scholarly journals Sand-capping stabilizes muddy sediment and improves benthic light conditions in eutrophic estuaries: laboratory verification and the potential for recovery of eelgrass (Zostera marina)

2021 ◽  
Author(s):  
Mogens Flindt ◽  
Nele Oncken ◽  
Kadri Kuusemae ◽  
Troels Lange ◽  
Nicolaj Aaskoven ◽  
...  
Keyword(s):  
Zostera Marina ◽  
Suspended Solids ◽  
Vertical Mixing ◽  
Light Limitation ◽  
Sandy Sediment ◽  
Muddy Sediment ◽  
Light Conditions ◽  
Water Turbidity ◽  
Restoration Practice ◽  
High Turbidity

Decades of eutrophication have increased water turbidity in Danish estuaries and led to light limitation of eelgrass (Zostera marina) growth. Former eelgrass areas are now denuded and consist of organic-rich muddy sediment with frequent resuspension events that maintain a high turbidity state. In addition, low anchoring capacity of eelgrass in the soft organic-rich sediments has contributed to eelgrass loss. When navigation channels in Danish estuaries are dredged, large amounts (~100.000 m3) of sandy sediment are shipped to remote dumping sites. Instead, we suggest that the dredged sand is used to consolidate adjacent muddy areas. We demonstrate in the present study that capping of fluid muddy sediment with 10 cm of sand is feasible without any vertical mixing and that this marine restoration approach can significantly lower the magnitude and frequency of resuspension events. Erosion of suspended solids change from 5 g m-2 min-1 in muddy areas to about 0.2 g m-2 min-1 in sand-capped areas, implying that sand-capping can significantly improve light conditions. Moreover, erosion thresholds increase from about 10-12 cm s-1 for mud to 40 cm s-1 for sand-capped mud. In conclusion, improved benthic light and increased anchoring capacity by sand-capping, a marine restoration practice, has the potential to facilitate restoration of otherwise lost eelgrass habitats.

SEAGRESS COVERAGE AND ECOSYSTEM CONDITION AT THE COASTAL AREA OF MADASANGER, JELENGA AND MALUK, WEST SUMBAWA

2013 ◽  
Vol 5 (1) ◽  
Author(s):  
Erny Poedjirahajoe ◽  
Ni Putu Diana Mahayani ◽  
Boy Rahardjo Sidharta ◽  
Muhamad Salamuddin
Keyword(s):  
Coastal Area ◽  
Seagrass Species ◽  
Seagrass Bed ◽  
Water Turbidity ◽  
Transect Sampling ◽  
Sampling Points ◽  
Ecosystem Condition ◽  
High Turbidity ◽  
Line Transects ◽  
Seagrass Coverage

The increase of temperature might affect the distribution and reproduction of seagrass. This research aims to determine the seagrass bed coverage and the ecosystem condition. Three line transects were established perpendicular to the coastal line with the distance of 50-100 m, or up to the border of the intertidal area. In each transect, sampling points were determined with a distance of 10-20 m. At the sampling points, a plot of 50 cm x 50 cm was established to measure the coverage percentage of seagrass vegetation. The seagrass species were also observed and recorded along the line transects. The percentage of seagrass coverage was measured using a method from Saito and Atobe (1994). The results showed that the coastal area of Jelenga has the highest percentage of seagrass coverage (>60%, healthy) among other coastal areas. This may be caused by the characteristic of Jelenga coast which was relatively calm, few visitors, low water turbidity, and high light penetration. While, other transects have percentage coverage of less than 60% (less healthy). There was one transect on Maluk coast which has coverage percentage of less than 29% (lack of seagrass species). The small coverage percentage on Maluk coast can be caused by the high number of visitors and high activity of fishing boats around the coast which results in high turbidity. Keywords: coverage, ecosystem condition, seagrass bed, west Sumbawa.

scholarly journals Use of Aloe vera as an Organic Coagulant for Improving Drinking Water Quality

