CARBON TUBES2AbstractCastelvecchi, D. (2008, Aug.docx

CARBON TUBES
2
Abstract
Castelvecchi, D. (2008, August 30). Carbon tubes leave nano
behind. Science News, 174(5),
9-9. Retrieved from http://www.sciencenews.org
This news article for science professionals describes an
accidental discovery of “colossal carbon tubes” by Los Alamos
National Laboratory researchers. Although the hair-sized tubes
are weaker than the nanotubes that have so far dominated
carbon fiber research, these remain 30 times stronger than
Kevlar and because of size, might be easier to weave together
into useful materials. If true, this could be significant: Many
geo-engineering plans require cables that can handle a great
deal of stress. If colossal tubes are strong enough, these might
help us build “space elevators,” which are cables that reach
from the planet’s surface into orbit, enabling us to implement
space-based solutions to climate change more easily. The tubes
even reportedly conduct electricity, which suggests a possible
use to tether floating wind turbines and to conduct power to
users on the ground, simultaneously. It is not yet clear from the
literature whether colossal tubes can do these jobs, but these
might be the best contenders discovered so far.
Waste Management & Research

30(8) 849 –858
© The Author(s) 2012
Reprints and permission:
sagepub.co.uk/journalsPermissions.nav
DOI: 10.1177/0734242X12448515
wmr.sagepub.com
Introduction
The slow biodegradation rate of municipal solid waste (MSW)
in
the landfills creates land-reuse bottlenecks. Land that could be
used for development is instead rendered unusable due to
unstable
landfills from the past. Numerous studies have shown that
leachate
recirculation in bioreactor landfills can accelerate the breaking
down of rubbish and can reduce long-term risk. There are
several
advantages to bioreactor landfills (Barlaz et al., 1990; Pohland
and
Kim, 1999; Reinhart and Townsend, 1997). Leachate is
reinjected
back into the landfill to promote in-situ anaerobic biological
deg-
radation. The advantages of leachate recirculation have been
dem-
onstrated by many researchers who performed numerous
lysimeters
and field tests (Chugh et al., 1998; Doedens and Cord-
Landwehr,
1989; El-Fadel, 1999; Erses and Onay, 2003; Kinman et al.,
1987;
Onay and Pohland, 1998; Otieno, 1994; Pohland, 1980; Pohland
and Kim, 1999, 2000; San and Onay, 2001; Tittlebaum, 1982;
Townsend et al., 1996). In addition, this method reduces the

nega-
tive effects from co-disposal of both organic or inorganic
hazard-
ous waste with MSW (Pohland and Kim, 1999). A study on an
in-situ bioreactor landfill in Nepean, Ontario, Canada showed
the
significance of leachate recirculation in increasing
biodegradation
efficiency (Warith, 2002). Some mechanisms, such as increasing
moisture content, offering better contact with the low
dissolvable
material, thus improving its availability also enhance micro-
organ-
ism activity. The improved activation of micro-organisms helps
degrade organic matters more quickly, thus shortening the
poten-
tial pollution time (Barlaz et al., 1990). The increased moisture
content (field capacity) by leachate recirculation enhanced
biologi-
cal stabilization in bioreactor landfills with a field capacity of
about or higher 45% of MSW (Valencia et al., 2009). In-situ
lea-
chate recirculation leads to the high decomposition efficiency of
more than 163 L m−2 of waste in North America (Benson et al.,
2007).
The landfill problem of how to accelerate biodegradation and
shorten the costly pollution monitoring period becomes impor-
tant. One of the solutions is to supply air to maintain the
aerobic
environment in the landfill site. The aerobic landfill technology
has been evaluated over the last few years to rapidly stabilize
and
detoxify the waste, reduce methane gas, volatile organic com-
pounds and odour emissions as well as eliminate off-site

