anaerobic fluidized bed treatment of vinasse

8/3/2019 Anaerobic Fluidized Bed Treatment of Vinasse

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B I O T E C H N O L O G Y L E T T E R SV o lu m e 1 4 N o . 5 0 n a y 1 9 92 ) p p . 4 3 3 - 4 3 8R e c e i v e d a s r e v i s e d 2 0 th M a r c h

A N A E R O B I C F L U I D IZ E D B E D R E A C T O R W I T H S E P IO L I T E A S S U P P O R T F O RA N A E R O B I C T R E A T M E N T O F V IN A S S E

M.D. Balaguer"Labora to r i d 'Eng inye r i a Q ufmica i Ambien ta l. Facu l ta t de C i~ncie s. Un ive r s i t a t de Gi rona .P1. Hosp i ta l , 6 . 17071 Girona . Spain . andM .T . Vicen t and J .M . P a r i sUn i t a t d 'Eng in ye r i a Qufmica . Depa r t amen t de Q ufmica .Un ive r si t a t Au tbno ma de B arce lona .08193 Bellaterra. Spain.

S U M M A R YAn an aerobic f lu id ized bed reac tor , u s ing sepio l i te as suppor t , fo r the t rea tmen t ofdis t i l le ry was tewater was s tar ted-up us ing a s tepped loading regime wi th addi t ion of

methano l . S ix d i f ferent steady s ta tes a t hydraul ic re tent ion t imes betw een 0 .5 and 2 .4 8 d ayswe re s tud ied ach iev ing a COD remova l e f f ic i ency o f 70 .5 t o 88 .6 %.

I N T R O D U C T I O N

The media used for b iof i lm a t tachment in anaerobic f lu id ized bed reac tors has as igni f icant e f fec t on reac tor per form ance . This me dia is f lu id ized by a h igh ver t ica l ve loci tyachieve d by a h igh ra te of recycle (Henz e and Harrem o~s , 1983) . This sys tem has a grea tpotent ia l for the t rea tment of so luble organic was tewaters due to i t s abi l i ty to mainta in alarge concent ra t ion of b iomass and excel lent mixing charac ter i s t ics for subs t ra te-b iomasscontac t ing (Meunier and Wil l iamson, 1981) . To date , a var ie ty of was tewaters have beensuccessfu l ly t rea ted by the anaerobic f lu id ised bed process (Henze and Harremo~s , 1983;Hickey and Ow ens , 1981).

A var ie ty of mater ia l s have been used as suppor t for the growth of a t tachedmic roorgan i sms . Sand i s t he m os t w ide ly used in f l u id ized bed r eac to rs . Ho we ver , med iawh ich have low er dens i ties than sand requi re lower superf ic ia l ve loci t ies for f lu id isa tion ,and the re fo re , l ower ene rgy consumpt ion . O the r t ypes o f med ia i nc lude ac t iva t e ca rbon(Chen e t a l . , 1985) , p um ice s tone (Balaguer e t a l . , 1991) , an thrac i te and granu lar ac t iva tedca rbon (Fox e t a l . , 1990).

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A major objec t ion to the use of anaerobic processes for indus t r ia l was tewatert rea tment is the long t ime requ i red for s tar t-up (Henz e and H arremo6s , 1983) due to the lowgrowth r a t e s o f me thanogens . One me thod o f encourag ing the g rowth o f me thanogen icbacter ia i s to supply a subs t ra te tha t m ay be d i rec t ly metabol i sed such as metha nol (Bul l e ta l . , 1983).

S t a r t -up pe r iod can a l so be r educed wi th t he adap t ion o f t he i nocu lum to t he spec i fi cwastewater proper t ies . I t i s preferable therefore to use a mix of severa l sources of ac t ivebiomass ins tead of b iomass f rom one source only (W ei land, 1990) .

This p aper presents the resul t s of the s tart -up for an anae robic f lu id ized bed reac tortreat ing dist i l lery wastewater and using sepioli te as support . Six different steady states athydraul ic re tent ion t imes (HRT) between 2 .48 and 0 .5 days were a lso s tudied andc o m p a r e d .

