Natural Resources, 2011, 2, 224-233
doi:10.4236/nr.2011.24028 Published Online December 2011 (http://www.SciRP.org/journal/nr)
Two-Stage Dilute Acid Hydrolysis of Dairy
Manure for Nutrient Release, Solids Reduction
and Reducing Sugar Production
S. K. Yawson, P. H. Liao, K. V. Lo*
Department of Civil Engineering, University of British Columbia, Vancouver, Canada.
Received July 30th, 2011; revised August 15th, 2011; accepted August 22nd, 2011.
ABSTRACT
The microwave enhanced advanced oxidation process (MW/H2O2-AOP) aided with dilute sulfuric acid was applied in a
two-stage treatment of dairy manure for nutrient release, solids reduction, and reducing sugar production. A much
higher hydrogen peroxide dosage (1.2 g H2O2/g TS) was used in Stage 2 than that in Stage 1 (0.38 g H2O2/g TS). Most of
the reducing sugar was produced in Stage 1, and only a small amount produced in Stage 2. The highest reducing sugar
yield of 15.5% was obtained at 160˚C, 0 mL H2O2, and 20 min of heating time. With a high hydrogen peroxide dosage
and a higher operating temperature of 160˚C in Stage 2, the nutrient release conversion rate was much higher in Stage 2
than Stage 1. All of total phosphorus was converted to orthophosphate, and a very high ammonia concentration was ob-
tained in the treated solution. The results indicated that th e MW/H2O2-AOP operated under the reducing process (with-
out hydrogen peroxide) provided the best yield of reducing sugar; however, when operated under an oxidative process
(with hydrogen peroxide), it favoured nutrient release and solid s disintegratio n. The concentra tion of tota l chemical oxi-
dation demand (TCOD) in the treated solution decreased with an increase of temperature, hydrogen peroxide dosage
and heating time. Soluble chemical oxidation demand (SCOD) concentration decreased with a very high hydrogen per-
oxide dosage. Volatile fatty acids (VFA) concentration decreased with an increase of hydrogen peroxide dosage. Ammo-
nia and orthop hosp hat e co ncentrations increased w i t h an i n crease of t emp erat ure an d hydrogen peroxid e dosage.
Keywords: Microwave, Advanced Oxidation, Solids Destruction, Reducing Sugar Generation, Nutrient Solubilization
1. Introduction
Dairy manure contains fats, proteins, lignin, carbohydra-
tes and inorganic residue, and is rich in a variety of nu-
trients including nitrogen, phosphorus, and minerals. It is
a bio-resource, which can be converted into valuable pro-
ducts, instead of a waste material to be disposed. Carbo-
naceous matters in dairy manure can be utilized for eth-
anol, methane and bio-fuel conversion, while nutrients
and metals, such as phosphorus, nitrogen, and potassium
can be used for struvite production. Lignocellulosic com-
ponents from dairy manure can be transformed into fer-
mentable saccharides via enzyme, or acid hydrolysis,
which can further be converted into ethanol and other
valuable products [1]. Lignocellulosic biomass is natu-
rally resistant to breakdown; a pretreatment step, such as
the acid hydrolysis is needed for breaking lignin seal and
disrupting crystalline structure of cellulose [2,3].
Acid hydrolysis can be achieved with various combi-
nations of acid concentration and operating temperature
in a one-stage or a two-stage process. Dilute acid hydro-
lysis is the most commonly applied process. It is used
either as a pretreatment of lignocellulose for subsequent
enzyme hydrolysis or as the actual hydrolysis to produce
fermentable sugar. In a one-stage acid hydrolysis, acid
breaks the matrix structure of the fiber, and polysaccha-
rides are converted into mono sugars [4]. In a two-stage
process, dilute acid is used in general in the first stage to
solubilize the hemicelluloses, and to reduce cellulose
crystallinity. This would effectively remove pentosans
prior to the main hydrolysis of cellulose. Concentrated
acid (12.5% to 75% of sulfuric acid concentration) is then
used to hydrolyze cellulosic materials to produce mainly
glucose in the second-stage process [5]. More sugars can
be produced from dairy manure in a two-stage hydrolysis
than that from a one-st age hydrolysis procedure [6].

