8202019 Effect of Organic Loading Rate on the Performance of Two-stage Anaerobic Digestion of the Organic Fraction of Mhellip

httpslidepdfcomreaderfulleffect-of-organic-loading-rate-on-the-performance-of-two-stage-anaerobic-digestion 18

Effect of organic loading rate on the performance of

two-stage anaerobic digestion of the organic fraction of

municipal solid waste (OFMSW)

Reyna I Rodriacuteguez-Pimentel Suyen Rodriacuteguez-PeacuterezOscar Monroy-Hermosillo and Florina Ramiacuterez-Vives

ABSTRACT

Two-stage anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) was carried

out hydrolysis and acidogenesis in a continuous anaerobic hydrolytic leach bed (AHLB) reactor

loaded at different rates (Bvfrac1438ndash7 gVSS L1 d1) and methanogenesis of leachates diluted with

municipal wastewater in an up1047298ow anaerobic sludge blanket (UASB) reactor at organic loading rates

of 66ndash13 gCOD Lr1 d1 In the AHLB reactor 51ndash76 and 58ndash71 volatile solids and chemical oxygen

demand (COD) removal ef 1047297ciencies were obtained During the hydrolysis and acidogenesis phases

the ef 1047298uents were at pH 493 the leachate had a volatile fatty acids concentration of 35 gL and the

biogas was composed only of CO2 The average methane production in the UASB in the load of

44 gVS L1 d1 in the AHLB was 332 LCH4 Lr1 d1 (yCH4frac1480) with COD removal ef 1047297ciency of 95

and methane yield 279 LCH4 KgVS1OFMSW degraded

Reyna I Rodriacuteguez-Pimentel (corresponding

author)

Oscar Monroy-Hermosillo

Florina Ramiacuterez-Vives

Biotechnology Department

Universidad Autoacutenoma Metropolitana

Av San Rafael Atlixco 186 Col Vicentina

09340 Iztapalapa DF

MeacutexicoE-mail isabelropihotmailcom

Suyen Rodriacuteguez-Peacuterez

Chemistry Department Universidad de Oriente

Patricio Lumumba sn 223006824

Santiago de Cuba

Cuba

Reyna I Rodriacuteguez-Pimentel

Division of Environmental Technology

Universidad Tecnoloacutegica de Nezahualcoacuteyotl

Circuito Universidad Tecnoloacutegica SN Col Benito

Juaacuterez 57900 Nezahualcoacuteyotl

Edo de Meacutexico

Meacutexico

Key words | hydrolysis leachate methanogenesis OFMSW (organic fraction of municipal solid

waste)

INTRODUCTION

Two-stage anaerobic digestion (TSAD) is effective for resi-

dues with high organic content which can ferment easily

(Bouallagui et al ) The physical separation of the hydro-

lytic-acidogenic and methanogenic phases allows for setting

up the best conditions for each of the microbial groups

involved (Cirne et al ) biopolymer (proteins lipids

starches) by enzymatic hydrolysis and acidogenesis yield

pH near to the pKa of volatile fatty acids (Ince ) while

a neutral pH is needed to produce methane The organic frac-

tion of municipal solid wastes (OFMSW) has 15ndash20 of

easily fermentable volatile solids (VS) with 106 g chemical

oxygen demand (COD)g VS (Browne et al

Browneamp Murphy Ramirez et al ) thus it is a suitable sub-

strate for TSAD The feed to the 1047297rst acidogenic reactor can

be lsquodryrsquo at the normal OFMSW water content of 80 or

less (Xu et al Tran et al Browne et al

Browne amp Murphy ) and lsquowet rsquo with total solids of less

than 20 (Bouallagui et al Shen et al ) The

main reactor con1047297gurations are leach bed and stirred tank

reactors respectively and an up1047298ow anaerobic sludge

blanket (UASB) reactor for methanogenesis (Table 1) The

broad line separating dry and wet fermentation is between

20 and 10 solids A variation is two stirred tanks in series

(Shen et al Bo amp Pin-Jing ) Most of the dry pro-

cesses uses leach bed reactors (Tran amp Palenzuela

Browne amp Murphy Ramirez et al ) A variation is

the Ramirez et al () process which combines wastewater

and OFMSW anaerobic treatments

To accelerate the hydrolysis of OFMSW some authors

recirculate a fraction of leachate mixed with water (Xu

et al ) or with ef 1047298uent from the UASB in order to

increase the hydrolysis pH and buffering capacity in the1047297rst step (Stabnikova et al Tran amp Palenzuela