M A T E R I A L S A N D M E T H O D S

W a s t e w a t e r C h a r a c t e r i s t i c sTh e wastew ater s tudied was the ef f luent of a w ine d is t il le ry . I ts m ain charac ter is t ics rangedas fo l lows (in Kg.m-3) : CO D, 25-40; so luble CO D, 13-16; pH, 4 .5-5 .2 ; am m onia n it rogen,0.045-0.060; total and volat i le solids, 20-25 and 13-15, respectively; total and volat i lesuspended sol ids , 9-11 and 0 .8-1 .4 , respect ive ly ; ace t ic ac id , 2 .20-3 .00; propionic ac id ,0 .11-0 .15; n-butyr ic ac id , 0 .25-0 .32; and i -va ler ic ac id , 0 .04-0 . t2 .A n a l y t i c a l m e t h o d sTotal and soluble COD, alkalini ty, total and volat i le solids (TS, VS) and total and volat i lesuspended so l id s (TSS , VSS) were de t e rmined acco rd ing to S t anda rd M ethods (APHA,1981) . A m m onia n i trogen and pH w ere mea sured wi th speci fic e lec t rodes . Gasch romatography was used fo r b iogas and VF A ana lys i s.l n o c u l u mThe inocu lum source was a mix tu re o f anae rob ic sludges p roceed ing f rom an UASB(Upf low Anaerobic Sludge Blanket ) reac tor t rea t ing pota to-s tarch wastewater and f rom ananaerobic reac tor t rea t ing p ig s lur ry , an d o f anaerobica l ly d iges ted sewage s ludge, y ie ld ingan in i t ia l vola t i le suspended sol ids concent ra t ion of 10 .78 Kg VS S.m 3.A n a e r o b i c f l u i d i z e d b e d r e a ct o rTh e exper im ents were per fo rme d wi th labora tory-sca le upf low f lu id ized bed reac tor wi th ato ta l volume of 0 .63 l i t res and a d iameter of 3 .2 cm. The reac tor conta ined 200 ml ofsepio l ite as b io logica l suppor t mater ia l wi th an ave rage d iam eter of 0 .53 m m (ca lcula ted asdescr ibed by Shieh e t a l . , 1981), and density of 1977.4 Kg.m 3. Sepioli te is a natural clayobta ined from T OL SA S.A. (Mad r id , Spain) . Cent r i fugal pum p was used to mainta in 50%expansion wi th in the reac tor . Feed was pumped upward the bed cont inual ly . Eff luent wascol lec ted in a se t t le r to separa te the so l id f rac t ion f rom the l iquid s tream. Gas p roduct ionwas measu red by means o f an e l ec tron ic gas coun te r . Reac to r t empera tu re was ma in t a inedat 35~ wi th external heat ing wa ter jackets .

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R E S U L T S A N D D I S C U S S I O N

Start-up p eriodStar t -up of the anaerobic f lu id ized bed reac tor was accompl ished over a 2-month

per iod us ing a procedure involving s tepped increases in organic load and subs t ra ter ep l acemen t by me thano l . A n in it ia l o rgan ic load o f 0 .47 K g CO D.m 3.d -1 was app l ied bydi lu t ing the was tew ater to an in i t ia l concent ra t ion of 1 .93 K g C O D .m -3, meth anol be ing 30%of thi s COD . Organ ic l oad was g radua l ly inc reased up to 5 .16 Kg CO D.m 3.d ~ , keep ingconstant the percentage of methanol . Af terwards , th is percentage was progress ive lydecreased: 20% at days 45-50, 10% at days 50-55, 5% at days 55-61 and 3% at days 61-63.Af t e r day 63 the me thano l con ten t was r educed to ze ro . HRT rema ined cons t an t a t 2 .48days dur ing th is per iod .

