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Introduction
Dr. Amimul Ahsan is a Senior Lecturer in the Department of Civil Engineering and a Researcher in the Institute of Advanced Technology, University Putra Malaysia, Malaysia. He has published extensively in Water and Environmental Engineering including 7 books, 9 book chapters and over 100 technical papers and reports. He has been serving on the advisory/editorial board of 16 international scientific journals for a long time as an Editor-in-Chief (4), as an Editor (4) and as EBM (8).
Current institution
Universiti Putra Malaysia | UPM
Department of Civil Engineering
Current position
Email: ashikcivil@yahoo.com, amimul@upm.edu.my
Skills and Expertise
Awards & Achievements
Award · Apr 2015
Vice-Chancellor Fellowship Award (UPM: Science and Technology) in 2015.
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Islamic University of Technology
Universiti Putra Malaysia
Universiti Putra Malaysia
Qassim University
Universiti Putra Malaysia
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Tetra Tech
Cadi Ayyad University
Oregon State University
Qassim University
University of Baghdad
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Projects (8)
Journal of Desalination and Water Purification
Journal of Desalination and Water Purification (Call for papers) The International Journal on the Advanced Technologies in Desalination and Water Treatment http://ababilpub.com/jdwp/
Journal of Advanced Civil Engineering Practice and Research
Journal of Advanced Civil Engineering Practice and Research (Call for papers) The International Journal on the Advanced Technologies in Civil Engineering http://ababilpub.com/jacepr/
Wastewater Biodegradation by Stabilized Solid Waste Materials
To carry out investigations on the use of stabilized solid waste materials as potential adsorbents for wastewater treatment.
Research
Research Items (165)
Potable and equitable drinking water (DW) is a fundamental human right and essential for human health. This study is conducted to assess the groundwater and jar water quality of the roadside restaurants and tea stalls used for drinking by the local people around the Gazipur City area in Bangladesh. Water samples from 173 restaurants and tea stalls are collected. The physico‐chemical and biological parameters are analyzed according to the guidelines and standards. The results illustrate that the color, EC, and Mn of 41%, 80%, and 62% of the samples, respectively, exceed the WHO and Environmental Conservation Rules (ECR) standards. In addition, E. coli and total coliform exceeding the threshold standards are found in 47% and 64% of the water samples, respectively. The contamination of DW by fecal coliforms is confirmed and supported by prior studies, which indicates that the DW supplied in restaurants and tea stalls are unsafe because of the possible presence of pathogens. These may cause potential health hazards to consumers from various water‐borne diseases. Poor sanitation, unhygienic practices, and improper disposal of wastewater are responsible for the microbial contamination of DW. So, the authorities in charge of these places should take the right regulatory steps, such as regular sanitation inspections, DW quality monitoring, hand‐washing practices, and better sanitation in these places.
Even though water is a renewable resource, the majority of the available water on the planet is unfit for human use. Moreover, the drinkable water demand is ever-increasing as a result of rising population, urbanization, and life standards, which makes the needs for sustainable, economic, and environment-friendly treatment alternatives of utmost importance. Seawater desalination using solar stills has been proposed as a promising alternative that may help to solve drinkable water scarcity issues. In the past decades, many studies have been conducted to assess the performance of different types of solar stills aiming to enhance their productivity. Computational fluid dynamic (CFD) numerical simulation is one of the approaches that have been used recently to assess the performance of solar stills. The present study performed a systematic review and bibliometric analysis to provide a comprehensive overview of CFD numerical simulation uses as a tool to assess solar stills performance. A total of 486 publications were collected initially from different databases for the period between 2012 and 2022. The collected publications were filtered through several stages reaching 43 publications of highest significance. The collected data were analyzed descriptively, and the bibliometric mapping was presented. Furthermore, the basics and principles of CFD numerical simulation of solar stills efficiency were described and discussed. Later, the previous studies were analyzed to understand the algorithms, methods, and still types used. Finally, future research scopes and conclusions were stated. The presented knowledge in this study can help to provide a deep overview of using CFD in studying the efficiency of solar stills and inspire researchers to identify future research ways and gaps.
Modern designs of solar still desalination technology are reported to tackle the cost and energy issues. However, the low productivity of this technology is the main challenge that inhibits its commercialization uses. In this study, a triangular solar still (TrSS) integrated with an external PVC pipe solar heater and an internal separated condenser is designed for the first time to enhance water desalination under Malaysian climate conditions. The daily water production of active still was 24% higher than that of passive one. The temperatures of water and ambient air, relative humidity inside the still and the intensity of solar radiation affect the daily distillate output of both stills. Besides, a few strong relationships were developed between the intensity of solar radiation and water productivity, between the daily average ambient temperature and water productivity, and between the daily average water temperature and water productivity. The desalinated water cost per liter is estimated and is reasonable. Finally, the water quality tests of raw seawater and product water were performed and analyzed. A significant improvement in the desalinated water quality is realized when compared with raw seawater quality. The product water was considered as safe drinkable water while comparing its quality with the World Health Organization (WHO) standards.
A simple mathematical model is developed for the prediction of Metribuzin removal efficiency through adsorption using activated carbon of olive-waste cake for any combination of input conditions. Based on earlier experimental results, factors from three independent variables (pH, initial Metribuzin concentration and adsorbent dose concentration) were incorporated in the model. All the factors are multiplied to derive a combined diminishing factor, which is multiplied with maximum achievable removal efficiency. It is found that although the model results are having good correlation (0.92) with the experimental results, those are slightly away from the ideal line. Through the introduction of an adjustment factor, model predictions are closely matching with the measured values having a correlation coefficient of 0.96. The primary model predicted results are having standard errors as RMSE = 6.34, MAE = 5.99 and RAE = 0.07, whereas the same error statistics of the adjusted model are 1.97, 1.71 and 0.01, respectively. Such modelling technique will predict removal efficiency for any combination of input parameters, which at times are required to be changed for other constraints.
A rigorous evaluation of future hydro-climatic changes is necessary for developing climate adaptation strategies for a catchment. The integration of future climate projections from general circulation models (GCMs) in the simulations of a hydrologic model, such as the Soil and Water Assessment Tool (SWAT), is widely considered as one of the most dependable approaches to assess the impacts of climate alteration on hydrology. The main objective of this study was to assess the potential impacts of climate alteration on the hydrology of the Yarra River catchment in Victoria, Australia, using the SWAT model. The climate projections from five GCMs under two Representative Concentration Pathway (RCP) scenarios-RCP 4.5 and 8.5 for 2030 and 2050, respectively-were incorporated into the calibrated SWAT model for the analysis of future hydrologic behaviour against a baseline period of 1990-2008. The SWAT model performed well in its simulation of total streamflow, baseflow, and runoff, with Nash-Sutcliffe efficiency values of more than 0.75 for monthly calibration and validation. Based on the projections from the GCMs, the future rainfall and temperature are expected to decrease and increase, respectively, with the highest changes projected by the GFDL-ESM2M model under the RCP 8.5 scenario in 2050. These changes correspond to significant increases in annual evapotranspiration (8% to 46%) and decreases in other annual water cycle components, especially surface runoff (79% to 93%). Overall, the future climate projections indicate that the study area will become hotter, with less winter-spring (June to November) rainfall and with more water shortages within the catchment.
Due to lack of confidence on potential yield and subsequent net benefit, wide-scale implementations of bioethanol from food/fruit waste are not accelerating. With the aim of enhancing stakeholders’ confidence, this paper presents a simple mathematical model formulation, which can estimate potential bioethanol generation capacity from rambutan waste under different input conditions. Mathematical formulation was derived based on three contributing factors such as pH, temperature and fermentation period. The factors were derived based on an earlier experimental study on production of bioethanol from rambutan waste. Results from the derived mathematical model were compared with the experimental measurements from earlier study. It is found that the proposed model is capable to accurately estimate potential bioethanol productions from rambutan waste. Model calculated results are having a coefficient of correlation of 0.98 with the measured data. Standard errors of the model's estimations are also quite low, having RMSE = 0.17, MAE = 0.14 and RAE = 0.02. For a wider industrial generation, a mathematical framework is proposed to calculate benefit-cost ratio of production costs against yield value considering the time value of the money. Such mathematical framework will assist decision makers on deciding optimum input parameters through optimised energy consumption.
Hello, is there anyone to help me to do groundwater pumping and monitoring wells data analysis using this software? I may pay you little ....Ahsan
Innovative removal of toxic nitrite and ammonia is one of the key approaches for efficient aquaculture biotechnology. This study suggests a fast removal technique of high-levels of nitrite and ammonia using recirculating aquaculture wastewater at 30‰ salinity. Four lab-scale moving bed biofilm reactors (MBBRs; R1, R2, R3, and R4) were operated in parallel for 56 days with different combinations of mature and fresh biofilms on biocarriers at 30% filling ratio. Nitrogen removal efficiency, biofilm physicochemical properties, and microbial analyses were conducted using PCR and sequencing techniques at the region of the 16s ribosomal RNA. The results showed that R4 (using mature biofilms) recorded the highest nitrite and ammonia removal (99.6% and 95.3%, respectively) compared to the control, R1 (94.1% and 89.4%). Meanwhile, the removal rate of ammonia in R4 was significantly the fastest compared to other reactors. Partial Least Squares-Discriminant Multivariate Analysis (PLS-DA) model showed a good prediction with very high accuracy and prediction (Q2 > 0.8) for the first three principal components pertaining to nitrite and ammonia removal. Planktosalinus genus was the most abundant in R4, while proteobacteria phylum was the dominant, followed by Marinobacter and Nitrospina in all reactors. Overall, the use of mature biofilms in MBBR was proven to increase bacterial diversity, enhancing nitrite and ammonia removal efficiency.
