| 1. |
- Korsak, Larisa, et al.
(författare)
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Wastewater treatment in Nicaragua
- 2003
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Ingår i: Proceedings of the 9th Annual IWA Specialised Conference "Design, Operation and Economics of Large Wasewater Treatment Plants".
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Korsak, Larisa, et al.
(författare)
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Alternatives of Sludge Use in Nicaragua
- 2005
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Ingår i: Proceedings of the 27th Annual HWEA Conference "New Technical Knowledge for Clean Water".
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 3. |
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| 4. |
- Korsak, Larisa, et al.
(författare)
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Evaluation of anaerobic sludge activity in wastewater treatment plants in Nicaragua
- 2006
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Ingår i: Water Pollution VIII. - 184564042X ; , s. 571-579
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Konferensbidrag (refereegranskat)abstract
- Sludge of three municipal anaerobic wastewater treatment plants was evaluated. This study was initiated due to the low activity observed in the anaerobic wastewater treatment plants in Nicaragua. An additional goal to select one of them, if possible, as an inoculum for the brewery treatment plant was proposed. Two of these plants work with an Imhoff tank and one with a Septic tank followed by an anaerobic upflow filter. The study consisted in the characterization of biomass in terms of Specific Methanogenic Activity (SMA), Volatile Suspended Solids (VSS), density, pH, and redox potential (RP). The treated waters were also analysed for nutrients, heavy metals and the organic load. The substrate used in the experiments for determining the methanogenic activity was acetic acid. NaHCO3 was added to maintain pH in the normal range of operation. The tests were carried out at a sludge load of 1.5 g VSS/l. The results indicate that treated wastewater does not have any impediment to proper development of microorganisms; no presence of toxic substances and enough essential nutrients were detected. The specific methanogenic activity of sludge (SMA) in the Imhoff tanks is relatively close and oscillates between 0.16-0.28 g CH4-COD/g VSS/day, and in the septic tank is 0.09 g CH4-COD/g VSS/day. These values agree with the methanogenic activity found in the literature for septic tanks (0.02-0.1 g CH4-COD/gVSS/day). The highest methanogenic activity measured during the test was 0.28g CH4-COD/g VSS/day in the sludge of the Imhoff tank in The Viejo city, so this sludge could be proposed as a seed for the brewery treatment plant.
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| 5. |
- García, Indiana, et al.
(författare)
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Presence of trihalomethanes in drinking water plants in Nicaragua
- 2006
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Ingår i: Journal of Water Supply. - 0003-7214 .- 1365-2087. ; 55:3, s. 221-231
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Tidskriftsartikel (refereegranskat)abstract
- The impact of enhanced coagulation on the formation of trihalomethanes (THMS) from drinking water was studied in four treatment plants in Nicaragua. Enhanced and conventional coagulation techniques were compared with regard to the removal of natural organic matter (NOM), which was measured by surrogate paramametres. The enhanced coagulation process showed a better removal of NOM, and as a consequence the THM formation was up to 50% lower than with conventional coagulation. The influences of chlorine dosage, temperature, PH and contact time on the THM formation in water treated by enhanced and conventional coagulation were also studied.
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| 6. |
- García, Indiana, 1966-
(författare)
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Removal of natural organic matter by enhanced coagulation in Nicaragua
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The existence of trihalomethanes (THMs) in a drinking water plant of Nicaragua has been investigated in order to see whether the concentration exceeded the maximum contaminant level recommended by the environmental protection agency of the United States (USEPA) and the Nicaragua guidelines. The influence of pH, temperature, chlorine dose and contact time on the formation of THMs were studied. The contents of organic matter measured by surrogate parameters such as total organic carbon, dissolved organic carbon, ultraviolet absorbance and specific ultraviolet absorbance were also determined in order to show which type of organic matter is most reactive with chlorine to form THMs. Models developed by other researchers to predict the formation of trihalomethanes were tested to see whether they can be used to estimate the trihalomethane concentration. In addition, empirical models were development to predict the THM concentration of the drinking water plant analysed. The raw water was treated by conventional and enhanced coagulation and these processes were compared with regard to the removal of natural organic matter (NOM). The significance of the results was assessed using statistic procedures. The average concentration of THMs found at the facility is below the USEPA and Nicaragua guideline values. Nevertheless the maximum contaminant level set by USEPA is sometimes exceeded in the rainy season when the raw water is rich in humic substances. Comparison between the water treated by conventional and enhanced coagulation shows that enhanced coagulation considerably diminished the trihalomethane formation and the value after enhanced coagulation never exceeded the guidelines. This is because enhanced coagulation considerably decreases the organic matter due to the high coagulant dose applied. The study of the trihalomethane formation when varying pH, time, temperature and chlorine dose using water treated by conventional and enhanced coagulation showed that higher doses of chlorine, higher pH, higher temperature and a longer time increases the formation of THMs. However, combinations of two and three factors are the opposite. The predicted THM formation equations cannot be used for the water at this facility, since the results shown that the measured THM differs significantly from the THM concentration predicted. Two empirical models were developed from the data for enhanced coagulation, using linear and non-linear regression. These models were tested using the database obtained with conventional coagulation. The non-linear model was shown to be able to predict the formation of THMs in the Boaco drinking water plant.
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| 7. |
- Garca, I., et al.
(författare)
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Removal of natural organic matter by conventional and enhanced coagulation in Nicaragua
- 2007
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Ingår i: Water Resources Management IV. - : WIT Press. - 9781845640743 ; , s. 399-409
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Konferensbidrag (refereegranskat)abstract
- Enhanced coagulation was applied to raw water from a drinking water plant in Nicaragua through bench scale jar test in order to reduce the presence of natural organic matter (NOM) and decrease the trihalomethanes (THMs) formation which has been linked to carcinogenic diseases. Due to the lack of information about the presence of chlorination by-products (CBPs) like trihalomethanes, a study of their formation by varying pH, contact time, temperature and chlorine dose was also performed; following conventional or enhanced coagulation treatment. The results show that enhanced coagulation decreases considerably the formation of THMs because it reduces strongly the presence of organic matter due to the fact that higher alum doses were used in comparison with conventional coagulation utilized at the facility. The removal of dissolved organic carbon (DOC) was improved from 44 at the facility to 67 with enhanced coagulation. Trihalomethanes concentration increases drastically when extreme conditions of the four parameters evaluated were applied exceeding the maximum contaminant levels of USEPA (80 g/L) but not the Nicaraguan target value (460 g/L) for both coagulation types.
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