Two-Stage Dilute Acid Hydrolysis of Dairy Manure for Nutrient Release, Solids Reduction and 225
Reducing Sugar Production
Various processes, such as thermal treatment, micro-
wave irradiation (physical treatment), hydrogen peroxide
(oxidative) or acid addition (chemical) have been used
for treating lignocellulosic biomass. They would de-
crease the degrees of polymerization and cellulose crys-
tallinity, and would also increase the accessible surface
area and pore size of lignocellulosics. As a result, the
subsequent enzymatic hydrolysis or acid hydrolysis pro-
cess for producing fermentable sugar could be enhanced
[7-10].
The microwave enhanced advanced oxidation process
(MW/H2O2-AOP), which uses a combination of micro-
wave irradiations and hydrogen peroxide to produce hy-
droxyl free radicals to react with organic compounds, has
been demonstrated for the production of reducing sugar,
as well as the release of soluble materials of nitrogen,
phosphorus and minerals from dairy manure [9,10]. The
effectiveness of the MW/H2O2-AOP is depending on
operating conditions selected, such as microwave tempe-
rature, hydrogen peroxide dosage, microwave intensity,
reaction time, and acid concentration. Hydrogen perox-
ide addition in the MW/H2O2-AOP would aid in nutrient
solubilization and solids destruction, however, it would
be detrimental to the yield o f reducing sug ar if its dosage
is too high. Reducing sugar formed in the process could
be further oxidized by hydrogen peroxide to form other
oxidation products, such as carbonyl compounds, VFA
and CO2 [9]. Bo th acid concen tration and temperature are
key factors affecting reducing sugar production [3,7]. A
higher reducing sugar production was obtained with
acidified dairy manure at pH 2 than at pH 4 [10]. To fur-
ther examine the effect of acid concentration on the pro-
cess, reagent grade cellulose fibers was subjected to the
MW/H 2O2-AOP at different sulfuric acid concentrations
(1%, 3% & 10% v/v), a very low hydrogen peroxide
dosage (0.01 g H2O2/g TS) and at temperature of 120 and
160˚C. The results indicated that the highest reducing
sugar production was obtain ed at sulfu ric acid con centra-
tion of 3% [10]. In view of these results, it was con-
cluded that for reducing sugar production as well as nu-
trient release from dairy manure, the process should be
operated at a higher acid concentration, a moderate hy-
drogen peroxide dosage and a high temperature, prefera-
bly more than 120˚C. This study, therefore, was con-
ducted to further investigate the feasibility of using the
MW/H 2O2-AOP in two-stage dilute acid hydrolysis of
dairy manure. The objective was to explore operating
conditions not only for reducing sugar production, but
also for solubilizin g nutrients from dairy manure, so that
the treated solution could be further utilized for ethanol,
bioenergy pr oduction and struvi t e recovery.
2. Materials and Methods
2.1. Apparatus
A lab-scale Milestone Ethos D Microwave Labstation
(Milestone Inc., USA) was used in this study. The sys-
tem operates at a frequency of 2,450 MHz with a maxi-
mum power output of 1000 W. The maximum operating
temperature and pressure are 220˚C and 435 psig, re-
spectively. The system has a real-time temperature con-
troller, and is capable of digesting up to 12 large weight
samples at the same time (Model 320, Milestone Inc.,
USA).
2.2. Substrate and Sample Preparation
Dairy manure was obtained from the Dairy Education &
Research Centre, University of British Columbia at Aga-
ssiz, British Columbia, Canada. Only the solids portion,
obtained after the liquid-solids separation (L/S) was used
in this study. Dairy manure diluted with distilled water to
give 5.4% total solids (TS) was used as the substrate for
the first stage acid hydrolysis (Stage 1). The manure ini-
tially had a SCOD concentration of 5.7 ± 1.0 g/L, TCOD
of 66.0 ± 6.6 g/L, total phosphorus (TP) of 355 ± 21
mg/L, orthophosphate of 48 ± 1.0 mg/L, total Kjeldahl
nitrogen (TKN) of 1420 ± 60 mg/L, ammonia o f 92 ± 2.4
mg/L and reducing sugar of 898 ± 415 mg/L, respec-
tively. The remaining solids from Stage 1 were used as
the substrate for the second stage acid hydrolysis (Stage
2). For Stage 2, the solids were obtained by centrifuging
the treated sample from Stage 1 at 4000 rpm, decanting
the soluble portion and oven drying the solids at 40˚C.