F igu re 1 shows the o rgan ic load , CO D remova l , am mo nia n i trogen concen t ra t i on andtota l and vola t i le so l ids concent ra t ion . COD removal ra tes increased rapid ly and remaineda round 90 % independen t ly o f t he o rgan ic l oad inc reases.

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10 2 0 3 0 4 0 5 0 6 0

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1'0 2'0 30 4'0 5'0 6'0T i m e ( d a y s )

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Figure 1 . - Scheme of the f lu id ized bed exper imenta l ins ta l la t ion

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Th e amm onia n i trogen concent ra t ion was low dur ing the ear ly s tart -up per iod butaf ter day 45 th is concent ra t ion began to increase . This was re la ted to the decrease of thepercentage of methanol in the inf luent . That was expected because methanol enhances theg rowth o f m e thanogen ic bac t e ri a . W h en the pe rcen tage o f m e thano l dec rease i n t he in f luen t,t he g rowth o f m e thanogen ic bac t e ri a a l so dec rease and the am mo nia n i t rogen consum pt ioni s l ower . So , t he am mo nia n i t rogen concen t r a ti on in t he e f f l uen t was i nc reased wh en thepercentage of methanol in the inf luent was progress ive ly decreased.

An accumula t ion of vola t i le fa t ty ac ids indica tes an ins tabi l iza t ion of the reac tor .Dur ing the s tar t -up only t races of ace t ic ac id was obta ined.

Steady state performanceSix d i f ferent HR T (between 2 .48 and 0 .5 days) w ere s tudied dur ing the

exper im enta l per iod . A concent ra t ion of 18 K g.m 3 was mainta ined in a l l s teady s ta tess tudied .

At ta inm ent of the s teady s ta te w as ver i f ied af ter an in it ia l per iod o f 3 t imes the H RTby checking the cons tant va lues of the charac ter i s t ics of the ef f luent measured dur ing anaddi t ional we ek. T he s teady s ta te adopted values of the charac ter is t ics w ere the m ean of thelas t measurements .

Th e s teady s ta te opera t ing charac ter is t ics of the anae robic f lu id ized bed reac tor a regiven in Table 1 .

Table 1 .- Per form ance of labora tory f lu id ized bed reac tor

HR T (d) 2 .00 1 .50 1 .l J0 0 .74 0 .50Load (Kg CO D .m 3.d 1) 9 .00 12.00 18.00 24.32 36.00CODr~o~al (% ) 72.2 2 83.00 78.1 6 88.56 70.55CODsol, ~o~a~ (% ) 89.32 N .D . 93.3 7 93.0 0 80.00CH4 (%) N .D . 69 .50 N .D . 80 .20 65 .24C O 2 (%) N .D. 29 .15 N .D . 19 .62 33 .39H2S (%) N .D . 1 .35 N .D . 0 .18 1 .36Biogas product ion(m3.m-3.d ~) 2.61 4.9 7 6.0 7 9.65 10.70pH 8.9 8.1 8.3 8.1 7.6AI /AP 0 .16 N .D. 0 .30 0 ,21 0 .36N . D . : N o t d o ne

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Rem ova l e f f ic i enc i e s we re qu i t e h igh . COD remova l r anged f rom 70 .55 to 88 .56and CO D so lub le r emova l we re obse rved to v a ry f rom 80 to 9 3 .37% . COD,ozremova l i s a lways h ighe r t han CO D remova l because o f t he h igh in f luen t vo l a t il esuspended sol ids va lues . The se so l ids are d i f f icul t to e l imina te in a f lu id ized bedprocess .

Th e ra t io of in termed ia te to par t ia l a lka l in i ty (AI /AP) , re com m end ed as an indica torof d iges ter s tabi l ity (R iplay e t a l . , 1986) , was used to fo l low-u p the s tabi li ty of the reac tor .I f th is ra t io i s kept be low 0 .4 the process i s s table (Balaguer e t a l . , 1989). In al l s teadys ta te s AI /A P r a t i o r ema ined be low 0 .4 :

At HR T o f 0 .74 days , a C OD remova l o f 88 .56% was ob ta ined a t o rgan ic load o f24 .32 K g .m 3 .d 1, bu t a t HR T o f 0 .5 days , COD remova l dec reased to 70 .55% .