This study compares the performance of the Hollow Fiber (HF) and Flat Sheet (FS) types of membrane bioreactors (MBRs) for the treatment of food and beverage (F&B) industry wastewater in a pilot-scale study of a wastewater treatment plant (WWTP). HF and FS membrane configurations were evaluated at two different Mixed Liquor Suspended Solid (MLSS) levels: 6000 mg/L and 12,000 mg/L. The performance of each configuration was evaluated in terms of Chemical Oxygen Demand (COD) and Total Suspended Solid (TSS) removals for effluent quality measurement. The transmembrane pressure (TMP), flux rate, and silt density index (SDI) were monitored and calculated for membrane fouling assessment. The results show that the rejection rates of COD and TSS for HF and FS membrane types were more than 84% for the two different MLSS levels. During the study, the HF membrane recorded 0.3 bar transmembrane pressure, which complies with the recommended range (i.e., two to three times of chemical cleaning). On the other hand, the FS membrane operates without chemical cleaning, and the TMP value was below the recommended range at 0.2 bar. It was found that the flux values recorded for both the HF and FS systems were within the recommended range of 40 L/m2/h. Analysis of SDI revealed that the calculated index ranged between 1 and 2.38 and was within the allowable limit of 3. Both types of MBR consistently achieved an 80% to 95% rejection rate of COD and TSS. Effluent quality measurement of treated F&B wastewater in this pilot-scale study using a WWTP integrated with an MBR indicated a good achievement with compliance with the Malaysia industrial effluent discharge standards.
The demand for freshwater is increasing day by day around the world. Hence alternative sources are being explored that can minimize the demand of traditional sources. Water from air conditioners (ACs) is a potential option. Therefore, the aim of this study is to examine the quality of condensate AC water to ascertain whether it is potable and to determine the amount of water that can be harvested from split-type ACs (3, 4, and 4.5 ton)/h. A general brand of AC was assessed in this study. A total of 270 AC water samples were collected from June to July 2017 covering a total floor area of 1,694.55 m2. The findings showed that, without proper treatment, AC water is unsafe to drink. However, according to lab test results, it can be made drinkable if it is boiled and filtered. Finally, a model is also proposed for continuously converting AC water into pure drinkable water.
Electrolysis systems have been widely investigated for treating wastewater in laboratory-scale experiments, and most researchers reported efficient treatment outcomes. However, industrial scale implementation often necessitates assessing and prioritising various options involving different combinations of input parameters, which often requires mathematical models. This study presents mathematical models for predicting removal efficiencies of four different pollutants using electrolysis. Parametric equations were developed based on experimental results conducted in a previous study. Proposed equations are dependent on treatment retention time and current intensity (voltage). Results revealed that the experimental data followed consistent patterns, which lead to the derivations of generalised equations which were able to closely predict pollutants’ removal efficiencies obtained through experimental measurement. The developed equations also confirmed that beyond an optimum voltage, a further increase in voltage does not render higher removals of the pollutants, which is essential for enhancing the feasibility of industrial scale applications.
For many remote and under-privileged communities, water filtration is the first step of treatments before boiling and/or other higher level treatments. Clogging is a common unavoidable hindrance to such systems, which causes reduced efficiency with regard to the flow rate of filtered water. Backwashing is commonly used to recover the filtration capacity of clogged filter media. This paper presents an improvement of a previously developed simple clogging and backwashing efficiency model for the third-generation IHE family filter, which was developed by Unesco-IHE Institute for Water Education. The earlier simple model considered a linear decay of flow rate due to clogging in a weekly timestep. With the aim of enhancing the model's accuracy, this work considered three other models (a linear model with a daily timestep, a power function model and an exponential model). The performance of the models was assessed using the root mean squared error and chi-squared (χ ² ) values derived from predicted and measured flow rates through the device during successive clogging and backwashing periods for up to 4 months. The improvements using the linear 1 day model over the linear 7 day model were insignificant. Among the tested models, the power function model provided the best predictions, with an average χ ² improvement of 33% over the previously developed linear model.
Water is among the most valuable resources that nature has endowed to human beings. Water has cut across all spans of life from cradle to grave. Since time immemorial, man continuously developed methods and techniques to harness the benefits of water and as well to protect himself from the destruction that may be caused by the same water. Therefore, for a hydraulic structure to answer its name, it must be capable of being used smoothly for the purposes it was designed for and also be able to be controlled effectively without the risk of causing any havoc to the environment. Using water, especially for agricultural purposes, cannot be overemphasized. Hence, this chapter discusses the hydraulic structures based on the work they performed, challenges facing hydraulic structures, and management procedures of the hydraulic structures in order to adequately and efficiently serve their purpose.
Water shortage is rising to become a global challenge due to the variations in climate change and population increment. Converting the seawater to potable water using the desalination technology is among the existing options highlighted by researchers. However, these processes are expensive and require much energy to operate. The solar desalination technology was reported as highly adequate since it utilizes the natural sunlight and the simple concepts of evaporation and condensation to produce the drinking water. The main challenge to date is the low productivity of the technology, which must be adequately improved in order to enhance productivity and optimize performance. In this study, the productivity and efficiency of conventional double slope solar still were assessed using a solar system. Two solar still models (active and passive) were fabricated with the same evaporation and condensation areas. The troughs were made of stainless steel with dimensions of 50×32 ×5 cm. In turn, while the cover was made of glass with dimensions of 48×60×0.3 cm and the inclination angle was 60o. In addition, the solar system consisted of two solar panels with 50 W capacity each, one battery of 100 Ah – 12 V, a charging controller of 30 A, and a single immersed DC water heater of 50 W – 12 V capacity. Both models were tested simultaneously for two sunny days, 24 hours each. The results showed that the water productivity of the active solar still was 55% higher than that of the passive solar still. On 15th July, the total amounts of solar still productivity were 7.85 L/m2/d and 19.3 L/m2/d for active and passive stills, respectively. This is due to the existence of the heating element in the active still which allowed it to produce water for 24 hours continuously. Moreover, the trough temperature was found to be the highest for both models, because it was made from steel. Finally, the produced water in both cases was found to be directly proportional to such parameters as solar radiation intensity and ambient temperature.
Surface water is the main source of potable water production around the globe. However, this source is projected to different pollutants from domestic, industries and farms. Therefore, producing drinking water with high-quality standards and minimizing the amount of organic and inorganic pollutants is required. Different technologies have been used and tested for drinking water production. Nanofiltration (NF) membrane is one of these technologies which can produce potable water with high-quality standards. However, the fouling issue remained the major problem facing membrane technology. Further, a membrane with small pores required more energy, but this issue can be solved using renewable sources of energy. In this paper, a brief review on NF membrane technology is presented in different ways including, NF membrane characteristics, separation and fouling mechanisms, and applications of NF in surface water treatment. It was observed that more improvement is needed to solve the fouling issue which is considered as a common problem in all membrane types. Additionally, the NF process was noted to be a promising method for surface water treatment and softening purposes.
Groundwater resource maintenance plays a vital role in preserving effective and sustainable conditions for the water resources planners. A well-known and contemporary geostatistical skill Kriging is used in this research to investigate an explicit picture of critical zones and spatial distribution of groundwater levels. Chapainawabganj district is chosen as a case study area located in the north-western part of Bangladesh because of its extensive withdrawing due to increased cultivation of crops that largely depends on groundwater. Groundwater level data of 23 monitoring locations for 10 years (2009-2018) are taken for analyses. The variogram models are plotted for every set of data. Three models are considered in Kriging method such as Exponential, Gaussian and Spherical. The best variogram model is taken by comparing four statistical goodness-of-fit measures (ME, RMSE, RMSS, ASE). Finally, the model for groundwater levels is used for ordinary Kriging on the ArcGIS platform and the analysis of variance shows the predicted water levels. In Ordinary Kriging, cross validation technique is used to assess the accuracy of forecasted spatial-level differences. The outcomes of this study demonstrated the needs of alternative water sources and monitoring programs especially for the critical zones over the study area for future sustainable groundwater management.
Palm oil is one of the leading agricultural crops in the world, as it dominates 34% of the global vegetable oil market, with approximately 64.6*10³ million kgs of production in 2017. However, along with its breakthrough, the generation of palm oil mill effluent (POME) as uncontrolled waste has become a serious matter and requires proper management to reduce its negative effects on the environment. Subsequently, the high organic content of POME makes it possible to convert waste into value-added products, such as biogas. A ratio of 0.5 for biological oxygen demand to chemical oxygen demand (BOD/COD) indicates a high possibility for biological treatment. Recently, the utilisation of POME as a cheap source for biogas production has gained an extraordinary amount of attention, and intensive research has been conducted on the upstream to downstream process. Finding the most suitable and efficient pretreatment technique and reactor configuration are vital parameters for the treatment and conversion of POME to biogas. This review describes existing pretreatment processes for POME and recommends recently manufactured high-rate anaerobic reactors as the most suitable and efficient pretreatment technique for maximising the extraction of biogas from POME.
Carbon dioxide (CO2) emitted from different sources into ambient air is a major contributor to air pollution. In addition, long-term exposure in humans contributes to symptoms such as tiredness, weakness, memory loss, confusion, nausea, and loss of appetite. The separation and storage of CO2 are important parts of utilizing low-carbon energy, which is needed to cope with climate change. Cost-effectiveness is an important factor for determining an optimal carbon separation strategy. Several review papers on CO2 capture and storage are available, but in most of these publications only the theoretical and operational aspects appear, while cost and techno-economic evaluations are missing. In this paper, different techniques for CO2 capture and separation are thoroughly reviewed with a focus on the associated economic costs. Presently, chemical and physical methods are widely used for CO2 separation; however, the hope is to switch to more environmentally friendly methods. This review reveals that, although biological separation processes are regarded as safe and sustainable, these methods are still time-consuming and involve high bioreactor management costs for. Another important finding is that chemical membrane technology is promising due to its low cost and simple operation.
