Enhancing Arsenic Removal from Bangladesh Groundwater by Controlled Iron Oxidation in Filters

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...Sanitary Engineerin

Tubewell platform color as a screening tool for arsenic in shallow drinking water wells in Bangladesh

The development of a simple and low cost technique for determination of arsenic (As) in drinking water wells is an urgent need to accelerate As mitigation policy. The aim of this study was to evaluate the potentiality of tubewell platform color as low-cost, quick and convenient screening tool for As. The result shows strong correlation between the development of red color stain on tubewells platform and As enrichment in the corresponding tubewells water compared to WHO (10 μg/L) and BDWS (50 μg/L), with 99% certainty. The red color stain in the platform indicates 98% sensitivity with WHO (10 μg/L) and BDWS (50 μg/L). With regard to WHO and BDWS, the corresponding efficiency of the platform color as screening tool for As are 97.3% and 97%. This study suggests that platform color can be potentially used for screening tubewells, help users switch to tube wells with low As and facilitate sustainable As mitigation efforts in developing countries

Sequential Fe²⁺ oxidation to mitigate the inhibiting effect of phosphate and silicate on arsenic removal

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−.Sanitary EngineeringWater Managemen

Critical issues of present medical waste management practice in Rajshahi city and its improvement strategies

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.Sanitary Engineerin

Anoxic storage to promote arsenic removal with groundwater-native iron

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.Sanitary EngineeringWater Managemen

Arsenic removal from iron-containing groundwater by delayed aeration in dual-media sand filters

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.Sanitary Engineerin

The COVID-19 Health Protocol among University Students: Case Studies in Three Cities in Indonesia

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 regularlySanitary Engineerin