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2024
Author(s):  
Abderrezzaq Benalia ◽  
Kerroum Derbal ◽  
Amel Khalfaoui ◽  
Raouf Bouchareb ◽  
Antonio Panico ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Suspended Solids ◽  
Aluminum Sulfate ◽  
Aloe Vera ◽  
Drinking Water Treatment ◽  
Water Turbidity ◽  
Turbidity Removal ◽  
Maximum Turbidity ◽  
Optimal Ph

The coagulation–flocculation–sedimentation process is widely used for removal of suspended solids and water turbidity reduction. The most common coagulants used to conduct this process are aluminum sulfate and ferric sulfate. In this paper, the use of Aloe vera as a natural-based coagulant for drinking water treatment was tested. The bio-coagulant was used in two different forms: powder as well as liquid; the latter was extracted with distilled water used as a solvent. The obtained results showed that the use of the natural coagulant (Aloe vera) in both powder (AV-Powder) and liquid (AV-H2O) forms reduced the water turbidity at natural pH by 28.23% and 87.84%, respectively. Moreover, it was found that the use of the two previous forms of bio-coagulant for drinking water treatment had no significant influence on the following three parameters: pH, alkalinity, and hardness. The study of the effect of pH on the process performance using Aloe vera as a bio-coagulant demonstrated that the maximum turbidity removal efficiency accounted for 53.53% and 88.23% using AV-Powder and AV-H2O, respectively, at optimal pH 6.

Observations of blanket characteristics in full-scale floc blanket clarifiers

2003 ◽  
Vol 47 (1) ◽  
pp. 197-204 ◽  
Author(s):  
L.C. Chen ◽  
S.S. Sung ◽  
W.W. Lin ◽  
D.J. Lee ◽  
C. Huang ◽  
...  
Keyword(s):  
Treatment Process ◽  
Combined Treatment ◽  
The Other ◽  
Raw Water ◽  
Water Turbidity ◽  
Capillary Suction ◽  
Zeta Potentials ◽  
High Turbidity ◽  
Water Supply Company ◽  
Clarified Water

We monitored the changes in concentrations, zeta potentials, sizes and capillary suction times of the solids flocs in the clarified water from eight floc blanket clarifiers of PingTsan Water Works of Taiwan Water Supply Company with low (<10 NTU) and high (>100 NTU) turbidity raw water. For the former, one-stage coagulation-sedimentation treatment was adopted which yielded a rather unstable blanket. Complete washout was noticeable when the PACl dosage was insufficient. On the treatment of high-turbidity raw water, on the other hand, the Works adopted the combined treatment process, that is, the raw water was first coagulated and settled in a pre-sedimentation tank, afterwards, its effluent was coagulated again and clarified in the clarifiers. The resulting flocs could form a networked blanket that was relatively stable to the shock load in raw water turbidity.

scholarly journals Enhanced Coagulation Efficiency of Moringa Oleifera Seeds Through Selective Oil Extraction

1970 ◽  
Vol 4 (1) ◽  
Author(s):  
Suleyman A. Muyibi ◽  
Saad A. Abbas Megat Johari M. M. Noor Fakrul Razi Ahmadun
Keyword(s):  
River Water ◽  
Moringa Oleifera ◽  
Oil Extraction ◽  
Kernel Weight ◽  
Turbid Water ◽  
Water Turbidity ◽  
Turbidity Removal ◽  
Kaolin Suspension ◽  
High Turbidity ◽  
Moringa Oleifera Seed

