Management of Leachate Generated from Long-Term Degradables of Municipal Solid Waste (MSW) in Open Dumps Using Effective Microorganisms (EM) Technology

Open dumping is the most common practice of final disposal of municipal solid waste (MSW) in most of the developing countries including Sri Lanka.Long-term degradables of MSW has been a precursor for leachate of high biological oxygen demand (BOD) and chemical oxygen demand (COD) to be generated due to organic compounds of higher molecular weights and treatment of such leachate seems to be a daunting task in many open dumps. Leachate generated from the Karadiana open dumpsite released to the Bolgoda lake results in many adverse effects on human health and aquatic ecosystem. Most of the organic compounds in the leachate are attributed to long term degradables, not readily biodegradable, and resist conventional treatment methods; hence, a reliable and efficient treatment system has been a long-felt need. In this study, the use of Effective Microorganisms (EM) technology for enhancing the biodegradability of long term degradables and subsequent treatment by advanced oxidation using Fenton oxidation is explored. A solution containing EMs (Lactic acid bacteria-9×107, photosynthetic bacteria-4×107, yeast-2×106 CFU/mL) (100 mL at day=1) was applied to the leachate with combinations of 0, 50, 75% dilutions having volumes of 1 L. At the time of application, COD levels of the said combinations were 20,030, 12,672 and 11,090 mg/L respectively. With the application of EMs (100 mL at day=1), COD levels were recorded to be 18,064, 3,951 and 3,002 mg/L respectively, after a retention time of 10 days. Further, Fenton oxidation was carried out subsequently for controls and for the ones added with EMs. The COD levels of controls were 2,400, 1,250 and 905 mg/L for 0, 50 and 75% dilutions respectively. The same treated with EMs were 1,009, 720 and 490 mg/L. Thus, it can be concluded that the application of EM technology is effective in reducing COD levels in the leachate generated from long term degradables.Keywords: Leachate, Municipal solid waste, Long term degradables, Effective microorganisms, Fenton oxidation, Chemical oxygen deman

Effectiveness of Domestic Reverse Osmosis Units for Removal of Fluoride and Hardness for Drinking Purposes in Chronic Kidney Disease of Unknown Etiology (CKDu) Affected Areas in Anuradhapura

The hypothesis having excessive fluoride and hardness levels in ground water in combination is said to have been associated with the onset of CKDu. Provision of good quality drinking water devoid of fluoride and hardness to levels less than nephrotoxic levels would be considered of paramount importance. In this respect, several types of water filters have been introduced to CKDu affected areas of which RO units are the most popular filters. Hence, this research aims at investigating the effectiveness of domestic RO units in removing fluoride and hardness levels reported in CKDu affected areas under different climatic conditions for a period covering dry and wet seasons. Two monsoons and the 2nd inter monsoon were simulated in the laboratory and the removal of fluoride and hardness by the RO unit were evaluated according to the drinking water guidelines.Northeast monsoon was subdivided into extreme wet and wet to dry periods. Hardness and fluoride concentrations in the raw water during above periods were 110 ppm and 578 ppm and fluoride concentrations were 0.52 ppm and 2.93 ppm respectively. In the above periods hardness values obtained in the permeate were 12 ppm and 24 ppm and the fluoride was completely removed during extreme wet period and 0.15 ppm fluoride was observed in wet to dry period. In the 2nd inter monsoon, hardness and fluoride concentrations in raw water were 1032 ppm and 7 ppm respectively and in the permeate 40 ppm hardness and 0.39 ppm of fluoride were observed. All the above fluoride and hardness values in the permeate do not comply with the required drinking water guidelines. Southwest monsoon was subdivided in to three periods namely extreme dry, dry and dry to wet. In extreme dry period hardness and fluoride in raw water were 1230 ppm and 15.5 ppm respectively. In the permeate hardness concentration varied from 48 ppm-184 ppm and fluoride concentrations varied from 0.19 ppm-1.67 ppm. At the latter stage both the fluoride and hardness values have exceeded the required drinking water guideline values. This happen when all the adsorption sites of the filter unit get saturated with the increase of the raw water concentration and then excess amount of water constituents will pass through the RO membrane. Flow rate was dropped from 0.24 litres/min to 0.03 liters/min during these periods implying that the membrane of the unit has started to get clogged. As the performance of the RO unit depends on the initial constituent’s concentration in the raw water, according to this study people can use RO unit for a period of 6 months without getting clogged.Keywords: Chronic kidney disease of unknown etiology, Fluoride, Hardness, Reverse osmosi