After continuous use of any filtration device, clogging of the filter media becomes apparent, which eventually causes poor performance of the filtration process. Back-washing is a common technique that is used for the recovery of the filtration capacity of clogged filter media. This paper presents the development of a simple clogging and back-washing efficiency model for a special filter medium. The ‘third-generation IHE family filter’ was developed by the Unesco-IHE Institute for Water Education and is widely used for treating arsenic-contaminated water in many countries, including Bangladesh. Several field tests were conducted at three different sites in Bangladesh having different qualities of influent water. The model coefficients developed were derived using the collected data on flow measurements through the device during successive clogging and back-washing periods of up to 4 months. The developed model with the selected model coefficients can simulate field measurements on flow retardation and recovery with good accuracy. Eventually, selected model coefficients (clogging factors) for the three sites were correlated with the respective ammonium and iron contents in the influent water. It was found that the clogging factor linearly varies with the ammonium and iron contents of the inflow water.
Groundwater extraction from wells located near streams can decrease stream flow. This is commonly referred to as 'alluvial well depletion'. Several analytical explanations were established for alluvial well depletion that differs in their mathematical intricacy. However, to date, only a few stream aquifer analysis tests have been documented in the literatures. To successfully quantify the level of stream aquifer interaction during pumping, it is required that the stream bed hydraulic conductivity is estimated. In this study, over 1000 borehole data were employed in GIS-based spatial analysis and was found to accurately predicts alluvial well depletion. In addition, spatial relationship between aquifer parameters were effectively established among some parameters such as: conductivity, topography, yield, soil type, recharge and aquifer media. It was established that the area with highest conductivity is generally characterised by the alluvial well depletion effect and groundwater flow pattern is not only controlled by the structure of the water table but also by the distribution of hydraulic conductivity. In addition, no association was found to exist between steep slope and the conductivity as very strong relationship ensued between areas with high recharge and soil media. Relatively high association was evident between aquifer media, recharge and soil media.These, apart from validating the quality of data used, have also endorsed several theoretical assertions.
Massive amount of rumen content and blood were produced from the slaughtered animal in a single day of Eid-ul-Azha in Bangladesh that creates an unhyg ienic and hazardous environment at that time. A convenient composting method can efficiently utilized these rumen contents and blood. For this purpose, three different treatments mentioned as rumen content only (T,), rumen content with biogas slurry (T,) and rumen content with cattle blood (T ) were studied with 3 replications for anaerobic composting. The parameters studied were Organic Matter (OM), Crude Protein (CP), Carbon Nitrogen ratio (C/N ratio), Crude Fiber (CF), Ether Extract (EE), Nitrogen Free Extract (NFE), ash and pH. The result revealed that amount of CP was higher in T (1 °.43%) followed by T, (16.2°%) after 90 days of anaerobic composting and the differences were significant (p<0.01) among treatment groups. Initial and final C/N ratios were 33. 46 and 31 . 42, 2°.66 and 23.88 and 2°.93 and 22.83 in case of T„ T, and T„ respectively. Final C/N ratio showed the significant difference (p<0.01) among different treatment groups. The pH of the final compost was significantly increased in T (22%) followed by T, (20%).
Unprocessed sago palm bark (SPB) is a material that has been newly utilised for preparations of activated carbons (AC), using physicochemical activation techniques comprising dual carbonisation and activation phases. Activations have been conducted utilising three agents: sulphuric acid (H2SO4), potassium hydroxide (KOH), and zinc chloride (ZnCl2). Characterisations of the porosities of AC preparations were performed using N2 adsorption-desorption to ascertain BET and micropore surface areas as well as micropore volumes and pore-size distributions. Existing groups on the AC surfaces were resolved using Fourier Transform Infrared Spectroscopy (FTIR) analyses. The morphologies of the activated carbons were assessed via scanning-electron microscopic methods (SEM) combined with energy-dispersive X-ray spectroscopic techniques (EDX). The maximal surface areas (1639.34 m2/g), pore volume (0.649 cm3/g), micropore volume (0.335 cm3/g), and micropore surface area (1,148.58 m2/g) of the prepared AC using sago palm bark were discovered at activation temperatures of 700oC and with chemical impregnation ratios of 1.51/ zinc chloride to precursors. In the instance of KOH and H2SO4 utilisation, the surface areas of the AC preparations corresponded to 970.38 m2/g and 630.73 m2/g with pore volume of 0.458 and 0.196 cm3/g, respectively.
With the aim of encouraging more waste diversions from traditional waste stockpiling and to reduce use of virgin materials in different engineering constructions, this paper presents the environmental suitability of reusing crushed used tyre instead of using virgin aggregate materials for road sub-base. Shredded tyre samples collected from a local recycling company in Melbourne were tested to evaluate any potential contaminant leaching from such material to the surrounding environment. Leaching tests were conducted for 100 potential contaminants following Australian Standard Leaching Procedure (ASLP) using three standard types of leaching solutions: acidic, neutral, and alkaline. From the series of leaching test results, it is clear that concentrations of all the assessed contaminants in the tested samples are either below their individual detection limits or below the Environmental Protection Authority (EPA) Victoria defined limits to label a material as hazardous. As such, in regards to leaching pollutants in the surrounding environment, tested crushed tyre samples are not hazardous and can be used for different engineering applications. Finally, a carbon footprint analysis was conducted considering a sustainable approach of using such crushed tyre with recycled concrete and recycled rock. It is found that through using such recycled materials carbon footprint savings per ton of road sub-base material would be 9.3 kg CO2e and 8.1 kg CO2e for using 2 and 3% tyre crumb, respectively.
In spite of continuous campaign and efforts large scale adoptions of solar panels are yet to be materialised, mainly due to lack of confidence on potential energy savings. This paper presents real efficiencies achieved from four houses in two Australian cities; Melbourne and Adelaide. Based on actual solar energy productions and actual incoming solar radiations during a monitoring period, efficiencies of solar panels installed in the selected houses were calculated. It was found that among the four monitored houses, a maximum efficiency of 7% was achieved. Considering this maximum achievable efficiency and annual average incoming solar radiations, potentials of energy savings for eight major cities of Australia are presented considering two different solar panel systems; 2 kW and 5 kW. It was found that for a typical 4-members household winter-demand, a 2 kW system and 5 kW system is expected to generate 19–29% and 49–73% of total energy. In addition, considering the current costs and expected savings, payback periods of different sized solar systems are presented for the eight cities.
Waste causes environmental pollution and greenhouse gas (GHG) emissions when it is not managed sustainably. In Bangladesh, municipal organic waste (MOW) is partially collected and landfilled. Thus, it causes deterioration of the environment urging a recycle-oriented waste management system. In this study, we propose a waste management system through pyrolysis of selective MOW for biochar production and composting of the remainder with biochar as an additive. We estimated the carbon (C), nitrogen (N), phosphorus (P) and potassium (K) recycling potentials in the new techniques of waste management. Waste generation of a city was calculated using population density and per capita waste generation rate (PWGR). Two indicators of economic development, i.e., gross domestic product (GDP) and per capita gross national income (GNI) were used to adopt PWGR with a projected contribution of 5-20% to waste generation. The projected PWGR was then validated with a survey. The waste generation from urban areas of Bangladesh in 2016 was estimated between 15,507 and 15,888 t day-1with a large share (∼75%) of organic waste. Adoption of the proposed system could produce 3936 t day-1biochar blended compost with an annual return of US $210 million in 2016 while it could reduce GHG emission substantially (-503 CO2e t-1municipal waste). Moreover, the proposed system would able to recover ∼46%, 54%, 54% and 61% of total C, N, P and K content in the initial waste, respectively. We also provide a projection of waste generation and nutrient recycling potentials for the year 2035. The proposed method could be a self-sustaining policy option for waste management as it would generate ∼US$51 from each tonne of waste. Moreover, a significant amount of nutrients can be recycled to agriculture while contributing to the reduction in environmental pollution and GHG emission.
Several studies have attempted to improve the productivity of solar stills and build expressive models for yield prediction. However, most of these models do not consider the amount of condensed water that falls from the condensing cover towards the solar still basin, especially in the case of small-slope covers. This oversight can significantly affect the accuracy of these models. In this study, we developed a fairly simple method to estimate the amount of distilled water produced every hour from the double-slope solar still hybrid with rubber scrapers (DSSSHS) in low-latitude areas. The proposed model is based on the determination of the best values for the unknown constant (C) and the exponent (n) for the Nusselt number expression used to formulate the equation for the estimation of the hourly yield of a solar still (HYSS). This was achieved by solving an optimization problem using the particle swarm optimization (PSO) algorithm in which the optimal yields were determined by estimating the optimal values of the unknown C and n parameters. This technique, which is used for the first time in this study to build a yield prediction model, avoided the conventional trial-and-error approach to calculating unknown coefficients in a proposed model. Furthermore, the use of rubber scrapers to collect the condensed water that accumulates on the inner surfaces of the condensing cover enhanced the accuracy of the measurement of solar still experimental yields, which consequently improved the accuracy of the model. The proposed model was validated against the experimental data collected in this study. The results showed that the built model was able to accurately estimate the HYSS values.
An experiment has been performed to study the effect of system integration by two different concentrator assisted de-salting systems. The compound parabolic concentrator (CPC) and compound conical concentrator (CCC) are used in this research work. Two solar desalination systems, the single slope solar still (SSSS) and pyramid solar still (PSS), have been integrated with a CCC and compound parabolic concentrator-concentric circular tubular solar still (CPC-CCTSS). To study the effect of system integration, a thick cloth prevents the entry of sunlight into the solar still top. Additionally the concentrator assisted de-salting systems are equipped with phase change material (PCM) for enhancement. In CCC-SSSS, the PCM fills the inside of hollow copper balls and the balls are placed in the SSSS basin. In the CPC-CCTSS, the PCM is loaded in the specially designed circular trough. Two methodologies are followed here to produce the fresh water even while the distillers are blocked from the sunlight. They are (1) thermosyphon effect in CCC-SSSS and (2) waste heat recovery from CPC-CCTSS. The results showed that the productivity of CCC- SSSS, CCC-SSSS with PCM, and CCC-SSSS (PCM) top cover shaded were found as 2680 ml/m2 /day, 3240 ml/m2/day and 1646 ml/m2/day, respectively. Similarly the productivity of the 30 CPC-CCTSS-PSS, CPC-CCTSS (PCM)-PSS and CPC-CCTSS (PCM)-PSS top cover shaded were found as 7160 ml/m2 /day, 7346 ml/m2/day and 5120 ml/m2/day. The productivity of the CCC-SSSS and CPC-CCTSS-PSS is examined and conclusions are drawn such as the solar radiation blocked distillers productivity did not drop to zero.
