Exploring the future impacts of urbanization and climate change on groundwater in Arusha,Tanzania

ABSTRACT

We combine satellite imagery, urban growth modelling, groundwater modelling and hydrogeological field expeditions to estimate the potential impacts in 2050 of rapid urbanization and climate change on groundwater in Arusha, Tanzania, and by extension similar areas in Sub-Saharan Africa. Our analysis suggests that a reduction of groundwater recharge by 30–44% will cause groundwater levels to drop by up to 75 m, mainly due to increased evapotranspiration and to an expansion in paved surface. If this scenario becomes reality, we predict that wells will run dry, creating health, social and environmental risks.     

Effect of CdO addition on photon,electron, and neutron attenuation properties of boro-tellurite glasses

This research article aims to study the effect of CdO addition on the radiation shielding characteristics of boro-tellurite glasses in the composition of 50B₂O₃ - (50-x) TeO2- xCdO, where x = 0, 10, 20, 30, 40 and 50 mol%. These glasses were exposed to gamma radiation and the transmitted gamma photons were evaluated for energies varying from 15 keV to 15 MeV using Geant4 simulation toolkit. The number of transmitted photons was then used to characterize the gamma shielding for the studied glasses in terms of linear/mass attenuation coefficients, MFP, Z_eff, and HVL. The simulation outcomes were theoretically confirmed by using Phy-X software. The beta (electron) shielding characterization of the involved glasses was also investigated by determining the projectile range and stopping power using ESTAR software. Additionally, the fast neutron shielding characterization of the glasses was achieved by evaluating removal cross-section (Σ_R). The results reveal that the CdO has a small influence on the shielding performance of the boro-tellurite glasses against gamma, beta, and neutron radiations. The shielding performance of the boro-tellurite glasses was compared with that of common shielding materials in terms of MFP. It can be concluded that the boro-tellurite glasses regardless of the concentration of CdO content have promising shielding performance to be used for radiation applications.     

The role of PbF2 on the gamma-ray photon,charged particles,and neutron shielding prowess of novel lead fluoro bismuth borate glasses

Journal of Materials Science: Materials in Electronics - The radiation shielding characterization of glasses is vital in establishing their role in nuclear protection applications. This study...     

Failure Analysis of an Effluent Treatment Plant in an Oral Care Industry

Reports of environmental pollution by industries worldwide call for an urgent need to assess wastewater treatment facilities in various industries. This study presents an assessment of a wastewater treatment plant in an oral care (toothpaste) industry. The industry was visited, facilities for wastewater treatment were assessed (based only on efficacy to remove selected environmental and human’s health-related pollutants) and measurement of essential design parameters and facility characteristics were conducted. The study revealed that the averages of flow rate, biochemical oxygen demand at 5 days (BOD₅), chemical oxygen demand (COD), suspended solids (SS), iron concentration, and total solids (TS) in the influent wastewater into the plant were 4.96 ± 0.6 m³/d; 90 ± 5 mg/L; 224 ± 8 mg/L; 1266.78 ± 10.24 mg/L; 0.31 ± 0.11 mg/L, and 2198.65 ± 20.44 mg/L, respectively. Individual efficacies were as follows: 0.49, 0.28, and 0.38% for SS, TS, and calcium, respectively. The overall efficacy of the wastewater treatment facility was found to be 0.020% which was significantly lower than expected. This indicates that no treatment was conducted on the wastewater and that the wastewater is being discharged into the environment essentially untreated. Equalization time (t _eq) was found to be 2.0 h with equivalent equalized BOD₅ concentration of 90 ± 5 mg/L, while expected volume for the equalization tank is 1.5 m³. It was concluded that failure (lower overall efficacy) of the system can be attributed to lack of an equalization tank, inadequate treatment processes, and refusal to apply standardized engineering code and practices. Although such conditions are rare in developed nations, these results demonstrate the problems in pollution control in developing communities.     