2.3. Sample Analysis
Dairy manure samples were centrifuged at 3500 rpm for
10 minutes, and the supernatant was extracted for analy-
sis of SCOD, orthophosphate, soluble ammonia, VFA
and reducing sugar. All of the chemical analyses, except
that of reducing sugar, followed the procedures outlined
in Standard Methods [11]. The colorimetric method was
employed to determine the total reducing sugar content
using anthrone reagent [12]. For orthophosphate analysis,
dairy manure samples were determined at 0.5% TS to
ensure correct measurement [13]. The initial dairy ma-
nure samples were also analyzed for TS, TCOD, TP and
TKN. All chemical analyses, except TS and COD, were
determined by a flow injection system, (Lachat Quik-
Chem 8000 Automatic Ion Analyzer, La chat Instrumen ts,
USA). A Hewlett Packard 6890 Series II gas chromato-
graph, equipped with a flame ionization detector (FID),
was used to measure VFA. Volatile separation was accom-
plished with an HP FFAP (free fatty acid phase) column
(0.25 m × 0.31 mm with 0.52  film thickness). The in-

Two-Stage Dilute Acid Hydrolysis of Dairy Manure for Nutrient Release, Solids Reduction and 226 Reducing Sugar Production
jection temperature was set at 175˚C and the flame ioni-
zation detector was at 250˚C. Helium was the carrier gas
at a head pressure of 69 kPa.
2.4. Experimental Design
Based on the results obtained from previous studies, an
acid concentration of 3% and a relatively moderate hy-
drogen peroxide concentration were selected for Stage 1
[9,10]. Acidified dairy manure (3% of H2SO4, 30 mL
each) was treated at two heating temperatures (120 and
160˚C), two heating times (20 and 60 min), and H2O2
dosages of 0 and 2.0 mL (0 and 0.38 g H2O2/g TS). A
total of eight experimental sets, each with six replicates
were performed in Stage 1 (Table 1). The rate of tem-
perature increase for all the experiments was set at 20˚C
per minute up to the designated treatment temperature
and subsequently held for the specified time period.
Following the microwave treatment, solids remaining
from each sample from Stage 1 were dried and used as
the substrate for the second stage (Stage 2). For Stage 2,
0.5 g of solids residue was dissolved in 30 mL of 3%
sulfuric acid solution, this was calculated as of 1.7% TS
in the solution. A heating temperature of 160˚C, and
heating time of 5 minutes were selected to facilitate the
breakdown of dairy manure fibers. Solids previously
treated at 0 mL H2O2 in Stage 1 were treated at 0 mL
H2O2 in Stage 2; similarly, substrates treated at 2 mL
H2O2 in Stage 1 were treated at 2 mL H2O2 in Stage 2
(Table 1). A much higher hydrogen peroxide dosage (1.2
g H2O2/g TS) was used in Stage 2 than that in Stage 1.
There were six replicates in each set of experiments.
3. Results and Discussion
3.1. Stage 1 Acid Hydrolysis
3.1.1. Re ducing S u gar Prod uc t ion
The effects of temperature, heating time and hydrogen
peroxide dosage on reducing sugar production are shown
in Table 2 and Figure 1. W hen heating time and d osage
were maintained constant, the yield of reducing sugar did
not increase with an increase of temperature from 120˚C
to 160˚C. When the temperatur e was maintain ed cons tant,
reducing sugar concentrations decreased with an increase
of heating time. A higher yield of reducing sugar was
obtained at no hydrogen peroxide (Figure 1). In the
presence of hydrogen peroxide, however, its yield de-
creased, as the reducing sugar produced were further
oxidized or decomposed. The higher temperature also
favored further oxidation reactions with the presence of
hydrogen peroxide, resulting in a lower reducing sugar
yield. The highest reducing sugar yield of 15.5% was
obtained at 120˚C, 0 mL H2O2, and 20 min of heating
time (Table 2). This was the highest reducing sugar yield
in the MW/H2O2-AOP applications conducted in our
laboratory [9,10]. The yield of reducing sugar was simi-
lar to the results with the conventional heating process
reported by Liao, et al. [1]. When raw dairy manure was
treated with 3% sulfuric acid at conventional heating for
1 hour, the yield was 12.28 g reducing sugar/g manure.
