Can. Insl. Food Sei. Teehno/. J. Vo!. 14. No. 2, pp. 144-146. April 1981Pergamon Press Ltd. Printed in Canada.

RESEARCH NOTE

Potato Processing Wastewater TreatmentUsing Horizontal Anaerobic Filters

R. C. Landine, G. J. Brown, A. A. Cocci, T. ViraraghavanADI Limited

1115 Regent StreetFredericton, New Brunswick E3B 4Y2

andK. C. Lin

Department of Civil EngineeringUniversity of New Brunswick

Fredericton, New Brunswick E3B 5A3

AbstractA laboratory model anaerobic filter was tested in the horizontal

configuration for potato processing wastewater treatment, with aview to using it in such a mode in an actual field installationinvolving earthen construction. The filter media consisted of25 mmto 40 mm diameter stones and the hydraulic detention time in thefilter during the study was 0.6 day. The reactor was dosed withdecanted primary clarifier influent from a potato processing plant,and lime addition was maintained at 500 mgj L of the influent. Theanaerobic filter achieved removals of biochemical oxygen demand(BOO), chemical oxygen demand (COD), and suspended solids (SS)of 91 %,91 % and 85%, respectively. The average organic loading rateduring the study was 1.35 kg CODj m3·d. The horizontal anaerobicfilter was found to provide organic matter removals comparable tothose of vertical-type filters.

ResumeOn a fait l'essai d'un liltre anaerobique pilote en configuration

horizon tale pour le traitement des eaux usees d'usine de pomme deterre, dans le but de l'utiliser de cette maniere dans une installationindustrielle construite en terre. Le vehicule du fillre a consiste enpierres de 25 mm a 40 mm de diametre, et le temps de detentionhydraulique dans le filtre a ete de 0,6 jour. Le reacteur fut alimenteavec l'affluent d'un clarificateur adecantation primaire d'une usinede pomme de terre. L'addition de chaux a ete maintenue a500 mgj Ld'affluent. Le filtre anaerobique a permis d'enlever 91 % de lademande en oxygene biochimique (DOB), 91% de la demande enoxygene chimique (DOC) et 85% des solides en suspension. Le tauxmoyen des intrants organiques durant cette etude fut de 1,35 kgDOe; m3·d. L'efficacite du liltre anaerobique horizontal a etetrouve comparable aux fill res de type vertical pour l'enlevement desmatii:res organiques.

IntroductionStabilization of many food processing wastewaters

by aero bic processes is rather difficult, energy intensiveand costly, essentially due to their variable nature andhigh strength reflected by high biochemical oxygendemand (BOO) and suspended solids (SS) concentra­tions, The BOO concentration is indicative of the

concentration of organic matter present. Such highstrength wastewaters are, however, quite amenable toanaerobic treatment. Anaerobic treatment producesless sludge, consumes less energy and is economicallyattractive. In addition, it has the potential for energyrecovery through the use of biogas produced,

The anaerobic filter, a type of anaerobic contactprocess, uses a submerged bed of packed media tosupport biological growth on the media and in theinterstitial spaces. In the anaerobic filter the bacteriagrow attached to the filter media and remain in thefilter, providing a long solids retention time (SRT) ofup to 100 days, even though the hydraulic detentiontime is much shorter. When high SRT values aremaintained, highly efficient treatment can be obtainedand at lower temperatures such as 15-20°e. Thus theanaerobic filter is best suited to treating wastewaterswith high soluble organic content and low suspendedsolids at moderate temperatures. McCarty (1970) in­dicated that the anaerobic filter may offer the mostpromise for treatment of wastes with BOO rangingfrom 500 to 6,000 mg/L, at temperatures of 15° to35° C. Experiments by Young and McCarty (1969)involved wastes with chemical oxygen demand (COD)values as high as 12,000 mg/ L. A recent review by -"Mueller and Mancini (1975) shows that the anaerobicfilter had been used in applications involving wasteswith COD values as high as 20,000 mg/ L.

Anaerobic filters have been used in a number ofbench and pilot scale investigations involving foodprocessing wastewaters. A full-scale anaerobic filterwas used to treat wheat starch wastes (Taylor, 1972).Pilot plant studies conducted in Idaho (Pailthorp etal., 1971) showed that approximately 70% reduction inCOD was obtained with an organic loading of 1.6kg/ m3.d while treating clarified potato processing

0315-5463/81/02144-03$2.00/0Copyright © 1981 Canadian Institute of Food Science and Technology

144

FEED + LIME

STIRREDCONTAINER

PERISTALTICPUMP

~,... _....:3...=.O=.5...;:...Cm__~I...• 4...:....:..:5..:....7..:..:Cm-'-'---_--I·1

ROCK MEDIA- 2.5"-4.0cm DIAM

2.2cm

IO.2cm DIAM

EFFLUENT

Fig. I. Schematic diagram of the horizontal anaerobic filter.

wastewater through a 2.44 m deep anaerobic filter.Nearly identical performance was obtained with a filter1.22 m deep. All these anaerobic filters used the upflowmode patterned after the work of Young and McCarty(1969). More recently, van den Berg and Lentz (1979)have conducted experiments using the downflow modeof operation. This paper describes the operation of alaboratory model anaerobic filter in the horizontalmode treating potato processing wastewater. The an­aerobic filter was tested in the horizontal mode with aview to using it in such a mode in an actual fieldinstallation involving earthen construction. As far ascould be determined by literature search, there hadbeen no previous modelling utilizing horizontal an­aerobic filters.

