Generally, abstracted groundwater is aerated, leading to iron (Fe²⁺) oxidation to Fe³⁺ and precipitation as Fe³⁺-(hydr)oxide (HFO) flocs. This practice of passive groundwater treatment, however, is not considered a barrier for arsenic (As), as removal efficiencies vary widely (15–95%), depending on Fe/As ratio. This study hypothesizes that full utilization of the adsorption capacity of groundwater native-Fe²⁺ based HFO flocs is hampered by rapid Fe²⁺ oxidation-precipitation during aeration before or after storage. Therefore, delaying Fe²⁺ oxidation by the introduction of an anoxic storage step before aeration-filtration was investigated for As(III) oxidation and removal in Rajshahi (Bangladesh) with natural groundwater containing 329(±0.05) µgAs/L. The results indicated that As(III) oxidation in the oxic storage was higher with complete and rapid Fe²⁺ oxidation (2±0.01 mg/L) than in the anoxic storage system, where Fe²⁺ oxidation was partial (1.03±0.32 mg/L), but the oxidized As(V)/Fe removal ratio was comparatively higher for the anoxic storage system. The low pH (6.9) and dissolved oxygen (DO) concentration (0.24 mg/L) in the anoxic storage limited the rapid oxidation of Fe²⁺ and facilitated more As(V) removal. The groundwater native-Fe²⁺ (2.33±0.03 mg/L) removed 61% of As in the oxic system (storage-aeration-filtration), whereas 92% As removal was achieved in the anoxic system.

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The study was conducted to evaluate medical waste management practices and to determine the critical issues in medical waste management in Rajshahi City. A survey was conducted to collect information about the practices related to waste segregation, collection procedures, types of onsite storage containers, onsite handling, processing and storage, primary dumping point, transfer and transport, treatment of wastes, and final disposal options. This study indicates that the rate of medical waste generation varies among health care establishment as 336.23 kg/day, 7.14 kg/day, 2.11 kg/day, 3.92 kg/day, 1.21 kg/day and 15.05 kg/day at Rajshahi Medical College Hospital, Christian Mission Hospital, Al-Madina Clinic, Mohanagar Clinic, Rajshahi Dental College and Popular Diagnostic Center, respectively. The highest 15 types of wastes are analyzed from wastes generated in Rajshahi medical college hospital. However, only two to six types of wastes are obtained in other health care facilities. The critical issues identified from this study are not accumulation of all types of wastes in every hospital, colour containers are not always used by many hospitals, collection of wastes from source of generation is not properly performed, primary dumping site is not cleaned after transferring and transporting the waste, there is no incinerator except Rajshahi Medical College Hospital and it is not used regularly, hazardous wastes are burnt in open place. Rajshahi City Corporation, the waste management authority, has no treatment and disposal facility for medical wastes. The wastes collected from all health care facilities are dumped by municipal authority along with the municipal solid wastes by open dumping method. From this study it can be mentioned that there is an urgent need to take immediate action for raising awareness and education on medical waste management issues. Moreover, trained and skilled medical wastes management workers are essential in Rajshahi City.@en