leachate
Enhanced leachate recirculation and
stabilization in a pilot landfill bioreactor
in Taiwan
Fu-Shih Huang1,2, Jui-Min Hung1 and Chih-Jen Lu1
Abstract
This study focused on the treatment of municipal solid waste
(MSW) by modification and recirculation of leachate from a
simulated
landfill bioreactor. Hydrogen peroxide was added to
recirculated leachate to maintain a constant oxygen
concentration as the leachate
passed again through the simulated landfill bioreactor. The
results showed that leachate recirculation increased the
dissolved oxygen
concentration in the test landfill bioreactor. Over a period of
405 days, the biochemical oxygen demand (BOD5) in the
collected
leachate reduced by 99.7%, whereas the chemical oxygen
demand (COD) reduced by 96%. The BOD5/COD ratio at the
initial stage
of 0.9 improved to 0.09 under aerobic conditions (leachate
recirculation with added hydrogen peroxide) compared with the
anaerobic
test cell 0.11 (leachate recirculation alone without hydrogen
peroxide). The pH increased from 5.5 to 7.6, and the
degradation rate of
organic carbon was 93%. Leachate recirculation brings about
the biodegradation of MSW comparatively faster than the
conventional
landfill operation. The addition of a constant concentration of
hydrogen peroxide was found to further increase the
biodegradation.

This increased biodegradation rate ultimately enables an MSW
landfill to reach a stable state sooner and free up the land for
further
reuse.
Keywords
Leachate recirculation, landfill, bioreactor, municipal solid
waste, hydrogen peroxide
1 Department of Environmental Engineering, National Chung
Hsing
University, Taichung City, Taiwan
2 Environmental Protection Bureau, Taichung City Government,
Taichung City, Taiwan
Corresponding author:
Chih-Jen Lu, Department of Environmental Engineering,
National
Chung Hsing University, No.250, Kuo Kuang Rd., South Dist.,
Taichung city 402, Taiwan
Email: [email protected], [email protected]
448515WMR30810.1177/0734242X12448515Huang et al.Waste
Management & Research
2012
Original Article
at UNIVERSITY OF TOLEDO LIBRARIES on February 14,
2016wmr.sagepub.comDownloaded from
http://wmr.sagepub.com/
850 Waste Management & Research 30(8)

treatment needs (Cossu et al., 2003; Jacobs et al., 2003; Kim,
2005; Purcell, 2000a, b; Read et al., 2001). Aerobic reactions
are
favorable because of the high removal efficiencies for the
buried
matter, thus decreasing the time required for stabilization
(Giannis et al., 2008). When the BOD5/COD ratio is below 0.1
with aerobic reactions, the decomposition of waste is almost
accomplished (Pohland and Harper, 1986). Aerobic pretreatment
of recirculated leachate might inhibit methanogenesis in the
MSW landfill site (Stegmann et al., 1987). Aerobic treatment of
MSW also has been proven to reduce the potential for metha-
nogenesis (Comilios et al., 1999). However, another additional
advantage is that aerobic decomposition can decompose lignin
to
cellulose and half-cellulose improving the follow-up
biodegrada-
tion (Szegi, 1988). In conventional landfill management, site
operations and leachate monitoring continue for many decades
after the closure of the landfill. The use of aerobic techniques
can
shorten that time by 10 years. This period might be further
reduced, as combining with leachate recirculation. This reduced
monitoring cost and earlier availability of the land for reuse are
the prime reasons for adopting the aerobic biodegradation
approach (Mehta et al., 2002; Price et al., 2003; Reinhart et al.,
2002).
The present situation in Taiwan, a country that has limited
available land, has forced the closure of landfills. The high cost
of
providing power for compressed air operations means that such
methods can only be used for short periods of time. Leachate
recir-
culation is an option, but being an anaerobic environment in