Bo amp Pin-Jing Browne amp Murphy )

The aim of this work was to test OFMSW from the uni-

versitary campus cafeteria separating the hydrolysis and

acidogenesis in a continuous hydrolytic anaerobic slurred

bed and the generated leachate diluted with municipal

wastewater for the production of biogas in a UASB

reactor

384 copy IWA Publishing 2015 Water Science amp Technology | 723 | 2015

doi 102166wst2015223

8202019 Effect of Organic Loading Rate on the Performance of Two-stage Anaerobic Digestion of the Organic Fraction of Mhellip

httpslidepdfcomreaderfulleffect-of-organic-loading-rate-on-the-performance-of-two-stage-anaerobic-digestion 28

MATERIALS AND METHODS

AHLB and UASB reactors

The anaerobic hydrolytic leach bed (AHLB) reactor consisted

of an 8 L glass column 145 cm internal diameter 60 cm

height with a conical bottom (Figure 1) It was fed from the

top with a weighed amount of OFMSW and 200 mLd of the

UASB ef 1047298uent it was started with 1 kg of digested OFMSW

from previous batch tests (pH 414 14 total solids (TS) 12

VS 16 CODTS protein 6 PTS and carbohydrates 1

carbohydratesTS (Ramirez et al ) It was fed with the

OFMSW at different solids loading rates (SLR) 38 44 44

(with R frac14 01) 6 and 7 (R frac14 02) gVS L1d1 The UASB reac-

tor consisted of a glass column (095 L) inoculated with

320 mL of granular sludge (52 gVSS L1) from a UASB reactor

treating leachates It was fed at different organic loading rates

(OLR g COD L1 d1) depending on the AHLB reactor results

The response variables were pH solids protein COD volatile

fatty acids (VFA) and carbohydrates in both the OFMSW and

the leachate and the generated biogas

System description

The OFMSW was fed to the continuous AHLB reactor at

W0 ( g V S d1) and the digested solids are withdrawn

at W1 The fermenting mass A is sprinkled with the ef 1047298uent

of a UASB reactor treating leachates (FL SL) and municipal

wastewater (Fw Sw) at a 1047298ow rate (FL frac14 200 mLd) given by a

dilution rate of 0025 LLr d The mixture of municipal

wastewater (MWW) and leachates yield the reactor feed

(FU0 SU0) which is converted to methane (QCH4) and an

ef 1047298

uent (FU SU) In some experimental runs part of theleachate was recycled (RFL) to the AHLB

Mass balances

The global COD balance shows the methane contribution

from both the OFMSW and the MWW (Equation (1))

V ds

dt frac14 W 0 X So thorn F m Sm W 1 X S1 F mSU

V LQ CH4

Y 1CH4frac14 0

Q CH4 frac14

W 0 X So W 1 X S1

V L thorn DU (Sm SU )

(1)

From the VS balance in the AHLB the hydrolysis con-

stant k was obtained from Equation (2)

V dSv

dt frac14 W 0Svo W 1Sv1 V LkSv frac14 0

k frac14 W 0Svo W 1Sv1eth THORN

V LSv (2)

COD and VS balances in the AHLB reactor

V ds

dt frac14 W 0 Xs0 thorn F L SU W 1 Xs1 F LSL Vr S

V dS

dt frac14 (W 0Sv0) (W 1 Sv1) thorn F L C U C Leth THORN V Ar i (3)

r i frac14 (W 0Sv0 W 1Sv1)

V A DL C L C U eth THORN

Table 1 | Reactor con1047297gurations for two stages (anaerobic digestion AD) of OFMSW

Fed VS

(gL)

