F.M. Muvea; G.M. Ogendi; S.O. Omondi
Abstract
The use of constructed wetlands for purifying pre-treated wastewater is a cost effective technology that has been found to be more appropriate for many developing countries. The technology is also environmentally friendly with the wetlands being habitats for many water birds and other aquatic organisms. ...
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The use of constructed wetlands for purifying pre-treated wastewater is a cost effective technology that has been found to be more appropriate for many developing countries. The technology is also environmentally friendly with the wetlands being habitats for many water birds and other aquatic organisms. This study assessed nutrient removal efficiency of two floating macrophytes (Lemna minor and Azolla pinnata). The data generated was analyzed using both descriptive and inferential statistics. The significance level was maintained at 0.05. The results showed that the wastewater physicochemical parameters did not vary during the study period. The concentrations of nitrites and nitrates increased over the experimental period in all the treatments (Azolla pinnata, Lemna minor and control), and the increase between the sampling occasions was statistically significant for the two nutrients (Nitrates: F=24.78, P= 0.00; Nitrates: F=198.26, P= 0.00). To the contrary, in all the treatments the concentrations of ammonia, total phosphorous, soluble reactive phosphorous and total nitrogen, decreased over the experimental period. The decrease in concentration for these nutrients between the sampling occasions was statistically significant (ammonia: F=195.57, p= 0.00; total phosphorous: F= 56.50, p= 0.00; soluble reactive phosphorous: F= 37.11, p= 0.00; total phosphorous: F= 104.025, p= 0.00). Azolla pinnata proved to be better than Lemna minor in the uptake of the nutrients particularly for the soluble reactive phosphorous (F= 35.18, P= 0.044). We conclude that the two macrophytes are good for wastewater treatment. It is recommended introduction and/or multiplication of Azolla pinnata in the constructed wetlands meant for wastewater treatment especially within the tropics.
A. Suresh; S. Tamilvanan; K. Harini; H.V. Seventhi; R. Deepan Guna; R. Mahalakshmi; S. Suriyapriya; D. Sharmila; M. Thenmozhi
Abstract
Thenutrient medium used for the cultivation of microalgae adds more cost to its value-added product as well as the commercial scale application. Therefore in this study, focused feasibility of cattle urine as a cheap source of nutrients for microalgal growth, because, it contains various minerals and ...
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Thenutrient medium used for the cultivation of microalgae adds more cost to its value-added product as well as the commercial scale application. Therefore in this study, focused feasibility of cattle urine as a cheap source of nutrients for microalgal growth, because, it contains various minerals and economical which may support the growth of microalgae and reduce the medium cost. To check this, fresh cattle urine was collected, characterized, diluted and inoculated microalgae species Oscillatoria-SRA (Stagnant rainwater algae), Oscillatoria-CWA (Cooum waste algae), Chlorella and Synecocystis separately and incubated under fluorescent light with 8 hours light and 16 hours dark cycle. The biomass was quantified after 15 days and found out variation in biomass quantity in all microalgae isolates. The maximum of 2.6 g/L biomass was produced in Chlorella sp., at 10% urine, followed by Synechocystis sp., (2.25 g/L in 10% urine), Oscillatoria sp.,-SRA (1.3 g/L in 5% urine) and Oscillatoria sp.,-CWA (0.3 g/L in 1% urine). Moreover, lipid quantity was shown at the maximum of 12% dry weight in Oscillatoria sp-SRA., trailed by the 10% in Chlorella sp., 7% in Synecocystis sp., and the least of 5% in Oscillatoria sp-CWA. This study divulged that cattle urine alone is being able to support microalgae growth at a significant amount, thus convalescing industrial production of microalgae ultimately will reduce the cost of microalgal value-added products.
F. Esfandi; A.H. Mahvi; M. Mosaferi; F. Armanfar; M. Hejazi; S. Maleki
Abstract
Eutrophication is considered as a serious problem in water reservoirs. Awareness about the eutrophic status of each reservoir could help in providing a better understanding of the problem in a global scale. The present study was conducted to assess temporal and spatial eutrophication index in a water ...
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Eutrophication is considered as a serious problem in water reservoirs. Awareness about the eutrophic status of each reservoir could help in providing a better understanding of the problem in a global scale. The present study was conducted to assess temporal and spatial eutrophication index in a water reservoir (Sahand dam) in the northwest of Iran. Physico-chemical parametres that are effective on eutrphic condition occurrence were analyzed, and trophic state index was calculated on a scale of 0-100 by measuring Secchi disk depth, chlorophyll a, total phosphorus, total nitrogen, total suspended solids, and phosphorus P/N ratio. Moreover, using the overlapping, the reservoir was mapped based on the mentioned index. Seasonal variation of dissolved solids in the reservoir was recorded due to precipitation and subsequent dilution and evaporation. Thermal stratification was observed during the summer months. The total trophic state index value was calculated as 55.5- 58.07, with minimum value belonging to P/N and maximum value belonging to suspended solids for individual parameters. There were some spatial and temporal differences for trophic state index in the reservoir. It was found that the whole area of the reservoir was in almost moderately upper-mesotrophic condition and in some target stations it was very close to eutrophic condition. The worst condition was observed in Qaranqu River as the main input to the reservoir. Due to the significant impact of suspended particles resulting from erosion of the surrounding lands on TSI value, there is an urgent need for mitigation measures to intercept eutrophication.
Environmental Science
A.R. Karbassi; S. Tajziehchi; N. Farhang Adib
Abstract
Estuaries are well known for their potential in removing metal from fresh water to provide micro-nutrients to aquatic life. In the present investigation, we have tried to bring out the metal removal potential of estuaries during accidental spills. For this purpose artificial river water containing high ...
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Estuaries are well known for their potential in removing metal from fresh water to provide micro-nutrients to aquatic life. In the present investigation, we have tried to bring out the metal removal potential of estuaries during accidental spills. For this purpose artificial river water containing high concentration of Mn, Cu, Zn, Ni and Pb were mixed with sea water at different salinity regimes. Water samples were taken from a station on the main branch of Tajan River that flows in to the Caspian Sea. For this purpose, solutions with a concentration of 5 mg/L of each studied metal (Mn,Cu, Zn, Pb) were prepared in Tajan River water. The salinity regimes include 3, 6, 8, 10 and 11 ppt. It was noted that metal concentration decreased by increasing salinity. Metals were flocculated at different rates: Cu (88%) > Ni (86%) > Pb (84%) > Mn (74%).Thus, as average about 80% of total elemental content flocculates. Hence, it was concluded that a large amount of micro nutrients is carried by the river and flocculated in the estuary where the river water mixes with the sea water which may play a vital role in supplying nutrients to the aquatic animals. Cluster analyses have shown that Mn and Ni are governed by EC, pH and salinity.