They also reported that the yield was very low at tem-
peratures below 110˚C, and a slight increase of the yield
was obtained with an increase of temperatures. The yield
did not increase at acid concentrations more than 3%,
while a very low yield of reducing sugar produced at an
acid concentration of 1%. Reducing sugars produced
from their study were mainly arabinose, galactose and
xylose. This indicated that hemicelluloses were solubi-
lized, and degraded into pentose under dilute acid con-
centration, and the residue solids were mainly cellulosics
[5]. Liao, et al. also stated that the conversion rate of
cellulose and hemicellulose to sugar from dairy manure
was very low under dilute acid and low temperatures
[14]. For the MW/H2O2-AOP, acid concentration, heat-
ing time and temperature, as well as interaction among
all three factors, affected reducing sugar yield from dairy
manure. The trend and the factors affecting reducing
sugar production for the MW/H2O2-AOP were also con-
sistent with the previous studies [9,10].
3.1.2. Nutrien t R e lease and S olids Disintegrat i on
The results of nutrient release and solid disintegration are
shown in Table 2. More ammonia and orthophosphate
were solubilized at 160˚C than at 120˚C (Figures 2 and
3). As high as 195% increase for ammonia and 307% for
orthophosphate were obtained at 160˚C, 2 mL of H2O2
and heating time of 60 min (Set 8). Up to 13% of the
TKN and 41% of the TP were released as ammonia and
orthophosphate, respectively. The lowest percentage in-
creases for both ammonia and orthophosphate were ob-
tained at 120˚C, 0 mL H2O2 and heating time of 20 min
(Set 1). The combined effects of temperature and time
also resulted in more nutrients being released. Higher
hydrogen peroxide dosages increased the amount of
ammonia and orthophosphate in solution (Figures 2 and
3). Hydrogen peroxide dosage affected more on ammo-
nia release than on orthophosphate release. Therefore,
the significant factors affecting ammonia release were
temperature and hydrogen peroxide dosage, while tem-
perature was the most significant factor affecting ortho-
phosphate release. To a lesser extent, heating time also
affected orthophosphate and ammonia release. Hydrogen
peroxide dosage was detrimental to the yield of reducing
sugar, but it did help solubilize phosphorus and ammonia.
The results were consistent with the findings of previous
studies [9,10,15].
The yield of ammonia and orthophosphate from this

Two-Stage Dilute Acid Hydrolysis of Dairy Manure for Nutrient Release, Solids Reduction and
Reducing Sugar Production
227
Table 1. Experimental design.
Stage Set no. TS (%) Temperature (˚C) H2O2 dosage (mL) Heating time (min)
1 1 5.4 120 0 20
2 5.4 120 2 20
3 5.4 120 0 60
4 5.4 120 2 60
5 5.4 160 0 20
6 5.4 160 2 20
7 5.4 160 0 60
8 5.4 160 2 60
2 1 1.7 160 0 5
2 1.7 160 2 5
3 1.7 160 0 5
4 1.7 160 2 5
5 1.7 160 0 5
6 1.7 160 2 5
7 1.7 160 0 5
8 1.7 160 2 5
Table 2. Overview of results for first stage of acid hydrolysis.
Set
no. Sugar (mg/L) Sugar (% TS)
S
COD (g/L) SCOD increase
(%)
TCOD
(g/L) VFA (mg/L) TKN (mg/L) NH4-N (mg/L)
NH4-N
increase
(%) TP (mg/L) PO4-P
(mg/L)
PO4-P
increase
(%)
1 8150 ± 996 15.1 21.4 ± 1.6 277 59.7 ± 9.41489 ± 1311117 ± 107140 ± 953 260 ± 14 128 ± 2169
2 3806 ± 745 7.0 22.4 ± 1.7 293 57.2 ± 4.4970 ± 2441187 ± 46208 ± 6126 248 ± 5 140 ± 71 95
3 5032 ± 723 9.3 21.9 ± 1.0 284 68.3 ± 4.4962 ± 2411250 ± 87148 ± 861 265 ± 7 132 ± 5178
4 3690 ± 880 6.8 23.0 ± 0.6 304 65.2 ± 9.0697 ± 2661165 ± 23224 ± 10144 242 ± 5 148 ± 10211
5 8356 ± 2987 15.5 28.2 ± 0.8 396 73.0 ± 8.168 7 ± 15 01194 ± 55172 ± 1087 254 ± 6 171 ± 7259
6 5124 ± 519 9.5 30.9 ± 1.7 444 67.1 ± 3.7319 ± 1581163 ± 7254 ± 11176 254 ± 8 180 ± 9279
7 4801 ± 597 8.9 28.4 ± 1.5 398 63.0 ± 7.7414 ± 2391206 ± 91209 ± 43127 259 ± 12 192 ± 6305
8 2538 ± 631 4.7 28.0 ± 3.3 391 62.7 ± 8.1291 ± 631028 ± 45271 ± 49195 237 ± 9 194 ± 9307
Figure 1. Reducing sugar produced from first stage of acid hydrolysis.

