oE the electric field ~ylose is fermented to 5 aLcohol by this species. In the case of other microbes it couLd be obser~ ed that not only greater a m ounts of substrate could be absorbed by the microbes in shorter time, but also that the separability of the biomass was essentially improved. M-icrobiaL systems dificuLt to float and unfLoatable srlbstances could be easiLy separated in presence of an electric field and the remaining concentration in the resid~laL water after separation of the biomass following the absorption o~ substrate showed essentiaLly lower ~alues of sewage water than in the known methods. The relatively 'nigher supply of substrate in the ceU obiously forces the celL to accelerated reaction and as a consequence an essentially faster reaction to ~he requ~l-ed end products w as observed.
Above aIL the need of polyelectrolytes in ilotation could be essentiaLly re-duced. For e~cample it was observed that a ilotation which ~ith convention~l m ethods without using an electric ield needed three quarters of an hour to an hour, could be inished in 4 to 5 minrltes, wherein a lower concentration of substrate remc~ined in the sewage water.
A fLotation is particuLarly favourable in the scope of waste water puri-ication plants, as the puriication plant is designed corresponding to the average require m ents. 13y flotation peak values in the occurrence of waste water to be pur;fied can be coped with very sim ply by the fact that the fLoated sludge which cannot be supplied any m(lre ul the normally dimensioned l~iological puri'Liccltioll stage is aiscll.3rge(l all(l burnt or is intermediatell stored in concerltrated form in orcler to be subjected after iards correspon-dillgly dil~lted to the convelltionc~l biologic~ purillicati(m. The ~lotation stage hereill mal;es above all short-term regr:lating intervent ions posssible becauseof the low need of time, as for instance the sepa;atioll of sludge whictl after repeated ventilation can be recycled to the mi~ing ve~s~sel. Also in this - s -~.~a~ it is pos~ible to take the difEerent occurr~rlce c~E ~ ater to be puri~ied into account ancl to ensure a reg~LLar through-put thro~lgh the biological puri-fication stage. The partial feedbacl; of floated sludge to repeated n~liYing a:Llo~s the addition o:E smaILer amo~lnts oE nutritious substances especiaILy 5 in domestic se~iage.
In the scope of the process according to the in~entioi3 it has proved favourable to use a terminaL voltage of 2 - 30 V preferably 4 - 12 V for the buiLd-up of the electric fieLd.
I~]SO if the adclition of polyelectrolytes can be (liminished, it is ad\an-10 tageous though particuLar1y in order to achieve im proved' conductivity ofthe solution to add polyelectrolytes to the m.iYture of subsrrate and micro-bi~l m aterial before applying the electric field . Surpr~ingly aLso the addition of ion exchangers invol~ ed an il!l provemellt of substrate absorption and f] otatio n .
Preferably the electr;.c ~i.e.kl .is app~ied :iutermittillgl.y. ~her~in the electric field is appliecl at :least in a f.-rst temporal stage of ~he reilction in ~ihiCIl the substrate is al)solbed by the m:icrobia:l !nateria~ !i.thin this fi~-s; Lempor~l stage a sigri.E:i.cant :improveillerlt of changing Or th~ microbes ~iith s~im~LL-taneous clim~ isllillg of the need of time an~l .sin~l~Ltalleous impro-~ement 20 oE EloatabiLity h.lS ShO~
In b:iocoenoses which do not ten(l to violen~ prodll ~tion of g~lS i;n mediate-ly after chargirlg :it is ad~ ancagec3lls to support flotat iorl b- e:lectrolyt ic d~
composition. In this case proceeding is s~itab:ly such as to app:L~ a teriil:ina:l ~o:Ltage at30ve tile decoinpo~iLion voltage oi the soLuti.ll o~ s.:bst.rate-biorn3ss 25 in the first tempor~-LI stage :in order to pronlot.e ilot..ltion o~ the biomass chclrge(~ ith substrate. In b:iocoenoses ;rich Libera~e &reater a:nounts of fernlen~atioll gases the terminal. ~olcage can be chosen to be lower.
Tn every case it it i'a~o~lrable t.o ~all~i nutr:iti~ ~i..i sub.~.t~3il. es alrea~'i .
bei'c)re ap~ r~iilg the clectric f-.-i.el(l ~Yhei ein it n~Ce~?~` Iry the pi3 is 5rol~gi~t :3(.1 to tl~e most Ea~our lble \.aL:.Ie i~or biologic 1L re.l~tic3il. ~ta.ldar(L;~ th;.' pti 3~
to the v~Llue most favourable Eor the subsec1uent bio1Ogical reaction alLo~.s further diminishing of the amount of polyeLectrolyte to be added.
