Agricultural Wastes Zhenyuan Zhang, Andrea M. Gonzalez, Evan G. R. Davies, Yang Liu*
ABSTRACT:
Agricultural wastes have become an
A study conducted by Nagle (2011) showed
increasing concern in recent years, as they may cause
that fruit residuals have high energy content. Results
significant environmental problems; however, they may
showed a mean waste-moisture content of 35%-75% wb,
also be used for several beneficial purposes, as feed
ash contents of 2.2-7.1 wt. % db and a high
stock for energy production, and for chemical recovery
volatile-matter content of 67-73 wt. % db, with heating
and chemical or dye adsorption. This review is divided
values found to range between 18.3 to 19.3 MJ/kg.
into the following four sections: agricultural waste
Faraco (2011) determined that residues from cereal
characterization, waste reuse and recycling, waste
crops, olive tree, tomato and grape provided abundant
treatment, and waste management and minimization.
lignocellulosic waste, which can be considered as potential raw material for large-scale ethanol production.
KEYWORDS: reuse, recycle, waste treatment, waste Biomass
management, characterization
Combustion
Byproducts.
Min
Doi: 10.2175/106143012X13407275695193
(2011) studied the gasification reactivity and chemical
Waste characterization
structure of char generated from the combustion of
Energy Content. In a thermal characterization
agricultural waste (corn straw and wheat straw), and
of biomass feedstock, Wilson (2011) found that waste
found that the char particles generated under high
must have a high H: C ratio and a relatively low O: C
pyrolysis temperatures had many smaller pores with
ratio.
thinner walls, larger surface area, and that they
—————————
experienced some melting. The results also indicated that
Department of Civil & Environmental Engineering, Markin/CNRL
Natural
Resources
Engineering
the chars’ microcrystals became larger at higher
Facility,
temperatures.
University of Alberta, Edmonton, AB, T6G 2W2, Canada; *
Corresponding
author
phone:
780-492-5515;
Heavy metals, like Hg, can be released from
Fax.
biomass burning. Huang et al. (2011) estimated average 780-492-0249; E-mail:
[email protected]
1386 Water Environment Research, Volume 84, Number 10—Copyright © 2012 Water Environment Federation
annual heavy metal emissions from biomass burning in China (including crop residual burning, forest and
Bacterial and Fungal Communities. Zhang
grassland fires, etc.) of 27 Mg/year.
et al. (2011) described how bacteria and fungi play an important role in determining the composition of
Agricultural and Natural Fibers. Cocozza et al.
(2011)
investigated
physical,
chemical,
agricultural waste. Experimental results showed that
and
WSC, ammonium, and nitrate influenced the temporal
spectroscopic characteristics of the residues of an
variation of bacteria community composition, while
endemic marine plant, Posidonia oceanica. They
variations in fungal community composition were more
concluded that the fibrous portion of P. oceanica can be
dependent on pile temperature, WSC, and moisture content. Bonetta (2011) investigated microbiological
used as a biofuel, due to its lower heating values between
contaminants stemming from the digested product of an
13.6 and 15.7 Mg/kg (Oswald, 2011). In addition, it was
anaerobic co-digestion of bovine manure and agricultural
found that while the leaves resembled a green waste with
byproducts, in a study involving microbiological
lower heating values around 10 MJ/ kg, which is not
analyses of bovine manure, fresh digested product, liquid
suitable for energy recovery. Kuan
et
al.
(2011)
investigated
and solid fractions, and stored liquid fraction of digested
the
product.
physicochemical characteristics of residues and soluble
more hygienic than bovine manure. The study also
fibrous residues produced from alkali-treated raw cereal materials (corncob and wheat straw)
Digested product was generally found to be
concluded that, in using animal manure for agricultural
with high
fertilization, anaerobic co-digestion of bovine manure
dietary-fiber content (49.87-68.65%). Cereal materials
and agricultural byproducts in a field-scale biogas plant
and insoluble fibrous residues were found to contain
does not increase human health risk.
essential minerals (in contrast to soluble fibrous residues), and showed 2,2-diphenyl-1-picrylhydrazyl
Decomposition. Barrena (2011) determined
radical scavenging ability, good emulsification ability
the potential for composition of individual samples by
and emulsion stability, mineral binding capacity, water
means of the oxygen uptake rate and the dynamic
capacity and oil holding capacity. The production of nanofibers
from
SF
by
electrospinning
respirometric index. High organic content concentration
proved
is not necessarily directly connected with degradability.
successful. Smith and Jones (2011) found that fresh coir
For example, materials with high lignin concentrations
fiber has an average absorption coefficient of 0.8 at
tend to have low biodegradability. Instead, the
frequencies greater than 1360 Hz and 20mm thickness. Increasing
the
thickness
can
help
to
respirometric characterization (oxygen uptake rate and
improve
lower-frequency sound absorption.