Adsorption kinetics of cadmium ions onto powdered corn cobs

Environmental pollution caused by the presence of toxic materials such as cadmium is becoming global problem and concern. This paper presents a report on kinetics of Cd²⁺ removal from aqueous solutions through adsorption using powdered corn cobs (PCC). Corn cobs were collected from a selected location, washed to remove sand, air dried, ground and sieved into different particle sizes. The selected properties of PCC were determined using acid digestion method. Adsorption capacities through kinetics of Cd²⁺ removal from synthetic solutions, typical raw water and domestic‐institutional wastewater were studied. Effects of pH, PCC particle size, initial concentration of Cd²⁺ and temperature on adsorption capacities were monitored through pseudo first‐ and second‐order models, Elovich and intraparticle diffusion models to present adsorption rate parameters. The study revealed that PCC contained 86.89% volatile solids, had 4.56% acid solubility, 0.52 water solubility and 2.33% ash content. PCC removed Cd²⁺ from aqueous solutions (synthetic, raw water, and wastewater). The relationship between time and concentration of Cd²⁺ remaining in the solution followed exponential functions with squared correlation coefficient ranging from 0.9928 to 0.9993, 0.8701 to 0.9284, and 0.8514 to 0.9290 for synthetic solution, raw water, and typical domestic‐institutional wastewater, respectively. Mechanism of cadmium adsorption onto PCC was in two separate stages linear portions in the first parts, while the final parts are curves indicating intraparticle diffusion. It was concluded that PCC is an effective adsorbent for Cd²⁺ removal. The estimated production cost was 0.068 USD as against 0.50, 2.12, and 3.12 USD for producing adsorbents from empty fruit bunches; pencom shell and sugar cane based activated carbons, respectively.     

Removal of lead ions from aqueous solutions using powdered corn cobs

This paper is a report on an investigation conducted on adsorption of lead ions (Pb²⁺) onto powdered corn cobs (PCC). Corn cobs were collected from a selected location in Nigeria. The corn cobs were crushed and pulverised into different particle sizes. Its compositions and adsorption properties of Pb²⁺ onto PCC were studied. The effects of pH, particle size of PCC, and initial concentration of Pb²⁺ on the adsorption properties were monitored. The adsorption capacities were analysed by using standard adsorption models. The models were evaluated statistically (total error, coefficient of determination (CD), model of selection criterion (MSC), and root mean square error). The study revealed that PCC contained 2.33%, 86.89%, 10.78%, 0.52%, and 4.56% ash, volatile, moisture, solubility in water, and solubility in 0.25 M of HCl by mass, respectively. Acid digestion of a gram of PCC indicated that PCC contained no chromium and lead, but contained 131 mg Fe, 54.79% carbon, 8.03% hydrogen, 0.41% nitrogen, 0.010 mg of Al, and 1.70 mg calcium. The isotherm models parameters were 28.509 L/mg and 0.141 mg/g; 0.138 mg/g and 11.494 L/mg; 0.142 L/mg and 0.013 mg/g; 0.129 mg/g and 25.641 L/mg, 28.509 L/mg, 3.795 mg/g and 2.336 for Langmuir, Freundlich, Temkin, activated sludge, and Redlich–Peterson. The PCC particle size, initial pH, and initial Pb²⁺ concentration had effects on the adsorption parameters. The statistical evaluations showed that the best model for adsorption of lead ions from raw water onto PCC based on lower errors, high CD (0.88), reliability (97.5%), and MSC (1.86) was Freundlich and followed by activated sludge model. It was concluded that PCC is a good adsorbent like powdered eggshell and other carbon‐based materials.     

Enhancement of shielding ability using PbF2 in Fe-reinforced bismuth borate glasses

Journal of Materials Science: Materials in Electronics - The PFBBF-x glasses with the chemical structure...     

