Browsing by Author "Karunaratne, HWGI"

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item: Thesis-Abstract
Removal of pollutants in parboiled paddy waste water
Karunaratne, HWGI; Gunasekera, MY
Parboiling is a widely used paddy processing method where paddy is soaked in water to hydrate before the subsequent steaming, drying and milling operations. A significant amount of water is used in this soaking operation which is then discharged as wastewater. The continuous discharge of this wastewater has become an environmental concern in the paddy parboiling industry in Sri Lanka.In this study important characteristics of the effluent generated from two existing paddy soaking operations practiced in Sri Lanka namely hot soaking and cold soaking were initially determined. This analysis was done for wastewater resulting from soaking two rice varieties available locally, namely LD 356 a red rice and BG 300 which is a white rice. Characterization study showed pollutant levels higher in paddy soak wastewater than the stipulated local discharge standards (Appendix C). Wastewater generated from both hot soaking and cold soaking of red rice variety showed relatively higher COD and BOD values compared to those of wastewater from white rice variety. Hot soaking wastewater had higher COD and BOD values than cold soaking wastewater. The wastewater generated from hot soaking of red rice which showed higher pollutant strength is further studied for pollutant removalmethods.Biological treatment methods such as aerobic, anaerobic and physical treatment methods such as coagulation and adsorption were investigated. Removal of pollutants by aquatic plants and biological treatment using various microbial seeding sources such as cow dung, rice straw, pond water and paddy field soil were also studied. Results show that microbial sources from pond water and paddy field soil were able to reduce COD in soak wastewater by 96% and 94% respectively at pH 8 under aerobic and dark conditions. Combined treatment of anaerobic digestion and coagulation was able to reduce 94% COD while the combination of adsorption and coagulation reduced COD by 92%. Treatment of a wastewater sample collected from a paddy parboiling rice mill in Marandagahamula area using pond water as the microbial source showed a 93% COD reduction.
item: SRC-Report
Removal of pollutants in soak water resulting from parboiling of paddy
(2009) Karunaratne, HWGI; Gunasekera, MY
Rice is the staple diet in Sri Lanka where parboiled rice is becoming fast popular. The parboiling process involves three main steps namely soaking, steaming and drying which improves various characteristics of rice. A significant amount of water is consumed in soaking operation. The wastewater generated from this operation is mostly discharged to inland water bodies and surface lands. The continuous discharge of this effluent is of environmental concern. Lab scale experiments were carried out to investigate the effectiveness of different wastewater treatment methods for removal of pollutants in soak water resulting from hot soaking of red rice variety named LD 356. Biological treatment methods such as aerobic, anaerobic and physical treatment methods such as coagulation and adsorption were investigated. Removal of pollutants by aquatic plants and biological treatment using various microbial sources such as cow dung, rice straw, pond water and paddy field soil were also investigated. Results show that microbial sources from pond water and paddy field soil were able to reduce COD in soak water by 96% and 94% respectively at pH 8 under aerobic and dark conditions. In seven days, 62% and 65% COD removal were observed by water hyacinth and salvinia respectively. Combined treatment of anaerobic digestion and coagulation was able to remove 94% COD while the combination of anaerobic digestion and adsorption removed 95% COD.
item: SRC-Report
Treatment of soak wastewater resulting from paddy parboiling process : combind methods approach
Karunaratne, HWGI; Gunasekera, MY
Parboiling is a process used to improve the milling characteristics of paddy. The wastewater generated from soaking operation in parboiling process has pollutant levels higher than the discharge standards. Lab scale experiments were carried out to remove Chemical Oxygen Demand (COD) in soak water resulting from hot soaking of a red rice variety named LD 356. Combined treatment of this wastewater using biological treatment with aeration and coagulation was able to remove 95.48% COD while coagulation and adsorption collectively removed 92.58%. The combination of adsorption and aquatic plant based treatment removed 90.64% COD in which adsorption alone removed 90%.
item: Conference-Extended-Abstract
Treatment of soak wastewater resulting from paddy parboiling process: combined methods approach
(2009) Karunaratne, HWGI; Gunasekera, MY
Parboiling is a process used to improve the milling characteristics of paddy. The wastewater generated from soaking operation in parboiling process has pollutant levels higher than the discharge standards. Lab scale experiments carried out to remove Chemical Oxygen Demand (COD) in soak water resulting from hot soaking of a red rice variety named LD 356. Combined treatment of this wastewater using biological treatment with aeration and coagulation able to remove 95.48% COD while coagulation and adsorption collectively removed 92.58%. The combination adsorption and aquatic plant based treatment removed 90.64% COD in which adsorption alone removed 90%.