land-
fill site, it does not have some of the aforementioned advantages
of
aerobic techniques. To obtain the advantages of both leachate
recirculation and aerobic decomposition, this study has adopted
the process of hydrogen peroxide enhanced leachate
recirculation
to increase dissolved oxygen concentration in the bioreactor
land-
fill. The application of experimental result from the pilot study
on
a full-scale landfill bioreactor could be summarized as
followings.
The collected landfill leachate has been recirculation into the
land-
fill site using: (a) overflow ponds, (b) injection into the gas
wells
(methane well), (c) sprinkling on the surface of closured
landfills,
and (d) injection into multiple-pore pipes buried under the top
soil
cover about 1 m. The above mentioned methods have been oper-
ated at different operating or closured landfill site in Taiwan.
Material and methods
Equipment
This research employed three bioreactor landfills. The bioreac-
tors were designed to be 2.58 m in diameter (ψ) and 3.66 m in
height (H). The effective sectional area was 5.22 m2. The
reactors
were composed of high-density polyethylene (HDPE). Figure 1
shows a schematic diagram of the in-situ field-scale pilot setup
Grand stone

Reactor cell
Municipal Solid Waste
Municipal Solid Waste
Collection pipe
Soil layer ≈ 15 cm
Soil layer ≈ 50cm
Gas collection
Buffer tank
Pump
Air compresor
Air pipe
Leachate collection tank
Check valve
Check valve
Leachate recirculation
Gravel
Leachate recirculation
Figure 1. Schematic of experimental landfill reactor.

Huang et al. 851
used in this study. Each pilot bioreactor landfill included a main
landfill cell, leachate collection pipes, a leachate equilibrating
tank, an aeration mixer with an air pump (0.45 hp), gas
collection
pipes, a leachate recirculation motor (0.5 hp), and water sprin-
kling system. After all of the piping was installed, the cell con-
necting parts were sealed to provide effective leak protection.
The MSW used in this study was collected from a transfer sta-
tion in Dali city, Taichung County, Taiwan. The MSW (by
weight)
consisted of 45.8% paper, 37.1% kitchen waste, 11.7% plastics,
2.2% branches and leaves, 1.97% glass, 1.3% fibres/cloth,
0.03%
scrap iron, 0% non-iron scrap metal, and other constituents
(pot-
tery, sand) totalling 0.2%. As a result of the Taiwanese custom
of
disposing of rubbish in plastic bags, rubbish was inserted into
the
cells after breaking the bags.
The MSW was buried in the cells in two layers. About 1.5 m
of rubbish was buried in two layers, separated by 15 cm of soil
in
the middle, then covered with an additional 50 cm layer of soil
on
the top. The cover soil was collected from a sanitary landfill

site
in Dali City, and it consisted of sandy loam with a small amount
of gravel. The cover soil was handled and applied in accordance
with the regulation of the Municipal Waste Recycling, Cleaning,
and Treatment Regulation of Tiawan.
In the final setup, leachate was recirculated from the leachate
circulation tank and sprinkled back onto the top layer of soil in
the cells to maintain the moisture content in the cell. Every
pilot
bioreactor had a packed weight of 3500 ± 175 kg of MSW, and
the average specific weight of the compacted waste in each
waste
cell was 224 kg m−3. Hydrogen peroxide, H2O2, at 35% was
added to one of the recycled leachates.
Operation
The three pilot landfill bioreactor’s leachate recirculation were
operated as the SBR sequencing batch reactor mould with
differ-
ent recirculation conditions. The operated pilot bioreactors with
or without the additions of H2O2 into the leachate recirculation
are as follows: (1) leachate with the addition of H2O2 to
bioreac-
tor A as the aerobic cell; (2) anaerobic circulation with leachate
recirculation alone into bioreactor B as the anaerobic cell; and
(3) aerobic/anaerobic circulations with the leachate that had
intermittent additions of H2O2 as the bioreactor C. Water com-
mensurate with the average rainfall of 5 years in Taiwan was
added to the collection tank and mixed with the collected lea-
chate to simulate the rainfall. After mixing for 3 min, the mixed
leachate was then recirculated into the bioreactor. In bioreactor
C, at 2-month intervals, hydrogen peroxide was added at a con-
centration of 200 mg L−1. After 121 days, this was increased to
a

