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STUDY ON THE QUALITY OF RICE HUSK ASH AT DIFFERENT FLUIDIZING VELOCITY IN A FLUIDIZED BED COMBUSTOR
M. Rozainee, S.P. Ngo, A.A. Salema, & K.G. Tan ABSTRACT
Rice husk ash has a rigid skeleton-like structure due to its high silica content, resulting in a
considerable amount of carbon being trapped in the skeleton and cannot be burned or gasified easily. This study was focused on investigating the
quality of rice husk ash at different fluidizing velocity during the combustion of rice husk in a fluidized bed combustor (ID 210 mm). When all
other parameters are held constant, the optimum fluidizing velocity aids in almost complete combustion, thereby releasing the entrapped carbon for
further conversion. This results in ash with consistently low carbon content (less than 2 wt%). The range of fluidizing velocities investigated was
from as low as 1.5 Umf to as high as 8 Umf. It was found that the optimum fluidizing velocity was approximately 3.3 Umf as the mixing of rice husk
with the bed was good with a high degree of penetration into the sand bed. The resulting ash was fine in size and retained its amorphous form with
low residual carbon content (at 2.88 wt %) and minimal sand contamination as shown by the x-ray diffraction analysis.
REGENERATION OF DIFFERENT TYPES OF GRANULAR ACTIVATED CARBONS WITH ADSORBED TRICHLOROETHYLENE USING WET PEROXIDE OXIDATION
Kiyokazu Okawa, Toshihiro Takeshita and Katsuyuki Nakano ABSTRACT
The objective of this study is to clarify the regeneration of different types of granular activated
carbons (GAC) with adsorbed trichloroethylene (TCE) using wet peroxide oxidation (WPO) under mild condition (180°C). TCE adsorbed on each GAC was
degraded by WPO. The rate of TCE degradation was higher in GAC with larger pore size. In the repeated regeneration of GAC, the adsorption capacity
of each GAC for TCE gradually decreased. Especially, the adsorption capacity of catalyzed GAC, CENTAUR (Calgon Mitsubishi Chemical Co.) decreased
more than other GAC with regeneration efficiency (q/q0) of 0.17 in the 4th step using 6 hours regeneration time. On the other hand, the adsorption
capacity of the largest pore size GAC, Diahope007 (Calgon Mitsubishi Chemical Co.), which has the fastest TCE degradation, did not decrease much in
2 hours regeneration time and the regeneration efficiency at 4th step was 0.93. Even though adsorption and regeneration was repeated, the BET
surface area and pore volume of each GAC were not reduced.
CHEMICAL PRECIPITATION OF AMMONIA-N AS STRUVITE FROM LANDFILL LEACHATE—EFFECT OF MOLAR RATIO UPON RECOVERY
Obuli P. Karthikeyan1, Research Scholar ABSTRACT
Struvite precipitation has the potential for removing ammonia-N from landfill leachate. A
laboratory scale study was performed to investigate the recovery of NH4+-N as struvite using MgCl2.6H2O and Na2HPO4 as Mg and P sources,
respectively. Seven different molar ratios (Magnesium: Ammonium: Phosphate) were used to optimize the removal efficiency of ammonia-N. Around 58%
of ammonia removal was obtained in 1:1:1 molar ratio. Maximum removal efficiency of 76 and 78 % achieved at the molar ratio of 2:1:1.5 and 1.5:1:2,
respectively. Leachate pH varied from 6.5 to 6.9 in supernatant samples obtained from different molar ratio. Leachate COD increased (from 3,461 mg/L
to 10,481 mg/L) and TOC decreased (from 2,448 mg/L to 1,825 mg/L) with ammonia removal in leachate. Leachate quality in terms of calcium, potassium,
nitrate, nitrite and phosphates were unaffected by the struvite precipitation.
