Issue 1 [March]

An investigation on parameters for modeling THMs formation

Chowdhury S. and Champagne P. , Pages:80-91

DOI:

https://doi.org/10.30955/gnj.000518

Paper Topic:

General

Issue:

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Abstract

Reactions between natural organic matter (NOM) and chlorine during disinfecting drinking
water form trihalomethanes (THMs) and other chlorinated by products (CBPs), some of which
are possible carcinogen to human health. A number of models have been developed to
predict THMs formation since the discovery of THMs in drinking waters. A fraction of these
models used a total of 22 different parameters while individual models used 3 to 8
parameters. Some existing models incorporated more than one parameter from total organic
carbon (TOC), dissolved organic carbon (DOC) and UV absorption capacity at 254 nm
(UV254), while all of these three characterize NOM in water; thus, there exist a possibility of illconditioned
coefficient estimation. This paper presents the results of an experimental
investigation on different parameters from four water supply systems in Newfoundland,
Canada. Strong correlations were found among total organic carbon (TOC), dissolved organic
carbon (DOC) and UV absorption capacity at 254 nm (UV254). This study along with the past
studies identified pH, temperature and reaction time as significant for THMs formation;
however, some existing models ignored these parameters. Although these models have good
performance in predicting THMs formation in respective environmental conditions, some
models might suffer weakness from mathematical point of view; thus needs to be carefully
applied. This study recommends using one parameter from TOC, DOC and UV254 and
chlorine dose, pH, temperature and reaction time for future modeling.

Identification of Ion sources in rainwater of a coastal site impacted by the gas and oil industry in the southeast of Mexico

Ceron R.M., Ceron J.G., Muriel M., Cardenas B. and Anguebes F. , Pages:92-100

DOI:

https://doi.org/10.30955/gnj.000407

Paper Topic:

General

Issue:

Issue 1

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Abstract

The purpose of this research was to study the chemical composition of rainwater to assess
the impact of marine aerosol and anthropogenic emissions by using back air-mass
trajectories. Fieldwork was done from July to November 2004, in a coastal site probably
impacted by gas and oil industry in Campeche, Mexico: San Antonio Cardenas.
Na+, Cl-, and Mg2+, were the most abundant ions, being sea-salt aerosol their unique source.
A significant portion of K+ and Ca2+ originated from non-sea-salt sources; and the sulphate
excess exceeded the background level reported for remote marine sites, suggesting that
besides of marine aerosol, there was a significant contribution of SO42- from anthropogenic
sources. NO3- concentrations in San Antonio Cardenas exceeded the background level
reported for coastal sites with minimal anthropogenic influence and showed a significant
correlation with SO42-, suggesting a common source. Agricultural practices are null, for this
reason NH4+ levels were low.
Mean pH value was 4.64, this acidity showed a good correlation with SO42- and NO3- levels,
and with the local meteorology. A sour gas recompression plant located 10 km at NE from
San Antonio Cardenas was identified as the main source of this strong acidity.

Utilization of calcium sulfide derived from waste gypsum board for metal-containing wastewater treatment

Mihara N., Soya K., Kuchar D., Fujuta T. and Matsuda H., Pages:101-107

DOI:

https://doi.org/10.30955/gnj.000505

Paper Topic:

General

Issue:

Issue 1

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Abstract

To achieve recycling of waste gypsum boards (CaSO4), production of calcium sulfide by
reductive decomposition of CaSO4 was investigated and the decomposition product of CaS
was used as a sulfuration agent in the treatment of nickel-containing simulated wastewater. At
the end of the experiment, residual nickel concentration and filtration characteristics of the
slurry formed by adding CaS to the nickel-containing wastewater were investigated.
Regarding the reductive decomposition of CaSO4, it was found that CaS could be effectively
generated by CaSO4 reductive decomposition with graphite and the CaS content in the final
product was greater than 80% when the reductive decomposition was carried out for one hour
at a temperature of 1273 K, under N2 atmosphere.
Then, in the sulfuration treatment of nickel-containing wastewater with CaS, the applicability of
CaS as a sulfuration agent was confirmed and the nickel concentration in the simulated
wastewater was reduced from 100 mg-Ni l-1 to a value below 1.0 mg l-1, when the CaS was
added to the simulated wastewater at CaS to Ni molar ratio of 1.3. Moreover, sulfide slurry
obtained by adding CaS was characterized by lower average specific filtration resistance and
compressibility coefficient, compared to hydroxide slurry formed by the conventional
precipitation treatment.