This study aimed to use sago palm bark to formulate a new adsorbent activated carbon (AC) contains highly surface area through physicochemical method via ZnCl2 activation. Conduction of the activation process was performed at varying impregnation ratios (0.5-2.0). Thermal decomposition was determined using thermogravimetric analysis (TGA). Porosity characterizations of AC were conducted by using N2 adsorption-desorption in order to characterise properties like pore volume, surface area, and micropore volume. To detect the presence of functional groups which were found on the surface of AC, Fourier Transform Infrared Spectroscopy (FTIR) analysis was utilised. Morphology of AC was determined using scanning electron microscopy (SEM) and X-ray spectroscopy (EDX). Experimental results showed that maximum AC surface area was 1737 m2/g. Activation temperature was revealed to be 700oC, with chemical impregnation ratio of zinc chloride to a precursor equal to 1.5/1.
Activated Carbon (AC) is an adsorbent having high surface area which makes the process of removing heavy metals from wastewater (such as landfill leachate) very effective. This study explored the utilization of three methods of modification of AC produced from coconut shell by treating it with nitric acid (HNO3), potassium permanganate (KMnO4) and heating at 600°C to improve the adsorption capacity. The AC can remove multi-pollutants in the filtration process which was used to treat landfill leachate. The water quality parameters such as pH, TSS, Ammonia-Nitrogen and a few heavy metals were considered in the present study. Results showed that the removal of these parameters was proportional with the increase of contact time and the bed depth of AC. The isotherm analysis of the adsorption of modified AC showed the best Removal Efficiency (RE) can be achieved when AC treated with KMnO4 for NH3-N, zinc, TSS and sulphide. The morphology of the AC was studied through Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX) pattern analysis and Fourier Transform Infrared (FTIR) analysis. It was found that various types of oxygen functional groups were introduced onto the surface of coconut shell derived AC through oxidation using HNO3. FTIR was used to characterize the surface oxygen functional groups. The surface functional groups such as N-H and C-H stretching played a significant role in heavy metals adsorption. Hence, it can be concluded that the hybrid technique by using electrolysis process with AC adsorption be an effective way to remove the suspended solids and heavy metals from landfill leachate and thus able to reduce environmental pollution.
Solar stills are very cost-effective technologies used in producing potable water. This work aims to investigate the productivity of two passive double sloped solar stills fabricated with different cover materials with similar shapes; polythene film (PSS) and glass (GSS). The first solar still was made of a transparent polythene film, PVC pipes and a black painted stainless steel trough as cover, frame and basin, respectively. The second one was fabricated using glass as cover, with similar basin material. Experimental outputs indicated that GSS had 1%–5% higher yield than PSS throughout the experiment. The fabrication cost of PSS was 5 times less than the cost of the GSS. The thermal energy efficiencies of PSS and GSS were obtained as 34.05% and 35.50%, respectively. A mathematical model for each solar still was developed using the relationships of heat and mass transfer and their calculated and experimental productivities were in good agreement. Water quality parameters tested showed that water produced from both solar stills met the WHO standards for drinking purposes. © 2017 American Institute of Chemical Engineers Environ Prog, 2017
This study investigated the effects of different parameters on the removal efficiencies of organic and inorganic pollutants in landfill leachate treatment by electrolysis. Different parameters were considered such as the electric potential (e.g., 24, 40 and 60 V), hydraulic retention time (HRT) (e.g., 40, 60, 80, 100 and 120 min), sodium chloride (NaCl) concentration (e.g., 1, 3, 5 and 7%), pH (e.g., 3, 7 and 9), electrodes materials [e.g., aluminum (Al) and iron (Fe)] and distance between electrodes (e.g., 1, 2 and 3 cm). The best operational condition of electrolysis was then recommended. The electric potential of 60 V with HRT of 120 min at 5% of NaCl solution using Al as anode and Fe as cathode (kept at a distance of 3 cm) was the most efficient condition which increased the removal efficiencies of various parameters such as turbidity, salinity, total suspended solids (TSS), total dissolved solids (TDS), biochemical oxygen demand (BOD), chemical oxygen demand (COD) and heavy metals (e.g., Zn and Mn). The higher removal percentages of many parameters, especially COD (94%) and Mn (93%) indicated that the electrolysis is an efficient technique for multi-pollutants (e.g., organic, inorganic and heavy metals) removal from the landfill leachate.
Wood chips are generated from wood industries, particularly from furniture manufacturing. The general reuse options are, however, currently limited to low-value applications. Driven by the adverse impacts of climate change, with the aim of achieving more environmental sustainability through reducing waste and increasing reuse/recycle options, this study investigated the feasibility of using wood chips as a pipe backfilling and embankment fill material. A laboratory assessment undertaken in this research shows that wood chips are suitable as a non-structural embankment fill material, but not as a pipe backfilling material. This research also presents the environmental benefits of using wood chips in natural landscaping and the effects of filter depth in such applications. It is found that wood chips significantly trap total suspended solids (TSS) and total nitrogen (TN), contributing to increased total phosphorus (TP) concentration. As such the use of such material in urban landscaping should be subjective depending on the level of concerns for specific pollutant(s) (TSS, TN and TP). With regard to the effect of filter media depth on pollutants' removal efficiencies, it is found that the pollutants' removal efficiencies linearly vary with filter media depth.
The increased amount of waste generation resulting from urbanization, population growth and improved life-style is a major concern for many developing countries like Bangladesh. A major portion (68 to 81%) of the urban waste of Bangladesh is composed of food waste, which produce CH4 as they decompose anaerobically. The trends of waste generation indicate a growing rate of 0.1343 million tonnes per year. This study estimates that greenhouse gas (GHG) of 1.29 million tonnes CO2 equivalent (CO2e) is emitted annually because of composting. This study also estimates that CH4 generated from existing solid waste is 250.95 million tonnes CO2e and 2.89 million USD could be saved as part of energy production through recovery of CH4 from landfill. The existing waste management policy neither includes any waste to energy recovery targets, nor does it explain any recycling or reuse targets. Besides, there are no provisions for incentives for waste minimization. Hence, this study proposes to formulate a comprehensive waste management policy considering reduction of greenhouse gas by reviewing existing laws on waste management system. A policy matrix for waste management has been proposed to overcome the flaws of existing environmental policy and regulatory framework.
In this study, a new double-slope solar still hybrid with rubber scrapers (DSSSHS) and a double-slope solar still (DSSS) were designed, manufactured and tested. The proposed design of DSSSHS makes use of the advantages of using a small slope of the condensing cover of the still that allows higher solar radiation to enter into the still. Disadvantages resulting from using the small slope are overcome by using the rubber scrapers. No researcher has yet used the scrapers in solar still. Experimental measurements and results were used to calculate the theoretical values of convective and evaporative heat transfer coefficients, in addition to the theoretical values of the yields. Results of the two models were compared to evaluate the advantages of using rubber scrapers in the new model. Using rubber scrapers in DSSSHS model enhanced the total internal heat transfer coefficient (h1) as well as the productivity. The maximum recorded value of the total internal heat transfer coefficient for the DSSSHS is found as 38.754 W/m² °C and the daily yield as 4.24 L/m² day with productivity improvement of 63%, for the case when the inclination angle of the glass cover is quite small (about 3.0°).
Safeguarding groundwater from pollution is largely a global political decision. These decisions are basically supported by DRASTIC (D=Depth to water, R=Recharge, A=Aquifer media, S=Soil media, T=Topography, I=Impact of vadose zone, C=Hydraulic conductivity) analysis. Furthermore, water quality index (WQI) is an effective tool for groundwater quality evaluation and management. This study identifies the relationship between these two indices [i.e., pollution vulnerability index (PVI) and WQI]. The DRASTIC index of the study area was found to be from 60.4 to 178 characterized by very low, low, medium high, and very high vulnerability constituting of 12.88, 24.38, 34.11, 21.99, and 6.63% of the study area, respectively. In addition, the WQI of the area according to the analyzed parameters is between 10.19 and 55.63. It was established that a good correlation (61%) was found to exist between the two indices; which may be an indication that most pollutants present in the groundwater are likely due to anthropogenic activities on the land surface.
Water is a critical component for living existence on earth. Clean water is the need of hour, but the amount of clean water available in earth is drastically reduced due to water pollution caused by industrialization and rapid urbanization. Overall global climatic and seasonal changes also have a significant impact on the reduction of amount of fresh water. The need for clean water is continuously growing due to rise in human residents for the last few decades. Use of contaminated water leads to several water borne diseases and based on the intensity of contamination sometimes it leads to death. There are various processes for obtaining fresh water from contaminated water, but the most economical and preferable method is solar distillation since the process involved in it is similar to natural hydrological cycle which requires only solar energy for its operation. Solar stills are potable and do not require any additional skills for its operation and maintenance which makes it user friendly. Integrated PV/T solar still is used for isolated communities facing electrical energy troubles and a scarcity of good quality water. The daily fresh water produced from passive solar still was found to be 2-5 kg/m2 whereas from an active solar still integrated with PV/T collector can produced daily yield of about 6-12 kg/m2. In this paper, a comprehensive review of integration of solar still and PV module has been presented.
