United States
Environmental Protection
Agency
Water Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-86/002 Mar. 1986
Project  Summary
Pilot Anaerobic  Biological
Treatment of  Pulp  Mill Evaporator
Foul  Condensate
Eugene Donovan, Jr.
   Three pilot plants were built to com-
 pare three types of anaerobic waste-
 water treatment systems: the upflow
 sludge bed, the anaerobic filter, and the
 fluidized bed. Startup of the systems
 was accomplished in 6 weeks by seed-
 ing them with sewage plant digester
 sludge acclimated  to the waste. The
 units removed 80% to 90% COD from
 the neutralized foul condensate of a
 paper mill at a loading of 6 to 7 kg
 COD/m3 per  day. At this loading, the
 anaerobic filter and upflow-bed sludge
 units  performed at about the same
 levels although effluent solids from the
 upflow bed were higher. The fluidized-
 bed system produced somewhat greater
 removals  of  organics and had the
 lowest effluent solids concentration.
   Operation of  the  systems will be
 continued for several additional months
 for further comparisons of the units'
 capacities and performances. Loadings
 will be increased at a rate that will per-
 mit the  units to maintain reasonable
 removal levels and  effluent volatile
 acids.
   This Project Summary was devel-
 oped by EPA's Water Engineering Re-
 search Laboratory.  Cincinnati. OH, to
 announce key findings of the research
 project that is fully documented in a
 separate report of the same title (see
 Project Report ordering information at
 back).

 Introduction
   Three pilot plants were designed and
 constructed to represent three relatively
 innovative  anaerobic processes for the
 treatment of industrial wastes: the up-
 flow sludge bed, the anaerobic filter, and
the fluidized bed. An initial, limited pro-
gram was conducted using  the  pilot
plants to gain operating experience and
to evaluate and demonstrate their per-
formance on a high-strength  industrial
waste water.
   Study objectives included:
   1. development of operating and
     treatment design parameters ap-
     propriate to each process;
   2. assessment of the applicability of
     the processes to various industrial
     wastewater classifications based
     on existing information and study
     results; and
   3. development  of final report to
     present the results of the study.

Methods and Materials

Description of Pilot Plants
   A fluidized-bed pilot plant was pur-
chased with a 3.65-m-high,  0.15-m-
diameter reactor containing 150 to 200
cm (fluidized depth) of quartz sand with
an average diameter of 0.4mm. The re-
cycle flow was pumped up through the
media to maintain the bed at about 30%
to 50% expansion. Waste was metered
into the recycle line, and effluent was
separated from the gas,  which  was
metered by a wet test meter before dis-
charge.
   A design was  developed for an
anaerobic filter and an upflow sludge bed
pilot plant. The flow schematics of the
two systems were  essentially identical
except that the anaerobic filter contained
media and did  not have the internal gas
separation and solids settling section.
The steel reactors were 3.65 m high and
0.76 m in diameter. The reaction zone in

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           13.1
                                                        Nutrient Additions to Foul Condensate
                  plastic pal,ring media.
                 '^r ELs!, it-TV- -,-M-I.	£_ -iSaiSlsiL™ sftj-, ..-..•u-BHUm.amn -a^r-a,,^
                                            Ammonium chloride
                                            Potassium phosphate
rovide additional clarification
                                                                                 Element
                                                                                                 Concentration in Waste, mg/L
                                                                                                           50
                                                                                               30
                                            nickel chloride
                                            ferfous chloride
                                            -Selenious acid
                                            Sodium tungstate
                                           -Ammonium molybdate
                                                 chloride
                                           jyianganese chloride _
                                            l-ime
                                           ~Soric acfd ~~
                                           "Th'iamine HCJ
                                                'otheffic acfd
                                            aaai§_was_i0.ffialjy neutralized with-both
                                           ,G.ay.slic	and.	lime	to,	avoid	possible in-
                                           .liitiJliQQ	sLloxleity	from, excessive con-
               on. and storage
       ical  laborator"was 'constructed
                                            Procedures
                                                                                                            0.25
                                                                                                            4.0
                                                                                                    	0.1	
                                                                                                            0.005
                                                                                                            0.02
                                                                                                            0.02
                                                                                                            0.02
                                                                                                     .	O.02
                                                                                                       -    AC,,
                                                                                                          20,
                                                                                                     ~ — ~"
                                                                  illi'llfli
                                                                          the studies for periods of several days at
                                                                          relatively constant conditions.