1 W

stage

2 W

sta ge SL Rηvs

YCH4

VS Reference

202 LB UASB 53384 344 Browne amp Murphy ()

140 LB UASB 453 200 Ramirez et al ()100 LB UASB 34533 145 Tran amp Palenzuela ()

83 LB UASB 16563 138 Xu et al ()

80 ST ST 10- 600 Shen et al ()

75 ST UASB 2489 462 Zhang et al ()

47 ST ST 1063 440 Bo amp Pin-Jing ()

28 LB UASB 1850 250 Stabnikova et al ()

SLR frac14 VS loading rate (gL d) ηvs frac14 VS removal ef 1047297ciency () YCH4VS frac14 methane yield on

fed VS (LkgVSin) LB frac14 leach bed ST frac14 stirred tank

Figure 1 | TSAD of OFMSW F 1047298ow rates (L d1) Q (volumetric gas 1047298ow rate S (g COD

L1) W (g OFMSW d1) A frac14 OFMSW volume in the reactor Subindex m

municipal wastewater L leachate U UASB reactor in1047298uent (0) Adapted from

Ramiacuterez et al (2014)

385 R I Rodriacuteguez-Pimentel et al | Effect of organic loading rate on the performance of two stages of anaerobic digestion Water Science amp Technology | 723 | 2015

8202019 Effect of Organic Loading Rate on the Performance of Two-stage Anaerobic Digestion of the Organic Fraction of Mhellip

httpslidepdfcomreaderfulleffect-of-organic-loading-rate-on-the-performance-of-two-stage-anaerobic-digestion 38

At the UASB

F U SU 0 F U SU V U Q CH4

Y 2CH4frac14 0

Q CH4 frac14 DU SU 0 SU eth THORNY 2CH4

where subindexes (i) 0 inlet 1 outlet U UASB AAHLB m

municipal wastewater L leachate W i mass (g OFMSWd)

XS is COD at OFMWS (gCOD g1) F is 1047298ow rate (L d1)

S is COD MWW (gCOD L1) V is the reactor volume (L)

Q CH4 is methane volume (L) Y 1CH4 is yield (LCH4gVS) Sv

is the VS concentration in OFMSW (g g1) k is the hydrolysis

rate constant (d1) Y 2 is methane yield (LCH4kg VS) r i

degradation rates (g L1 d1)

Characterization of the OFMSW and MWW

The OFMSW was collected daily from the cafeteria of the

Metropolitan Autonomous University Iztapalapa (MAU-I)

milled and crushed to a particle size between 1 and 5 mm

and analyzed for pH solids COD proteins carbohydrates

and lipids MWW was taken from the university sewer

Analytical methods

The COD proteins and carbohydrates of OFMSW were

determined by suspending one gram of OFMSW in100 mL of distilled water Lipids were determined by

taking 2 g of dry solids

ForVFAa sample of 15 mL of leachate wascentrifugedat

1120 G for 15 minutes The obtained supernatant was1047297ltered

across a nitrocellulose membrane (Millipore 045 μm) taking a

1 mL aliquot and 1047297lled up to 50 mL with distilled water then

an aliquot of 950 μL was acidi1047297ed with 50 μL of 22 M HCl

For Elemental analysis of the OFMSW a 10 g sample

was dried at 60 W

C broken to a particle size of 0149 mm

and between 2 and 3 mg of sample was burned in the

Perkin Elmer model PE 2400 series II (Waltham MA

USA) at combustion reduction and detector temperaturesof 925

W

C 640 W

C and 825 W

C respectively using helium

hydrogen as transport gases

The generated biogas volume was measured by a brine

(NaCl 250 g L1) column displacement

Alkalinity COD TS VS lipids and pH were determined

by Standard Methods (APHA AWWA WPFC ) Carbo-

hydrates and proteins were determined by colorimetric

techniques (Lowry et al Dubois et al ) The VFA

determination was carried out in a gas chromatograph HP

5890 (Agilent Santa Clara CA USA) with 1047298ame ionization

detector with a capillary column AT 1000 using nitrogen as

gas carrier to 5 mL min1 the temperature of the detector

and injector were 200 W

C with a ramp of 25 W

C min1

Biogas composition was determined using a gas chro-matograph (GowMAC 580 series Gow-Mac Inc

Bethlehem PA USA) with a thermal conductivity detector

operating at a polarity of 120 mA with a Carbosphere

80100 packed column The temperatures of the column

detector and injector were 140 W

C 190 W

C and 170 W

C

respectively with a ramp of 25 W

C min1 using helium as

transport gas (25 mL min1 at 40 psi)