Preferably, an electric field with essentially horizontaL iines of flux is used. In such an electric fieLd the eLectrodes are usucilly arranged verticaILy 5 and the production of gas setting in at the surface supports the fLotation of the bio m ass.
Since the bio m ass shaIL not be subjected to an electric fieLd du.-ing the actual biological reaction ~hich can be carried out as an anaerobic or aerobic reaction, and above all in order to use an optional method of pro-lO ceed-ing for the subsequent reaction, as fer m entation, putrefaction, respiration or a usual sLudge vessel, the proces~s accorcLing to the invention is effected so that charging of the bio m ass with substrate and biologicaL reaction of the biomass charged ~ith substrate is carried out in separate r,esse~s, wherein tt1e m aterial charged :~ith substrate is separate(! ancl supplied to ~he reaction 15 space and the biomass i~ recycle~1 to the mi~ir1g space after reac ion in the reaction space. By proceeding thus the most different biomasses can be ta',~en into account. While for instance yeast liberates carbon dio.~ide ~ery fas-and thereEore does not re(~r1ire special s~1pport by electlolytic decomposition for fast an(1 co~1 plete ELotation in the f:irst stage oE charging of the micro-20 bial materiaL ~ith the substrate, it is preterable to apply higher voltagesto activated .sludge ~ ich is bac31y Loatable in the ~irst st~ges of the reaction in wlLic11 charging oE the biomass takes place in order to promote ~lotat,ion.
The electric tielcl can be app:Lied most preferE1b1y ~ithin the scope oE
the methoc1 accorc1in~ to the invention by arrar~ g eLectro~les i~1 a disLE~nce 25 fro m each other in the mi:cing space and/or f~lo-ation spacP, ~;hich ~listance is 0,5 - 2 m m/V, pre'.e1aL1ly 1 in m~V in the ra11~,e o~ 2 - 30 ~ 3epen~1ing on the voltage choser1. Coniplyil1g ~;ith these concLirior1s an optimum in re-lation to the charging o~ the microhes ;;ith substrate a11d 3J~. relation to the .`iol~aion 0~ ~lle C'lal`'e(~ )nla~; co~ be o1-se1ve~1. E~rei`er;~1~1y the p^ 1cC~iS
30 is effecier1 so that the ~listE1nce of e1ectrodes in t.1e 11Oi~aLion s?ace as com-~2~
, pared ~iLh th~ d;stance cE the el clrodes in the m~ lg space and/or thetermina1 voltage in the mL~;ing space as coml)ared with the termilaL voltagle in the Elotation space are chosen greater l~ithin the scope of this process degradable anodes i. e. of zLu m-irLiu m 5 or iron as ~eIL as anodes resistant to the electrolitic decomposition can be usecl. Separation of the charged bio .n ass can be sustained by using Loccu-lating agents. The stim ulating effect of the eLectric rieLd for the absorption of substrate couLd be found both for anaerobic and for aerobic reactions.
Favourably the process according to the invenhon can be effected con 10 ~inuously wher~irl after mixing the substrate with microbial mateIial this miYture is continuously suppLied to a irst space in ;hich charging of the nLi-crobial materiaL ~ith the substrate occurs uslder the infLuence of the elect~ic field In t;Lis first space also the ~:lotation is effected an l the biomas~s is separated . The thus separated and charged bio m a~ss can be bio1Ogically con-15 verted in a subsequent reacti.on space.
~ fter the b:iolog:ic1~. reac~ion the b:iomass can be recjcled after de-gradation of the substrate witiLin the scope of the process according to the inventiorl wherefrom a partic-Llally economicaL proceeding results.
In the folLowing the inventiol is made clear by ev~amples of embodiment~
r:xa m ple Do nestic sewage with a biologiczl need oE o:~.gen BSB5 of 550 mgtl was m:i.xed with acti.vated sLudge in the ratio l:l. The content of dlied matter in the activated sl.l.ldge~ (returll sLu(i~ e ) ~ as S.0 g/l. ;~ i ter a sL;.n-ing and~or 25 mi.~ing time of appro:~O 2.5 min tile biomass was subjected to an eLec~r.ic fieLd. The distance of the electrodes herein ~as 15 m m and a secondary ter ninaL voltage of 16 V alld a current den~it~ of 0.5 .~/dm~ ;ere chosell.
The time of tloLd :in the electric field was ~) miil Subs~- ~uentl~ a concentraiioll of 25 g dried mattel/kg of the f.loated sLu(ige and loading of t he res~duaL
30 ~ater BSB5 oE ~0 mg/1 ere found.
. ~.