1387 Water Environment Research, Volume 84, Number 10—Copyright © 2012 Water Environment Federation
respirometric index) could be a significantly more
Gall et al. (2011) raised concerns about
reliable parameter.
manure used as agricultural fertilizer, which can
Arslan (2011) studied the effect of aeration
introduce natural and synthetic hormones to both
rates on agricultural waste composting. In the study, fruit
agricultural fields and aquatic ecosystems. In a study in
and vegetable wastes were composted at different rates
the Midwestern United States, hormone concentrations
and parameters such as moisture, temperature, pH,
in subsurface tile drains were found to increase during
electronic conductivity, C/N, and cellulose were tested.
effluent irrigation and storm events. Problems also
He concluded that, because the C/N ratio is an important
appeared to persist over winter, with pollutant-releases to
indicator of stabilization in compositing, the optimum
drainage ditches after snowmelt increasing hormone
aeration rate for aerobic composting of vegetable-fruit
concentrations in the water (87 ng/L for total estrogens
wastes was 0.62 L/min kg VS.
and 52 ng/L for natural androgens).
Research conducted by Gassara et al. (2011) in Reuse and Recycle
Quebec showed that solid wastes from fruits may release greenhouse gases to the atmosphere. Thus, although
Chemical Adsorption. Chen et al. (2011)
current management strategies comprising incineration,
showed that the maximum Cu (II) and Zn (II) adsorption
landfill,
fermentation
capacities of corn straw-based biochar reached 12.52
produced high value enzymes and animal feed, the
mg/g and 11.0mg/g, respectively, indicating that plant
production of greenhouse gases must also be considered.
residue-derived biochars can act as very effective
Specifically, treating 16209 t apple pomace with landfill
sorbents. Acheampong et al. (2011) investigated the
method resulted in greenhouse gas emissions of 1841 t
biosorption of Cu (II) onto coconut shell, coconut husk,
CO2 eq. per year.
sawdust and Moring oleifera seeds. Their results
composting,
and
solid-state
indicated that an exchange of Mg (II) and K (I) for Cu Agricultural Water Pollution. Li (2011)
(II), precipitation, and electrostatic forces were involved
found that long-term exposure to agricultural waste
in the sorption process.
water has caused a gradual deterioration in the water
Aktas and Morcali (2011) compared the gold
quality of Poyang Lake, the largest fresh-water lake in
uptake from dilute gold chloride solutions with 100 ppm
China, with increases in TSS, CODCr, BOD5, TN and
gold (Au3+) using Lewatit TP 214 and activated rice
TP. A second study estimated the total waste N released
husk. The results showed activation energies of 28.44
to surface water in China at 11.4 kg N in 2008, a figure
and 26.41 kJ/ml, and uptake capacities of 93.3 and 109.6
amounting to 40% of the total fertilizer N application to
mg Au/g for activated rice husk and Lewatit TP 214,
China’s cropland (Gu, 2011).
respectively.
1388 Water Environment Research, Volume 84, Number 10—Copyright © 2012 Water Environment Federation
Othman (2011) indicated that Cd (II) can be
In contrast, PAC could only remove 69.2 and 77.8% of
removed from aqueous solutions, using Tamrix articulate
Cr (VI) and cyanide, respectively, under the same
wastes modified chemically by esterification with maleic
conditions (maximum adsorption capacity of 47.6 and
acid. The maximum adsorption capacity of 195.5 mg/g
39.4 mg/g).
was achieved in a pH 4 solution at 30 °C with a contact time of 120 min, an initial concentration of 400 mg/L,
Dye adsorption. Dursun and Tepe (2011)
and an adsorbent dose of 0.3 g/L. The sorption process
found that dehydrated beet pulp carbon, an agricultural
was spontaneous, exothermic and was best described by
low cost by-product, can be used as an effective
a pseudo-second-order equation. Blázquez et al. (2011)
adsorbent to remove Chemazol Reactive Red 195 from
investigated the biosorption of Pb (II) from aqueous
aqueous solution. The maximum dye adsorption capacity
solution using olive tree-pruning waste at pH 5 in a batch
was obtained as 58.0 mg/g at 50 °C at an optimized pH
system. Spontaneous and exothermic, the process was
value (1.0). Adsorption was found to be strongly
best described with the pseudo-second-order kinetic
pH-dependent, endothermic and spontaneous.
