Duckweeds are of special interest, as they are naturally growing weeds that have the capacity to tolerate and remove toxic pollutants, including heavy metals from the environment. Studies have revealed that duckweed (Lemna minor) can tolerate and remove heavy metals from aqueous solutions. In the present study, the efficiency of L. minor in the removal of Ni and Cr individually from aqueous solutions was investigated at concentrations of 3.05, 3.98 and 4.9 mg/L for Ni and 1.91, 2.98, and 4.2 mg/L for Cr. Experiments were run for 22 days, after which the metal content in the plant was estimated by atomic absorption spectrophotometer (AAS). The duckweed showed higher percentage of Ni removal than Cr. Specific Growth Rate (SGR) was found to be reduced at high concentrations of both Ni and Cr. Statistical analysis suggested that the growth of the plant was affected by the toxic effect of both Ni and Cr. Bioaccumulation of Ni was higher than Cr in L. minor. The mechanism of removal of both Ni and Cr followed second order kinetics. It is suggested that these duckweeds can remove Ni and Cr from aqueous solution and can also accumulate the same in considerable concentrations, at low initial metal concentrations.

Collection of Municipal Solid Waste (MSW) accounts for a significant proportion of most municipal budgets, and has drawn some degree of researchers‟ interest. This study was conducted in Ota, Southwest Nigeria, to explore the use of Visual basic program as an innovative tool to select the most economic haulage system among three systems found in literature (conventional-, modified- and Stationary- hauled system) for collection and transfer of MSW to disposal sites. Factors that affect the costs of collection and transportation of waste such as: vehicle cost, total time spent on waste collection, and gross travel cost, were considered in the analysis. The result of the study shows that the stationary hauled method of waste collection is the optimal and economical method of collection. This method recorded a 56% and 43% reduction in total cost of daily travel per waste collection, as compared to the conventional and the modified systems, respectively. The application of visual basic program proffers implementable solutions to reduce the cost of MSW transportation to disposal sites. This would reduce travel time and costs of vehicle fueling, and increase the prompt collection of waste which would in turn facilitate the development of an aesthetically balanced and environmentally friendly municipality that would perhaps boost economic development.

The aim of the present study was to evaluate Vitamin C (VC) as a potent natural antioxidant to mitigate the genotoxic effects of Arsenic trioxide and sodium fluoride in Swiss albino mice in vivo. The study was divided into eight groups consisting of control treated with normal saline (Group I), Group II, III, IV, V, VI, VII and the VC group with only Vitamin C (500 mg/kgbw). Arsenic trioxide (4 mg/kgbw) and Sodium fluoride (8 mg/kgbw) were administered singly, as well as in combination to swiss albino mice, with and without VC. In this study, the genotoxic effect of arsenic (As) and fluoride (F) in mice using comet, chromosomal aberration and lipid peroxidation assay was investigated. The results revealed that VC efficiently ameliorates the genotoxic effect of As and F by increasing the frequency of chromosomal aberrations and primary DNA damage along with increased malondialdehyde (MDA) level. In conclusion, VC mitigates the genotoxic effects of the two well-known water contaminants (As and F) effectively and efficiently at the given concentration in vivo.

Municipalities in developing countries spend the highest proportion of their annual budget on unsatisfactory solid waste management service. Until recently, solid waste management services in Ethiopia were mainly the responsibilities of municipalities, which culminated in inadequate service provision. Thus, the integration of Micro and Small Enterprises (MSEs) by the government has recently being considered as an option. Participation of MSEs in SWM started in 2003/04 in Addis Ababa, the capital city of Ethiopia and expanded to other cities following the proclamation of a National Solid Waste program in 2007. This review is aimed at identifying the role of MSEs in solid waste management in selected cities, including the opportunities and challenges for future directions. Limited resources and lack of support, perception and awareness of the community, inadequate training, unorganized fee collection strategy and limited revenue were among the challenges identified. The benefits and potential opportunities include organized and quality service delivery, environmental protection and safety, job opportunity, willingness to pay and social equity. In conclusion, the findings in this review show the importance of MSEs in solving solid waste management problems. However, the challenges need due considerations and appropriate interventions such as legalization of the informal sector, clear working guidelines and regulations, close support and monitoring, and transparent system in general.

This research compares the performance of floating systems planted with Vetiveria zizanioides as a hydroponic approach for removing nutrients from two contaminated waters. For this purpose, two pilots with overall net volume of 60 litres were constructed and inoculated by secondary treated domestic wastewater (STDW) and irrigation water obtained from Minab reservoir (IWMR) in batch mode. Regarding the experimental results, the total nitrogen removal efficiency reaches more than 40 and 75%, in two and four days’ detention time, respectively, while these figures are 75 and 85% for phosphorus. The comparative statistical analyses verify that the results reveal significant differences in nitrogen removal, its uptake and the shoots’ dry weight. Conversely, phosphorus removal, its uptake and the roots’ growth are not significantly different. The regression analysis shows that the nitrogen uptake is well correlated with the shoots’ expansion rate as a matter of substrate type. The decay coefficient rates of nitrogen and phosphorus are calculated as 0.43 and 0.52 day-1, respectively. It is then concluded that this system should be used for wastewater treatment rather than for surface water purification. However, it can be recommended as an environmental friendly approach for both, because of the high efficiency in nutrients’ removal and the aeration capability.