Two-Stage Dilute Acid Hydrolysis of Dairy Manure for Nutrient Release, Solids Reduction and 228 Reducing Sugar Production
Figure 2. Ammonia release from first stage of acid hydrolysis.
Figure 3. Orthophosphate release from first stage of acid hydrolysis.
study was comparable to the results reported by other
groups [16,17]. Similarly, the release of 20% - 40% solu-
ble phosphorus and 9% - 14% ammonia were reported
with microwave-based thermochemical treatment of
dairy manure [17]. Pan et al., [16] however, reported that
the MW/H2O2-AOP process could achieve up to 85% of
total phosphate release from dairy manure filtrate at
120˚C. This was due to the fact that a very high hydro-
gen peroxide dosage was applied in their study.
The MW/H2O2-AOP not only solubilizes phosphorus
and ammonia, but also reduces total suspended solids
(TSS) [15]. The concentration of SCOD increased with
an increase of temperature as showed in Figure 4. The
SCOD could further be oxidized and/or decomposed into
CO2 at a higher temperature and a longer reaction time,
therefore, its concentration decreased as shown in Set 8
(160˚C, 2 mL of H2O2 and reaction time of 60 min.
VFA existed mainly as acetic acid, and with some pro-
pionic, butyric and heptanoic acids. Highest VFA release
was at 120˚C, 0 mL of H2O2 and a reaction time of 20
min. VFA concentration decreased with an increase of
temperature, hydrogen peroxide dosage and reaction time
(Figure 5). The decrease in VFAs with a higher tem-
perature and a longer reactio n time could be due to either
vaporization of VFAs or oxidation to CO2 generation as
the end product [15].
3.2. Stage 2 Acid Hydrolysis
The results of Stage 2 of acid hydrolysis are shown in
Table 3; up to 4% of additional reducing sugar could be
obtained. The higher reducing sugar yield was obtained
in the process without adding hydrogen peroxide (Figure
6). It was not very effective in producing reducing sugar
in the second stage of acid hydrolysis, with a short reac-

Two-Stage Dilute Acid Hydrolysis of Dairy Manure for Nutrient Release, Solids Reduction and 229
Reducing Sugar Production
Figure 4. SCOD release from first stage of acid hydrolysis.
Figure 5. VFA release from first stage of acid hydrolysis.
Figure 6. Reducing sugar yield from second stage of acid hydrolysis.

Two-Stage Dilute Acid Hydrolysis of Dairy Manure for Nutrient Release, Solids Reduction and 230 Reducing Sugar Production
Table 3. Overview of results for second stage of acid hydrolysis.
Set no. Sugar (mg/L) Sugar yield
(% of TS) SCOD (g/L) TCOD (g/L) VFA (mg/L)TKN (mg/L)NH4-N (mg/L) TP (mg/L) PO4-P (mg/L)
1 667 ± 154 4 2.6 ± 0.3 14.9 ± 0.1 26 ± 1 193 ± 22 35 ± 3 20 ± 2 20 ± 1
2 129 ± 104 0.77 1.7 ± 0.6 11.2 ± 0.3 200 ± 89 176 ± 14 126 ± 3 19 ± 2 25 ± 2
3 31 9 ± 1 0 6 1.9 1 2.1 ± 0.4 16.4 ± 0.5 51 ± 35 156 ± 2 5 26 ± 2 22 ± 4 23 ± 2
4 25 ± 18 0.15 1.0 ± 0.2 13.7 ± 0.3 125 ± 49 151 ± 22 131 ± 5 20 ± 2 26 ± 2
5 299 ± 94 1.79 1.9 ± 0.2 24.8 ± 0.3 21 ± 0 1 37 ± 2 1 27 ± 2 20 ± 2 23 ± 1
6 2 ± 1.7 0.01 0.9 ± 0.3 19.8 ± 0.5 93 ± 27 177 ± 20 112 ± 7 20 ± 1 23 ± 2
7 29 ± 23 0.18 0.8 ± 0.0 19.9 ± 0.2 0 ± 0 173 ± 7 31 ± 1 24 ± 2 29 ± 9
8 1.5 ± 1.0 0.01 0.8 ± 0.0 16.9 ± 0.2 98 ± 20 180 ± 5 114 ± 7 21 ± 2 26 ± 2
tion time of five minutes, even at 160˚C. A low reducing
sugar yield was also due to very high hydrogen peroxide
dosage used in this stage (1.2 g H2O2/g TS). As reported
earlier in Stage 1, a high hydrogen peroxide dosage fa-
vors further oxidation process, as a result, it decreases
reducing sugar yield . The other reason was probably due
to the inherent characteristic of dairy manure; a high ni-
trogen content and crystallinity of lignocelluloses in
dairy manure [14]. A high conversion rate of reducing
sugar could only be obtained with very high acid con-
centrations wherein both hemicelluloses and cellulose
could be converted after decrystallization pretreatment
[14]. In order to achieve a much higher reducing sugar
yield from the residue solids obtained from Stage 1, a
much higher acid concentrations and/or a longer reaction
time need to be used in Stage 2.