model, while equilibrium results were best represented
Kumar et al. (2011) found methylene blue dye
with the Langmiur and Sips isotherms, with maximum
from aqueous solution can be absorbed onto cashew nut
sorption capacities of 26.24, 33.39 and 32.15 mg/g at 25,
shell. The process was controlled by both surface and
40 and 60 °C, respectively.
Kong et al. (2011) reported
pore diffusion, and the external mass transfer was the
that biochar prepared from soybean stalk using
rate-determining step. The authors concluded that
oxygen-limited pyrolysis was efficient at removing
cashew nut shell is effective for the removal of the
phenanthrene and Hg (II) from aqueous solution.
methylene blue dye. Moussavi and Khosravi (2011)
Sorption isotherms were best described by linear and
found that cationic dyes (e.g. methylene blue) can be
Toth model isotherms for phenanthrene and Hg (II),
removed from aqueous agricultural waste solutions
respectively, and direct competitive sorption was
through adsorption to pistachio hull waste. The removal
observed when both phenanthrene and Hg (II) were
efficiency of methylene blue reached 99.7 % at 70 min
present in the aqueous solution.
Moussavi and Talebi
contact time when pH and PHP dosage were 8 and 1.5
(2011) compared the co-adsorption of Cr (VI) and
g/L, respectively. Adsorption efficiency increased with
cyanide from electroplating wastewater using powdered
increasing temperature. The study concluded that
pistachio hull (PHP) and powdered activated carbon
pistachio hull waste could be a very efficient and
(PAC). With 2 g/L of PHP and 60 min of contact, PHP
low-cost adsorbent, and thus a promising alternative for
could
dye removal from industrial wastewaters.
completely remove
Cr
(VI)
and
cyanide
(maximum adsorption capacity of 117.6 and 151 mg/g).
1389 Water Environment Research, Volume 84, Number 10—Copyright © 2012 Water Environment Federation
Gao et al. (2011) showed that Reactive
biologically that can then be chemically converted to a
Brilliant Red K-2G in aqueous solution can be removed
wide variety of chemicals and fuels. Agricultural wastes
by chestnut shells, a low-cost adsorbent. Spontaneous
or residues with a high lignocellulose content (such as
and exothermic, adsorption followed a pseudo-second
paper and bagasse) can be used as feedstock and usually
order process with the adsorption rate governed by
have a high yield rate of biological fuel as compared to
external mass transfer. Amine, hydroxyl and phenolic
low lignocellulose content agricultural waste. Gautam et
compounds were found to be active binding sites.
al. (2011) compared gasification of different biomass
Parvarthi et al. (2011) showed that malachite green can
feedstock from agricultural waste. After gasification,
be removed from aqueous solution by cassava peel-based
peanut hull pellets were found to have the highest
activated carbon. Effects of the adsorbent dosage, initial
heating value of 6.1 MJ/m3, whereas poultry litter
dye concentration, pH and contact time were considered,
gasification gave the lowest heating value of 4.8 MJ/m3.
and results indicated that silver nitrate-treated cassava
Keskin et al. (2011) reviewed the use of
peel performed better than sulphuric acid treated and raw
photosynthetic bacteria to capture solar energy and to
carbons. Safa and Bhatti (2011) indicated that Everdirect
drive the nearly complete conversion of substrates to
Orange-3GL and Direct Blue-67 dyes can adsorb directly
hydrogen and carbon dioxide. The process, also called
onto rice husk from aqueous solution. The sorption
photo-fermentation, can potentially use various industrial
process was associated with hydroxyl functional-group
and agricultural waste streams rich in sugars or organic
activity and was influenced more by pH than by either
acids as feed stocks to produce the desired amount of
the initial dye concentration or the biosorbent dose.
hydrogen. Malatji et al. (2011) indicated that briquettes made from wood and agricultural waste can be gasified
Energy. Cheng and Chang (2011) used bagasse
for
hydrogen
cellulases/xylanase pasteurianum
can
production.