Statistical analysis

An analysis of variance (ANOVA) test of means was carried

out using Tukey-Kramer at a signi1047297cance level α of 005

RESULTS AND DISCUSSION

Characterization of the OFMSW

MWW and OFMSW were characterized (Table 2) and the

results show their large variability due to the fact that they

were taken fresh every day The average moisture content

of the OFMSW was 82 similar to that reported by Wang

et al () and Hernaacutendez et al () for mixtures of kitchen and dining room residues COD shows the maximum

capacity for methane production yielding 171 gCODkg

OFMSW while the wastewater contribution was negligible

Table 2 | OFMSW MWW characterization (n frac14 162)

Parameter

OFMSW (W0)

MWW (Fm)

g L1

Digestate (W1)

TS 18plusmn 6 017plusmn 002 10plusmn 77

VS 16plusmn 6 0 8plusmn 34

CODTS 95plusmn 37 034plusmn 016 134plusmn 49

Protein (PrTS) 39plusmn 27 0 14plusmn 08

Carbohydrates (ChTS) 55plusmn 44 0 02plusmn 002

Lipids (LpTS) 13plusmn 9 0 8plusmn 5

VFA ND 016plusmn 0005 ND

Ammonium ND 024plusmn 008 ND

CN 12plusmn 2 ND 98plusmn 17

pH 57plusmn 05 82plusmn 03 49plusmn 06

ND Not determined

386 R I Rodriacuteguez-Pimentel et al | Effect of organic loading rate on the performance of two stages of anaerobic digestion Water Science amp Technology | 723 | 2015

8202019 Effect of Organic Loading Rate on the Performance of Two-stage Anaerobic Digestion of the Organic Fraction of Mhellip

httpslidepdfcomreaderfulleffect-of-organic-loading-rate-on-the-performance-of-two-stage-anaerobic-digestion 48

Some parameters such as the elementary analysis and

CN relation are similar to those reported elsewhere

(Zhang et al Xu et al Nagao et al ) and the

proteins carbohydrates and lipids in the kitchen residues

reported by Bo amp Pin-Jing () and Zhang et al ()

Generally a CN ratio range of 20ndash

30 was considered to be the optimum condition for anaerobic digestion (Poyuelo

et al ) but recent studies have pointed out that anaero-

bic digestion performed well at lower CN ratios of 15ndash20

(Zhang et al )

Removal of VS at the AHLB

The VS pro1047297le the COD and VFA throughout the whole

study show dependence on the average SLR (Figure 2(a)

and 2(b)) The VS output is relatively constant at about

25 irrespective of the large variation at the inletTable 3 shows the AHLB reactor performance at the SLR

that was tested At increasing SLR the VS and COD removal

ef 1047297cienciesand VFAproduction rates increase to a maximum

of 79 71 and 0213 g L1 d1 respectively The pH for

the 1047297rst four runs remains at an average of 493plusmn 056

which is lower than the initial value due to the acidogenic

conditions producing VFA and a biogas of 100 CO2

(Selvam et al Ramirez et al ) The hydrolysis rateconstant k can be found per each of the different runs by

means of Equation (2) The average value is 0027plusmn

0018 d1 which is an acceptable value for all runs

The recycle ratio R shows no clear in1047298uence on the per-

formance as it was masked by the increase to an SLR of

6 gVS L1 d1 Xu et al () recycled 50 of the leachates

diluted with water and a percolating agent to obtain 63

solids removal

The last run shows a probable reactor breakdown as the

pH drops to 39 and the removal ef 1047297ciencies drop to 53 and

45 as well as the VFA production rate as reported by

Browneamp Murphy () Byincreasing the SLR the VFA pro-

duction rate increases in the leachate as also found by

Bouallagui et al () mainly acetic (63) and butyric

(18) acids (as with Jian et al ) except in the last load

when the propionic acid increases (29) and the total VFA

production decreases to 61 causing a loss in VS and COD

removal ef 1047297ciencies as also observed by Shen et al ()

Methanogenesis in the UASB reactor

The leachate was mixed with MWW to be fed to a UASB

reactor as a practice to treat both OFMSW and MWW apractice that can be innovated in future for other cities