Removal mechanisms and efficiencies of selected heavy metals in constructed wetlands

The removal efficiencies and mechanisms of Pb, Cr, Cd and Zn removal were investigated in batch type constructed wetlands comprising water hyacinth (Eichhornia crassipes (Mart.) Solms) using a mass balance analysis. This study was conducted for 15 weeks in four 590 l capacity tanks containing 3.1, 5, 0.2 and 1.1 mg/l of Pb, Cr, Cd and Zn respectively. Removal efficiencies from the wastewaters were in the range of 92.1-99.6%, 31.3-100%, 46.3-94.4% and 25.1-94.8% for Pb, Cr, Cd and Zn, respectively. The results showed that water hyacinth roots play a crucial role in the removal of Pb and Cr by means of precipitation, though phytoremediation was insignificant. However, phytoremediation through rhizofiltration seemed to govern the removal of Cd and Zn. We conclude that constructed wetlands comprising water hyacinth is a promising low cost option for removing the above heavy metals within the ranges investigated

Removal of Fluoride and Hardness in Dietary Intake (water) in Chronic Kidney Disease of unknown Etiology (CKDu) Prevalent Areas by Domestic Reverse Osmosis Units

The origin of Chronic Kidney Disease of unknown etiology (CKDu) that is rapidly invadingthe dry zone of Sri Lanka has not yet been identified. However, occurrence of the disease isthought to be linked with excess levels of fluoride and hardness in drinking water. Hence, thestudy herein focuses to evaluate the suitability of domestic Reverse Osmosis (RO) units;which introduced in CKDu affected areas to remove excess fluoride and hardness.Accordingly, the drinking water quality in CKDu prevalent areas in terms of fluoride andhardness was simulated in the laboratory and the removal of aforesaid constituents usingdomestic ROs was investigated.According to water quality analyses, domestic RO units effectively removed hardness even atextremely high initial concentrations, such as 1,730 mg/L (as CaCO3). Excessive removal ofCalcium and Magnesium by the RO units was observed, thus remineralization of thepermeate up to 80-100 mg/L as CaCO3 is required to ensure health benefits. Meanwhile,fluoride removal was observed to be highly dependent upon initial fluoride and hardnessconcentrations. It was not possible to suggest an „optimum removal level‟ for fluoride, wherepermeate fluoride concentration exceeded the maximum permissible WHO Drinking WaterGuideline value of 1.5 mg/L. However, it may arise at a point where fluoride and hardnessconcentrations in raw water fall within 1.7-3.5 mg/L and 570-1,130 mg/L as CaCO3,respectively.Plausible reasons for ineffective removal of fluoride could be the relatively small size andlow ionic charge of fluoride. Additionally, high concentration of heavy ions may interferewith fluoride adsorption of activated carbon filter in the domestic RO unit. Effective fluorideremoval could be achieved by adopting appropriate pre-treatment methods for hardnessremoval. Separate threshold levels for fluoride and hardness levels in drinking water shouldbe defined, especially for CKDu patients.Keywords: Chronic Kidney Disease, Domestic reverse osmosis units, Fluoride, Hardnes

Use of Reverse Osmosis Reject Water for Value Addition in Coco Substrate Industry