produced hydrolyze
by cellulosic
Because
in a down-draft gasifier for electricity generation. Their
Clostridium
results showed a gasification performance comparable to solid pine wood.
materials
effectively, they were used to hydrolyze natural
Meeuwse (2011) evaluated the potential use of
agricultural waste (i.e., bagasse) for H2 production by
lipid-accumulation fungi for the production of biodiesel
using separate hydrolysis and fermentation process. The
precursors from agricultural wastes. A model was
hydrogen yield in this study was around 0.96 mol H2/mol
developed to describe the growth, lipid accumulation and
glucose.
substrate
consumption
of
the
oleaginous
fungus
Forrest et al. (2011) used the MixAlcoTM
Umbelopsis isabellina in submerged chemostat cultures.
process to convert biomass to carboxylate salts
However, the approach may not be valid for lower
1390 Water Environment Research, Volume 84, Number 10—Copyright © 2012 Water Environment Federation
dilution rates because of practical problems with the
palm oil empty fruit bunches. Tye et al. (2011) discussed
filamentous fungus.
second-generation bioethanol as a renewable energy
Missagia et al. (2011) studied the densification
source, in particular in the transportation sector. They
characteristics of Brazilian rice husks by using a
estimated that the biomass available from agricultural
laboratory compactor for pellet production. They found
waste is 50.9×106 kg/year in Malaysia, with the potential
that rice husk pellets with 17% water content and ground
to
with 2, 4 and 6 mm sieves were durable and stable.
approximately 21.5% of total Malaysia’s energy
Shie et al. (2011) evaluated several energy
generate
13.3×106
kg/year
of
bioenergy
–
requirement.
indicators and four potential gasification technologies,
El-Zawawy et al. (2011) studied the conversion
through an energy life-cycle assessment using rice straw
into glucose of rice straw, banana plant waste and corn
as a bio-fuel source. Results indicated that each of the
cobs for ethanol production through acid and enzyme
gasification technologies has a positive energy benefit;
hydrolysis. The materials were first pre-treated by
further, major components of the energy life cycle
applying the chemical pulping and steam explosion
assessment were the calculation of the energy inputs for
method and microwave treatment, and then submitted to
transportation and pre-treatment.
acid hydrolysis using 5% sulfuric acid or enzyme
Cuetos
et
al.
(2011)
investigated
the
hydrolysis using Trichoderma reesei cellulases. The
co-digestion of swine manure and three energy crop
results
residues (maize, rapeseed or sunflower residues) to
subsequent ethanol production yields varied according to
determine methane yields and reactor behavior. Batch
the type of pre-treatment and the hydrolysis method.
experiments were conducted with swine manure having
Gu et al. (2011) discussed biofuel production using
25, 50 and 75% volatile solids. Results indicated that the
waste nitrogen on untilled or marginal land in China.
addition of crop residues increased the amount of biogas
They estimated that in 2008 the total waste nitrogen lost
produced, with the highest yield obtained when
to surface water and the total potential biofuel produced
co-digesting rapeseed (3.5L/day).
Omar et al. (2011)
by waste nitrogen were 11.3×109 kg/year and 16.4×1012
characterized oil palm empty fruit bunches for
kJ/year, respectively. The net energy balance of biofuel
microwave-assisted pyrolysis and determined that they
production using waste N in China was 5.7×105
have fuel and chemical characteristics similar to other
kJ/km2/year – much higher than other major biofuel
biomass types. High water content, high volatile content
production systems currently in use. The total maximum
and moderate potassium content were identified. The
land requirement for the total energy consumption in
result showed that microwaves were the best heating
China was found to be 17.5% of China’s total untilled
source for biomass with above characteristics similar to
land resource.
showed
that
glucose
concentration
1391 Water Environment Research, Volume 84, Number 10—Copyright © 2012 Water Environment Federation
and
Kahiluoto et al. (2011) reported that energy
nitrate losses (152, 145, 145 kg N/ha, respectively)
recovery and nutrient recycling from agrifood waste and
compared to the control (50 kg N/ha).
by-product biomass had the potential to mitigate climate
Jacinthe et al. (2011) determined that manure
change and eutrophication in two regions in Finland.