concentration of 500 mg L−1 until the end of the 405-day
experiment.
The sampling frequency was once per week in the first 3
months in the post-closure cell, every 2 weeks from the 4th to
6th
month, once per month from the 7th to 10th month, and every
second month from the 11th to 16th month (until the end of the
experiment). The leachate recirculation frequency in the first 6
months was the same as that used for the sampling. In
subsequent
months it was once per month until the end of the experiment.
The experiment period was 405 days from 26 July 2008 to 4
September 2009.
Analysis method
The conductivity (EC), pH, redox potential (ORP), and
dissolve oxygen concentrations were measured with a portable
meter WTW Cond 315i, pH 330, and Oxi 330, respectively.
BOD5 and COD concentrations were determined according to
the
standard methods of the American Public Health Association
(APHA, 2005). The volatile fatty acid (VFA) analysis was car-
ried out with a high-performance liquid chromatograph and
vari-
able wavelength ultraviolet (HPLC/UV) (Hewlett Packard 1100
series) equipped a stainless steel Chrompack column (TC-C18,
Agilent) of dimensions 4.6 mm × 250 mm × 5 µm film. The con-
centrations of CH4 and CO2 gases were determined by a gas
chro-
matography with thermal conductivity detector (GC/TCD)
(Hewlett Packard 6890) equipped with a capillary column (DB-
624, J & W scientific) of dimensions 0.53 mm × 30 m × 3 µm
film. All samples were tested in triplicate.

Results and discussion
pH and ORP
The pH value of the A, B, and C cell leachate, with the three
dif-
ferent operation modes, ranged from 5.5 to 7.6. The pH value
was
more acid in the initial stage, and latter stage leaned toward
slightly alkaline. The bioreactor biochemically reacted from
hydrolysis in the initial stage to initiate acidic decomposition,
and through the methanogenesis process, then gradually reached
the mature steady stage. These trends are illustrated in Figure 2.
The change of pH values from the initial stage to steady state
tended to be similar to the pattern found in an actual field
experi-
ment in Canada (Nepean, Ontario) and in pilot-scale studies of
MSW in Toronto (Warith, 2002). Figure 2 shows that the pH
value in the aerobic (A) cell about 7 after 3 months, and in the
anaerobic (B) cell it was below 7 after 4 months of operation.
This shows that bioreactor A had accomplished the acidic stage
earlier than bioreactor B.
Most measurements of ORP were negative, approximately
−159 ± 45 mV. The lower ORP values show in Figure 3
indicated
there was little available oxygen after the covering with soil.
Even the addition of H2O2 (200–500 mg L
−1) was not enough to
change the ORP value. Hence, the oxygen provided by this con-
centration of H2O2 was unable to make the test cell completely
aerobic. This means some of the biodegradation belongs to
facul-
tative aerobic digestion because the majority of the ORP was in
anaerobic conditions. By transforming organic matters to

organic
acid, ORP decreased gradually. This phenomenon is generally
associated with anaerobic environments (Pohland and Kim
1999).
The fact that the leachate temperature was higher than the sur-
rounding temperature shows that the decomposition reaction
must be considered mesophilic biological decomposition. In
addition, the leachate had higher conductivity values (EC)
(Figure 4), showing that the leachate (including the cover soil
composition) contained various kinds of salt. This effect may
have been produced from kitchen waste, because of the use of
high amounts of salt in food, as is the Taiwanese habit.
The system was acidogenic at the initial stage and then gradu-
ally changed into a methanogenesis stage. A large amount of
organic acid (VFA) was produced in the acidogenesis stage and
was then gradually transformed to methane and carbon dioxide.
Therefore, the pH value slowly became slightly alkaline. The
lea-
chate had an increased bicarbonate (HCO3
−) because some of the
produced carbon dioxide was dissolved in the leachate. That
meant the pH value did not rise again after trending toward
alkaline.
BOD5 and COD