                                                                          Acclimation and Startup
                                                                            ''jAnaerobically  digesting  sludge was
                                                                         ""obtainid""from	i"""loca'f sewage freatrrient
                                                                          plant and put into a reactor tank 2 months
                                            Studies
                                              treata'BTilty'
                                                                                      before pilot plant construction. The pall
                                                                                      ring media to_ be used in the anagrgbic
                                                                                      ^jj______j_.__._,_, __  ^j^-	
                                            sarnpies of the neutralized foul conden-
                                                           ,_,..    -         '	
                                                           tne  waste_
                                                            "Dut"'tEat'
                                                                         ...... liejytra Ijzed^
                                                                         jHcreasing
                                                                                      actor to accIFmat¥t!ie"^udaeT"Aiicircula-~
                        1.8-2.8
                                    ie ^acclimation  to the  waste was     ting pump was used for mixing.
                               necessary. The sludge was acclimated by       The pall rings, coated with slime, were
                                       ^n^^asirrathecoricentrationof	gut  into the filter, 'and mpjst,,fl.f,tba.,ac-
                                 'SSe""fed to the sludge wfine~also^e3-     climated sludge was placed into tn"e_up-_
                               ing acetic aid Jo maintain  the_sjudge _   flow bed pilotjjnrt Liqujd effluent^was^
                               "-ctrvity'TablellistsaveFageresultsfrom"     ::=:i-.-?.. .-VT.--T    —,  -?----—-
                                                                                                   ^                   ^
                                                                                      used~t6~fill the fIuidized-bed reactor
                     7,000-12J)00
                     8,000-16,000
                        ,'BO-W.
                                            Table 3
                                            Unit
                                            Summary of Screening Study Results*
                                          •feear
                                           Wo"
                                                                   Detention  Loading _jEffluent
                                                                             !rfifffipm  j-tfijj —
                                                                                     Effluent
                                                                     Time
                                                         Days
                                                                                                                   	A Gas
 m-e	
            0.5
                                               Batch
                                                      Condensate
                                                     •Wo /
                                                           75
                                                                                 0.0
                                                                     irifflrs"*-! • «BII fflir mxv a
                                                                       70
                                                                                 1.9
                                                                             1625
                                                                             465
                                                                                                   829
                                                                                                   560
                                                                                                            30,4
                                                                                                            977
                                                                                                         057
IMffiEpJ,!..	,Illli»,JMa3|S..,H§S,l£ISlBSl,ffid	for	t	  c_Batch
                                                                       23_ „ , _ 0 t
bhoru's were"added in     D-  Con'     Condensate:
                                    No.2-14g/L    4.5
                            upf/ow   No. 3-9.6g/L    5,3
       	tg	erjsup	Sj^
                    '
                               £,.-- Con-     Condensate.
                                       s
                                                                     2.1 	7.0      2023
                                                                                       520 _   9.3 7_  .  OJ5]_ -
                                                                                          n H i in mi HI in n i • in iii linn iiiiif
                                                                                                           iiiiniiniii mi 11 in in mini n« n in
                                                                                         1278
                                                                                         2906
                                                                                       750
                                                                                       1712
                                                                                                   1545
                                                                                                           90.9
                                                                                                           69.7"'
85.5	
         0:55
         0.94
                                                                                        JL021	._. 2O60
                                                                                                6815
!IISJS3£|fiiM^

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initial waste was made up consisting of
80% of a 14,000-mg/L acetic acid solu-
tion and 20% foul condensate. The waste
was neutralized to pH 6.8 with lime and
caustic, and nutrients were added. The
resulting COD was 12,500 mg/L, and
volatile acids were 11,700 mg/L. The
pilot units were filled with the waste, and
the effluent recycle was started. A small
flow of waste was fed to each unit from
day 8 to 20 to make up for sample and
minor system losses. Volatile acids in the
systems  decreased to less than 1800
mg/L in  10 to 15 days.
   Starting on day 21, waste flows to the
units were increased gradually over the
next 25 days. Effluents from the upflow
bed  and filter  were settled in small
clarifiers for  1  to 3 hr. Detention and
settled solids returned to the units. The
raw waste composition was increased to
40% foul condensate on day 14, 60% on
day 24, and  100% on day 31.  Supple-
mental acetic acid was added to the foul
condensate to maintain influent COD at
about  15,000 mg/L until day 46. The
flows, loadings, and removals in the pilot
units are listed in Table 4 for day 52.