Responsibility of Bi2O3 Content in Photon,Alpha, Proton,Fast and Thermal Neutron Shielding Capacity and Elastic Moduli of ZnO/B2O3/Bi2O3 Glasses

The effect of Bi₂O₃ content on photon, alpha particle, proton, fast and thermal neutron shielding capacity, and elastic moduli of 10ZnO-(90-x)B₂O₃-xBi₂O₃ (ZBB-glasses): x?=?25–50 mol% has been investigated. The mass density and Bi-content of the ZBB-glasses had the greatest impact on the values of mass and linear attenuation coefficients. The mass and linear attenuation coefficients values were followed the trend (ZBB25)_MAC,LAC?<?(ZBB30) _MAC,LAC?<?(ZBB35) _MAC,LAC?<?(ZBB40) _MAC,LAC?<?(ZBB45) _MAC,LAC?<?(ZBB50) _MAC,LAC. The mean free path (MFP) and half value layer (HVL) were having the same trend and opposite to which obtained in mass and linear attenuation coefficients. All the ZBB-glasses showed almost similar charged particle shielding capacity. However, ZBB50 had a comparable charged particle absorption efficiency. There was a 57% growth in fast neutron removal cross section as Bi₂O₃ molar concentration increased to 50% in the ZBB-glass matrix. ZBB50 possesses the highest fast neutron removal cross section among the ZBB-glasses. In terms of thermal neutron absorbing capacity, the presence of B in the glass matrix ensures that the ZBB-glasses are good thermal neutron absorption. ZBB25 has the highest thermal neutron absorption capacity among the investigated glasses. Generally, ZBB-glasses can be adopted for photon, thermal neutron, proton, and alpha particle shielding purposes. In addition, elastic (shear, longitudinal, and Young’s) moduli and Poisson’s ratio are changed significantly with the increase of Bi₂O₃ content mol% in ZBB-glasses.

     

Failure Analysis of a Dissolved Air Flotation Treatment Plant in a Dairy Industry

Environmental pollution in Nigeria presents an urgent need to assess wastewater treatment facilities in various industries. This article presents an assessment of dissolved air flotation (DAF) operation in a dairy industry. The industry was visited, wastewater treatment facilities were assessed (based only on efficacy to remove selected environmental health-related pollutants) and measurements of essential design and characterization parameters were taken. The study revealed that the averages of flow rate, biochemical oxygen demand at 5 days (BOD₅), chemical oxygen demand (COD), suspended solids (SS) and total solids (TS) of the influent wastewater into the plant (DAF) were 3.45 L/s, 1652.37, 3304.67, 2333.82, and 4396.10 mg/L compared to effluent quality of 560.37, 1127.33, 172.33, and 1866.67 mg/L for BOD₅, COD, SS, and TS, respectively. The pH of the wastewater is being adjusted by addition of lime before the effluent equalization tank and individual efficacies of the system were 66.09, 65.89, 65.89, 57.54, 8.68, and 94.49% for BOD₅, COD, SS, TS, DS, and total nitrogen, respectively, with overall efficacy of 38.10%. It was concluded that failure (lower overall efficacy) of the system can be attributed to setting of lime in the oversized equalization tank (50 m³ instead of 16.82 m³ per 8 h shift), the lack of application of standardized engineering code and practices (provision of underground tank in the process, lack of complete coagulation processes, coagulation and flocculation units), lack of adequate aeration unit and lack of reliable systems for automatically adjusting dosage of coagulant and flocculant. Although, DAF unit is the centerpiece of a DAF-based system design, there are several other supporting systems important to optimal DAF operation. These observations, coupled with the analysis in this report, demonstrate that the facilities necessary to minimize continuous environmental pollution are lacking. Pollution will become an increasing problem unless pollution preventing codes and standards are developed; incorporated into government regulations and the regulations are enforced.     

CeO2-doped bismosiliconate-borotellurite glasses: linear/nonlinear optical properties as well as photon/neutron attenuation effectiveness

Journal of Materials Science: Materials in Electronics - Linear/nonlinear optical properties as well as photon and neutron attenuation/transmission properties of CeO2-doped...