Figures 5 and 6 present the BOD5 and COD concentrations,
showing the biodegradation of organic matter in the anaerobic
process (cell B) and the aerobic processes (cells A and C) was
different. The BOD5 and COD values showed that the biodegra-
dation in leachate from cells A and C was more rapid than that
from cell B. The BOD5/COD ratio (Figure 7) concurs with this.
This result proves that the cell A with partial aerobic
environment
is an advantage to landfill biodegradation.
After bioreactor A had been buried for half a month, the BOD5
and COD of the leachate were found to be higher than those of
bioreactor B. The main reason was due to the hydrolysis of
organic matter and the biodegradation of the fatty acids
produced
during this stage. The partially aerobic system could have aided
the hydrolysis and acidification reaction of the organic matter in
MSW, causing the sugar and fatty acid/amino acid concentration
Figure 2. pH of leachate collection from pilot landfill tanks
with different operating conditions.
Figure 3. ORP of leachate collection from pilot landfill tanks
with different operating. conditions.
Huang et al. 853
Figure 4. EC of leachate collection from pilot landfill tanks

Figure 5. BOD of leachate collection from pilot landfill tanks
Figure 6. COD of leachate collection from pilot landfill tanks
of cell B to be higher than that of cell A after 2 weeks of opera-
tion. The rate of anaerobic decomposition was relatively slow.
Finally BOD5 reached approximately 100 mg L
−1, suggesting
that the biodegradation was already nearly accomplished, and
the
BOD5/COD ratio was less than 0.1 at that point. The leachate
concentration of the organic matter showed the decomposition
of
the organic matter had nearly achieved steady state after 8
months
of operation. In other words, this operation had significantly
reduced the time required for the buried MSW to reach the
steady
state. It was less than one year.
The experimental results suggest that bioreactor A and C
with their partial aerobic environments had an advantage with
buried MSW biodegradation. The result of this pilot-scale
experiment did show that the addition of H2O2 led to a

somewhat improved aerobic environment, further enhancing
biodegradation.
VFAs and DOC
Bioreactors A, B, and C produced VFAs, including formic, ace-
tic, propionic, butyric, and valeric acid. The VFAs shown in
Figure 8 were represented as acetic acid. It must be noted that
in
the present experiment no formic acid was found after 4 months
of operation, so formic acid is not listed here. Figure 9 also
shows
that the VFAs of the anaerobic cell digested more slowly than
those of the aerobic cells. However, bioreactors A, B, and C had
no organic matter accumulation after initiating biodegradation
for 5.5 months. This phenomenon proves that all three cells had
Figure 7. BOD/COD of leachate collection from pilot landfill
tanks with different operating conditions.
(m
g
V
L
−
1 )
Figure 8. Total VFA of leachate collection from pilot landfill
tanks with different operating conditions (The VFA
concentrated
were represented as acetic acid).

Huang et al. 855
already reached a steady stage with no more biodegradation in
either aerobic or anaerobic conditions. A similar situation
caused
DOC (dissolved organic carbon) (Figure 9) and BOD5
concentra-
tions of the leachate to decrease significantly.
Gas
Gas samples were collected using a pumping process. Figure 10
shows that the CO2 concentration increased continuously, so
bio-
degradation appears to have still been proceeding. In
comparison
with the concentration of organic acid (VFAs) and the methane
produced, bioreactors A, B, and C had all become gradually
stable
after being buried for 5.5 months. Methane production was
already
reduced and, as mentioned above, the leachate already had a
sig-
nificant decrease in BOD5 value. This phenomenon proves that
all
three cells had already tended toward a stable condition.
It is notable that in cell A (the aerobic cell) the low CH4
volume signalled that very rapid hydrolysis of organic matter
was taking place. This is illustrated in Figure 11. The appear-