application to cultivated land not only increased the
They found that energy recovery corresponded to 5-10%
nutrients in the soil, but also contributed to soil carbon
of the fossil energy used in the region, and led to a
sequestration. They suggested that, in comparison with
one-third reduction of all agriculture-based GHG
conventional
emissions. The reduction in fertilizer manufacture with
practices increased the size of the soil microbial
efficient recycling contributed to an additional one-fifth
community, and organic farming process added carbon
reduction in GHG emissions along with a 14-20%
substrate more efficiently as compared with the
reduction in energy use. Nutrient recycling corresponded
community present in conventional practice.
to 99% of P and 45-72% of N in the yields harvested.
farming
practices,
organic
farming
Paradelo et al. (2011) indicated that vineyard soil amended with grape marc vermicompost could be
Biofertilizers, Cultivation Materials and Soil
used in carbon and nitrogen mineralization. They
Amendments. Figueiro and Graciolli (2011) used rice,
concluded that 17 kg/km2/year and 21 kg /km2/year of
bean, wheat and sorghum straw, banana leaf and maize
bulk vermicompost should be added if the present mean
cobs as the substrate in cultivating Pleurotus florida, an
temperature and a 2 °C increment in temperature are
edible mushroom. They found that substrates with a C/N
considered, respectively, in order to sustain initial levels
ratio around 45, high ash content and high levels of P, K,
of organic matter.
Ca, Mg and Mn formed the best cultivation medium.
Kunhikrishnan et al. (2011) studied the
Carneiro et al. (2011) evaluated nitrate leaching from the
transformation and photoavailability of Cu in Gawler
application of cattle slurry (CS), sewage sludge and
and Adelaide Hills (Australia) soils treated with recycled
urban waste compost to a maize and oat double-cropping
water and Cu uptake by Indian mustard (Brassica juncea
system. Several treatments were considered, including a
var. Varuna) plants. Monitoring of CaCl2 extractable and
nitrification inhibitor with a mineral fertilizer treatment
pore water free Cu2+ concentrations indicated that
(MIN) and CS, an organic residue with a high C/N ratio
increasing the level of Cu led to elevated concentrations
(pulp mill sludge – PMS) together with mineral fertilizer
in plants. However, the presence of organic carbon in the
(PMS+M), and split applications of sewage sludge and
recycled water reduced the Cu uptake compared to
urban waste compost. PMS+M,
split
Milli-QTM water. Rittmann et al. (2011) reported on P
applications of sewage sludge showed higher annual
recovery from animal waste, which required conversion
MIN and
1392 Water Environment Research, Volume 84, Number 10—Copyright © 2012 Water Environment Federation
of organic P into inorganic P and can be accomplished
could be applied to vast plantations of short rotation
through anaerobic treatment.
coppice in Europe, although the use of more P-rich
Zanon et al. (2011) demonstrated the use of
residues might be more economical.
tomato crop residues as a soil amendment to control
Odlare et al. (2011) investigated the potential
bacterial wilt caused by Ralstonia solanacearum.
risks and benefits of using compost and biogas residues
Experiments with tomato growth substrate amended with
from source-separated household waste in agriculture as
tomato debris and artificially inoculated with the
compared to a traditional mineral fertilizer. They found
pathogen were carried out. Heat treatments at 45 °C
that biogas residues produced crop yields almost as high
decreased tomato wilt indices and eradicated the
as those obtained using a mineral fertilizer. Biogas
pathogen; in contrast, lower temperature treatments at 25
residues and
°C did not eradicate the pathogen even after six weeks of
respiration, potential ammonium oxidation, and nitrogen
continuous treatment.
mineralization with no apparent negative effects.
compost
improved
substrate-induced
Carbonell et al. (2011) assessed the effect of
Etter et al. (2011) investigated the production
municipal solid waste compost (50 Mg/ha) and NPK
of struvite in Nepal (MgNH4PO4∙6H2O) using urine as
(nitrogen, phosphorous, potassium) fertilizer (33 g/plant)
fertilizer, as well as means for optimizing the process.
amendments on the concentration of metals in soils and
They reported that a reactor with an external filtration
different parts of maize plants. Municipal solid waste
system had a higher P-removal capacity (90%),
compost
compared to a reactor based on sedimentation only
and
NPK
fertilizer
enhanced
biomass
production, but the solid waste compost increased the
(50%).
concentration of Cu, Pb and Zn in the soil, while NPK
Nakatani et al. (2011) examined effects of
fertilizer increased Cd and Ni, and decreased the Hg
tannery sludge applications, with total N-content of 0 to
concentration. The concentration of metals was higher in
1200 kg N/ha, on the structure of bacteria and microbial
roots than in above-ground parts of the plant, with no
activity in agricultural soil. The first sludge application
significant differences between the two amendments.