~22¢3~3~`7 For the purposs-~ of co m parison the sa m S? test w as repeated t;ithout using an eLectric fieLd. Starting fro m a miYture of sewage water and activated sL~Idge in the ratio of l:l Witil a starting volume of 1 1 a sedimentation rate of 0.24 m/h was found, corresponding to a time of hold ot 2 h. The sludge 5 volume was 330 .nl, ~herein the resid~aL load in the decanted liqtLid was 2lO mg/l, expressed in BSB5. From this comparison the esseni~lly lower load of the residual ~ater and the essenti~lLy faster chargingof the biomass under the infLuence of the electric field emerge clearly.
10 Example 2:
A sugar solution of the concentration 200 gtl ~ as m~Yed with a yeast sLurry. The content of dried matter was 100 g~L .^~fter a time of stil~-ing and/or miYing of 10 min an electric ield was app~is-~d, whers~in the slistance of the electrodes was 5 m ~n and the term:Ln~l Yolt tge was chosen to be 15 bet~,een 4 and 5 V. l`he c~lrrent density .~as chosen between C).~ and ~ .~Jcdm2, wherein the time of ilold in the electric fiekl :~tclS lû n~rt. B~ proceeding thus, a s~lgar concentration of 163 g~l in tlle floated sLndge and a sugar concentration of 37 g/l in the flotation water collld be lound.
For tne purpose of comparison the sar,~.e process w as repeated without 20 appLying an els-~ctric field, but witil addition o a considerable a mount of a polyelectroLyte. Starting fro m ths-~ abo~ e slescribed m i~YtUl e of the sugar solution witll tl~e yeast slul-ry, afts~r a(lsliLion of l )O g/~ oi polyelectrol~ te and a tinte oE stisrirlg ansi/or mi:~ing o IQ rilin, a fLotatio~ th tne c~rbon c~ioY-ide Cormed in tlle fcrmelltation ~as effscted for 13 Illin. Ln spits~ of the longer 25 llotal:ion time compars~s'i with the flotation in tne s~le~ ;liC fi~_ld a sugar cc,n-centratiorl of only 13~3 g/l itl the floate~ l3-t~ s sugi!r conru~ntr;srion oL only 62 g/L in the s'`locatioll w.3t~r :.~ers~ fourl~l.
A plllsatitl~ direct: rlllrellt with a p~lL~ ion Lre lus~llc; o,~ al pro:~. 100 llz has pIol~ed pastic Ll~arl~ slLitable~
DUI:iS~C~, thc~ tlot~ltioil l.c~ll sepIIr^sbl~ iloc.c~ r~ for l)fS;I 'lear~in :~ILtLt~s a~
_c~_ very shor~ tim e. These aoccules h.-lve an exceILent charging. The structure of the floccules is not necessarily convenient, though, for further biological reaction in an activatecl sludge vessel and it can be advantageous to destroy the structure of the floccules before the biological reaction by ventilation.
5 Such a ventilation of sludge can also be used to recycle a portion of the sludge to the mixing vessel and thus to subject a sludge constant in relation to biological dried matter to biological conversion. The residual waste water from the Qotation process can usually be directly supplied to the main canal.
The separation of mixture, flotation and biological reaction allows a nu m ber 10 of recircuLations, wherein particularly the iu~terposecl sludge ventilation is of great advantage for recycling a part of the sludge to the mixing vessel or for destroying the structure of floccules to im prove subsequent conversion.
Parts of the ventilated sludge can also be subjected to a further sludge treatment together with the sludge taken Erom the preliminary or a secondary 15 sedimentatioll tank by which a sim ple adaptation to the e:cisting plant capacity is m ade possible.
In the following bacteria, yeasts and the li'i;e, mixed with a corresponding substrate, are understood by microbial systems. Such ;nicrobial s)stems are often designated as biomass which effects a biological reaction as a self-contained system. In particular, microbial systems are acti~,ated or cligested sludge. Equally, tile microbial biocoenoses as are present in the acetic or lO alcoholic fermentation shaIL be classed under the concept of microbial systems.
Such microbial systems take in the s~lbstance usuall~ by absorption to the cell membrane. ~Yithin the ran8e oE the ceLl membralle first degradation reac--tions take place. The absorption rate of the substrate -~s determirled among other ti~ings by tlle concelltration of the primclry metabolites in the c~ll plasm.
15 Depending on the t~,pe of the employed microorgal~isms such a microbial system is able to effect a certa n biological reaction or to convert certain substancescontained in the sul~strate.