ance of biodegradation caused a rapid conversion to the metha-
nogenesis stage; therefore, the aerobic cell was quicker to
reach the methane stage than the anaerobic cells in the middle
period of the experiment. At the later stage there was no such
phenomenon in either the aerobic or the anaerobic cells due to
the deprivation of oxygen. The ratio of methane to carbon
dioxide was greater than 1 during the first 6 months (Figure
12); this is similar to the in-situ field and the above-mentioned
research values. As the ratio of BOD5/COD in leachate was
less than 0.1, the biodegradation was already significantly
decreased, and the concentration of carbon dioxide was
greater than the concentration of methane after 7 months of
operation.
Figure 9. DOC of leachate collection from pilot landfill tanks
Figure 10. CO2 of the gas collected collection from pilot
landfill tanks with different operating conditions.
After the cells had been buried for 5 to 6 months, methane
continued to be produced. Even though the organic acid had
decreased below a measurable level, the system had already
reached a relatively stable stage. This proves that organic acid
was almost instantaneously transformed to methane. Although
there appeared to be a lack of organic acid, this was simply a
result of easily biodegradable organic matter being rapidly con-
verted. Therefore, almost no organic acid was observed in the

final stage. In contrast, at that point methanogenesis had
become
the dominant stage. This means that the rate of organic acid
pro-
duction was lower than the rate of transformation. For this rea-
son, methane could be quantified but no accumulation of
organic
acid could be found in the system.
Discussion and suggestions
According to the BOD5, COD, and DOC concentrations in the
leachate, the produced gas (CH4 and CO2), and the reduction
of buried MSW volumes, the rate of organic matter biodegra-
dation in bioreactor A was higher than that in bioreactor C,
and bioreactor C was superior to bioreactor B. In the reduction
of VFAs, bioreactors A and C biodegraded more rapidly than
B. During the initial period of leachate recirculation (operated
in the first 2 months), the advantage of leachate recirculation
was not apparent with respect to the amount of organic matter
degraded. Therefore, recirculation does not need to be oper-
ated initially. From the point view of in-situ operation, it can
even be said to be unsuitable to use recirculation in the initial
stage, so as not to influence the field operation. This approach
can be an advantage when applied to operate post-closure
landfills as the addition of liquid hydrogen peroxide into lea-
chate is relatively easily operated for landfill leachate recircu-
lation. If the biodegradation rate in the landfill site can be
enhanced, the landfill site can reach a stable state quickly. The
site area can then be developed for other beneficial uses, such
as a park.
Figure 11. CH4 of the gas collected collection from pilot

Figure 12. CH4/CO2 of the gas collected collection from pilot
Huang et al. 857
In addition, the area should be divided (layered) when burying
MSW. In the pilot landfill, the buried mass of organic matter
weighed approximately 1035 kg, and during the operational
period, cell A used up to 4.79 kg of H2O2 altogether (4.79/0.35
=
13.69 kg; 35% purity). This indicates that each kg of H2O2 can
offer 0.47 kg of oxygen by weight. A key aspect is to
understand
over what operational period hydrogen peroxide needs to be
added to keep an aerobic condition. The addition of 35% H2O2,
did not inhibit the bacteria growth when the concentration was
increased from 200 to 500 ppm. The use of a H2O2 at a
concentra-
tion of 500 ppm in the cell was still within the tolerable range
for
the micro-organism growth in the bioreactors. The addition of
H2O2 to the aerobic bioreactor accelerated the decomposition of
MSW, but the most appropriate addition of hydrogen peroxide
from the efficiency and cost point of view is still uncertain at
the
present time. Therefore, the following further research is going
to
carry on, such as: (1) the extent of biodegradation as BOD/COD
ratio less than 0.1, (2) the effect on various H2O2 concentration
on the microbial activity, (3) the volatile suspension solid

