Sequential iron (as Fe²⁺) oxidation has been found to yield improved arsenic (as As(III)) uptake than the single-step oxidation. The objective of this study was to gain a better understanding of interactions with phosphate (PO₄³⁻) and silicate (SiO₄²⁻) during sequential Fe²⁺ and As(III) oxidation and removal, as these are typically found in groundwater and known to interfere with As removal. The laboratory experiments were performed using single and multi-step jar tests with an initial As(III/V), Fe²⁺, PO₄³⁻, SiO₄²⁻ concentrations, and pH of 200 μg/L, 2.5 mg/L, 2 mg/L, 16 mg/L and 7.0, respectively representing the targeted natural groundwater in Rajshahi district, Bangladesh. The sequential Fe²⁺ and As(III) oxidation in the multi-step jar tests indicated that the PO₄³⁻ hindrance on As removal in the first Fe²⁺ oxidation step was compensated for in the second. Moreover, smaller Fe flocs (<0.45 μm) were observed in the presence of SiO₄²⁻, potentially providing more surface area during the second Fe²⁺ oxidation step leading to better overall As removal. Altogether it may be concluded that controlling the As(III) and Fe²⁺ oxidation sequence is beneficial for As removal compared to single-step Fe²⁺ oxidation, both in the presence and absence of PO₄³⁻ and/or SiO₄²⁻.

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Groundwater arsenic (As) contamination is a severe drinking water quality problem and threatens human health in Bangladesh and other countries. Chronic exposure to As-contaminated drinking water has resulted in tens of millions of people suffering from skin lesions, hyperkeratosis, melanosis, skin cancer, and cancer of internal organs. The World Health Organization (WHO) recommends that As concentrations in drinking water should not be more than 10 μg/L. However, according to Bangladesh Drinking Water Standard (BDWS), the recommended value for As in drinking water is 50 μg/L. Nevertheless, groundwater in an extended area of Bangladesh contains As concentrations higher than those recommended values, and sometimes, it even exceeds 1500 μgAs/L. Various treatment technologies, including adsorption, chemical precipitation, ion exchange, membrane filtration, nanofiltration (NF), and reverse osmosis (RO) have been studied to remove As from water. However, these options are typically energy-intensive and/or consume chemicals that make the treatment methods expensive. In addition, commonly available treatment systems are complicated to operate and maintain, needing regular parts’ replacement and aftermarket services, and skilled personnel who may not be locally available. Consequently, these technologies are not sustainable on the long run in vulnerable communities. Therefore, there is a need for simple, economic, and energy-efficient alternatives, utilizing locally available materials and crafts without the need for chemical dosing...@en

The COVID-19 pandemic has caused lifestyle changes for everyone and led to the practice of regulated health protocols for preventing the spreading or severity of the COVID-19 pandemic. This study examines the differences in health protocols and health practices among university students. The designed online survey was conducted among 292 university students in three cities in Indonesia, i.e., Yogyakarta, Semarang, and Surakarta. A forced-entry multivariate regression was conducted using all RANAS (risk, attitude, norms, ability-self-regulation) sub-factors as independent variables and health protocol obtained from PCA as the dependent variable. The results showed that the students’ health protocol and health practices were practiced with varying frequency. A face mask covering the chin and nose was the most practiced health protocol, while reducing mobilization by maintaining distance was the most violated health protocol among students. We also found that four health protocol practices are highly correlated, i.e., handwashing in public spaces, physical distancing, frequency of using the mask, and avoiding crowded places. In addition, three significant psychological factors were identified, which were positively associated with the student’s health protocol practice, i.e., belief about time (attitude) (OR: 0.119; CI: −0.054–0.136; p ≤ 0.05), personal norm (norm) (OR: 0.232; CI: 0.149–0.539; p ≤ 0.01), and action control (self-regulation) (OR: 0.173; CI: 0.046–0.427; p ≤ 0.05), where the personal norm is the most significant one. Finally, to minimize the COVID-19 transmission among students, especially when they back to onsite learning, it was important to create students’ sense of ethical self-obligation to follow and practice standard health hygiene correctly and regularly@en