For im provirlg the charging of the microorganisms ~:ith the subs~rate to be converted polyelectrolytes are added ~ ich ob~iously e:cert an in1uence 20 upon ttle transport processes througil the cell m e m l-rane. The additioll or`
greater amounts of polyelectrolytes StlOWS oEten negative inEluences upon the activ-ity of Lil(' microbes w;~ich can be e~pLIined b~ the fact that the transport proce~-se.s througrl the ceL1 m e m brane are blocl~ed~ nu m ber of microbial systems are e:cceedingly dit'~icult to float and tne separatior, of ~5 the substrates to be convertecl i5 succe~sslil orLl.y to an unsatisfdctory e:~terlt.
The additiorl of greater arnounts oE polyelectrol)tea has lisadvantaca~eous efL'ects on the se~.!age load. Furtller m ore, a nu m ber of bio1O~,ical reactions in such microbial systems go on very s1OI~1ly becal;se a fast abs~rp~ioll of t'-ne substrdte to be degrcl~late~l by the microbes is not pos~ible.
The invention aims .at increasing the chargillg rat~ of micro'ui,l1 ma;eri.~l a~
by the substrate, at ~liminishing dramaticaLly the amoun~: oE polyelectrolytes to be adcied, and at irnpro~,ing the floatability of the charged biomass. In order to solve this proble m the invention con ~ists essentially in applying an electric field in the miYing space and/or :in a ~otation de~ice after mi.~ing 5 the substrate ~ith the microbial m aterial using pulsating direct current, and in effecting a biolog:ical reaction subsequently without appl~ing an electric field. Ilerein it turned out to be essential that puL~ating direct current is used for build-up of the electric field. Such a pulsating direct current can a]so be a swe:lling current which starting ~rom a minimum value has hr-llf-lO waves of only one single polarity. By using such an electric field after mi.~ingthe substrate with the microbial m aterial it has been surprisingly found that the substrate is absorbed to an increasLng extent by the microbes, wherein the concentrations of the prim ary m etabol:ites to be e~;pected ob~iously clo not exert an influer-ce wort:ll rnentioning upon tile substIate resorption rate.
15 It is alrea(ly l~no~r-l to subject sewage ~aters to elect~-olysis bec'ore biological purificatioll. Until now, ho~lever, there was a prej~lcLice of the eYperts agaiJlst subjecting the bio m ass to the influence of an electrLc f-ield. The surpri~iing etfects oE the inf1uence ot an elecLric ielrl built up with p~lsatulg d:irect current upon the t-iorna~ss can be pos-~ibly eY~pk~ ed by the fact that the charge 20 dist~ibution :in the ce~l m e m brane is changed by the il~1uerlce of the electric ~ie:ld, by ~hich the transport processes throuc,h the ce11 men.lbrane are e.ssell-tially acceLerrlted. 'L`he superiority of using p~Llsating d~rect currellt in corn-par-Lsorl ~ ith smoc)th direct currellt could be proved b~ e.~;pe!imen~, althuu~h an e:~act e~;plallation coukl not be found. 'I`he super~orit.y .owar-ds the use _5 of alterllatillO curr-erlt s~ith posLtive and negative halL-.~avc?s r~ be indicated by the fact that inver-sioll of pol~rit y of such half~ ves in zero crossover d:isturbs a~ain Lhe activation of the cell rn e n~ b~-alles. ~ pplying such an electric l~iekl an a~l~iitiona1 absorption of subs;rate by Lhe mic.robes coul~l be observe(l an(l in isolated cases it could e~ t?n be i. bsr r ~ ed that the alicrobes 30 absorb substclnces t hey usuaLl-. do not co~ erL. 'I`hl s~ .'or e~:a m ple în : he t71 species Saccharom~!ces cere~ iae (b~ewer's yeast) it was observed that apart ~ro m the he.~;oses usuaUy converted by tl~is species it absorbs also pentoses in the electric l~ieLd uncler anaerobic conditions. Subsequently, it was obser-ved that under the influence oE the electric field ~ylose is fermented to 5 aLcohol by this species. In the case of other microbes it couLd be obser~ ed that not only greater a m ounts of substrate could be absorbed by the microbes in shorter time, but also that the separability of the biomass was essentially improved. M-icrobiaL systems dificuLt to float and unfLoatable srlbstances could be easiLy separated in presence of an electric field and the remaining concentration in the resid~laL water after separation of the biomass following the absorption o~ substrate showed essentiaLly lower ~alues of sewage water than in the known methods. The relatively 'nigher supply of substrate in the ceU obiously forces the celL to accelerated reaction and as a consequence an essentially faster reaction to ~he requ~l-ed end products w as observed.
Above aIL the need of polyelectrolytes in ilotation could be essentiaLly re-duced. For e~cample it was observed that a ilotation which ~ith convention~l m ethods without using an electric ield needed three quarters of an hour to an hour, could be inished in 4 to 5 minrltes, wherein a lower concentration of substrate remc~ined in the sewage water.