analy-
sis in post-closure cell, and (4) the comparison of the efficiency
of decomposition and the cost of operation of the hydrogen per-
oxide addition method to the force aeration method.
Conclusions
The results of the addition of H2O2 to a recirculated leachate
sys-
tem are presented in the following list.
1. In terms of its effect on the biodegradation of organic
matter,
the addition of H2O2 resulted in a faster biodegradation rate
than leachate recirculation alone. The continuous addition of
H2O2 was found to be superior to an intermittent operation
mode.
2. The addition of the hydrogen peroxide at 200 to 500 ppm did
not inhibit the microbial growth in the landfill bioreactor.
3. Biodegradation tended towards stability when the BOD5/
COD ratio was less than 0.2. The CO2 concentration was
higher than the CH4 concentration, when the system reached
the stable stage.
4. Leachate recirculation or the addition of hydrogen peroxide
could shorten the MSW landfill operation time in comparison
with the conventional landfill operation. The reduced opera-
tion time and pollution monitoring cost are economic benefits
for the operation of MSW landfills with leachate recircula-
tion. Furthermore, freeing up the landfill land enables the
land to be utilized much earlier, providing additional eco-
nomic and environmental benefits.
5. Some major principles of leachate recirculation has been

sug-
gested to be of value in Taiwan: (a) avoidance of resulting
run-off; (b) no recirculation during wet weather; (c) control
of the recirculation rate to be less than the evaporation rate,
(d) no recirculation in the operating area, and (e) recirculation
of the pre-treatment leachate (with grit removal or with both
grit removal and aeration).
Acknowledgements
The authors gratefully acknowledge the financial support of the
Environmental Protection Administration of the Executive
Yuan,
Taiwan, ROC, in funding and subsidizing this research and also
the
landfill in Dali District, Taichung City for offering a field study
location.
Funding
This research was supported by Environmental Protection
Administration of the Executive Yuan, Taiwan, ROC.
References
APHA (American Public Health Association) (2005) Standard
Methods for
the Examination of Water and Wastewater, 21st edn.
Washington, DC,
USA: APHA.
Barlaz M, Ham R and Schaefer D (1990) Methane production
from munici-
pal refuse: a review of enhancement techniques and microbial
dynamics.
Critical Review in Environmental Control 19: 557–584.
Benson C, Barlaz M, Lane D, et al. (2007) Practice review of

five bioreactor/
recirculation landfills. Waste Management 27: 13–29.
Comilios DP, Ham RK and Stegmann K (1999) The effect of
municipal
landfill solid waste pretreatment on behavior: a literature
review. Waste
Management and Research 17: 10–19.
Chugh S, Clarke W, Pullammanappallil P, et al. (1998) Effect of
recirculated
leachate volume on MSW degradation. Waste Management and
Research
16(6): 564–573.
Cossu R, Raga R and Rossetti D (2003) The PAF model: an
integrated
approach for landfill sustainability. Waste Management 23: 37–
44.
Doedens H and Cord-Landwehr K (1989) Leachate
recirculation. In:
Christensen TH, Cossu R and Stegmann R (eds) Sanitary
Landfilling:
Process, Technology and Environmental Impact. London:
Academic
Press Inc., pp. 231–249.
El-Fadel M (1999) Leachate recirculation effects on settlement
and
biodegradation rates in MSW landfills. Environmental
Technology
20: 121–133.
Erses S and Onay TT (2003) In situ heavy metal attenuation in
landfills under

methanogenic conditions. Journal of Hazardous Materials 99:
159–175.
Giannis A, Simantiraki F, Somara M, et al. (2008) Monitoring
operational
and leachate characteristics of an aerobic simulated landfill
bioreactor.
Waste Management 28: 1346–1354.
Jacobs J, Scharff H, Van Arkel F, et al. (2003) Odour reduction
by aeration of
landfills: experience, operation and costs. In: Proceedings
Sardinia 2003,
the Ninth International Waste Management and Landfill
Symposium,
Cagliari, Italy.
Kim H (2005) Comparative studies of aerobic and anaerobic
landfills using
simulated landfill lysimeters. PhD thesis, University of Florida,
USA.
Kinman RN, Nutini DL, Walsh JJ, et al.(1987) Gas enhancement
techniques
in landfill simulators. Waste Management and Research 5: 13–
25.
Mehta R, Barlaz MA, Yazdani R, et al. (2002) Refuse
decomposition in the
presence and absence of leachate recirculation. Journal of
Environmental
Engineering 128(3): 228–236.
Onay, T.T., Pohland, F.G., 1998. In situ nitrogen management
in controlled
landfills. Water Research 32, 1383–1392.