Figure 3 shows the OLR evolution through the experiments

It shows that the COD removal ef 1047297ciencies were higher

than 90 working at alkalinity ratios higher than 06 with

methane production rates increasing with organic loading

rate Adaption periods in each run varied but the data were

obtained in a pseudo steady state (more than 5 HRT with con-

stant values) The HRT was of 1 day for the 3 1047297rst runs In run

3 the OLR decreased to 7 because part of the leachates were

used in recirculation to the AHLB The next experiments

were run at 9 and 13 by decreasing HRT to 05 d

Table 4 shows the performance of the UASB reactor at the different SLR in the AHLB reactor by combining

MWW with leachates and HRT distinct OLR (6ndash13

gCODL1 d1) in the UASB

It is observed that although the optimum SLR to obtain

a better solids destruction is 6 when the UASB is integrated

the best loading rate is 44

In this study we obtained removal ef 1047297ciencies for COD

of 95 above that obtained by Zhang et al () ShenFigure 2 | (a) VS pro1047297le of the AHLB reactor lozinlet outlet (b) COD diams VFA and timesVS

of the leachate

387 R I Rodriacuteguez-Pimentel et al | Effect of organic loading rate on the performance of two stages of anaerobic digestion Water Science amp Technology | 723 | 2015

8202019 Effect of Organic Loading Rate on the Performance of Two-stage Anaerobic Digestion of the Organic Fraction of Mhellip

httpslidepdfcomreaderfulleffect-of-organic-loading-rate-on-the-performance-of-two-stage-anaerobic-digestion 58

Table 3 | AHLB reactor performance at different SLR

SLR (gVS L1 d

1) W1 pH K (d1) ηVS () ηCOD () r fVFA (g L

1 d1)

38plusmn 070 486plusmn 063ab

0018 63plusmn 106ab

58plusmn 156ab

0074plusmn 001a

44plusmn 019 522plusmn 035 b

0028 77plusmn 36 b

58plusmn 21ab

0175plusmn 003 b

44plusmn 049 513plusmn 068ab 0026 75plusmn 33 b 61plusmn 06ab 0093plusmn 003a

6plusmn 050 451plusmn 036ab

0037 79plusmn 28 b

71plusmn 104 b

0213plusmn 004 b

7plusmn 15 392plusmn 026a

0027 53plusmn 162a

45plusmn 78a

0085plusmn 001a

Leachate recirculation reg of 10 and 20 η removal ef 1047297ciencies Means with the same letter are not signi1047297cantly different

Figure 3 | UASB performance OLR loz QCH4

Table 4 | UASB reactor performance at different organic load rate (OLR) for each SLR in the AHLB

SLR gVS L1 d

1

Lx ww

OLR gCOD Lr 1 d

1ηCOD QCH4 L Lr

1 d1 YCH4 LCH4kgVS

1 d1g COD d

1

38plusmn 070 13 092 66plusmn 066 96plusmn 14a

210plusmn 04a

228plusmn 26 b

44plusmn 019 20 23 9plusmn 170 95plusmn 21a

332plusmn 09 bc

279plusmn 94c

44plusmn 049 17 23 7plusmn 101 95plusmn 2a

259plusmn 03a

238plusmn 137 bc

6plusmn 050 26 23 9plusmn 046 89plusmn 1 b

316plusmn 03ab

180plusmn 30a

7plusmn 15 19 092 13plusmn 145 96plusmn 17a

442plusmn 07c

155plusmn 152a

SLRfrac14 solid load rate Lxfrac14 leachate wwfrac14wastewater Means with the same letter are not signi1047297cantly different

388 R I Rodriacuteguez-Pimentel et al | Effect of organic loading rate on the performance of two stages of anaerobic digestion Water Science amp Technology | 723 | 2015

8202019 Effect of Organic Loading Rate on the Performance of Two-stage Anaerobic Digestion of the Organic Fraction of Mhellip

httpslidepdfcomreaderfulleffect-of-organic-loading-rate-on-the-performance-of-two-stage-anaerobic-digestion 68

et al () and Bo amp Pin-Jing () and yields above those

reported by Stabnikova et al () Xu et al () and Tran

amp Palenzuela ()

CONCLUSIONS

An anaerobic digestion centered process combining the

treatment of municipal wastewater and organic solid

wastes was assayed A leach bed reactor was used to hydro-

lyze the OFMSW and the produced leachates were mixed

with MWW and treated in a UASB reactor to obtain

methane The mixing degree will depend on the WWTP

capacity but it can be as small as to provide a dilution suf 1047297-

cient to load 25 g COD L1 d1 as reported elsewhere

(Ramirez et al )