All groundwater is vulnerable to pollution, but the level of susceptibility depends on the spatial peculiarities of a region. Among the numerous vulnerability assessment methodologies, the geographical information system-based DRASTIC model is the most sophisticated and achieves reliable results even in complex areas. Fractured-rock aquifers are not only complex, but they are also potential sources of radioactive and other types of waste and are liable to high recharge rates. Hence, they can serve as a conduit for fluid (and potentially) contaminants. Therefore, in this study, a new parameter, ‘fracture media’ (F), is fashioned to replace the weakest parameter (i.e. depth to water, D) in the standardized DRASTIC model to create a new model (FRASTIC) for the complex fractured aquifer system. The proposed model was tested on a case study area (Kano, Nigeria), and the FRASTIC minimum and maximum indices obtained were in the range of 63–170. The region was characterized as having very low (covering 0.16% of the total study area), low (55.52%), medium (42.53%), and high (1.79%) vulnerability based on the standardized classification system. In addition, the modified FRASTIC model was further developed using the sensitivity analysis (SA) and recorded the highest vulnerable area coverage (32.86%) within Kano. Thus, the modified FRASTIC model is appropriate for the complex nature of the study area because it contributes appreciably to defining the vulnerable zones. The single-parameter SA was employed to obtain effective weights for two modified models, which were then implemented to improve efficacy. Conventional nitrate validation indicated that there is a strong correlation between nitrate and vulnerability for the modified models. In addition, a new approach for identifying the relationship between the water quality and vulnerability indices was developed by this study and was proven to be an effective validation tool.
Lignocellulosic biomass resources are renewable materials that can be converted to fermentable sugars and subsequently into ethanol. Water hyacinth (Eichhornia crassipes) is a cellulosic aquatic plant that has high carbohydrates, low lignin content, and notable reducing sugars content in its structure. Based on the literature review in the case of water hyacinth, the most frequently used pretreatment methods were acid and alkali, while ionic liquid and microwave-assisted methods were used rarely. The dominant sugars were glucose, xylose, galactose, arabinose, and mannose. Based on the findings, cellulase and S. cerevisiae were mostly used for enzymatic hydrolysis and fermentation of water hyacinth to ethanol, respectively. This review presents the recent studies in pretreatment, hydrolysis, and fermentation of water hyacinth biomass into ethanol.
Two raw materials,sago palm bark (SPB) and date pits,were utilizedas precursorsto prepare high porosity activated carbon (AC). The porosity of these two raw materials wascompared with thatof commercial AC made from coconut shells. The physicochemical activation method was used for AC preparation,and it consistedof two steps,carbonization and activation. The activation processwas performedusing zinc chloride (ZnCl2) as an activation agent.N2 adsorption-desorption analysis was carried out to characterize the porosity of AC. Thermogravimetric analysis(TGA) was conductedfor the two raw materials. The adsorbent made from SPB,which showed the maximum surface area of 1634m2/g atthe700°C activation temperaturefor one hour, while the surface area of prepared AC from date pits was 1367m2/g. Both prepared ACs had a larger surface area thancommercial AC made with coconut shell (1348m2/g). Manufacture of low-cost activated carbon using sago palm bark and date pits by physiochemical activation. Available from: https://www.researchgate.net/publication/313104319_Manufacture_of_low-cost_activated_carbon_using_sago_palm_bark_and_date_pits_by_physiochemical_activation [accessed Feb 3, 2017].
The effect of osmotic stress was carried out to determine the resistance to salt toxicity using 4 Continuous Stirred Tank Reactor (CSTR). A CSTR digestion study revealed that digesters seeded with an inoculum from a conventional mesophilic digester treating municipal wastewater and fed on domestic wastewater (DW) plus salts were able to acclimate successfully to a final salt concentration of 10 g l⁻¹. The digesters showed some disturbances during the acclimatisation period as indicated by reductions in specific methane production (SMP), specific biogas production (SBP), pH and increases in Intermediate Alkalinity/Partial Alkalinity (1A/PA) ratio and Volatile Fatty Acid (VFA) concentration. This study revealed the order of disturbance was Sodium Chloride (NaCl) > Potassium Chloride (KCl) > KCl + NaCl. The average values for SMP after stabilisation were below those in the controlled digester, at 0.335 (controlled), 0.323 (NaCl), 0.316 (KCl + NaCl) and 0.308 l CH4 g-1 COD added (KCl).
Landfilling has become the most effective solid waste disposal option in developing countries. Aged Refuse (AR) in this context is solid wastes from landfill which has become stabilized after several years of placement. The aged refuse sampled from Air Hitam landfill site in Malaysia is characterized as follows: moisture content 29.5%, Loss on Ignition (LOI) 9.90%, porosity 51%, ash content 95.99%, bulk density 1.23 g/cm3, hydraulic conductivity 0.31 cm/min, electrical conductivity 143.10 ms/cm and Carbon-Nitrogen-Sulphur (CNS) of 0.64%, 0.04% and 0.009%, respectively. Cation Exchange Capacity (CEC) is 2.69 meq/100 gm, with exchangeable cations of Calcuim, Magnesium, Potassium and Sodium. The SEM/EDX showed available specific surface area of 3.376 m2/g and negligible heavy metals presence with abundance of Silicon and Oxygen as compounds. The AR texture is similar to loamy clay, with the abundance of microbes at 7.1 × 106 CFU/100 ml, which removed up to 92.1. 88.6, 68.0, 84.7 and 95.1% of COD, turbidity, chromium, NH3-N and colour, respectively from fishpond wastewater.
Emulsions are showing rising application in food processing industries because of their unique physicochemical and functional properties. There are wider ranges of food products where emulsions are used to encapsulate, deliver, and protect food components such as oil-soluble flavors, vitamins, colorants, preservatives, and other bioactive ingredients. It has ability to promote the product physicochemical properties like texture, taste, other sensory attributes, for example coloring and flavoring strength and processability. The utilization, properties, and stability depends on types of emulsion classified based on particle size into macro or conventional emulsion, microemulsion, and nanoemulsion. Among them, microemulsions and nanoemulsions are becoming more popular in food processing industry due to the advantage of stability and optical clarity. This chapter describes about the emulsification techniques for micro- and nanoemulsion, emulsion droplet properties, physicochemical properties of nanoemulsions, stability, approaches use for observing the properties of micro- and nanoemulsion, possible risk and potential application in food production and food processing industry.
The study was observed placement of barbs on river channel sidewall showing river flow fortifies towards the bank stability using current flow and channel bed changes investigation solver model. The model was run by setting of barbs constructed at one bank sidewall and both bank sidewalls of the river channel. The current flow depth and discharge used were averagely 0.044 m and 0.028 m3/s. The model reproduced results on flow velocity, depth and bed elevation after placed of barbs with time. The simulation outcomes established the environs of barb stretched a significant reduction in scour alongside the river bank sidewall which persuaded sediment deposition beside increase the center channel current velocity. At the upward side of the structures, sediment bars were formed along the river bank sidewall for sub-critical flow which induced sedimentation and bank stability. Moreover, scour occurred at downward side of barb end due to hydraulic bounce and turbulence current that increased flow velocity and enhanced the river channel conveyance. Furthermore, it was observed that stream barbs placed at both bank sidewalls would be able to encourage center channel flow and persuade the bank stability.
In this study, the effect of surface roughness on scale deposition on steel pipes, under identified condition in multiple-effect distillers (MED), was studied using roughness measurements of the scaled surfaces. The results showed that the desired roughness value was achieved by roller burnishing (RB). A correlation was developed between the roughness value and the accumulated scale thickness on the outer surface of the tubes (scale thickness [μm] = 3.1987 Ra). The roughness of the scaled surface increases by increasing the amount deposited scale. The scale deposition increases by increasing the surface roughness and concentration factor (CF). An optimum value of roughness of about 0.25μm was obtained at 60-80N RB, because it was found to have the lowest amount of scale. The accumulated scale contains mainly of calcium and magnesium in addition to the sodium and potassium salts as well as iron and zinc from the metal surface, too. Salt crystallization increases with increasing the concentration factor. Water analysis was convenient with the tube’s surface analysis. The anti-scalant (Veolia Hydrex® 9209) was found to better covers the lower rouhgness pipes and did play its role in preventing the scale through the threshold mechanism.
In the present investigation, a detailed experimental study is carried out on a conventional single slope solar still with sand heat energy storage for improving the yield of fresh water. Yield of the solar still depends on the type of energy storage material used in the basin. Yield of the present study is compared with the solar still without any storage medium. Similarly, mathematically correlations of yield as a function of water and basin temperature were depicted. The results show that the use of sand as energy storage in cuboidal boxes the yield of solar still has improved by 145% than that of conventional single slope solar still. The total yield from the solar still with and without energy storage materials was found to be 5.1 and 1.9 kg/m2day respectively.
Water supply access in many developing countries is yet to fulfill Millennium Development Goals. Many local governments are incapable of managing their water resources either due to funding constrains or lack of adequate work force. This often results into poor services with low quality, insufficient and inconsistent delivery of water, leakage and wastage creating water shortages. The water stress resulting from urbanization is more acute in terms of Dhaka city due to its capital city-centric development strategies attracting rural-urban migration, which have resulted into an unplanned horizontal and vertical expansion of the city without having facilities for relevant infrastructures. Therefore, it is important to carry out a risk assessment on existing water supply distribution systems to address the challenges of frequent leaks contributing to cross contamination and system loss arising from unplanned development and aging of pipes. The objective of this study is to identify the physical risk for various zones under Dhaka City based on existing distribution systems and its susceptibility to leakage. The assessment requires analyses of distribution system, its length, number of leaks in the pipes detected every month, population density, number of consumers, characteristics of areas whether industrial or residential areas, low lying and vulnerable to flooding. The study finds that Zone IV possesses a very high risk due to an average leak of 93 per month with 1,571,960 people are exposed to vulnerability while Zone II, III, V, VI having average monthly leaks of 39, 36, 26, and 34 respectively are high risk zones.