A fLotation is particuLarly favourable in the scope of waste water puri-ication plants, as the puriication plant is designed corresponding to the average require m ents. 13y flotation peak values in the occurrence of waste water to be pur;fied can be coped with very sim ply by the fact that the fLoated sludge which cannot be supplied any m(lre ul the normally dimensioned l~iological puri'Liccltioll stage is aiscll.3rge(l all(l burnt or is intermediatell stored in concerltrated form in orcler to be subjected after iards correspon-dillgly dil~lted to the convelltionc~l biologic~ purillicati(m. The ~lotation stage hereill mal;es above all short-term regr:lating intervent ions posssible becauseof the low need of time, as for instance the sepa;atioll of sludge whictl after repeated ventilation can be recycled to the mi~ing ve~s~sel. Also in this - s -~.~a~ it is pos~ible to take the difEerent occurr~rlce c~E ~ ater to be puri~ied into account ancl to ensure a reg~LLar through-put thro~lgh the biological puri-fication stage. The partial feedbacl; of floated sludge to repeated n~liYing a:Llo~s the addition o:E smaILer amo~lnts oE nutritious substances especiaILy 5 in domestic se~iage.
In the scope of the process according to the in~entioi3 it has proved favourable to use a terminaL voltage of 2 - 30 V preferably 4 - 12 V for the buiLd-up of the electric fieLd.
I~]SO if the adclition of polyelectrolytes can be (liminished, it is ad\an-10 tageous though particuLar1y in order to achieve im proved' conductivity ofthe solution to add polyelectrolytes to the m.iYture of subsrrate and micro-bi~l m aterial before applying the electric field . Surpr~ingly aLso the addition of ion exchangers invol~ ed an il!l provemellt of substrate absorption and f] otatio n .
Preferably the electr;.c ~i.e.kl .is app~ied :iutermittillgl.y. ~her~in the electric field is appliecl at :least in a f.-rst temporal stage of ~he reilction in ~ihiCIl the substrate is al)solbed by the m:icrobia:l !nateria~ !i.thin this fi~-s; Lempor~l stage a sigri.E:i.cant :improveillerlt of changing Or th~ microbes ~iith s~im~LL-taneous clim~ isllillg of the need of time an~l .sin~l~Ltalleous impro-~ement 20 oE EloatabiLity h.lS ShO~
In b:iocoenoses which do not ten(l to violen~ prodll ~tion of g~lS i;n mediate-ly after chargirlg :it is ad~ ancagec3lls to support flotat iorl b- e:lectrolyt ic d~
composition. In this case proceeding is s~itab:ly such as to app:L~ a teriil:ina:l ~o:Ltage at30ve tile decoinpo~iLion voltage oi the soLuti.ll o~ s.:bst.rate-biorn3ss 25 in the first tempor~-LI stage :in order to pronlot.e ilot..ltion o~ the biomass chclrge(~ ith substrate. In b:iocoenoses ;rich Libera~e &reater a:nounts of fernlen~atioll gases the terminal. ~olcage can be chosen to be lower.
Tn every case it it i'a~o~lrable t.o ~all~i nutr:iti~ ~i..i sub.~.t~3il. es alrea~'i .
bei'c)re ap~ r~iilg the clectric f-.-i.el(l ~Yhei ein it n~Ce~?~` Iry the pi3 is 5rol~gi~t :3(.1 to tl~e most Ea~our lble \.aL:.Ie i~or biologic 1L re.l~tic3il. ~ta.ldar(L;~ th;.' pti 3~
to the v~Llue most favourable Eor the subsec1uent bio1Ogical reaction alLo~.s further diminishing of the amount of polyeLectrolyte to be added.
Preferably, an electric field with essentially horizontaL iines of flux is used. In such an electric fieLd the eLectrodes are usucilly arranged verticaILy 5 and the production of gas setting in at the surface supports the fLotation of the bio m ass.
Since the bio m ass shaIL not be subjected to an electric fieLd du.-ing the actual biological reaction ~hich can be carried out as an anaerobic or aerobic reaction, and above all in order to use an optional method of pro-lO ceed-ing for the subsequent reaction, as fer m entation, putrefaction, respiration or a usual sLudge vessel, the proces~s accorcLing to the invention is effected so that charging of the bio m ass with substrate and biologicaL reaction of the biomass charged ~ith substrate is carried out in separate r,esse~s, wherein tt1e m aterial charged :~ith substrate is separate(! ancl supplied to ~he reaction 15 space and the biomass i~ recycle~1 to the mi~ir1g space after reac ion in the reaction space. By proceeding thus the most different biomasses can be ta',~en into account. While for instance yeast liberates carbon dio.~ide ~ery fas-and thereEore does not re(~r1ire special s~1pport by electlolytic decomposition for fast an(1 co~1 plete ELotation in the f:irst stage oE charging of the micro-20 bial materiaL ~ith the substrate, it is preterable to apply higher voltagesto activated .sludge ~ ich is bac31y Loatable in the ~irst st~ges of the reaction in wlLic11 charging oE the biomass takes place in order to promote ~lotat,ion.