In this laboratory based study, varying quantities of oil, corresponding to 20 % w/w, 25 % w/w and 30 % w/w kernel weight extracted from Moringa oleifera seeds ( S1, S2, S3) respectively  were applied in the coagulation of model turbid water (kaolin suspension) and turbid river water samples from River Batang Kali and River Selangor in Malaysia to determine the percentage oil removed which gave the best coagulation efficiency. For model turbid water (kaolin suspension) coagulation of low turbidity of 35 NTU, medium turbidity of 100 NTU and high turbidity of 300 NTU, sample S2  gave the best turbidity removal corresponding to 91.7%, 95.5% and 99% respectively. Application of sample S2 to River Batang Kali with low initial turbidity of 32 NTU and high initial turbidity of 502 NTU gave a highest turbidity removal of 69% and 99% respectively. Application to River Selangor with medium initial turbidity- of 87 NTU and high initial turbidity of 466 NTU gave a highest residual turbidity' of 94% and 98.9%,  respectively.Key words: Moringa oleifera seed, selective oil extraction, coagulation, model turbid water (kaolin suspension), river water, turbidity removal.

Roughing filtration as an effective pre-treatment system for high turbidity water

2011 ◽  
Vol 64 (7) ◽  
pp. 1419-1427 ◽  
Author(s):  
Zahiruddin Khan ◽  
Rahimuddin Farooqi
Keyword(s):  
Water Treatment ◽  
Treatment Plant ◽  
Water Treatment Plant ◽  
Dose Requirement ◽  
Water Turbidity ◽  
Effluent Quality ◽  
Coagulant Dosage ◽  
High Turbidity ◽  
Pre Treatment ◽  
Effective Water

Effective water treatment is the prime goal of every water treatment facility. Chakwal Water Treatment Plant in Pakistan has been treating high-turbidity surface water through crude coagulation, sedimentation and slow sand filtration since the early 1980s. The process has always been tedious in terms of high coagulant dosage, large volumes of sludge and short filter runs especially after wet spells. A laboratory-scale study was conducted to see if roughing filtration, as the pre-treatment process, would help in reducing coagulant dose and sludge volume and improving effluent quality. Results indicated that up-flow rouging filtration with media grades decreasing in the direction of flow could reduce wet weather raw water turbidity (by more than 90%) and coagulant dose. Overall, the plant could save over US $54,000 annually in terms of coagulant cost only. Longer filter runs, improved product water quality leading to lower chlorine dose requirement, would be additional benefits.

scholarly journals Modelling the risk of mortality of Corbicula fluminea (Müller, 1774) (Bivalvia: Corbiculidae) exposed to different turbidity conditions

2014 ◽  
Vol 74 (2) ◽  
pp. 509-514 ◽  
Author(s):  
WEP. Avelar ◽  
FF. Neves ◽  
MAS. Lavrador
Keyword(s):  
Environmental Changes ◽  
Corbicula Fluminea ◽  
Mortality Rates ◽  
Aquatic Communities ◽  
Water Turbidity ◽  
Erosion Processes ◽  
Risk Of Mortality ◽  
High Turbidity ◽  
Study Sites ◽  
The One

The provision of sediment in rivers, due to erosion processes that occur in the environment, consists of a major source of pollution and alteration of the physicochemical conditions of water resources. In addition, the increase in water turbidity may cause siltation, dramatically impacting aquatic communities. Specifically considering the bivalve Corbicula fluminea (Müller, 1774), the aim of this study was to analyse the effect of exposure to different turbidity conditions of sediments, as a risk factor for the animals. For this purpose, a docking device was designed to ensure water circulation in a closed system and to maintain the desired levels of turbidity. Although C. fluminea can generally tolerate environmental changes in aquatic systems, an intolerance to high turbidity levels was experimentally observed, expressed by the mortality rate of the animals when exposed to conditions above 150 nephelometric turbidity units (NTU). This value was similar to the one recorded at study sites in the rivers Pardo (Serrana-SP-Brazil) and Mogi Guaçu (Porto Ferreira-SP-Brazil) during the rainy season. Using a logistic regression model, the experimental results were analysed and the observed mortality rates indicate that the exposure of the animals to turbidity levels above 150 nephelometric turbidity units (NTU), for periods longer than 120 hours, may be considered a probable cause of mortality for the species.

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