Considering the AHLB reactor the optimum SLR is

6 g VS L1 d1 based on solids destruction and COD

reduction but when combined with the UASB reactor the

best load is 44 g VS L1 d1 based on the methane to VS

yield (Y CH4frac14 279 LCH4kg VSd)

As leachates are highly degradable the UASB ef 1047297ciency

is 95 this process helps in the recovery of methane from

diluted wastewaters

The proposed system is able to separate hydrolysis and

acidogenesis in the 1047297rst reactor maintaining conditions

that favor this phase (pH VFA) and methanogenesis in

the second reactor

ACKNOWLEDGEMENT

This work was granted 1047297nancial support from Mexico Cityrsquos

Science Technology and Innovation Secretary (SECITI)

(PICSO12-104 14512059)

REFERENCES

APHA AWWA WPFC Standard Methods for the

Examination of Water and Wastewater 17th edn Am PubHealth Assoc Washington DC USA

Bo Z amp Pin-Jing H Performance assessment of two-stage

anaerobic digestion of kitchen wastes Environmental

Technology 35 (10) 1277ndash1285

Bouallagui H Torrijos M Godon J J Moletta R Ben Cheikh

R Touhami Y Delgenes J P amp Hamdi M Two-

phases anaerobic digestion of fruit and vegetable wastes

bioreactors performance Biochemical Engineering Journal

21 193ndash197

Bouallagui H Touhami Y Ben Cheikh R amp Hamdia M

Bioreactor performance in anaerobic digestion of fruit

and vegetable wastes review Process Biochemical 40

989ndash995

Browne J Allen E amp Murphy J Improving hydrolysis of

food waste in leach bed reactor Waste Management 33 (11)

2470ndash2477

Browne J amp Murphy J The impact of increasing organic

loading in two phase digestion of food waste Renewable

Energy 71 69ndash76

Cirne D Lehtomaumlki A Bjoumlrnsson L amp Blackall L

Hydrolysis and microbial community analyses in two-stage

anaerobic digestion of energy crops Journal of Applied

Microbiology 103 516ndash527

Dubois M Gilles K Hamilton J Roberts P amp Smith F

Colorimetric method for determination of sugars and related

substances Analytical Chemistry 28 350ndash356

Hernaacutendez-Becerril Ma C Maacuterquez-Benavides L Gonzaacutelez-

Peacuterez D J amp Buenrostro-Delgado O The effect of

moisture on the anaerobic degradation of municipal solid

waste from Metepec (Meacutexico) Waste Management 28

514ndash520

Ince O Performance of a two-phase anaerobic digestion

system when treating dairy waste water Water Research 32

(9) 2707ndash2713

Jian Y Heaven S amp Banks C Strategies for stable

anaerobic digestion of vegetable waste Renewable Energy

44 (1) 206ndash214

Lowry O H Rosebrough N J Farr A L amp Randall R J

Protein measurements with the folin phenol reagent The

Journal of Biological Chemistry 193 265ndash275

Nagao N Tajima N Kawai M Niwa Ch Kursawa N

Matsuyama T Yussoff F amp Toda T Maximum organic

loading rate for the single-stage wet anaerobic digestion of

food waste Bioresource Technology 118 210ndash218

Puyuelo B Ponsaacute S Gea T amp Saacutenchez A Determining

CN ratios for typical organic wastes using biodegradable

fractions Chemosphere 85 653ndash659

Ramiacuterez F Rodriacuteguez R De Jesuacutes A Martiacutenez F Rodriacuteguez S

amp Monroy O Two-phase anaerobic digestion of

municipal organic solid wastes Journal Advances in

Biotechnology 3 (2) 210ndash218

Selvam A Xu S Yang X amp Wong J Food waste

decomposition in leachbed reactor role of neutralizing

solutions on the leachate quality Bioresource Technology

101 1707ndash1714

Shen F Yuan H Pang Y Chen S Zhu B Zou D Liu Y

Ma J Yu L amp Li X Performances of anaerobicco-digestion of fruit amp vegetable waste (FVW) and food waste