Previous studies corroborated that water enriched with various compounds is a major reasonfor Chronic Kidney Disease of Unknown Aetiology (CKDu) in Sri Lanka. Reverse osmosis(RO) units are being introduced in the CKDu prevalent areas for water purification.Generally, the RO reject water is disposed of directly to the ground and/or used for irrigationpurposes because it contains several minerals, which are favourable for the growth of plants.However, this practice may cause any negative environmental issues.Calcium nitrate is used as a value addition in coco substrate industry to wash out sodiumfrom the coir products because sodium competes with other cations which are essential forplant growth in the process of adsorption. However, discharging the spent calcium nitratesolution to land for irrigation purposes may lead to nitrate pollution. This study investigatesthe possibility of using RO reject water, which has considerably high amounts of calcium, asan alternative for the use of calcium nitrate, which may also lead to reduction of cost ofimporting calcium nitrate. Leachability tests were carried out using husk chips as the solidmedium with RO reject water and calcium nitrate as the treatment solution, respectively.When RO reject water was used as the washing solution, the results manifested (amount ofcalcium, magnesium adsorbed and sodium, potassium leached out) that the leachabilitypotential was well within the acceptable range as per the protocols. Based on the findings,RO reject water could be proposed as an alternative source to calcium nitrate.Keywords: Calcium nitrate, Coco substrate, Husk chips, Reverse osmosis, Water purificatio

Migration of Phthalic Acid Esters from PET Water Bottles: Implications of Reusing Empty Bottles for Storing Ambient and Warm Water for Subsequent Consumption

Phthalic Acid Esters (PAEs) are a group of emerging contaminants that are widely used as a plasticizer in manufacturing polyethylene terephthalate (PET) bottles to improve softness, flexibility, durability, longevity and workability. Some of PAEs have, however, been identified to be carcinogenic. People in Sri Lanka often use the PET bottles for storing ambient and warm water repeatedly for subsequent consumption. With the reuse of bottles, PAEs are easily detached and migrated to the water, because of weak chemical bonding between the main polymer structure and PAEs. However, no comprehensive studies on the migration of PAEs from the material of the bottle to water in the context of different reuse efforts of storing ambient and warm water have been reported; hence, this study. Ten different commercial brands of PET bottles were selected. The initial storage temperature of selected PET bottles was measured and they were under room temperature conditions. It was ensured that they were not exposed to the direct sunlight under storage condition. Three bottles of each brand were filled with warm water (initial temperature 60±2º C) and another three with the same water at room temperature (27±2 ºC) and kept for 12 hours. The PAE levels of the water in the bottles were analysed by Gas Chromatography-Mass Spectrometer (GC-MS) using EPA method 8061A. Six PAEs, bis (2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), diethyl phthalate (DEP), benzylbutyl phthalate (BBP), dimethyl phthalate (DMP) and di-n-octyl phthalate (DnOP) were quantified.The same bottles were subject to PAE analyses for six consecutive reuse events. Characterisation of PET bottles of two brands was done to investigate the thermally induced structural changes using the Fourier-Transform Infrared spectroscopy, Scanning Electron Microscopy, Differential Scanning Calorimetry and X-Ray powder Diffraction.In general, DMP, DEP, DnBP, BBP, and, DnOP were not detected in the water under room temperature (27±2º C) and 60±2º C. Among the six different PAEs tested, DEHP was the only PAE that has leached out at room temperature and at 60ºC for different brands. Results manifested the maximum and minimum levels of DEHP being migrated after each event of reuse at room temperature to be 82±4 μgL-1 and 17±2 μgL-1, respectively, and the maximum and minimum levels of DEHP leached out at 60±2 ºC were 133±3 μgL-1 and 26±2 μgL-1, respectively. Characterisation studies indicate that there were structural changes with each reuse event at 60±2 ºC in comparison to those at room temperature. In conclusion, this study provides evidence of migration of DEHP from the material of the bottle to water in the reuse efforts for storing warm water for subsequent consumption. Hence, regulating the quantities of DEHP to be added during the manufacturing process of PET bottles and the reuse efforts of empty PET bottles is of utmost importance to minimize the potential health and environmental impacts.Keywords: DEHP, PAE, Polyethylene terephthalate, Reuse, Temperatur