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[AHW23-P04] Reuse of water via groundwater sustentation in storage level in Dhaka, Bangladesh
キーワード：Dye water , Reuse of waste water, Ground water depletion
This study predicts that reuse of waste water will retard the groundwater mining that deals with environmental remediation. Depletion of aquifer storage for groundwater abstraction is now the serious problem in Dhaka, Bangladesh. Almost 82 % of the supply of water have been withdrawn and used by the Dhaka Urban water agency for both domestic and industrial uses from underground1 and many textile factories take their own water from underground without any oversight. To fulfill this huge demand of water, groundwater level is declining by 2-3 meters each year. Considering the existing depletion rate, the groundwater table will go down to about 110 to 115 meters by 2050 if any preventive measure would not be taken. Currently, 98% of untreated domestic sewage and significant amounts of industrial wastewater discharge from over 7000 industries are contributing to the presence of waste water in the urban rivers. Although the success story of Bangladesh’s textile sector and garments industry looks very impressive, the industry has faced a lot of challenges in its journey to the top in the form of working condition, safety and the compliancy of the environment in its waste management2. However, to treat these generated wastes or effluent from dye industries, waste chemicals except dyes are removed from the waste water roughly with an expensive ETP system (effluent treatment plant) by maintaining water standard. However, the treated colorful water with toxic contaminant and with high TOC (total organic carbon), are not ready for reuse.
For the purpose of reusing the dye water, this research has developed the procedure for the preliminary treated discharged dye water from the ETP system, and applied combined continuous methods stepwise for the removal of organic and inorganic contaminant in water. At the first step, 1) coagulation and adsorption was made by Mg-salt in saline water for the removal of concentrated dye from water, 2) in next step, other inorganic waste compound with degradable organic content was removed by Fenton Reaction, 3) in third step, electrolysis method was applied for the trace amount of dye and heavy metals, 4) in fourth step, bacteria, foulant and oil was removed by the microbubble which can generate pressure waves through shrinking and subsequent by self-collapsing phenomenon and by the potential to attract organic substances like oil using microbubble-system, 5) finally, RO (reverse osmosis) filter was used for the separation of huge amount of major ions from the clean water. After following the different five continuous treatment steps, the water qualities were met the standard of domestic water lebel3. As waste management and the reliability and safety of water reuse systems is widely demonstrated, it is believed that water reuse via less groundwater abstraction will continue to expand as an essential topic in sustainable water resources management in Bangladesh.
References: 1) Nahar et al., 2013, Environ Earth Sci,69, 127–140.
2) Maalouf et al., 2021, Sustainability, 13, 4313.
3) Nahar et al., 2014, Environ Geochem Health, 36, 1079–1094.
For the purpose of reusing the dye water, this research has developed the procedure for the preliminary treated discharged dye water from the ETP system, and applied combined continuous methods stepwise for the removal of organic and inorganic contaminant in water. At the first step, 1) coagulation and adsorption was made by Mg-salt in saline water for the removal of concentrated dye from water, 2) in next step, other inorganic waste compound with degradable organic content was removed by Fenton Reaction, 3) in third step, electrolysis method was applied for the trace amount of dye and heavy metals, 4) in fourth step, bacteria, foulant and oil was removed by the microbubble which can generate pressure waves through shrinking and subsequent by self-collapsing phenomenon and by the potential to attract organic substances like oil using microbubble-system, 5) finally, RO (reverse osmosis) filter was used for the separation of huge amount of major ions from the clean water. After following the different five continuous treatment steps, the water qualities were met the standard of domestic water lebel3. As waste management and the reliability and safety of water reuse systems is widely demonstrated, it is believed that water reuse via less groundwater abstraction will continue to expand as an essential topic in sustainable water resources management in Bangladesh.
References: 1) Nahar et al., 2013, Environ Earth Sci,69, 127–140.
2) Maalouf et al., 2021, Sustainability, 13, 4313.
3) Nahar et al., 2014, Environ Geochem Health, 36, 1079–1094.