Agricultural Wastes - Ingenta Connect

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.


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.


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).


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


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


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


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


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.


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


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

(