Results
   All three units produced gas at about
0.5 L/g COD removed, at loadings in the
lower range used in design of full-scale
systems. A relatively constant load to the
units was maintained for  several weeks
to observe performance at steady state as
several batches of waste were fed to the
units. The  clarification of effluent and
return of solids wasdiscontinued. During
this period, the COD concentration in the
foul condensate batches varied and was
considerably  lower than  that obtained
during the  laboratory screening  and
startup period. As a result, the loadings
and flows to the units were somewhat
more, variable than desired during this
attempt at a steady-state loading.
   Results of the anaerobic filter up to
day 70 were fairly consistent; however, a
60% increase in influent COD concentra-
tion resulted in an 85% load increase on
day 70 and  produced an  increase in
 effluent volatile acids. At the same time,
 a 30% decrease in gas production also
 occurred. This decrease could not be di-
 rectly attributed to any single factor, but it
 might have been caused by a drop in pH
 from 7.3 to 6.6, the higher volatile acid
 concentrations, or a change in a waste
 constituent. Loading was reduced to zero
 on day 74, and a new waste batch was
 put on line on day 75 at a loading of about
 5 kg/m3 per day.  Effluent  volatile  acid
 levels dropped back to the 1000 to 1500
 mg/L range through day 80. During this
 6-day period, COD removal was 86.5%,
 effluent volatile acids were  1200 mg/L,
 and gas production was 0.52 L/g of COD
 removed, indicating recovery of the unit.
   The results with the  upflow bed unit
 were similar to these for the anaerobic
 filter. Flow and loading were maintained
 relatively uniformly through day  75 ex-
 cept for  two days. Scale  buildup  and
 debris from  the initial sludge seed  oc-
 casionally clogged the recycle lines, re-
 sulting in flow blockages and variations.
 The scale formed by precipitated calcium
 compounds also caused problems in the
 heaters on both the filter and upflow bed.
 Starting  with day 76, only  caustic was
 used for neutralization, with about 20
 mg/L calcium added as nutrient to  the
 raw waste. On day 66, a new waste load
 was introduced,  and  effluent volatile
 acids increased. The load was decreased,
 and volatile acid level decreased. On day
 70, a new waste batch was brought on
 line  at much higher condentration, re-
 sulting in 100% increase in loading. Gas
 production dropped markedly, but it re-
 covered  on the following day. The  unit
 operated well  until  pump problems  de-
veloped around day 78 and influent flow
 had to be reduced.
   Flow and loading to the fluidized bed
was fairly constant for the initial 15 days,
and effluent volatile acids were low. A
 power outage resulted in a  low flow on
day 64. On day 70, when the new high-
strength waste was brought on line, load-
 ing increased  100%. However, effluent
volatile acids did not increase, and gas
production increased 35% over the next 2
to 3 days. This experience contrasts with
those of the two large pilot plants during
the same time period: they experienced
increases in volatile acids and gas reduc-
tion for 1 or 2 days. From day 70 to 78, the
loading was about the same as during the
first 15 days. During  this period, the
system performance improved,  as  indi-
cated by the lower effluent volatile acids.

Conclusions
   Table 5 compares average results for
the three  systems over a 23-day period
ending on day 69. Loading and detention
times were similar for all three units. The
effluent parameters  for the anaerobic
filter and upflow bed were practically the
same. The fluidized bed produced greater
organic removals and lower effluent con-
centrations. Gas production on the basis
of waste  volume, COD  removal,  and
methane  content was essentially the
same for  all three units. Effluent sus-
pended solids were  fairly  high in the
three systems, but effluent solids de-
creased markedly  in the  filter  and
fluidized bed toward the end of this study
period. The upflow bed experienced high
solids losses during  this same period,
indicating the potential need for external
clarification, at least  under these condi-
tions.
 Table 4.
            Day 52 Flows, Loadings, and Removals*
Flow,
Unit L/day
Fluidized-bed 12
Anaerobic filter 850
Upflow unit 710
COD
Loading,
kg/m3
per day
5.07
7.14
7.18
Volatile
Acids, mg/L
1200
846
1031
COD,
mg/L
1990
1599
2025
%CODR
83.2
86.5
82.9
Gas,
L/day
66
4392
3456
 influent COD. 11.844 mg/L.

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         X^	WW;	Pi	n	mm


         _ _            	:,:,:;,|i,,i	j&ciiwat.	,..,,..,
         fapje^ .§_•,,  ,  fAversge Results for_ the Three Anaerobic Systems for Days 46 through 49
W-AjWeiobic, „
                                                                   	upflow
                                                                   Fluiaized
                                             iiilffcii	,,	
                                           , .i1?:,!: , i? ...... :!! 3; slill1 :ii !s .i!
                                                l1 :ii !s .i! I:1,1 1 H,!1:" J 'i
                                                   7. /
                  i BOD removal
                  WMS'WlWt	'I'fl'itiS''? HI*!	li,:".:
             ,,' :,i : I?1':1!!' ii gin i,:!!, :,i; „„: iii i1!1!"; • "i iff.  , 7'iiiiiiiiiii '•'.. piiw; liiiii;,' :i' i,i,:iiir iiift1:; 'Hi J IlsTiiiiiti,1 ,il
            production, L/L	^	|	,	 ,iii	5.4	

                              	" 	 S3	
            Eugene J. Donovan. Jr. is with HydroQual, Inc., Mahwah, NJ 07430.
           • T. David;_,Ferguson_ is the_ EPA^ Project^ Officer_ (see below).
                 —,,--—— ..... ,-——-———-— ..... ,___i .....
                                                                       iiiiiiip:iif!iii!
                                                                        5.1
                                                                                    w::n;]tjmMam^'wa'as:M\\mmK\'A
                                                                                        	TB578,	
                                                                                        "	siw	"	
                                           Ul:"1!"l'll"!ll!ll"612S
                                    ".	!	   2110	
                                                                     •W§1.
                                                                     f?od	
                                                  282
                                                                     1278
                                                                                           127
              Evaporator Foul Condensate," (Order No. PB 86-143 633/AS; Cost: ' $f(>.9~5,
              subject to change) will be available only from:
                    National Technical Information Service
                    5285 Port Royal Road
                    Springfield, V A 221 61
                    Telephone: 703-487-4650
            The EPA Project Officer can be contacted at:
                    Water Engineering Research Laboratory
                    U.S. Environmental Protection Agency
                    Cincinnati, OH 45268
                                  	Lllkliif I I !•	/ 	|,|l."'-:; 
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