The electric tielcl can be app:Lied most preferE1b1y ~ithin the scope oE
the methoc1 accorc1in~ to the invention by arrar~ g eLectro~les i~1 a disLE~nce 25 fro m each other in the mi:cing space and/or f~lo-ation spacP, ~;hich ~listance is 0,5 - 2 m m/V, pre'.e1aL1ly 1 in m~V in the ra11~,e o~ 2 - 30 ~ 3epen~1ing on the voltage choser1. Coniplyil1g ~;ith these concLirior1s an optimum in re-lation to the charging o~ the microhes ;;ith substrate a11d 3J~. relation to the .`iol~aion 0~ ~lle C'lal`'e(~ )nla~; co~ be o1-se1ve~1. E~rei`er;~1~1y the p^ 1cC~iS
30 is effecier1 so that the ~listE1nce of e1ectrodes in t.1e 11Oi~aLion s?ace as com-~2~
, pared ~iLh th~ d;stance cE the el clrodes in the m~ lg space and/or thetermina1 voltage in the mL~;ing space as coml)ared with the termilaL voltagle in the Elotation space are chosen greater l~ithin the scope of this process degradable anodes i. e. of zLu m-irLiu m 5 or iron as ~eIL as anodes resistant to the electrolitic decomposition can be usecl. Separation of the charged bio .n ass can be sustained by using Loccu-lating agents. The stim ulating effect of the eLectric rieLd for the absorption of substrate couLd be found both for anaerobic and for aerobic reactions.
Favourably the process according to the invenhon can be effected con 10 ~inuously wher~irl after mixing the substrate with microbial mateIial this miYture is continuously suppLied to a irst space in ;hich charging of the nLi-crobial materiaL ~ith the substrate occurs uslder the infLuence of the elect~ic field In t;Lis first space also the ~:lotation is effected an l the biomas~s is separated . The thus separated and charged bio m a~ss can be bio1Ogically con-15 verted in a subsequent reacti.on space.
~ fter the b:iolog:ic1~. reac~ion the b:iomass can be recjcled after de-gradation of the substrate witiLin the scope of the process according to the inventiorl wherefrom a partic-Llally economicaL proceeding results.
In the folLowing the inventiol is made clear by ev~amples of embodiment~
r:xa m ple Do nestic sewage with a biologiczl need oE o:~.gen BSB5 of 550 mgtl was m:i.xed with acti.vated sLudge in the ratio l:l. The content of dlied matter in the activated sl.l.ldge~ (returll sLu(i~ e ) ~ as S.0 g/l. ;~ i ter a sL;.n-ing and~or 25 mi.~ing time of appro:~O 2.5 min tile biomass was subjected to an eLec~r.ic fieLd. The distance of the electrodes herein ~as 15 m m and a secondary ter ninaL voltage of 16 V alld a current den~it~ of 0.5 .~/dm~ ;ere chosell.
The time of tloLd :in the electric field was ~) miil Subs~- ~uentl~ a concentraiioll of 25 g dried mattel/kg of the f.loated sLu(ige and loading of t he res~duaL
30 ~ater BSB5 oE ~0 mg/1 ere found.
. ~.
~22¢3~3~`7 For the purposs-~ of co m parison the sa m S? test w as repeated t;ithout using an eLectric fieLd. Starting fro m a miYture of sewage water and activated sL~Idge in the ratio of l:l Witil a starting volume of 1 1 a sedimentation rate of 0.24 m/h was found, corresponding to a time of hold ot 2 h. The sludge 5 volume was 330 .nl, ~herein the resid~aL load in the decanted liqtLid was 2lO mg/l, expressed in BSB5. From this comparison the esseni~lly lower load of the residual ~ater and the essenti~lLy faster chargingof the biomass under the infLuence of the electric field emerge clearly.
10 Example 2:
A sugar solution of the concentration 200 gtl ~ as m~Yed with a yeast sLurry. The content of dried matter was 100 g~L .^~fter a time of stil~-ing and/or miYing of 10 min an electric ield was app~is-~d, whers~in the slistance of the electrodes was 5 m ~n and the term:Ln~l Yolt tge was chosen to be 15 bet~,een 4 and 5 V. l`he c~lrrent density .~as chosen between C).~ and ~ .~Jcdm2, wherein the time of ilold in the electric fiekl :~tclS lû n~rt. B~ proceeding thus, a s~lgar concentration of 163 g~l in tlle floated sLndge and a sugar concentration of 37 g/l in the flotation water collld be lound.