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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Storage containers are usually used to provide a constant water head in decentralized, community groundwater treatment systems for the removal of iron (Fe) and arsenic (As). However, the commonly practiced aeration prior to storage assists in rapid and complete Fe²⁺ oxidation, resulting in poor As removal, despite sufficient native-Fe²⁺ in the source water. In this study, it was found that application of anoxic storage enhanced As removal from groundwater, containing ≥300 µg/L of As(III) and 2.33 mg/L of Fe²⁺ in an As affected village of Rajshahi district in Bangladesh. Although the oxidation of Fe²⁺ and As(III) during oxic storage was considerably faster, the As/Fe removal ratio was higher during anoxic storage (61–80±5 µgAs/mgFe) compared to the oxic storage (45±5 µgAs/mgFe). This higher As removal efficacy in anoxic storage containers could not be attributed to the speciation of As, since As(V) concentrations were higher during oxic storage due to more favorable abiotic (As(III) oxidation by O₂ and Fenton-like intermediates) and biotic (As(III) oxidizing bacteria, e.g., Sideroxydans, Gallionella, Hydrogenophaga) conditions. The continuous, in-situ hydrous ferric oxide floc formation during flow-through operation, and the favorable lower pH aiding higher sorption capacities for the gradually formed As(V) likely contributed to the improved performance in the anoxic storage containers.

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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

This study aimed to evaluate the potential of handpump tubewell platform color as a low-cost, quick and convenient screening tool for As and Mn in drinking water tubewells. For this study, groundwater samples and corresponding tubewell platform pictures were collected from 272 shallow tubewells in Matlab Upazila of South-Eastern Bangladesh. The result shows that arsenic concentration within the surveyed (n = 272) tubewells, 99% (n = 269) exceeded the World Health Organization (WHO) guideline value of 10 µg/L, and 98% (n = 267) exceeded the Bangladesh drinking water standards (BDWS) of 50 µg/L. In relation to the platform color concept, within 233 (total 272) red colored platform tubewells, 230 (99%) exceeded the WHO guideline value of 10 µg/L, and 229 (98%) tubewells exceeded BDWS of 50 µg/L. This result shows a strong correlation between the development of red color stain on tubewell platform and As concentrations in the corresponding tubewell water. This study suggests that red-colored platform can be used for primary identification of tubewells with an elevated level of As and thus could prioritize sustainable As mitigation management in developing countries where water comes from reductive shallow aquifers. This study did not confirm the potential for Mn screening, as red discoloration by Fe oxides was found to mask the black discoloration of Mn oxides. It is recommended to further investigate this screening tool in regions with a higher well-to-well variability of As contaminations, as in the presented study As was found >10ug/L in 99% of the tubewells.@en

Biological aerated filter (BAF), sand filtration (SF), alum and Moringa oleifera coagulation were investigated as a pre-treatment for reducing the organic and biofouling potential component of an ultrafiltration (UF) membrane in the treatment of lake water. The carbohydrate content was mainly responsible for reversible fouling of the UF membrane compared to protein or dissolved organic carbon (DOC) content. All pre-treatment could effectively reduce these contents and led to improve the UF filterability. Both BAF and SF markedly led to improvement in flux than coagulation processes, and alum gave greater flux than M. oleifera. This was attributed to the effective removal and/or breakdown of high molecular weight (MW) organics by biofilters. BAF led to greater improvement in flux than SF, due to greater breakdown of high MW organics, and this was also confirmed by the attenuated total reflection-Fourier transform infrared spectroscopy analysis. Coagulation processes were ineffective in removing biofouling potential components, whereas both biofilters were very effective as shown by the reduction of low MW organics, biodegradable dissolved organic carbon and assimilable organic carbon contents. This study demonstrated the potential of biological pre-treatments for reducing organic and biofouling potential component and thus improving flux for the UF of lake water treatment.@en