Pollution makes river waters hard to treat: experts

Water of the Buriganga and Shitalakhya rivers has become difficult to treat due to high level of pollution, said Dr MA Taher Khandker, director general of Bangladesh Haor and Wetland Development Board at a seminar yesterday. “Water in the Buriganga and Turag rivers have literally turned into poison,” said Khandker in his presentation at the seminar titled 'Pollution of Rivers around Capital Dhaka: Mitigation Options' at Water Development Board (WDB) office. Dissolved Oxygen (DO) level, an indicator of measuring river health and aquatic life in its water, stands at zero milligram (per litre) at different points of Buriganga, Turag, Tongi Khal and Balu during dry season, he said.He said ideally it should remain seven to eight milligram (per litre) in the rivers' water. But the DO level is dropping significantly due to unabated dumping of wastes and toxic substances into rivers and water bodies.While DO level is alarmingly low in the rivers of Dhaka, load of Biochemical Oxygen Demand (BOD) (amount of oxygen used for decomposition of organic matters), is high in the Buriganga and Shitalakhya rivers, he said. Tolerable BOD load may remain three milligram (per litre) at best but it remains many times higher than the tolerable level and may escalate further if pollution continues in the rivers, he said. Six rivers, including the Buriganga, Turag, Dhaleswari, Tongi Khal, Balu and Shitalakhya, encircle the capital city with around 110 km length, he said, there is no other capital in the world with such fantastic circular waterway. Khandker suggested water flow augmentation in the rivers and setting up wastewater treatment plants. There are many laws against environmental pollution and destruction of rivers and wetlands but hardly those laws have been enforced, WDB Additional Director General Kamrul Huda said. The board, under the water resources ministry, organised the seminar, chaired by WDB Additional Director General Wafi Md. Kamrul Huda. Government's high officials and engineers of WDB attended the seminar.