MODELING LANDFILL GAS GENERATION TO DETERMINE TARGETS AND STRATEGIES TO REDUCE GREENHOUSE GASES FROM LANDFILLS
Shirley Thompson1, Jennifer Sawyer2, Rathan Kumar Bonam1, and Stephen Smith1 ABSTRACT
The future impact of different waste management policies on greenhouse gas (GHG) emissions from
landfills was estimated using the Scholl Canyon methane generation model. This scenario modeling provided a useful decision-making tool to
determine appropriate targets for reductions in emissions and strategies to reach feasible goals. At low rates of 25% total waste diversion in
Canada, the GHG emissions continue to rise due to historical organic waste emitting methane for 30 years to 50 years following landfill closure at
higher rates than is reduced by organic diversion. At diversion rates of 50%, which is less than that already occurring in Prince Edward Island,
GHG emissions decreased slightly. If 75% of total waste is diverted, which occurs in most European Union countries, a 30% reduction of GHG would
result after 25 years. Waste diversion has a gradual impact on GHG: composting, recycling and extending producer responsibility provide the
long-term solution to reduce GHG production and waste generation. However, diversion does not prevent emissions from waste already in place.
“End-of-pipe” methane recovery technology burns methane from historical waste, decreasing GHG to create alternative energy, preferably, or by
simply flaring the methane. Both methane recovery and waste diversion should be pursued to maximize GHG reduction.
AN ASSESSMENT OF MODIFIED COMPOSTING BARREL FOR SUSTAINABLE ORGANIC WASTE MANAGEMENT IN BANGLADESH
M. Azizul Moqsud
M. Habibur Rahman
Shigenori Hayashi, Professor and Director ABSTRACT
An assessment of the efficiency of a modified steel barrel, and comparison of its performance with the conventional barrel using as a composting
reactor in Bangladesh are presented in this paper. To ensure quick and uniform aerobic digestion and to get rid of bad odor, two modifications were
made on the conventional barrel by: (1) providing 0.0125 m diameter openings throughout the sides and (2) placing a 0.0254 m diameter perforated
polyvinyl chloride (PVC) pipe in the middle portion of the barrel. The test results show that the volume of composting wastes became 70% and 50% of
its original volume after and before the modification of the composting barrel, respectively after 4 weeks. Nutrients in the compost were comparable
with those reported elsewhere and these were in more suitable range after the modification of the composting barrel. The carbon-nitrogen ratio (C/N)
of compost was found in the ideal range (11-15) in the modified composting reactor but it was quite high (24-25) in the conventional barrel. No
pathogenic bacteria were found in the compost, as the elevated temperature in the modified composting barrel destructed during composting. The
benefit-cost ratio is more than 1 for a large scale composting project with the modified barrel. This modified barrel composting plant proves to be
an efficient, eco-friendly, cost-effective, and nuisance-free solution for the management of organic solid wastes in Bangladesh.
STABILIZATION OF BLUE MUSSEL (MYTILUS EDULIS L.) PROCESSING WASTE WITH Ca(OH)2
Thomas L. Gallant1,2, John A. MacLeod1, Robert Gordon2, ABSTRACT
Mussel processing waste (MPW) is often treated as landfill or casually applied to soil. Leachate and
odour problems associated with even short-term storage make land application difficult. Work was initiated to examine MPW stabilization via addition
of hydrated lime (Ca(OH)2) with effectiveness rated through degree of liquefaction, change in pH, and CO2 evolution. For assessment of liquefaction
and pH, Ca(OH)2 was combined with fresh MPW at 1%, 5% and 10% (w:w) with control of no lime. For assessment of CO2 evolution, MPW with 2% Ca(OH)2
(w:w) was compared to fresh MPW, liquid fraction of MPW, and liquid hog manure. Materials were contained in 20 L plastic containers with variables
measured after seven days. Liquefaction (g produced/litre of waste) was 89, 45, 7.5, and 0, for control, 1%, 5%, and 10% treatments, respectively.
The 5% and 10% treatments had significantly higher pH (~11 and ~12) compared to the 1% and control treatments (both ~6.0). The lime-treated MPW
emitted less CO2 (1.22 g L-1 d-1) than the fresh (2.95) and liquid (5.02) MPW. A small amount of added Ca(OH)2 can provide short-term stabilization
of MPW and increase its usability for agriculture.
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