Study of modern nano enhanced techniques for removal of dyes and metals

Industrial effluent often contains the significant amount of hexavalent chromium and synthetic dyes. The discharge of wastewater without proper treatment into water streams consequently enters the soil and disturbs the aquatic and terrestrial life. A range of wastewater treatment technologies have been proposed which can efficiently reduce both Cr(VI) and azo dyes simultaneously to less toxic form such as biodegradation, biosorption, adsorption, bioaccumulation, and nanotechnology. Rate of simultaneous reduction of Cr(VI) and azo dyes can be enhanced by combining different treatment techniques. Utilization of synergistic treatment is receiving much attention due to its enhanced efficiency to remove Cr(VI) and azo dye simultaneously. This review evaluates the removal methods for simultaneous removal of Cr(VI) and azo dyes by nanomicrobiology, surface engineered nanoparticles, and nanophotocatalyst. Sorption mechanism of biochar for heavy metals and organic contaminants is also discussed. Potential microbial strains capable of simultaneous removal of Cr(VI) and azo dyes have been summarized in some details as well

Impacts of land use change on streamflows in the Damansara watershed, Malaysia.

Land-use change has significant impacts on hydrologic processes at the watershed level. In this study, hydrologic models and spatial data were used to assess the effects of land-use changes and predict the effects of two future land-use scenarios on the flood regime of the Damansara Watershed. Due to urban growth, the Damansara Watershed has seen increasing streamflows and experienced occasional flooding. The hydrology was modeled using the Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) model, and land-use changes were quantified with land-use maps. Actual storms were used to calibrate and validate HEC-HMS rainfall-runoff model. The calibrated HEC-HMS model was used to simulate future streamflows and to forecast the impact of land-use changes on downstream peak streamflow. The model also estimated the contribution of individual sub-basins to downstream peak streamflows of the entire watershed. The model predicts that changes in land-use will increase the peak streamflow, and the increase is directly proportional to the rate of urbanization. It was found that the sensitivity of the hydrologic response to land-use change increases as the recurrence interval of rainfall events decreases, and that those impacts are more pronounced in different sub-basins. The results of this study provide support for land-use planning and the management of watersheds

Potential of support-vector regression for forecasting stream flow

Vodotok je važan za hidrološko proučavanje zato što određuje varijabilnost vode i magnitudu rijeke. Inženjerstvo vodnih resursa uvijek se bavi povijesnim podacima i pokušava procijeniti prognostičke podatke kako bi se osiguralo bolje predviđanje za primjenu kod bilo kojeg vodnog resursa, na pr. projektiranja vodnog potencijala brane hidroelektrana, procjene niskog protoka, i održavanja zalihe vode. U radu se predstavljaju tri računalna programa za primjenu kod rješavanja ovakvih sadržaja, tj. umjetne neuronske mreže - artificial neural networks (ANNs), prilagodljivi sustavi neuro-neizrazitog zaključivanja - adaptive-neuro-fuzzy inference systems (ANFISs), i support vector machines (SVMs). Za stvaranje procjene korištena je Rijeka Telom, smještena u Cameron Highlands distriktu Pahanga, Malaysia. Podaci o dnevnom prosječnom protoku rijeke Telom, kao što su količina padavina i podaci o vodostaju, koristili su se za period od ožujka 1984. do siječnja 2013. za podučavanje, ispitivanje i ocjenjivanje izabranih modela. SVM pristup je dao bolje rezultate nego ANFIS i ANNs kod procjenjivanja dnevne prosječne fluktuacije vodotoka.Stream flow is an important input for hydrology studies because it determines the water variability and magnitude of a river. Water resources engineering always deals with historical data and tries to estimate the forecasting records in order to give a better prediction for any water resources applications, such as designing the water potential of hydroelectric dams, estimating low flow, and maintaining the water supply. This paper presents three soft-computing approaches for dealing with these issues, i.e. artificial neural networks (ANNs), adaptive-neuro-fuzzy inference systems (ANFISs), and support vector machines (SVMs). Telom River, located in the Cameron Highlands district of Pahang, Malaysia, was used in making the estimation. The Telom River’s daily mean discharge records, such as rainfall and river-level data, were used for the period of March 1984 – January 2013 for training, testing, and validating the selected models. The SVM approach provided better results than ANFIS and ANNs in estimating the daily mean fluctuation of the stream’s flow

Experimental Study on Tsunami Risk Reduction on Coastal Building Fronted by Sea Wall

This experimental study was conducted to idealize the efficacy of sea wall in controlling the tsunami forces on onshore structures. Different types of sea walls were placed in front of the building model. The tsunami forces and the wave heights were measured with and without the sea wall conditions. Types of sea wall, wall height, and wall positions were varied simultaneously to quantify the force reductions. Maximum of 41% forces was reduced by higher sea wall, positioned closer proximity to the model whereas this reduction was about 27% when the wall height was half of the high wall. Experimental investigations revealed that wall with adequate height and placed closer to the structures enables a satisfactory predictor of the force reduction on onshore structures. Another set of tests were performed with perforated wall placing near the building model. Less construction cost makes the provision of perforated sea wall interesting. The overall results showed that the efficacy of perforated wall is almost similar to solid wall. Hence, it can be efficiently used instead of solid wall. Moreover, overtopped water that is stuck behind the wall is readily gone back to the sea through perforations releasing additional forces on the nearby structures

A simple load sensor based on a bent single-mode–multimode–single-mode fiber structure