Other wine d is t i l le ry was te s tudies have been repor ted us ing o ther anaerobicprocesses such as the anaerobic f i l te r (Bod es e t a l . , 1982) and the U ASB reac to r (Crave i roe t aL ,1986) wi th 92% and 83% COD remova l a t o rgan ic l oads o f 14 and 13 .2 Kg .m3 .d 1and HRT of 1 .6 and 2 .4 days , respect ive ly .

M ethan e p roduc tion ave raged 0 .35 , 0 .36 and 0 .28 1 CHa .g~ C O D r e m o v a l at H R Tof 1 .5 , 0 .74 and 0 .5 days , respect ive ly . This is 89 .7%, 92 .3% and 71.8% respect ive ly ofthe theore t ica l va lue of 0 .39 1 CH4.g -~ CO D rem oval predic ted by s to ichiom etry a t 35~

Th e wastew ater s tudied in th is wo rk was t rea ted wi thou t any nut r ient addi t ion or an yneu t ra l iza t ion o f t he pH o f t he i ncom ing was te .

C O N C L U S I O N S

Th e s tar t-up proced ure , by us ing a s tepped loading regim e wi th addi t ion of m ethanolas in i tia l co-subs t ra te , took a per iod of 66 days . D ur ing th is per iod , C OD rem oval rem aineda round 90% whi l e o rgan ic load inc reased f rom 1 .15 to 5 .16 K g .m 3 .d 1.

At HR T o f 0 .74 days , a CO D remova l o f 88 .56% was ob ta ined a t o rgan ic l oad o f24.32 Kg.m-3.d 1 wi th a gas produc t ion o f 9 .65 m3.m-3.d~ .

A C K N O W L E D G E M E N TThi s w ork was support ed in pa r t by a f e l lowsh ip fo r young s tuden ts o f t he C . I .R . I .T .

(Genera l i ta t de Cata lunya) .

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REFERENCESAP HA (198 1). 15th ed. Am erican Public Health Association, Washington.Balaguer, M .D ., V icent , M .T., Casst i , C. and Pad s, J.M . (1989 ). Tecnologfa del Agua,60, 73-76.Balaguer, M .D ., V icent , M .T. and Pads, J.M. (1991). Environ. Technol. , 12, 1167-1173.Bodes, A ., Rayn al, J. and Jover, J.P. (198 2). Proc. 1st Int. Conf. Fixed Film BiologicalPocesses, 1337-1351.Bull, M.A., Steritt , R.M. and Lester, J.N. (1983). Biotechnol. Lett., 5, 333-338.Chen, S.J. , Li , C.T. and Shieh, W.K. (1985). Chem. Technol. Biotechnol., 35B , 183.Craveiro, A.M., Rocha, B.B.M. and Schmidell , w. (1986). Water Treatment Conference,307-319. Aquatech'86. Amsterdam.Fox, P ., Suidan, M .T. and Band y, J.T. (1990). Wa t. Res ., 24, 827-835.Henze, M. and Harremo~s, P. (1983). Water Sci. Technol., 15, 1-101.Hickey, R.F. and Owens, R.W. (1981). BiotechnoL Bioeng. Symp., 11,399-413.Meunier, A.D. and Williamson, K.J. (1981). Environ. En g. Div. Am. So c. Civ. Eng ., 107,307-317.Ripley, L.E ., B oyle, W.C . and Converse, C.J. (1986). J. Water Pollut. Control Fed., 58,406-411.Shieh, W .K., Sutton, P.M ., K os, P. (1981). J. Water Pollut. C ontro l Fed ., 53, 1574-1584.Weiland, P . (1990). Int. W orkshop on Anaerobic Treatment Technology fo r M unicipal andIndustrial Wastewater. Valladolid (Spain).

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anaerobic fluidized bed treatment of vinasse

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