الفهرس 
Review of literatureOnly 14 pages are availabe for public view
 |  | from | 131 |  |  |
| | | from | 131 | | |
Abstract
Summary
81
Summary
Microcystins (MCs) are a group of biologically active monocyclic
hepatopancreatic peptides produced by some bloom-forming cyanobacteria in water. They
are well known for their toxic effects on aquatic organisms and humans. Also, they have
attracted much attention for their acute lethal toxicity to human and animals.
In human, MCs are mainly considered as hepatotoxins causing high incidence of
liver cancer in populations’ dependent upon MC-contaminated drinking water, cause death in
human when exposed to them through hemodialysis. In animals, MCs cause deaths in wild
animals and cattle however; cattle having survived acute intoxication may develop hepatic
photosensitization.
Plants, vegetables and food crops irrigated with microcystin contaminated water
are negatively affected including their quality with a reduction in their yields. Plants in
general are capable of accumulating MCs in their tissues so that consuming these
contaminated crop and plants are considered a risk factor for human health. Additionally,
MCs cause illness and even death in aquatic life. It was reported that MCs have been
accumulated in various aquatic organisms which are further consumed by human.
The harmful cyanobacterial blooms in natural water have become an increasing
environmental problem all over the world due to increasing the discharge of wastewater
containing nitrogen and phosphorus to rivers and lakes. And these toxic blooms are dominant
in eutrophic lakes, ponds, lagoons, streams and reservoirs worldwide. Many countries in the
world suffer from the problem of intensive cyanobacterial blooms in surface water. Discharge
of urban, agricultural and industrial wastes into the water sources worldwide lead to
eutrophication that cause increase in the cyanobacterial blooms. As well as excessive
agricultural use of manure and fertilizers cause eutrophication of the surface water bodies
leading to harmful algal blooms development.
MC-LR has been detected in surface water and included in surface water
environmental quality standards and drinking water hygiene standards in different countries
to ensure the drinking water safety. Therefore, regular surveillance of microcystin in the
intake source water should be kept on providing safe drinking water to prevent exposure of
consumers to cyanobacterial metabolites. As well as the present study aimed to present trials
for efficient removal of the biological toxin produced by cyanobacteria and preserves the
human and livestock health using cheap available adsorbent materials.
In this study the water samples were collected from 18 sampling locations
representing three water types (river, irrigation and wastewater) in Sohag and Assiut
Governorates. A total of 72 water samples were collected including river water samples (20),
irrigation water samples (20) and wastewater samples (32). After extraction of the collected
water samples, the microcystins were quantified using ultra-high performance liquid
chromatography (UPLC). After detection of microcystins in the collected samples they were
removed from the real sample that was previously quantified, using cheap available adsorbent
materials (Rice straw, Corn straw and Sawdust) and compared them with the commercially
available adsorbent material (activated charcoal).
Summary
82
The results obtained in this study revealed that:
Physical parameters of river, irrigation and wastewater smples collected from
Sohag and Assiut Governorates:
The temperature of river water sampling locations was 27.2 ± 2.86 oC which was
higher than the maximum permissible limit of river water (22 and 24 oC for class I
(satisfactory) and class II (doubtful), respectively). Water temperature can be affected by
many ambient conditions. These elements include sunlight/solar radiation, heat transfer from
the atmosphere, stream confluence and turbidity. Shallow and surface waters are more easily
influenced by these factors than deep water. Temperature of irrigation water was 28.8 ± 2.58
oC which was within the maximum permissible limit (40 oC). The temperature value at the
sampling locations of wastewater samples was 28.62 ± 1.18 oC.
The pH of river water, irrigation water and wastewater sampling locations were
7.47 ± 0.14, 7.6 ± 0.15 and 7.41 ± 0.3, respectively. PH values of irrigation water and
wastewater were within the maximum permissible limits of 6.5-8.5 and 5.5- 9.5, respectively.
The pH of the water is affected by increase influx of carbon dioxide which causes the
increase of pH. However, it does not rule out the possibility that temperature also affects the
pH.
Chemical parameters of river, irrigation and wastewater collected from Sohag
and Assiut Governorates:
The chemical oxygen demand (COD) of the collected river water, irrigation water
and wastewater samples ranged between 2.2-14.2 mg/L (8.74 ± 4.68), 1.3-107 mg/L (37.05 ±
42.48) and 2.2-126 mg/L (24.01 ± 34.16), respectively. COD values of the collected irrigation
water and wastewater samples were within the acceptance limit (100 mg/L) and (6-12 mg/L),
respectively.