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The effects of water depth in solar stills were studied in many earlier works. It was revealed that in the previous experimental works, the water surface-cover distance (WCD) was altered with the change of the water depth. However, in this research, the effects of water depth and WCD were investigated separately, and effects of water depth on the performance of solar stills with the same WCD were examined for the first time. In this way at first, some experiments were conducted in the summer and winter seasons using the stills with the same water depths, but different basin depths (i.e. different WCDs). It was found that WCD can affect the amount of distillate yield up to 26%. Thus, it was concluded that to study the effect of water depth accurately, different stills should be employed at the same time (to keep WCD constant). In the second step, some experiments were conducted using four stills in the summer, fall and winter seasons to examine the effects of water depth, while the WCD was constant. In addition, the stills with different water depths were modeled analytically and their performance was investigated. Moreover, an empirical relationship was obtained between the distillate yield and the water depth. By comparing the results of this empirical relation with previous studies, it was revealed that the past researches reported a lower dependency (in the average 15%) of the distillate yield on the water depth, since in their experimental works, WCD was changed along with the water depth.
Activated carbon (AC) is used in different states of applications after its discovery as a strong and reliable adsorbent. An overview on AC is presented together with revisiting the sources of AC generation; methods used to generate AC comprising of pyrolysis activation; physical activation; chemical activation and steam pyrolysis. The important factors affecting the AC production, the possible applications of AC and their future prospects are also discussed. AC is applied in water, wastewater and leachate treatments in many countries, especially to polish the color, remove the odor and some heavy metals. It is cheap and available, and can be produced from agricultural waste materials, e.g. rice husk, palm oil shell and coconut shell. The AC’s fine and porous structure and an extremely large particle surface area (>1000 m2/g) results in making it possessed powerful adsorptive properties. Therefore, the adsorption process using AC is found to be a potentially viable method of removing pollutants from aqueous solutions.
Adsorption is one of the methods that can be used for metal removal. In this study five metals were used cadmium, chromium, lead, copper and nickel (Cd, Cr, Pb, Cu, and Ni) over a concentration range from 0.8 to about 7 mg l(-1) for each metal. Adsorbents were prepared with increasing chitosan to bentonite ratio from 0 to 0.67 g chitosan/g bentonite. The study showed that adsorption of metals on plain bentonite and chitosan modified bentonite can fit well with Langmuir and Freundlich adsorption isotherms. Furthermore, the bentonite adsorption capacity will decrease with the increase of chitosan/bentonite ratio. This study concluded that bentonite is a good adsorbent. However, the applicability of bentonite as potential adsorbent may be limited by its physical properties such as slow settling rate and difficulty to use it as an adsorbent in adsorption columns. Despite the decrease of maximum theoretical adsorption capacity as a result of chitosan modification, the addition of small amount of chitosan can improve the physical characteristics of bentonite clay to be used as an adsorbent.
This study was conducted to characterize the native soil at shrimp Gher and agricultural land in Khulna, Bangladesh. Eight locations were selected and among them five Ghers from south part of Dumuria which is about 60 km away from KUET campus, Khulna, Bangladesh. In the laboratory, various parameters such as salinity, organic content, chloride, pH, alkalinity, conductivity and moisture content were determined by following standard methods. The chloride and alkalinity were determined manually and pH, conductivity and salinity were determined by digital meter. The organic and moisture content both were highest at 30 cm depth for both the cases of shrimp Gher and agricultural land. Chloride was highest at 15 cm depth for both the cases shrimp Gher and agricultural land. Alkalinity was highest at 30 cm depth for shrimp Gher, however, the lowest was for agricultural land. It is concluded that the salinity and organic content vary with depth, age and soil condition.
Knowledge of fractures and their connectivity in geologic media is paramount to groundwater resource management. However, the theory of connectivity between the fractures and their measurement techniques, and its application in modelling are still under great debate. Various studies indicated that the aquifers of the basement complex rocks in Kano are regolith and the fractures are connected at various depths. However, no study has stated the extent (spread) of the underlain fractures, their position, the connectivity between the fractured zones and whether or not all the fractured rock aquifers are productive (water available within fractures). Therefore, this study was undertaken with a view to addressing these challenges. It is established using the GIS-based spatial analysis approach that 52.28 % of the underlain aquifers are productive. The minimum and maximum depths of the underlain fractured rocks are 19.8 and 50.6 m, respectively. Only 19 % of the total study area is unproductive while 42.35 % of the underlain basement complex is characterized by fractures. These fractures are completely saturated.
This study investigated the effect of an internal reflector (IR) on the productivity of a single-slope solar still (during the summer and winter) experimentally and theoretically. A mathematical model was presented which took into account the effect of all walls (north, south, west and east) of the still on the amount of received solar radiation to brine, and the model was validated with the experimental data. The model can calculate the yield of the still with and without IR on various walls. The results show that the simultaneous use of IR on front and side walls enhances the still's efficiency by 18%. However, installation of an IR on the back wall can increase the annual efficiency by 22%. The installation of IRs on all walls in comparison to a still without IR can increase the distillate production at winter, summer and the entire year by 65%, 22% and 34%, respectively. Furthermore, the effect of cloud factor on the installation of IRs on all walls was examined, and the results indicate that the increasing the cloud factor decreases the influence of IRs significantly.
Desalination is a process that involves the removal of salts and non-ionic minerals from seawater to produce freshwater that is fit for human consumption. This process produces brine, which is typically redisposed into the sea. The relatively high salt concentration in the disposed brine increases the salinity of water and soil, which adversely affects the environment. However, brine is found to be rich in economically valuable minerals. In order to effectively manage the disposed brine, this study proposes an integrated technique using solar and evaporation ponds to filter valuable minerals from concentrated brine. The results of this study demonstrate that the proposed technique can be effectively employed for this purpose. Furthermore, this helps reduce desalination costs and complies with the notion of renewable energy production and eco-friendliness.
A daily water balance model is used for the performance analysis and calculation of potential rainwater savings from household rainwater tanks under different scenario for a major Australian city, Melbourne. To investigate the climatic variabilities of rainwater tank outcomes nine representative years (three for each dry, average and wet condition) are selected from historical rainfall data. For the three climatic conditions, a number of rainwater tank outcomes (water savings, townwater augmentation, overflow) are presented in relations to tank volume, roof area, number of people in a house (i.e., water demand). For spatial variability investigation, two distant (25 km apart) localities within Melbourne were selected; one in central Melbourne and the other in North Melbourne. It is demonstrated that significant climatic and spatial variabilities exist in regards to studied rainwater tank outcomes, except for very few conditions having tanks connected with large roofs under low demand scenario. Also, computed variabilities are higher than the expected climatic variabilities computed for an Australian inland city, Canberra. Eventually, an economic analysis is presented showing potential money savings and payback periods for different tank options.
N.N. Nik Daud). GRAPHICAL ABSTRACT HIGHLIGHTS Aged refuse bioreactor (ARB) • Aged refuse bioreactor (ARB) is widely used in wastewater treatment. • Review on pollutant removal efficiencies in wastewater using ARB. • Wastewaters from different sources treated by ARB are discussed. • Factors affecting the pollutants removal in ARB operation are focused. • It provides a sustainable approach to treat various wastewaters & leachate. KEYWORDS ABSTRACT Aged refuse Leachate Wastewater Bio-reactors Removal rate Efficiency ARTICLE HISTORY Municipal landfilling has remained the universal method for solid waste disposal; however, its limitation is the generation of landfill leachate, which is a major environmental issue. The aged refuse bioreactor/biofilter (ARB) can remove numerous pollutants from various wastewaters using the principle of waste control by waste. It can remove organic pollutants also. Wastewater treatment by ARBs has been proved to be technically practicable, environmental friendly, economically favorable and simple to operate than other conventional biological methods. Researchers have carried out diverse studies centered on operational and environmental factors including temperatures, loading rates, height of aged refuse, and aerobic or anaerobic conditions. To this end, this article takes an overview of significant pollutant removal efficiencies using ARB in wastewater treatment, highlighting particularly landfill leachate, sewage and livestock wastewater. As the construction of new landfills is not an easy task, it is rather practicable to reclaim and excavate aged refuse from landfills in order to utilize it and at the same time to provide more space for new waste at site.
Most of the studies on rainwater tanks focused on sizing and/or optimum design. Some studies proposed different methods of estimating rainwater tank outcomes. Several studies used monthly rainfall data to estimate rainwater tank outcomes. However, quantification using daily rainfall data will be much more realistic than using monthly rainfall data. This paper presents development of generalised equations for domestic rainwater tank outcomes for an Australian city, Adelaide, using a daily water balance model, which incorporates measured daily rainfall data. To investigate the climate variabilities of rainwater tank outcomes, 15 representative years (five for each dry, average and wet condition) are selected from historical rainfall data. For the three climate conditions, rainwater tank outcomes such as water savings and town water augmentation amounts are presented in relation to tank volume, roof area and rainwater demand. Eventually, six equations, one for each climate condition and one for each outcome,...
Most of the studies on rainwater tanks focused on sizing and/or optimum design. Some studies proposed different methods of estimating rainwater tank outcomes. Several studies used monthly rainfall data to estimate rainwater tank outcomes. However, quantification using daily rainfall data will be much more realistic than using monthly rainfall data. This paper presents development of generalised equations for domestic rainwater tank outcomes for an Australian city, Adelaide, using a daily water balance model, which incorporates measured daily rainfall data. To investigate the climate variabilities of rainwater tank outcomes, 15 representative years (five for each dry, average and wet condition) are selected from historical rainfall data. For the three climate conditions, rainwater tank outcomes such as water savings and town water augmentation amounts are presented in relation to tank volume, roof area and rainwater demand. Eventually, six equations, one for each climate condition and one for each outcome, are proposed.