Protection of environment by the use of fly ash in road construction

Escioglou P. and Oikonomou N., Pages:108-113

DOI:

https://doi.org/10.30955/gnj.000442

Paper Topic:

General

Issue:

Issue 1

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Abstract

Fly ash is an important industrial by-product that comes from the combustion of coal, for the
production of electrical energy. In our country, only a small percentage is used for the
construction of technical projects, while the rest is stockpiled, causing serious problems.
Because of its great availability and its low cost, further possibility of its usage should be
investigated. In the present assignment, clay soils, natural and crushed sand-gravel were
stabilized with different quantities of fly ash, for the creation of durable forest roads.
From research, it has been found that stabilization with fly ash, improves the natural and
mechanical characteristics of soils (plasticity, compressive strength and particle size
distribution). As a result, the improvement of the forest road networks from one side and the
economy in natural inert materials and the exploitation of fly ash from the other, the
importance of such an intervention in the protection of the forest ecosystem and the natural
environment in general are obvious.

Recycling techniques of polyolefins from plastic wastes

Achilias D.S., Antonakou Ε., Roupakias C., Megalokonomos P. and Lappas A. , Pages:114-122

DOI:

https://doi.org/10.30955/gnj.000468

Paper Topic:

General

Issue:

Issue 1

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Abstract

Disposing of plastic wastes to landfill is becoming undesirable due to legislation pressures,
rising costs and the poor biodegradability of commonly used polymers. In addition,
incineration meets with strong societal opposition. Therefore, recycling either mechanical or
chemical, seems to be the only route of plastic wastes management towards sustainability.
Polyolefins, mainly polyethylene (LDPE or HDPE) and polypropylene (PP) are a major type of
thermoplastic used throughout the world in a wide variety of applications. In Western Europe
alone approximately 22 million tones of these polymers are consumed each year,
representing an amount of 56% of the total thermoplastics.
In the present investigation the recycling of LDPE, HDPE and PP was examined using two
different methods: the dissolution/reprecipitation and pyrolysis. The first belongs to the
mechanical recycling techniques while the second to the chemical/feedstock recycling. During
the first technique the polymer can be separated and recycled using a solvent/non-solvent
system. For this purpose different solvents/non-solvents were examined at different weight
percent amounts and temperatures using either model polymers as raw material or
commercial waste products (packaging film, bags, pipes and food retail products). At all
different experimental conditions and for all samples examined the polymer recovery was
always greater than 90%. The quality of the recycled polymer was examined using FTIR and
DSC. Furthermore, pyrolysis of LDPE, HDPE and PP was investigated with or without the use
of an acid FCC catalyst. Experiments were carried out in a laboratory fixed bed reactor. The
gaseous product was analyzed using GC, while the liquid with GC-MS. A small gaseous and
a large liquid fraction were obtained from all polymers. Analysis of the derived gases and oils
showed that pyrolysis products were hydrocarbons consisting of a series of alkanes and
alkenes, with a great potential to be recycled back into the petrochemical industry as a
feedstock for the production of new plastics or refined fuels.

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Issue 1 [March]

An investigation on parameters for modeling THMs formation

Identification of Ion sources in rainwater of a coastal site impacted by the gas and oil industry in the southeast of Mexico

Utilization of calcium sulfide derived from waste gypsum board for metal-containing wastewater treatment

Protection of environment by the use of fly ash in road construction

Recycling techniques of polyolefins from plastic wastes

Pages

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Issue 1 [March]

An investigation on parameters for modeling THMs formation

Identification of Ion sources in rainwater of a coastal site impacted by the gas and oil industry in the southeast of Mexico

Utilization of calcium sulfide derived from waste gypsum board for metal-containing wastewater treatment

Protection of environment by the use of fly ash in road construction

Recycling techniques of polyolefins from plastic wastes

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