was found to stimulate biological activity strongly up to
Dimitriou and Rosenqvist (2011) reported that
300 days after application through increases in
the gross margin for short rotation coppice is only
inorganic-N and soil pH; enzymatic activities related to
positive if biomass production is greater than 1.442 t
N-cycling
GJ/km2, but the use of sewage sludge and wastewater as
most-influenced properties.
fertilizer increases the gross profit margin by 39 and 199
a lower and shorter effect on microbial activity, leading
€/GJ. They estimated that 6000 PJ of renewable energy
to no measurable difference between treatments after 666
could be produced annually if all sludge and wastewater
days.
(asparaginase
and
urease)
were
the
The second application had
1393 Water Environment Research, Volume 84, Number 10—Copyright © 2012 Water Environment Federation
Paradelo et al. (2011a) studied the effect of two
used in P recovery. The feasibility of its use, in
municipal solid waste composts (at 3% and 6% dry
combination with Zr, was investigated for P recovery
weight) as amendments for contaminated agricultural
from secondary effluent and side-stream liquid, which
soil on the availability of Cu, Pb and Zn. The results
contained 5.9 and 68.2 mg/dm3 P, respectively. After
showed that the composts reduced the solubility of the
secondary effluent treatment with Zr-SOW gel, a
metals, in particular Cu and Pb, and reduced the
dynamic adsorption capacity of 1.3 mol P/kg was
leachability of the three metals.
attained. Further, the adsorbed P was successfully eluted
Rigane and Medhioub
(2011) investigated the physicochemical properties of six
as a concentrate, using 0.2 M NaOH.
organic soil improvers (almond shell, sesame bark, olive
Velmurugan et al. (2011) reported that
cake, olive mill wastewater sludge, poultry manure, and
Monascus purpureus KACC 42430 can produce
mixtures of compost-manure) made from agricultural
pigments in solid-state fermentation, using corn cob
waste.
as
powder as a substrate. They achieved a pigment yield of
components in reconstituted anthropic soils showed
25.42 OD Units/g using 60% (w/w) initial moisture
differences in soil organic matter content, pH and
content, incubation at 30 °C, inoculation with 4 ml of
electrical conductivity, with subsequent effects on the
spores/gram of dry substrate, and an incubation period of
yield and quality of tomatoes.
7 days.
The
application
of
these
treatments
Pigment concentration was higher than those
produced from other agricultural waste substrates and Chemical generation and recovery. Gopinath
was stable at acidic pH, high temperatures, and in salt
et al. (2011) determined that amino acid can be produced
solutions.
from rice straw and wheat bran hydrolysates by recombinant
pentose-utilizing
Khanifar et al. (2011) reported that tryptophan
Corynebacterium
can
be
produced
from
microbial
protein
of
glutamicum. The ethambutol-triggered production of
lignocelluloses waste. Wheat straw was treated with heat
l-glutamate was up to 93 +/- 4 mM by the wild
at 100 °C under alkaline conditions and Pleurotus
type-derived recombinant, while l-lysine production was
floridas was cultivated using solid-state fermentation.
up to 42 +/- 2 mM by the recombinant lysine. By
Tryptophan was analyzed using alkaline hydrolyses with
providing carbon and energy sources, the result revealed
Ba(OH)2, 4 Normal at 110 °C for 48 hours of the
that acid hydrolysates of agricultural waste materials
extracted protein. Tryptophan was 0.96 g/100 g of the
may provide an alternative feedstock for large-scale
extracted protein as detected by an A-200 amino nova
amino acid production.
analyzer. The study determined the nutritional benefit
Ohura et al. (2011) indicated that orange waste,
that could make this single cell protein an appropriate
an available and inexpensive agricultural waste, could be
animal feed.