In this paper, we present an application of evolved neural networks using a real coded genetic algorithm for simulations of monthly groundwater levels in a coastal aquifer located in the Shabestar Plain, Iran. After initializing the model with groundwater elevations observed at a given time, the developed hybrid genetic algorithm-back propagation (GA-BP) should be able to reproduce groundwater level variations using the external input variables, including rainfall, average discharge, temperature, evaporation and annual time series. To achieve this purpose, the hybrid GA-BP algorithm is first calibrated on a training dataset to perform monthly predictions of future groundwater levels using past observed groundwater levels and additional inputs. Simulations are then produced on another data set by iteratively feeding back the predicted groundwater levels, along with real external data. This modelling algorithm has been compared with the individual back propagation model (ANN-BP), which demonstrates the capability of the hybrid GA-BP model. The later provides better results in estimation of groundwater levels compared to the individual one. The study suggests that such a network can be used as a viable alternative to physical-based models in order to simulate the responses of the aquifer under plausible future scenarios, or to reconstruct long periods of missing observations provided past data for the influencing variables is available.

Evaluation of the geochemistry and hydrochemical quality of Bam salt dome located in southern Iran, was conducted in this study. Two composite samples from salt units were collected and analysed by XRD and XRF to determine their mineral and elemental compositions. Water samples were also collected from the only spring in the area and analysed for major anions, cations and some toxic elements. The results indicated halite as the major mineral present, while quartz, anhydrite and dolomite were present at minor levels. The presence of anhydrite and dolomite together with quartz had negative effects on edible salt quality. The dominant water type in the area was sodium-chloride. Negligible sulphate and calcium contents may be attributed to anhydrites detected in the geological texture of the study area. According to a Schoeller diagram, the water is not suitable for drinking. Concentrations of toxic metals in the salt sample were significantly higher than those in water samples. Such a result can be viewed as an opportunity to produce edible salts from the evaporation of spring water.

Noise is one of the main parameters to be considered to achieve a healthy indoor ambience in ferries. Therefore, the noise standards need to be more specialized and specifically based on real sampled data and case studies. In the present research, the noise levels in a ship, under different working conditions, were sampled and compared with those specified in the new and old standards. An initial study showed two main noise sources- clients and main engine- that influence other indoor environments, reducing the quality of life on board. The real-time data revealed that the maximum noise level limits set by the International Maritime Organization (IMO) in the older Resolution A.468 (XII) was mostly respected, except in areas where maintenance of the noise level was difficult, owing to the continuous influx of people, especially at the time of boarding and disembarking of the passengers and at the food self-service areas. In this sense, under the new Resolution MSC.337 (91), the maximum noise level allowed in the accommodation has been reduced by 5 dB (A), but this environment does not meet the standard. More results show that future standards must not only consider the noise level in a working place and add another variable, such as, the number of working hours, to obtain a representative equivalent energy, and they must also consider that a simple modification of this standard implies a redesign of most of the indoor ambiences onboard.

A student-centric research education program with the active participation of undergraduate students is initiated. The aim is to imbibe ―responsible citizenship behavior‖ in them so that each member becomes conscious and well trained to take up environmental-related issues and challenges for long-term sustainability of the ecosystem. In this work, we report spectrophotometer-based estimation of hexavalent chromium (57-268 gL-1) and lead (34–158 gL-1) concentrations in different surface waters and groundwater samples in and around the city of Hyderabad, India. Our results indicate that the studied surface water bodies and aquifers are contaminated to variable degrees and pose a serious threat to the ecosystem. In view of low geochemical baseline values for chromium and lead, the origin of heavy metal pollution is inferred to be anthropogenic, mainly originating from industrial effluents. The toxicological data are integrated with health data for risk assessment and impending health hazard. Finally, the novelty of this student-centric research program is highlighted.

This comprehensive work explores the research performed inoptimization of the collection bin and in recycle bin location-allocation issues in solidwaste management. Although the collection phase of solid waste management accountsfor a significant proportion of the municipal budget, it has attracted only limitedattention of the researchers. Optimization of the collection bin and recycle bin location-allocation problems in solid waste management can be advantageous with respect to binaccess to every individual person of municipality, reduction in the numbers of opendumping yards, considerable profit if the recycled products are properly processed, andas an effort toward sustainable and green world. Hence, the topic of interest should bepursued, especially in developing countries, to enable development of a cost-efficient and sustainable solid waste management system.