Otieno FAO (1994) Stabilization of solid waste through leachate
recycling.
Waste Management and Research 12: 93–100.
Purcell B (2000a) Aerox landfilling: the operational
implication. Waste
Management: 2: 27–28.
Purcell B (2000b) Aerox landfilling: the operational
implication. Waste
Management : 3: 25–27.
Pohland FG (1980) Leachate recycle as landfill management
option. Journal
of the Environmental Engineering Division (6), 1057.
Pohland FG and Harper S (1986) Critical review and summary
of leachate
and gas production from landfill. Cincinnati, OH: US
Environmental
Protection Agency, Report No. EPA/600/2-86/073.
Pohland FG and Kim J (1999) In situ anaerobic treatment of
leachate in land-
fill bioreactors. Water Science and Technology 40: 203–210.
Pohland FG and Kim JC 2000. Microbially mediated attenuation

poten-
tial of landfill bioreactor systems. Water Science and
Technology
41: 247–254.
Price GA, Barlaz MA and Hater GR (2003) Nitrogen
management in bioreac-
tor landfills. Waste Management 23: 675–688.
Read AD, Hudgins M, Harper S, et al. (2001) The successful
demonstra-
tion of aerobic landfilling: the potential for a more sustainable
solid
waste management approach? Resource Conservation and
Recycling 32:
115–146.
Reinhart D and Townsend T (1997) Landfill Bioreactor Design
and
Operation. New York, NY: Lewis Publishers.
Reinhart DR, McCreanor PT and Townsend T (2002) The
bioreactor landfill:
its status and future. Waste Management and Research 20: 172–
186.
San I and Onay TT (2001) Impact of various leachate
recirculation regimes
on municipal solid waste degradation. Journal of Hazardous
Materials
87: 259–271.
Stegmann R and Spendlin HH (1987) Enhancement of
biochemical pro-
cesses in sanitary landfills. International Sanitary Landfill
Symposium

2: 1–16.
Szegi H (1988) Cellulose Decomposition and Soil Fertility.
Budapest,
Hungary: Akademiai Kiado, pp. 126–132.
Tittlebaum ME (1982) Organic carbon content stabilization
through land-
fill leachate recirculation. Journal WPCF (Water Pollution
Control
Federation) 54: 428–433.
Townsend TG, Miller WL, Lee H, et al. (1996) Acceleration of
landfill sta-
bilization using leachate recycle. Journal of Environmental
Engineering
122: 263–268.
Valencia R, Vanderzon W, Woelders H, et al. (2009) Achieving
“Final
Storage Quality” of municipal solid waste in pilot scale
bioreactor
landfills. Waste Management 29: 78–85.
Warith M (2002) Bioreactor landfill: experimental and field
results. Waste
Management 22: 7–17.

CARBON TUBES2AbstractCastelvecchi, D. (2008, Aug.docx

CARBON TUBES2AbstractCastelvecchi, D. (2008, Aug.docx

Recommended

Recommended

More Related Content

Similar to CARBON TUBES2AbstractCastelvecchi, D. (2008, Aug.docx

Similar to CARBON TUBES2AbstractCastelvecchi, D. (2008, Aug.docx (20)

More from tidwellveronique

More from tidwellveronique (20)

Recently uploaded

Recently uploaded (20)

CARBON TUBES2AbstractCastelvecchi, D. (2008, Aug.docx