Materials and MethodsThe horizontal anaerobic filter was constructed of

plastic pipe, with a diameter of 10.2 cm and a length of91.4 cm giving a total volume (media and liquid) of6.22 L and a liquid volume of 2.61 L. The filter mediaconsisted of 25 mm to 40 mm diameter stones. Figure Ishows the details of the anaerobic filter.

The filter was seeded using solids from an upflowanaerobic filter treating potato processing wastewaterwhich had been in operation for 5 moo The reactor wascontinuously dosed with decanted primary clarifierinfluent from a potato processing plant right fromstart-up. Lime was added to the influent throughoutthe study such that a concentration of lime in the

,influent was maintained at 500 mg!L of the influent..' The lime addition was necessary to maintain near

neutral pH, as the waste pH before lime addition was

Table I. Performance of horizontal anaerobic filter.

in the range of 4 to 5. The filter was operated at 20°C,i.e., room temperature, as previous studies indicatedthat the performance of the filter would not appre­ciably decrease at this temperature in view of the longSRT available in the filter.

The wastewater was fed to the system from a stirredcontainer (12 L capacity) through a peristaltic pump.The system reached stability after approximately I moand was in steady-state operation for a period of6 mo,during which continuous monitoring was carried outto observe its performance. The hydraulic detentiontime in the filter (in days) is equal to daily flow throughthe filter divided by the void volume of the filter andthe detention time was found to be 0.60 day (void ratio= 0.42). The system was operated without recycle.

Results and DiscussionTable I presents a summary of the performance of

the horizontal anaerobic filter. It may be seen from thetable that the filter achieved BOO and COD removalsof91 %. The effluent concentrations (BOO and SS) didnot exhibit significant variations through the study,though the influent concentrations varied more rela­tively, as may be seen from Figure 2. Subsequently, thefilter feed strength was increased to an average COD of3,450 mg! L using diluted brusher water. (Brushers aresecondary mechanical devices used in the peel removalprocess and the waste stream from these units is termedbrusher water.) During a I mo operation period, theaverage organic loading rate was 2.19 kg COD!m3·dand the average COD removal was 86%

Generally these results demonstrated that horizon­tal anaerobic filters are feasible for the treatment of

DescriptionBOO (mg/L)

Range Average '

COD (mg/L)Range Average1

SS (mg/L)Range Average3

Influent4EffluentEfficiency of

removal (%)

770-132068-140

109098

91

1310-2310122-240

1890165

91

155-63540-60

34150

85

'Time weighted average BOO loading on filter-0.78 kg/mJ.d.lTime weighted average COD loading on filter-1.35 kg/mJ.d.JTime weighted average SS loading on filter-0.24 kg/ mJ.d.4Lime dosage of 500 mg/ L added to the feed.

Can. Inst. Food Sci. Technol. J. Vol. 14, No. 2, April 1981 Landineet al. (145

t 400

AV G =1090 moll

fBOO (INFLUENT)

1000

1200

.00

000

NOT E

OATA NOT COLLECTEOOURING._ THE 26-37OAY PERIOO

AYG':)41 mg/l

AYG '~

--~-------------"----------'r:~~=-~~-:7'--==:::::::::.:.: All G=, 50 mg/'+----',..0----.20----.-'0----0,-0----.',-0---•.,.0----7,-0----.'0------""'.0--'-''-'--'-''-''-=''''"0-'0-'---,'-,0----.'20

OAYS OF STEAOY STATE OPERATION

200

zo~ 600

<0:c:I­Zw<.lZ

8

Fig. 2. Biochemical oxygen demand (BOD) and suspended solids (SS) of influent and effluent during operation of the horizontal anaerobicfilter.

potato processing wastewater. Full-scale applicationin such a mode would be expected to yield similarresults. It is believed that anaerobic filters in thehorizontal configuration would provide COD re­movals comparable to those of vertical type filterswhose performances were summarized by Mueller andMancini (1975).

ReferencesMcCarty, P. L 1970. Biological treatment of food processing

wastes, Proceedings, First National Symposium on FoodProcessing Wastes, Portland, OR.

Mueller, J. A and Mancini, J. L 1975. Anaerobic filter-kineticsand application. Proceedings, 30th Industrial Waste Con­ference, Purdue University, Lafayette, IN.

Pailthorp, R. E., Richter, G. A. and Filbert,J. w. 1971. Anaerobicsecondary treatment of potato process wastewater. Presentedat the 44th Annual Conference, Water Pollution ControlFederation, San Francisco, CA.

Taylor, D. w, 1972. Full scale anaerobic trickling filter evaluation.Proceedings, Third National Symposium on Food Process­ing Wastes, EPA-R2-72-o18.

van den Berg, Land Lentz, C. P. 1979. Comparison between up anddownflow anaerobic fixed film reactors of varying surface­to-volume ratios for the treatment of bean blanching waste.Presented at the 34th Industrial Waste Conference, PurdueUniversity, Lafayette, IN.

Young, J. C. and McCarty, P. L 1969. The anaerobicfilterfor wastetreatment. J, Water Pollut. Control Fed. 41:RI40.

Accepted September 8, 1980

146/ Landine et al. J. Insf. Can. Sci. Technol. Aliment. Vcl. 14, No. 2. Avril1981