Browsing by Author "Chinthaka, S.D.M."

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    In-vitro Study on Geosmin and 2-Methylisoborneol Producing Four Species of Native Cyanobacteria
    (Uva Wellassa University of Sri Lanka, 2019) Ganegoda, S.S.; Wijesekara, W.M.A.; Chinthaka, S.D.M.; Wanniarachchi, D.D.C.; Manage, P.M.
    The production of odiferous metabolites, such as Geosmin and 2-methlyisoborneol (2- MIB) cause muddy and moldy taste and odor in water is a major limitation in safe and adequate provision of potable waters in worldwide. The biological functions of these odorants have not known, and cyanobacteria are the major producers of Geosmin and 2- MIB in natural waters as a result of their secondary metabolites. Objective of the current study was to investigate four laboratory cultured cyanobacteria’s ability to produce Geosmin and 2- MIB. Production of Geosmin and 2- MIB was studied using native cyanobacteria isolated from Unnichchi tank in Baticolloa district, Jayanthi tank in Ampara district and Padawiya tank in Anuradhapura district where taste and odour issues are prevailing. Isolation of cyanobacteria was carried out using dilution and spread plate method by maintaining cultures in BG 11 medium with antibiotics. The cultures were identified as Oscillatoria sp., Psudoanabena sp., Lyngbya sp., and Nostoc sp. using the 16s rRNA sequencing. 10 ml aliquots of two months old axenic cultures were subjected to Solid Phase Micro Extraction (SPME) and Gas Chromatography Mass Spectrometry (GC/MS) analysis with BG 11 culture medium as control. The concentration of Geosmin produced from the cyanobacteria were ranged between 10.8 ng/L to 162.6 ng/L whereas 2- MIB levels ranged from 50.8 ng/L to 532.5 ng/L. Axenic cultures of Nostoc sp. recorded the highest Geosmin level (162.6 ng/L) and highest 2- MIB level was detected from Psudoanabena sp. (532.5 ng/L). Further Nostoc sp. recorded a significant high level of 2- MIB level (379.6 ng/L) compared to Oscillatoria sp. and Lynbya sp. (p < 0.05). It can be concluded that above species are commonly available cyanobacteria species in Sri Lankan water bodies and popular Geosmin and 2- MIB producers.
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    Monitoring Tributyltin (TBT) Contamination of Southern Coastal Waters in Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2019-02) Bandara, K.R.V.; Chinthaka, S.D.M.; Manage, P.M.
    Tributyltin (TBT) is an organotin compound belongs to the group of Persistent Organic Pollutants (POPs) and one of the active ingredient in antifouling paints used for boat hulls, docks, fish nets in order to prevent the growth of aquatic fouling organisms. The presence of TBT in the aquatic environment is extremely toxic to target and non-target organisms and it is responsible for severe sexual disorders like sex changes called imposex leading to sterile aquatic populations which lead to decline of animal diversity. According to WHO, the No Observed Effective Level (NOEL) of TBT is below 1 ngL-1. However, there are no information has been recorded regarding the TBT contamination in water and its adverse effect on aquatic organisms in Sri Lanka. Therefore, the study aims to monitor the contamination status of TBT in southern coastal area in Sri Lanka. Coastal water samples were collected from river canals, fishing harbors and river mouth along the Southern Coastal area from Dehiwala to Mirissa. TBT was extracted by using a newly optimized Solid Phase Micro Extraction (SPME) method. Hydridization process was followed for quantification by using the Gas Chromatography-Mass Spectrometry (GCMS) in parts per trillion level (ppt). Results showed that the highest TBT concentration in highly polluted Dehiwala (3.4ngL-1) and Wellawatta canals (3.4ngL-1). TBT concentrations in fishing harbors at Ambalangoda, Galle, Mirissa and Beruwala were range from 1.4 ngL-1 to 3.2ngL-1 where in Madu and Benthota river mouth were 0.8ngL- 1 and 0.9ngL-1 respectively. The recovery of the TBT extraction method was 87±0.1% for the artificial sea water. Thus, the preliminary results of the study showed that high contamination of TBT may adversely effect on marine biodiversity.
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    Study of Removal Efficiency of Rhodamine B Dye from Industrial Waste Water with Different Energy Sources Using TiO2 Photocatalys
    (Uva Wellassa University of Sri Lanka, 2021) Manamperi, N.T.; Chinthaka, S.D.M.
    Various hazardous chemicals discharged to the environment without proper treatments are responsible for whispered pollution. Economical treatment of these hazardous industrial wastes is in high demand in waste treatment sector. Fabric dyes are one of such visible pollutants that are very difficult to treat. In this study, photodegradation processes of Rhodamine B dye in real effluent that was discharged from a fabric dye plant are investigated using various light sources and TiO2 photocatalyst. The UV visible spectrum of the effluent that contains Rhodamine B dye was used to monitor the degradation process. The effect of four different light sources such as sunlight, UV C light, LED blue and LED cool white light were investigated. Physical conditions such as amount of photocatalyst, exposure time, and mass transfer effect were investigated for the kinetics of removal of Rhodamine B. LED blue and LED cool white light show very small effect for this removal process even at high intensities. Sunlight and UV-C light were found to be very effective for the degradation of Rhodamine B dye in fabric plant effluent. The degradation rate of Rhodamine B under sunlight in the presence of TiO2 photocatalyst found to be significantly higher than that for UV C light. However, both light sources are found to be practically usable. Under the sun light, not only Rhodamine B dye but also most of the other chemicals in the effluent were almost entirely eliminated. When sunlight was employed, the degradation rate was highly fluctuated with the change of intensity of sun light. The mass transfer effect is identified as crucial factor for the removal kinetics. Under the agitation, UV-C light also shows removal rate comparable with that of sunlight. Therefore, though less effective than sunlight, UV-C light has higher potential using in industrial applications with proper wavelength, agitation rate and intensity tune up. The pilot plant is under construction in a fabric dye plant based on the outcome of this study. Keywords: Photocatalyst; Degradation; UV light; Rhodamine B; Dyes