Hydrogen perox ide addition favored the release of nu-
trients and solids disintegration from diary manure (Ta-
ble 3). Due to the high hydrogen peroxide dosage of 1.2
g H2O2/g TS, very high percentage of ammonia solubili-
zation, ranging from 63% to 86% was obtained. Low so-
luble ammonia concentrations were for those sets with-
out hydrogen peroxide addition (Figure 7). A high yield
of ammonia occurred at high microwave temperature of
160˚C and with H2O2; this was consistent with findings
of previous studies [9,10]. Phosphorus was completely
solublized into solution, with or without hydrogen per-
oxide (Figure 8). Temperature was the most significant
factor affecting orthophosphate release. The solubiliza-
tion of COD and formation of VFAs were influenced to a
large extent by hydrogen peroxide dosage (Table 3 ). Th e
presence of hydrogen peroxide resulted in less amounts
of SCOD in the solution (Figure 9). This could be due to
the conversion of all soluble organics in the substrate to
CO2 at the higher temperatures of 160˚C. TCOD concen-
tration in the treated solution was much less for the sets
with hydrogen peroxide than those without. This was
also an indication of CO2 formation as the end product in
the process. Solid residues previously treated (Stage 1) at
lower temperatures (120˚C) and shorter heating times (20
min) released more SCOD compared to residues previ-
ously treated at higher temperatures (160˚C) and longer
heating times (60 min). The presence of hydrogen per-
oxide resulted in an increase of VFAs. There were no
clear trends for the release of VFA with respect to heat-
ing time (Figure 10).
The trend for nutrient release and solids disintegration
for Stage 2 were similar to that of Stage 1. Due to the
very high hydrogen peroxide dosage in Stage 2, a much
lower reducing sugar yield was produced. However, a
much higher yield of both soluble ammonia and ortho-
phosphate was obtained. It is therefore recommended
that the MW/H2O2-AOP should be operated under the
reducing process for the production of reducing sugar,
and under the oxidative process for the solubilization of
nutrients and solid disintegration.
4. Conclusions
The MW/H2O2-AOP can b e an effectiv e method in treat-
ing dairy manure for nutrient release, solids reduction
and reducing sugar produ ction, ev en with a ver y low acid
concentrat ion of 3% .
For reducing sugar production, the MW/H2O2-AOP
should be operated under a reducing process (without hy-
drogen peroxide). Almost all of the reducing sugar was
converted in Stage 1, and only a small amount of addi-
tional reducing sugar was produced in Stage 2.
With a high hydrogen peroxide dosage and a higher
operating temperature of 160˚C in Stage 2, the nutrient
release conversion rate was much higher in Stage 2 in
than Stage 1. All of total phosphorus was converted to
orthophosphate, and a very high ammonia concentration
was obtained in the treated solution. For nutrient release
and solids disintegration, the MW/H2O2-AOP should be
operated under an oxidative process (with hydrogen
peroxide) to have the best result.

Two-Stage Dilute Acid Hydrolysis of Dairy Manure for Nutrient Release, Solids Reduction and 231
Reducing Sugar Production
Figure 7. Reducing sugar yield from second stage of acid hydrolysis.
Figure 8. Orthophosphate y ield from second stage of acid hydrolysis.
Figure 9. SCOD yield from second stage of acid hydrolysis.

Two-Stage Dilute Acid Hydrolysis of Dairy Manure for Nutrient Release, Solids Reduction and 232 Reducing Sugar Production
Figure 10. VFA yield from second stage of acid hydrolysis.
5. Acknowledgements
The authors wish to acknowledge research funding from
the Natural Science and Engineering Research Council
of Canada (NSERC).
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