Leachate poses serious danger to the neighbouring environment whereby it contaminates groundwater by deep percolation and causes greenhouse effect by releasing methane gas. Combined processes of electrolysis (iron electrodes) and adsorption by activated carbon, AC (palm shell) were used in this study to treat raw leachate obtained from Jeram Sanitary Landfill, Malaysia. Combinations of voltage and hydraulic retention time (RT) were used thereby selecting 24 Volts (V) and 50 minutes (min) respectively in respect of the electrolysis process. Adsorption process was conducted immediately after the electrolysis process. Highest efficiencies were recorded on the parameters checked (pH, Salinity, BOD 5 and COD) using the best combination of the voltages and the RTs (i.e. 24 V and 50 min) chosen. The results obtained shown that the BOD 5 and COD removal efficiency were 84.32% and 85.94% respectively. Salinity removal efficiency of 71.43% was obtained and the pH values yielded from 8.00 to 9.37 meaning that, it was classified as alkaline. The study focuses on a simple technology that could lead to environmental sustainability. Therefore, more broadly research regarding to technological concept of making a mini-model is recommended in the area of leachate treatment by oxidation process using different set of electrodes. Also, other parameters such as ammonia nitrogen, colour and some heavy metals could also be checked to establish their relationship with this method.
Soil erosion is a gradual process that occurs when the impact of water or wind detaches and removes soil particles, causing the soil to deteriorate. Due to soil erosion by water, the sediment attached nutrients (e.g. phosphorus) deteriorates water quality in surface water body (e.g. lakes and streams). Rainfall intensity and vegetation type highly influence the soil erosion. In order to understand the scenario of soil erosion due to rainfall, plane and inclined bed surface models (area of 4m2) are developed and the soil characteristics for both bed surfaces are studied. A rain gauge is fabricated and the amount of error (%) in rain gauge was measured by comparing the rainfall data collected from this rain gauge and a plastic bucket. This study shows that the amount of soil erosion due to rainfall is much higher in inclined surface than plane surface and the soil type of plane and inclined surfaces is silty sand. By knowing the rainfall, the volume of eroded soil can be estimated by using the developed equation in this study for silty sand surface. The vegetation impact on soil erosion shows that for the same amount of rainfall, erosion rate is higher on bared bed at earlier stage than the vegetated one. The vegetation reduces the erosion rate. It is also found that the organic content of soil in both surface conditions increases with respect to time.
Journal of Desalination and Water Purification The International Journal on the Advanced Technologies in Desalination and Water Treatment Aims and Scope Journal of Desalination and Water Purification (JDWP) is a fast track international journal publishing peer-reviewed papers on the advanced technologies in desalination and water treatment to cope with water demand, including sustainable sources of potable water. Journal of Desalination and Water Purification (JDWP) welcomes theoretical and experimental research as Full Text Papers, Short Communications, State-of-the-Art Reviews and Letters to Editors. Short Communications should be concise and novel with advanced knowledge that warrants speedy communication to the readership. The journal includes, but is not limited to, the following topics: Desalination, renewable energy, heat and mass transfer, thermal, membranes, coagulation, sedimentation, energy, energy recovery, seawater, brackish water, environmental impacts; health considerations; risk assessment; cost, performance, water purification, water quality, water treatments, environment, leachate; wastewater, greywater, rainwater, stormwater treatment and reuse; industrial, agricultural and environmental applications; quality aspects; design and application of water reuse systems; economic, social and policy issues; surface and ground water sources. FREE OPEN ACCESS JOURNAL. PUBLISH QUARTERLY. 30 DAYS TO PUBLISH. For Editorial Board Members: http://ababilpub.com/ebm-jdwp/ For Aims and Scope: http://ababilpub.com/scope-jdwp/ For Forthcoming Articles: http://ababilpub.com/article-jdwp/
Majority of the investigations on rainwater harvesting focused on sizing and potential water savings including studies proposing different methods of estimating rainwater tank outcomes. Several studies used monthly rainfall data to estimate rainwater tank outcomes. However, quantification using daily rainfall data will be much more accurate compared to using monthly rainfall data. A vast majority of works using daily rainfall data used daily water balance model for analysis. Again most of the studies using daily water balance model used historical rainfall data, calculated water savings for many years and then presented an average of all the calculated years' total outcome(s). 'Raintank Analyser' is a tool, which uses the same methodology and widely used; used by the South Australian policy makers for producing relevant design charts. In contrast, eTank, a daily water balance model was developed to produce potential rainwater savings, augmented townwater supply, tank overflow, reliability and payback period for three distinct climate conditions (dry, average and wet years). This paper presents comparison of eTank calculated potential water savings with those calculated by 'Raintank Analyser' under similar conditions for a rainfall station in central Adelaide. In general, 'Raintank Analyser' produced water savings are very close to the eTank calculated water savings in average year. However, through the eTank produced potential water savings in dry and wet years, it is found that significant climatic variations exist. Magnitudes of climatic variations under different scenario are presented. Again, to assess spatial variability, three more rainfall stations from different regions of Adelaide metropolitan were selected. eTank was used to calculated potential water savings in three climatic conditions (dry, average and wet years) for various combinations of roof and tank sizes. Again it is found that depending input variable conditions (tank size, roof area and climate) significant spatial variations exist within some of the regions. Also, it is found that potential water savings not only depends on total rainfall amount of a particular area, but also on other input conditions; i.e. under similar conditions an area with lower annual rainfall may provide higher water savings due to rainfall pattern.
Municipal landfilling has remained the universal method for solid waste disposal; however, its limitation is the generation of landfill leachate, which is a major environmental issue. The aged refuse-based bioreactor/biofilter (ARB) can remove numerous pollutants from various wastewaters using the principle of waste control by waste. It can remove organic pollutants also. Wastewater treatment by ARBs has been proved to be technically practicable, environmental friendly, economically favorable and simple to operate than other conventional biological methods. Researchers have carried out diverse studies centered on operational and environmental factors including temperatures, loading rates, height of aged refuse, and aerobic or anaerobic conditions. To this end, this article takes an overview of significant pollutant removal efficiencies using ARB in wastewater treatment, highlighting particularly landfill leachate, sewage and livestock wastewater. As the construction of new landfills is not an easy task, it is rather practicable to reclaim and excavate aged refuse from landfills in order to utilize it and at the same time to provide more space for new waste at site. HIGHLIGHTS Aged refuse-based bioreactor (ARB) is widely used in wastewater treatment. Review on pollutant removal efficiencies in wastewater using ARB. Wastewaters from different sources treated by ARB are discussed. Factors affecting the pollutants removal in ARB operation are focused. It provides a sustainable approach to treat various wastewaters & leachate.
This research article briefly summarizes the augmentation of condensate output by using concentrators. This study compares a single slope solar still, a compound conical concentrator (CCC) solar still and a compound parabolic concentrator- tubular solar still (CPC-TSS). The effect of miniaturization of the absorber (increase in the concentration factor) and some modifications in the solar still assembly shows a remarkable increase in output. The measured daily yield rate of the single slope solar still, CCC solar still and CPC-TSS per square meter of absorber area is 2,100, 18,000 and 6,100 ml, respectively. It was found that the CCC solar still provides the maximum yield.
Awareness about restoring and preserving historically important structures and artifacts is gradually growing in many parts of the world. These artifacts and structures represent the culture, tradition and past of a nation. They are often also a source of national income through tourist activities. Besides masonry and wood work, metallic forms and relics are a vital part of the heritage which needs to be conserved. Certain metals have been used significantly throughout history in the creation of objects and structures. However, metals are prone to decay over time, particularly decay through corrosion. The basic mechanisms of metal corrosion, the various types of corrosion and existing remedial solutions are reviewed in this paper. The most significant factor affecting metal corrosion was found to be the surrounding environment, especially in marine areas. Different remedial measures can be implemented on corroded metals according to their specific properties. Recommendations for further study are offered at the end of the paper.
Awareness about restoring and preserving historically important structures and artifacts is gradually growing in many parts of the world. These artifacts and structures represent the culture, tradition and past of a nation. They are often also a source of national income through tourist activities. Besides masonry and wood work, metallic forms and relics are a vital part of the heritage which needs to be conserved. Certain metals have been used significantly throughout history in the creation of objects and structures. However, metals are prone to decay over time, particularly decay through corrosion. The basic mechanisms of metal corrosion, the various types of corrosion and existing remedial solutions are reviewed in this paper. The most significant factor affecting metal corrosion was found to be the surrounding environment, especially in marine areas. Different remedial measures can be implemented on corroded metals according to their specific properties. Recommendations for further study are offered at the end of the paper.
Experiments were carried out using granular activated carbon (GAC) adsorption techniques to treat wastewater contaminated with organic compounds caused by diverse human activities. Two techniques were assessed: adsorbent GAC prepared from coconut shell (GACC) and adsorbent GAC from palm shell (GACP). A comparison of these two techniques was undertaken to identify ways to improve the efficiency of the treatment process. Analysis of the processed wastewater showed that with GACC the removal efficiency of biochemical oxygen demand (BOD), chemical oxygen demand (COD), turbidity, total suspended solids (TSS) and total dissolved solids (TDS) was 65, 60, 82, 82 and 8.7%, respectively, while in the case of GACP, the removal efficiency was 55, 60, 81, 91 and 22%, respectively. It can therefore be concluded that GACC is more effective than GACP for BOD removal, while GACP is better than GACC for TSS and TDS removal. It was also found that for COD and turbidity almost the same results were achieved by the two techniques. In addition, it was observed that both GACC and GACP reduced pH value to 7.9 after 24 hrs. Moreover, the optimal time period for removal of BOD and TDS was 1 hr and 3 hrs, respectively, for both techniques.
As a Reader/Lecturer in environmental engineering, i may do collaboration with u for some topics, e.g. ecological footprint, economics of CO2 reduction, water, transportation, urban planning, food, waste. tq.