(FW) single-phase vs two-phase Bioresource Technology

144 80ndash85

Stabnikova O Liu X amp Wang J Anaerobic digestion of

food waste in a hybrid anaerobic solidndashliquid system with

leachate recirculation in an acidogenic reactor Biochemical

Engineering Journal 41 198ndash201

Tran L Palenzuela A amp Nakasaki K Anaerobic digestion

of organic fraction of municipal solid waste (OFMSW) in

389 R I Rodriacuteguez-Pimentel et al | Effect of organic loading rate on the performance of two stages of anaerobic digestion Water Science amp Technology | 723 | 2015

8202019 Effect of Organic Loading Rate on the Performance of Two-stage Anaerobic Digestion of the Organic Fraction of Mhellip

httpslidepdfcomreaderfulleffect-of-organic-loading-rate-on-the-performance-of-two-stage-anaerobic-digestion 68

et al () and Bo amp Pin-Jing () and yields above those

reported by Stabnikova et al () Xu et al () and Tran

amp Palenzuela ()

CONCLUSIONS

An anaerobic digestion centered process combining the

treatment of municipal wastewater and organic solid

wastes was assayed A leach bed reactor was used to hydro-

lyze the OFMSW and the produced leachates were mixed

with MWW and treated in a UASB reactor to obtain

methane The mixing degree will depend on the WWTP

capacity but it can be as small as to provide a dilution suf 1047297-

cient to load 25 g COD L1 d1 as reported elsewhere

(Ramirez et al )

Considering the AHLB reactor the optimum SLR is

6 g VS L1 d1 based on solids destruction and COD

reduction but when combined with the UASB reactor the

best load is 44 g VS L1 d1 based on the methane to VS

yield (Y CH4frac14 279 LCH4kg VSd)

As leachates are highly degradable the UASB ef 1047297ciency

is 95 this process helps in the recovery of methane from

diluted wastewaters

The proposed system is able to separate hydrolysis and

acidogenesis in the 1047297rst reactor maintaining conditions

that favor this phase (pH VFA) and methanogenesis in

the second reactor

ACKNOWLEDGEMENT

This work was granted 1047297nancial support from Mexico Cityrsquos

Science Technology and Innovation Secretary (SECITI)

(PICSO12-104 14512059)

REFERENCES

APHA AWWA WPFC Standard Methods for the

Examination of Water and Wastewater 17th edn Am PubHealth Assoc Washington DC USA

Bo Z amp Pin-Jing H Performance assessment of two-stage

anaerobic digestion of kitchen wastes Environmental

Technology 35 (10) 1277ndash1285

Bouallagui H Torrijos M Godon J J Moletta R Ben Cheikh

R Touhami Y Delgenes J P amp Hamdi M Two-

phases anaerobic digestion of fruit and vegetable wastes

bioreactors performance Biochemical Engineering Journal

21 193ndash197

Bouallagui H Touhami Y Ben Cheikh R amp Hamdia M

Bioreactor performance in anaerobic digestion of fruit

and vegetable wastes review Process Biochemical 40

989ndash995

Browne J Allen E amp Murphy J Improving hydrolysis of

food waste in leach bed reactor Waste Management 33 (11)