1394 Water Environment Research, Volume 84, Number 10—Copyright © 2012 Water Environment Federation
Bajwa et al. (2011) evaluated the properties
Kim (2011) reviewed techniques to recover
and suitability of residual plant fibers as reinforcement in
salts from rejected brine from desalination plants,
thermoplastic composites. Five fiber filler treatments
agricultural drainage and other industries, including
were investigated: control (oak wood fiber filler - OWF),
hybrid systems that combine two or more techniques. He
cotton burr and sticks (CBS), CBS with 2% (by weight)
also conducted economic analysis comparing, using and
second cut linters (CBL), CBS with 30% (by weight)
disposing of the concentrate. Liou and Yang (2011) reported nanosilica can
guayule whole plant (GCP), and CBS with 30% (by weight) guayule bagasse (CGB). The results showed that
be
produced
from
rice
husk
by
using
a
although the physical and mechanical properties of the
dissolution-precipitation technique. They indicated that
composites varied, all exhibited potential for use as fiber
hydrochloric acid produced silica with a higher surface
fillers.
area than sulfuric, oxalic, and citric acids. Results Tuan et al. (2011) investigated the preparation
showed the highest surface area of 634 m2/g, the highest
and properties of silver nanoparticles (4-30 nm) loaded
pore volume of 0.811 cm3/g, pore diameters from 3 to 9
in coconut husk-based activated carbon, and their
nm, and uniform particle size of 5-30 nm. Min et al. (2011) compared the characteristics
application in the treatment of microbial infection. The nanoparticle-loaded activated carbon had a surface area
of
pectins
prepared
from
apple
pomace
using
of 890 m2/g and showed similar morphology and
water-based extraction combined with physical and
methylene adsorption ability compared to non-loaded
enzymatic treatments, and chemically-extracted pectins.
activated carbon, with the added advantages of a low
Pectins produced by physical/enzymatic treatments had
minimal-inhibitory concentration of Escherichia coli and
lower galacturonic acid and yield, a higher degree of
strong As (V) adsorption.
esterification, decreased viscosity and less elastic
Sarangi et al. (2011) studied the effect of
properties under high shear-rate conditions than those
temperature on nano-crystalline silica and carbon
produced through chemical extraction. However, pectins
composite powder produced from pyrolysing rice-husk
extracted by both methods showed shear-thinning
ash. The phase transition and crystallite sizes of silica
properties when subjected to steady shear.
and carbon, as a function of heat treatment at temperatures ranging from 400 to 1200 °C over two
Construction material. A study conducted by
hours, were examined through X-ray diffractometry,
Khorami et al. (2011) compared bagasse, wheat and
scanning electron microscopy and Fourier transform
eucalyptus fiber to produce fiber cement boards. The
infra-red spectroscopy.
results showed that the flexural behavior of fiber cement boards depends on the type, length, diameter, aspect ratio
1395 Water Environment Research, Volume 84, Number 10—Copyright © 2012 Water Environment Federation
and texture of the fibers. It also showed that increasing
sawdust showed the lowest reduced sugar yield (1.12
fiber content from 2% to 4% of the cement weight can
mg/ml) when treated with enzyme, and the lowest
increase flexural strength.
saccharification rate (5.92%) when treated with alkaline.
Karademir et al. (2011) indicated that luffa
Chan (2011) showed that rice husks can be
fibers and yarn waste could be used in combination with
used as a catalyst in the preparation of phenols from
recycled cellulose fibers for insulation and packaging
CsOH and aryl iodides using CuO on mesoporous silica.
materials.
The brightness of the control sheets, sound
Further, the loading of the catalyst was found to be as
absorption, air permeability, thermal stabilities, print
low as 1 mol-%, which makes rice husk a very attractive
density and tone values were all improved; however,
green catalyst.
luffa fibers and yarn waste also significantly reduced the burst and tensile indexes.
Treatment Anaerobic Treatment. Govasmark et al.
Enzyme and Catalyst. Khan et al. (2011)
(2011) found low chemical and microbiological risks
investigated the production of amylase from industrial
from the anaerobically digested residue (ADR) produced
and agricultural waste by microbial action using
in three Norwegian full-scale biogas plants (BGP), and
thermophilic actinomycetes. They studied six strains of
intended for agricultural use. The ADR showed high
actinomycetes (AH-I to AH-VI) and determined that the
concentrations of Zn and Cu in the solid fraction, and
strain AH-II was the best for the production of amylases.
high concentrations of Cd in the liquid fraction, which
The effect of metal ions and optimal conditions for
classifies it as a quality 1 organic fertilizer according to
maximum amylase production were also assessed.
Norway standards. Two pollutants, diethylhexylphthalate
Begum and Alimon (2011) investigated the
and PAH 16, were found in high concentrations, while
induction of cellulose enzyme by Aspergillus oryzae
only two out of eleven pesticides detected, imazalil
ITCC-4857.01, and the potential of the induced enzyme
(