For tne purpose of comparison the sar,~.e process w as repeated without 20 appLying an els-~ctric field, but witil addition o a considerable a mount of a polyelectroLyte. Starting fro m ths-~ abo~ e slescribed m i~YtUl e of the sugar solution witll tl~e yeast slul-ry, afts~r a(lsliLion of l )O g/~ oi polyelectrol~ te and a tinte oE stisrirlg ansi/or mi:~ing o IQ rilin, a fLotatio~ th tne c~rbon c~ioY-ide Cormed in tlle fcrmelltation ~as effscted for 13 Illin. Ln spits~ of the longer 25 llotal:ion time compars~s'i with the flotation in tne s~le~ ;liC fi~_ld a sugar cc,n-centratiorl of only 13~3 g/l itl the floate~ l3-t~ s sugi!r conru~ntr;srion oL only 62 g/L in the s'`locatioll w.3t~r :.~ers~ fourl~l.
A plllsatitl~ direct: rlllrellt with a p~lL~ ion Lre lus~llc; o,~ al pro:~. 100 llz has pIol~ed pastic Ll~arl~ slLitable~
DUI:iS~C~, thc~ tlot~ltioil l.c~ll sepIIr^sbl~ iloc.c~ r~ for l)fS;I 'lear~in :~ILtLt~s a~
_c~_ very shor~ tim e. These aoccules h.-lve an exceILent charging. The structure of the floccules is not necessarily convenient, though, for further biological reaction in an activatecl sludge vessel and it can be advantageous to destroy the structure of the floccules before the biological reaction by ventilation.
5 Such a ventilation of sludge can also be used to recycle a portion of the sludge to the mixing vessel and thus to subject a sludge constant in relation to biological dried matter to biological conversion. The residual waste water from the Qotation process can usually be directly supplied to the main canal.
The separation of mixture, flotation and biological reaction allows a nu m ber 10 of recircuLations, wherein particularly the iu~terposecl sludge ventilation is of great advantage for recycling a part of the sludge to the mixing vessel or for destroying the structure of floccules to im prove subsequent conversion.
Parts of the ventilated sludge can also be subjected to a further sludge treatment together with the sludge taken Erom the preliminary or a secondary 15 sedimentatioll tank by which a sim ple adaptation to the e:cisting plant capacity is m ade possible.
Claims (19)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the biological conversion of a substrate in which the substrate and a microbial material are mixed and the thus obtained microbial system is maintained under reaction conditions, in which, after mixing the sub-strate with the microbial material, an electric field is applied to the mixing space and/or to a flotation device, using pulsating direct current, and subsequently a biologi-cal reaction is effected without applying an electric field.
2. A process according to claim 1, in which for build-up of the electric field terminal voltages of 2-30 V
are used.
are used.
3. A process according to claim 1, in which for build-up of the electric field terminal voltages of 4-12 V
are used.
are used.
4. A process according to claim 1, 2 or 3, in which at least one of the polyelectolytes and ion exchangers are added to the mixture consisting of substrate and micro-bial material before applying the electric field.
5. A process according to claim 1, 2 or 3, in which the electric field is applied intermittently.
6. A process according to claim 1 in which the electric field is applied at least in one of the first temporal stages of the conversion in which the substrate is absorbed by the microbial material.
7. A process according to claim 6 in which in the first temporal stage a terminal voltage above the decomposi-tion voltage of the substrate-biomass-solution is applied to promote the flotation of the biomass charged with substrate.
8. A process according to claim 1, 2 or 3 in which nutritious substances are added to the mixture before apply-ing the electric field, wherein, when required, the pH is standardized to the required value.
9. A process according to claim 1, 2 or 3 in which an electric field with essentially horizontal lines of flux is applied.
10. A process according to claim 1 in which charg-ing of the biomass with substrate and the biological reac-tion of the biomass charged with substrtate is effected in separate vessels, wherein the material charged with substrate is separated and supplied to a reaction space and the biomass after reaction in the reaction space is recycled to the mix-ing space.
11. A process according to claim 10 in which the biomass after ventilation in a ventilation vessel is re-cycled to the mixing space.
12. A process according to claim 11 in which the reaction space is an activated sludge vessel.
13. A process according to claim 1, 2 or 3 in which at least one electrode in the mixing space and the dictation device is arranged in a distance from each other which in a range of 2-30 V is 0.5-2 mm/V.