2470ndash2477

Browne J amp Murphy J The impact of increasing organic

loading in two phase digestion of food waste Renewable

Energy 71 69ndash76

Cirne D Lehtomaumlki A Bjoumlrnsson L amp Blackall L

Hydrolysis and microbial community analyses in two-stage

anaerobic digestion of energy crops Journal of Applied

Microbiology 103 516ndash527

Dubois M Gilles K Hamilton J Roberts P amp Smith F

Colorimetric method for determination of sugars and related

substances Analytical Chemistry 28 350ndash356

Hernaacutendez-Becerril Ma C Maacuterquez-Benavides L Gonzaacutelez-

Peacuterez D J amp Buenrostro-Delgado O The effect of

moisture on the anaerobic degradation of municipal solid

waste from Metepec (Meacutexico) Waste Management 28

514ndash520

Ince O Performance of a two-phase anaerobic digestion

system when treating dairy waste water Water Research 32

(9) 2707ndash2713

Jian Y Heaven S amp Banks C Strategies for stable

anaerobic digestion of vegetable waste Renewable Energy

44 (1) 206ndash214

Lowry O H Rosebrough N J Farr A L amp Randall R J

Protein measurements with the folin phenol reagent The

Journal of Biological Chemistry 193 265ndash275

Nagao N Tajima N Kawai M Niwa Ch Kursawa N

Matsuyama T Yussoff F amp Toda T Maximum organic

loading rate for the single-stage wet anaerobic digestion of

food waste Bioresource Technology 118 210ndash218

Puyuelo B Ponsaacute S Gea T amp Saacutenchez A Determining

CN ratios for typical organic wastes using biodegradable

fractions Chemosphere 85 653ndash659

Ramiacuterez F Rodriacuteguez R De Jesuacutes A Martiacutenez F Rodriacuteguez S

amp Monroy O Two-phase anaerobic digestion of

municipal organic solid wastes Journal Advances in

Biotechnology 3 (2) 210ndash218

Selvam A Xu S Yang X amp Wong J Food waste

decomposition in leachbed reactor role of neutralizing

solutions on the leachate quality Bioresource Technology

101 1707ndash1714

Shen F Yuan H Pang Y Chen S Zhu B Zou D Liu Y

Ma J Yu L amp Li X Performances of anaerobicco-digestion of fruit amp vegetable waste (FVW) and food waste

(FW) single-phase vs two-phase Bioresource Technology

144 80ndash85

Stabnikova O Liu X amp Wang J Anaerobic digestion of

food waste in a hybrid anaerobic solidndashliquid system with

leachate recirculation in an acidogenic reactor Biochemical

Engineering Journal 41 198ndash201

Tran L Palenzuela A amp Nakasaki K Anaerobic digestion

of organic fraction of municipal solid waste (OFMSW) in

389 R I Rodriacuteguez-Pimentel et al | Effect of organic loading rate on the performance of two stages of anaerobic digestion Water Science amp Technology | 723 | 2015

8202019 Effect of Organic Loading Rate on the Performance of Two-stage Anaerobic Digestion of the Organic Fraction of Mhellip

httpslidepdfcomreaderfulleffect-of-organic-loading-rate-on-the-performance-of-two-stage-anaerobic-digestion 78

two-phases system Int J Environmental Management 9

5ndash17

Wang J Shen D amp Xu Y Effect of acidi1047297cation percentage

and volatile organic acids on the anaerobic biological process

in simulated land1047297ll bioreactors Process Biochemistry 41

1677ndash1681

Xu S Y Lam H P Karthikeyan P O amp Wong J W

Optimization of food waste hydrolysis in leach bed coupled

with methanogenic reactor effect of pH and bulking agent

Bioresource Technology 102 3702ndash3708

Zhang B Zhang L L Zhang S-C Shi H-Z amp Cai W-C

The in1047298uence of pH on hydrolysis and acidogenesis of

kitchen wastes in two-phase anaerobic digestion

Environmental Technology 26 329ndash339

ZhangR El Mashad HHartman K Wang F Liu G Choate C

amp Gamble P Characterization of food waste as feedstock

for anaerobic digestion Bioresource Technology 98 929ndash

935

Zhang C Su H Baeyens J amp Tan T Review the anaerobic

digestion of food waste for biogas production Renewable and

Sustainable Energy Reviews 38 283ndash292

First received 19 December 2014 accepted in revised form 27 April 2015 Available online 12 May 2015

390 R I Rodriacuteguez-Pimentel et al | Effect of organic loading rate on the performance of two stages of anaerobic digestion Water Science amp Technology | 723 | 2015

8202019 Effect of Organic Loading Rate on the Performance of Two-stage Anaerobic Digestion of the Organic Fraction of Mhellip

httpslidepdfcomreaderfulleffect-of-organic-loading-rate-on-the-performance-of-two-stage-anaerobic-digestion 88

C o p y r i g h t o f W a t e r S c i e n c e amp T e c h n o l o g y i s t h e p r o p e r t y o f I W A P u b l i s h i n g a n d i t s c o n t e n t

m a y n o t b e c o p i e d o r e m a i l e d t o m u l t i p l e s i t e s o r p o s t e d t o a l i s t s e r v w i t h o u t t h e c o p y r i g h t

h o l d e r s e x p r e s s w r i t t e n p e r m i s s i o n H o w e v e r u s e r s m a y p r i n t d o w n l o a d o r e m a i l a r t i c l e s f o r

i n d i v i d u a l u s e