A load sensor is demonstrated using a single-mode-multimode-single-mode (SMS) fiber structure, which is sandwiched between two CR-39 plastic polymer plates. A larger effective transverse strain can be achieved when the distance, D2, between the stage and the edge of the multimode fiber is larger. A higher sensitivity is obtained when D2 = 7 cm with a value of −0.0102 nm/mN, as compared to −0.0027 nm/mN when D2 = 3 cm. In contrast, an FBG integrated in a similar manner has shown an indiscernible change in the wavelength shift as compared to that produced by the SMS device. The result indicates that the proposed SMS device is suitable for sensing a small load or transverse strain with a reasonably high sensitivity

Novel deep eutectic solvent-functionalized carbon nanotubes adsorbent for mercury removal from water

Due to the interestingly tolerated physicochemical properties of deep eutectic solvents (DESs), they are currently in the process of becoming widely used in many fields of science. Herein, we present a novel Hg2+ adsorbent that is based on carbon nanotubes (CNTs) functionalized by DESs. A DES formed from tetra-n-butyl ammonium bromide (TBAB) and glycerol (Gly) was used as a functionalization agent for CNTs. This novel adsorbent was characterized using Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, XRD, FESEM, EDX, BET surface area, and Zeta potential. Later, Hg2+ adsorption conditions were optimized using response surface methodology (RSM). A pseudo-second order model accurately described the adsorption of Hg2+. The Langmuir and Freundlich isotherms models described the absorption of Hg2+ on the novel adsorbent with acceptable accuracy. The maximum adsorption capacity was found to be 177.76 mg/g

Trendline and Monthly Variations of Nitrate in Water Supply Wells in Upper Egypt

Safe drinking water is among the most important environmental as well as health challenges facing Egypt. Groundwater from the aquifer of the Nile valley in Upper Egypt accounts for about 40% of the overall source of drinking water. Nearly, all rural residents rely on groundwater as the source of drinking water. Irrigation water is the main source of groundwater recharge in Nile Valley. Moreover, nitrate fertilizer utilization in Egypt has risen significantly due to the requirement for further agricultural production. Nitrate levels higher than the permissible limit (45 mg/L) for drinking water have been related to health issues. To determine the effect of agrochemical nitrate on the health of pumping water, municipal water wellfields established in Upper Egypt have been examined. Pumped water from those municipal wells (60 m depth and 2000 m3/day gross pumping rate) was evaluated from 2000 to 2018 to accomplish this objective. Monthly analysis of the quality of groundwater, in particular nitrate, has been conducted. Sulfate and nitrate concentrations as well as other consistency metrics were assessed. Water sampling findings show that the water already comes under the drinking-water limits. Nevertheless, increased nitrate and sulfate values are found beyond naturally existing levels in the aquifer. Consequently, to determine the possible future likelihood of nitrate contamination in such municipal wells, the trendline of nitrate level has been used. The observations suggest that the intensive utilization of nitrogen fertilizer in Upper Egypt in the last 30 years would endanger the quality of the groundwater supply. Resultantly, the usage of nitrogen fertilizers in Upper Egypt must be regulated and continuous groundwater monitoring must be implemented

The effectiveness of groundwater recharges well to mitigate flood

Management of urban storm-water is characterized by the use of hydraulic structures like culvert, manmade channels, water ways, detention basins, infiltration trench, spillway, dams and other drainage structures to either convey or store the storm-water downstream. But in some cases these structures may not be effective to either convey or store the excess runoff because of some inherent factors like topography, soil type, and other factors could include high rain intensity over a long duration and poor drainage design. In the case of Batu Pahat, Johor, Malaysia, some of the contributing factors include; flatness of the catchment area and low infiltration rate of the top layer soil (clayey). The method of injecting some of the storm-water into the ground (aquifer) through a recharge well (perforated pipe), so as to reduce the peak flow rate reaching these structures was adopted to mitigate flood. This method was evaluated by means of carrying out experiment on a physical model and on an actual site. The determination of the effectiveness of this method was carried out by simulating storm-water accumulation in a reduced scaled physical model. This small scaled model had a rainfall simulator fitted with a sand tank, the sand tank contained soil materials of different grain size and different coefficient of permeability. The model is 100 ± 60 ± 40 cm in dimension and a perforated pipe of 3.5 cm is fixed in the model to simulate recharge well. By varying the rainfall intensity and rainfall duration on the model a relationship was established between the rainfall characteristics and movement of stormwater into the ground by using the recharge well to mitigate flood. The results obtained from the physical model are then compared with results obtained from an actual site where an actual recharge well is present. On the physical model the reduction in rainwater when the recharge well is present is about 6.07% of the total rainwater on average and on the prototype is 2.8, 7.2 and 3.5% of the total rainwater that fell on a catchment of 100,000 m2 for three different rain events. Apart from the high water table noticed at the actual site, other data obtained from the actual site indicated that the recharge well system will be successful when it is adopted to mitigate flood in a site similar in physical and soil properties to the physical model

Innovative Techniques in the Context of Actions for Flood Risk Management: A Review

The general purpose of this review paper is to provide an overview of various flood protection strategies because flooding is becoming more frequent and is affecting more areas, displacing people, and increasing fatalities around the world. The concern surrounding climate change resulting in sea level rise, increasingly frequent storm events, and the need for adaptive actions to better control urban storm water runoff motivates the completion of this paper. Understanding the impact of climate change aside from dangerous weather conditions essential for designing effective mitigation strategies, but first, there needs to be a clear and strong understanding of the effects of extreme events. This review represents engineered storm water practices that are adaptive, in combination with the non-structural measures such as urban planning, will help reduce flood impact