The total nitrogen (TN) values of the collected river water irrigation water and
wastewater samples were 2.61 ± 1.61 mg/L, 4.70 ± 2.98 mg/L and 4.62 ± 4.94 mg/L. TN
values for irrigation water and wastewater samples were within the permissible limit of 35
mg/L and 5-10 mg/L, respectively.
The total phosphorus (TP) concentration of the sampled river water was variable
between 0.08- 4 mg/L (1.42 ± 1.21 mg/L) and was higher than the permissible limit (0.2-0.4
mg /LP for class I and class II, respectively). The TP value of the collected irrigation water
samples ranged between 0.14-2.25 mg/L (0.83 ± 0.60 mg/L). The TP values of the collected
wastewater samples were ranged between 0.2-18.6 mg/L (1.92 ± 4.19 mg/L) which was
higher than the permissible limit (not more than 2 mg/L) giving indication of organic
contamination in these sampling locations.
Summary
83
The concentration of the dissolved oxygen (DO) in the collected samples was
over-range because it was higher than the maximum detection limit of the kit (10-800 μg/L).
Concentration of microcystins in different water samples:
Microcystins were measured in all collected river water samples, 12 (60%) of
them contained microcystins concentration lower than the maximum permissible limit
established by WHO, these samples were collected from Palasfora, Sohag and Elmaragha and
the other 8 (40%) samples contained concentration higher than that established by WHO,
these samples were collected from Almonshah and Mishta. The hazard quotient of
microcystins through ingestion of river water from location SR4, Sohag Governorate was
more than 1 for children indicating high potential risk to the children who drink river water
from this location.
Microcystins were detected in 16 (80%) of total collected irrigation water samples.
The concentration of MCs was lower than the maximum permissible limit established by
WHO in 8 (40%) irrigation water samples which were collected from Banga and Tema and
higher than the MPL in the last 12 (60%) samples which were collected from Tema2, Sudfa
and Mawqif almuealimin.
Finally, MCs could be detected in the 32 collected wastewater samples, where the
concentration was lower than the WHO guideline in 4 (12.5%) samples, equal to the WHO
guideline in 4 (12.5%) samples and higher in 24 (75%) of the total collected wastewater
samples.
Removal of microcystins (MCs)
The efficiency of rice straw for MCs removal from the acidified water samples
reached up to 82.8 % and that for removal from the neutral water samples reached up to
75.4%. Therefore, rice straw as adsorbent material is more efficient in removal of
extracellular MCs from both acidified and neutral water samples.
However, the removal efficiency of MCs from acidified water samples using corn
straw reached up to 73.4% and the removal capability from neutral water samples using was
up to 85.8%. Concerning using of corn straw as adsorbent material for microcystins removal
it is more efficient in removal of intracellular MCs from acidified water samples whereas
more efficient in removal of extracellular MCs from neutral water samples.
The ability of sawdust to remove MCs from acidified water samples was up to
95.4% while its capability to remove them from neutral water samples reached up to 96.4 %.
Sawdust is the most effective adsorbent material in removal of total MCs from both acidified
and neutral water samples. Also, it is more efficient in removal of intracellular than
extracellular MCs from acidified water samples while it is more efficient in removal of
extracellular MCs from neutral water samples.
Summary
84
The efficiency of MCs removal from acidified water sampled using activated
charcoal was up to 89.5% whereas its ability to remove them from the neutral water samples
reached up to 95.9%. Activated charcoal showed high efficiency of total MCs removal
from both acidified and neutral water samples.
Conclusively, hence the need for major intervention, such as low-cost
pretreatment of water, education of the user about the need for regular observation of
the physical appearance of the water and promotion by health authorities of container
hygiene to be achieved through regular brushing and sanitizing of containers to keep
the vessel free of biofilm.
The selected cheap adsorbent materials (rice straw, corn straw, sawdust)
showed good efficiency for MCs removal from both acidified and neutral water
samples. Therefore, the current study recommends the use of the selected cheap
adsorbent materials (rice straw, corn straw and sawdust) to purify the water and
remove the MCs as well as avoiding contamination of the environment by these left-
over crops. The application of these cheap available materials achieves our goals of
this study which are removal of MCs from water sources with effective, applicable and
available materials in addition getting rid of these wastes which represent a source of
environmental contamination.