14. A process according to claim 1, 2 or 3 in which at least one electrode in the mixing space and the flotation device is arranged in a distance from each other which in a range 2-30 V is approximately 1 mm/V.
15. A process according to claim 1, 2 or 3 in which the electrode distance in the flotation device is selected to be greater than the electrode distance in the mixing space and/or the terminal voltage in the mixing space is selected when greater than the terminal voltage in the reaction space.
16. A process according to claim 1 in which the electric field in the mixing vessel and/or flotation vessel separated from the reaction space is maintained over a period of 2-10 minutes.
17. A process according to claim 1 in which the electric field in the mixing vessel and/or flotation vessel separated from the reaction space is maintained over a period of approximately 5 minutes.
18. A process according to claim 1, 2 or 3 in which the substrate is preliminarily purified.
19. A process according to claim 11 in which the electric field in the mixing vessel and/or flotation vessel separated from the activated sludge vessel and/or ventilation vessle is maintained over a period of 2-10 minutes.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ATA2471/83 | 1983-07-05 | ||
| AT247183A AT386187B (en) | 1983-07-05 | 1983-07-05 | METHOD FOR THE BIOLOGICAL IMPLEMENTATION OF SUBSTRATES |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1229807A true CA1229807A (en) | 1987-12-01 |
Family
ID=3534948
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000458126A Expired CA1229807A (en) | 1983-07-05 | 1984-07-04 | Process for biological conversion of substrates |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0133614B1 (en) |
| JP (1) | JPS6038092A (en) |
| AT (2) | AT386187B (en) |
| CA (1) | CA1229807A (en) |
| DE (1) | DE3476750D1 (en) |
| ZA (1) | ZA844889B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3707575A1 (en) * | 1987-03-10 | 1988-09-22 | Arasin Gmbh | METHOD AND DEVICE FOR PURIFYING EXHAUST AIR OR EXHAUST GAS |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1013890A (en) * | 1958-01-02 | 1965-12-22 | Neidl Georg | A method for the purification of sewage or sludge |
| DE1467785A1 (en) * | 1963-12-27 | 1968-12-12 | Franz Baake | Method and device to keep organic substances fresh for longer - or to ferment them faster |
| DD74753A1 (en) * | 1968-07-05 | 1970-07-20 | Forsch Ind Enzymologie Tech Mikrobiologie | Process for influencing the redox ratios in aerobic and anaerobic fermentations with microorganisms |
| IT951262B (en) * | 1972-04-08 | 1973-06-30 | Gianessi M | PROCEDURE AND APPARATUS TO CAUSE THE ACCELERATION AND THE INCREASE OF THE GROWTH OF MICROORGANISMS |
| GB1481480A (en) * | 1974-02-02 | 1977-07-27 | Kernforschungsanlage Juelich | Process and apparatus for increasing the permeability of the membrane of cells of organisms |
| DE2558750C3 (en) * | 1975-12-24 | 1980-04-03 | Kernforschungsanlage Juelich Gmbh, 5170 Juelich | Production of a mass of living organisms having a cell wall and suspended in a physiological solution |
| IL62822A0 (en) * | 1980-05-30 | 1981-07-31 | Ppg Industries Inc | Fermentation process |
| CH656374A5 (en) * | 1981-12-18 | 1986-06-30 | Benno Perren | METHOD FOR CONTINUOUSLY SEPARATING SUBSTANCES CONTAINED IN A POLLUTED LIQUID, AND DEVICE FOR CARRYING OUT THE METHOD. |
-
1983
- 1983-07-05 AT AT247183A patent/AT386187B/en not_active IP Right Cessation
-
1984
- 1984-06-19 DE DE8484890114T patent/DE3476750D1/en not_active Expired
- 1984-06-19 EP EP19840890114 patent/EP0133614B1/en not_active Expired
- 1984-06-19 AT AT84890114T patent/ATE40817T1/en not_active IP Right Cessation
- 1984-06-26 ZA ZA844889A patent/ZA844889B/en unknown
- 1984-07-04 JP JP59138873A patent/JPS6038092A/en active Pending
- 1984-07-04 CA CA000458126A patent/CA1229807A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| ZA844889B (en) | 1985-02-27 |
| ATE40817T1 (en) | 1989-03-15 |
| EP0133614A2 (en) | 1985-02-27 |
| ATA247183A (en) | 1987-12-15 |
| EP0133614B1 (en) | 1989-02-15 |
| DE3476750D1 (en) | 1989-03-23 |
| AT386187B (en) | 1988-07-11 |
| EP0133614A3 (en) | 1987-05-06 |
| JPS6038092A (en) | 1985-02-27 |
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