This work overviews the solar radiation basics and insolation of different surfaces is presented. A complete solar radiation modelling and investigation on the effect of horizontal plate, yearly tilt, monthly tilt, and single-axis and double-axis tracking surface on the insolation are carried out to conduct performance evaluation using the case study in Dhahran city of Saudi Arabia. The increments received by insolation for the yearly tilt, monthly tilt, and single-axis and dual-axis tracking surface with respect to traditional flat-plate collector is estimated. The results show that the yearly optimal tilt angle due to the south is close to the 0.913 time latitude of Dhahran. It is found that the yearly irradiation gains using yearly and monthly optimal tilts relative to flat panel installation are 7% and 14%, respectively. The yearly insulation gains made by single-axis and dual-axis continuous tracking surfaces are 33% and 48%, respectively.
The uncontrolled formation of leachate during a waste-disposal process has become a serious issue in landfill management. An innovative filtration process for treating leachate by using aged refuse as a medium in biofilter has been studied recently. The aim of this study is to treat leachate by using aged refuse varied by years (4, 8, and 11 years) as a biofilter medium. To achieve the target, a few objectives were listed: i) to construct the biofilter system in a laboratory scale, ii) to explore the use of aged refuse (AR) as a biofilter medium to treat leachate from the selected landfill in Malaysia, and to assess the quality of leachate treated with different aged refuse regarding physical properties, chemical properties, and microbe activity. Results showed that the initial concentration of leachate parameters is: i) chemical oxygen demand (COD) was 981.47 mg/L, biochemical oxygen demand (BOD) was 527.16 mg/L, and iii) ammonia-nitrogen (NH3-N) was 2,815.56 mg/L and iv) bacterial count is 3.3x10(6) CPUs. After treating with aged refuse, the quality of leachate is increased based on the concentration reduction of COD, BOD, and N H-3-N in the range of 30% to 49%, 17% to 48%, and 68% to 92%, respectively.
The paper making industry is characterized by high rate of water consumption and hence high rate of wastewater generation. The purpose of this research was to assess and optimize the existing complete mix activate sludge treatment plant that is used to treat the high strength paper mill effluent with the highest possible efficiency at a reasonable cost. The collected paper mill wastewater is equalized in an equalization tank before being pumped to the treatment plant. The treatment plant includes chemical treatment unit, complete mix activated sludge and granular media filtration unit. The results showed that effluent of a chemical treatment unit was found to be relatively similar to the laboratory simulated plain sedimentation unit. It can be concluded that addition of chemical coagulant can be eliminated with an overall saving of chemical addition costs. The complete mixing activated sludge achieved good removal of biochemical oxygen demand (BOD) and chemical oxygen demand (COD). Furthermore, the results showed that the plant is operated under low BOD:P ratio. The treatment efficiency of the plant can be improved by increasing the phosphorous dose to the plant to have BOD:P ratio of 100:0.5 to 100:1. It was found that 50% of the treated effluent is recycled to the manufacturing process, however this percentage can be increased through proper plant optimization and control of nutrient addition to the activated sludge unit.
A model of urban stormwater improvement conceptualisation (MUSIC) developed and widely used in Australia, estimates pollutant transport from catchments and stormwater treatment through different systems. MUSIC also provides life-cycle costing estimates for different treatment systems. Following a series of tests for several stormwater treatment systems' efficiencies around the world, MUSIC was further tested for a grass swale system in Taiwan. The tested model was then used for the cost optimisation of three different types of treatment systems: grass swale, bio-retention system and porous pavement. For each treatment system, cost verses expected pollutant removal efficiency curves are presented for the treatments of total suspended solids (TSS), total phosphorus (TP) and total nitrogen (TN). Eventually, different systems were compared in regards to costs in achieving the same removal efficiency. It is found that within lower cost range, bioretention system will provide highest removal efficiency for all the three pollutants considered in this study.
Khulna is the third largest metropolitan city in Bangladesh and a centre with intensive commercial and industrial activities. Rapid urbanization and increased migration of people from rural and coastal areas has put tremendous pressure on its existing solid waste management. The status of the existing municipal solid waste (MSW) management tiers such as generation, source storage, collection, on-site storage, transportation, and open dumping has been identified in this study. The daily generation of MSW is estimated as 520 Mg, of which food and vegetable wastes are the main com-ponents (79% on average). The major source of generated MSW is residential areas, which is 85.87% of total generation, whereas 11.60% in commercial areas, 1.02% in institutional areas, 0.55% in street sweeps and 0.96% in other areas. About 50% of total generated waste is disposed daily to the dumping site and the rest remains uncollected and unmanaged. Non-governmental organizations and com-munity based organizations play an important role in primary collection, composting of organic wastes and medical waste management.
As the quantity of disposing waste material is increasing in road construction, researchers are exploring the use of alternative materials which could preserve natural sources and save the environment. One of these sustainable materials is steel-furnace slag which is a synthetic aggregate produced as a consequence of the electric arc furnace (EAF). Steel slag was selected due to its characteristics, which are almost similar to conventional aggregates, and the fact that it is easily obtainable as a by-product from the steel industry. The same gradations of mixtures were produced using normal crushed aggregate as control samples. The experimental research has been articulated in a preliminary study of the chemical, leaching, physical, and mechanical properties of the electric arc furnace (EAF) steel slag. In addition, the outstanding benefits of steel slag were highlighted. All the mixtures with EAF steel slag have satisfied the requisites for acceptance in the road sector technical standards, thus resulting as suitable for use in the construction of road infrastructures.
Abstract Landfill leachate contains a high concentration of organic pollutants that are active agents in water pollution. This study was conducted to remove various pollutants from landfill leachate through electrolysis and activated carbon (AC) treatments. A simple electrolytic reactor was designed to investigate the removal efficiency of these treatments for biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSSs), and total dissolved solids (TDSs) from landfill leachate at different electric current densities (CDs) and retention times (RTs). The results showed that the highest removal efficiencies for BOD and COD were 75.6 and 57 %, respectively, under a 7-V current for 4 h. It was also found that BOD, COD, TSS, and TDS removal efficiencies improved in proportion to an increase in CD and RT. However, pH gradually increased with an increase in CD and RT. A number of treated leachate samples were further polished by AC filtration to compare the effect of this additional process on the removal of color, BOD, COD, TSS, and TDS. This secondary treatment resulted in a higher removal of color and other pollutants than electrolysis alone. At 4 h RT, the BOD removal efficiency was 54.6 % at 3 V and 66.4 % at 5 V, and the efficiency increased to 61.5 and 70.5 %, respectively, after treatment by AC filtration. Under the same conditions, COD removal efficiency increased from 7.5 to 38.5 % at 3 V and from 31.1 to 49.5 % at 5 V. TSS and TDS removal efficiencies were also significantly improved by AC filtration. It is therefore concluded that 7 V of CD and 4 h of RT are the optimum parameters for removing pollutants from leachate and that the secondary treatment of AC filtration is an efficient method of further polishing.
Purpose – The purpose of this paper is to examine the effects of thick wall parameters of a cavity on combined convection in a channel. In other words, conjugate heat transfer is solved. Design/methodology/approach – Galerkin weighted residual finite element method is used to solve the governing equations of mixed convection. Findings – The streamlines, isotherms, local and average Nusselt numbers are obtained and presented for different parameters. It is found heat transfer is an increasing function of dimensionless thermal conductivity ratio. Originality/value – The literature does not have mixed convection and conjugate heat transfer problem in a channel with thick walled cavity.
This work presents a few important factors that affect the performance of a triangular pyramid solar still. An experimental work has been conducted to find the effect of water depth on the performance of the triangular pyramid solar still. From the present study, it is concluded that the convective and evaporative heat transfer coefficients are important for designing solar distillation systems and the effect of temperature difference between the evaporative and condensing surfaces is also important to optimize the operating temperature range. The condensing area of the solar still is more than that of evaporating area. Thus the experimental results showed that the effect of depth of water in the solar still affects the fresh water production. Nevertheless, outdoor experimental tests were conducted to study the effect of wind speed variations to cool down the glass cover. It was found that increasing the wind speed from 1.5 to 3 m/s and to 4.5 m/s has the effect of increasing the still productivity by 8 and 15.5% respectively.
In this article, a model is developed for unsteady natural convection heat transfer and fluid flow in a partially cooled enclosure with a hollow cylinder through it. The right vertical wall of the enclosure is cooled partially. The location of the partial cooling is set up in three different configurations; namely, bottom (P 1), middle (P 2), and top (P 3). A hollow cylinder is located at the middle of the enclosure to simulate a double-pipe heat exchanger. Three values of Grashof number are applied in this work, i.e., 104, 105 and 106, and three lengths of the cooler, i.e., 0.2, 0.4 and 0.6. Finite element method was utilized to solve the unsteady dimensionless conservation equations of mass, momentum and energy. It is found that the length and location of cooler does not have a significant effect on the natural convection for the case of the low Grashof number. The maximum heat transfer rate is reached when the cooler is located at the middle of the vertical wall.
In Bangladesh, 30 per cent of its total population is living in urban areas and by 2030 the rate of urbanization will be more than 40 per cent. There is a tremendous pressure of influx of people in Dhaka city. Current trend of urban migration is driven by rural poverty, river erosion and natural calamities forcing them to migrate to Dhaka city in search of better livelihoods. These newcomers floating people in the city end up sleeping in public places such as street corners, railway and bus stations as well as other available places including abandoned buildings. The existing infrastructure facilities developed in Dhaka megacity cannot cope with the minimum living requirements of this poor working class floating population. The Dhaka city is exposed to an array of urban problems that could not be discussed in one paper. This article explores the nature and pattern of housing developed under public sector and the policies and strategies that the Government of Bangladesh is pursuing particularly for the middle and poor class who are living permanently in Dhaka city in temporary shelters or on floating basis.
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