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CONTENTS
Volume 6, Number 1, March 2017
 

Abstract
New technologies or improvement of the existing technologies are required to enhance the efficiency of removal of pollutants from wastewater. In this study we attempted to produce and test the activated carbon produced from the refused tea waste for the removal of dyes from wastewater. The objectives of this investigation were to produce activated carbon from refused tea waste by chemical activation, evaluate its performance for the removal of color produced from Acid Yellow 36, and the modeling of its dye removal with the kinetic study. The activation was performed in two steps namely carbonization at 375+-25oC and chemical activation with HCl at 800oC under the absence of Oxygen. Adsorption isotherms and kinetic studies were performed with a textile dye, Acid Yellow 36, at different concentrations (20-80 mg/L). The maximum dye removal (~90%) observed at 80 mg/L dye concentration and it reduced at low dye concentrations. Maximum adsorption ( 71.97 mg/g) was recorded at 96 h at 29+-1oC. Low pH increased the dye adsorption (pH=2; 78.27 mg/g) while adsorption reduced at high pH levels indicating that the competition occurs in between OH- ions and AY36 molecules for the adsorption sites in RTAC. The Langmuir isotherm model clearly explained the dye adsorption, favorably, by RTAC. Moreover, kinetic studied performed showed that the pseudo second order kinetic model clearly describes the dye adsorption. Based on the results obtained in this study, it can be concluded that RTAC can be used for the removal of textile dyes.

Key Words
refused tea activated carbon; adsorption; textile dye; isotherm

Address
Somasiri Wijetunga and Chathurika DFA Gunasekara: Department of Agricultural Engineering, Faculty of Agriculture, University of Ruhuna, Kamburupitiya, Sri Lanka

Abstract
Powdered marble wastes (PMW) generated by Utique marble cutting industries (North of Tunisia) with abundant amounts were used in this study as low-cost materials to investigate the stabilization of heavy metals (Pb, Zn, Fe) in sludge generated from a local Zn-Electroplating factory. Powdered marble wastes were evaluated by means of chemical fractions of heavy metals in sludge and concentrations of heavy metals in leachate from columns to determine their ability to stabilize heavy metals in contaminated sludge. Results indicated that chemical fractions of heavy metals in sludge were affected by application of the PMW mineral materials and pH, however, the effects varied with heavy metals. Application of the powdered marble wastes mineral materials reduced exchangeable metals in the sequence of Pb (60.5%)>Fe (40.5%)>Zn (30.1%). X-ray diffraction and hydro-geochemical transport code PHREEQC analysis were successfully carried out to get a better understanding of the mechanisms of reactive mineral phases involved in reduced exchangeable heavy metals in sludge after PMW material amendments. Therefore, metal immobilization using powdered marble wastes materials is an effective stabilization technique for industrial metallic hydroxide sludge.

Key Words
powdered marble wastes; heavy metals; stabilization; sludge; Zn-Electroplating

Address
Khalifa Riahi:
1) Higher Institute on Rural Engineering and Equipment Medjez El Bab, University of Jendouba, Tunisia
2) Laboratory LRME, Faculty of Science of Tunis, University of Tunis-El Manar, Tunisia
Safa Chaabane:
1) Higher Institute on Rural Engineering and Equipment Medjez El Bab, University of Jendouba, Tunisia
2) National Agronomic Institute of Tunisia, University of Carthage, Tunisia
Béchir Ben Thayer: Higher Institute on Rural Engineering and Equipment Medjez El Bab, University of Jendouba, Tunisia

Abstract
This paper discussed plurality in urban governance in Nigeria and its implication on delivery of urban environmental services, with a focus on water supply, sanitation and solid waste disposal. Conceptually, it explained urban governance as the sum total of the ways of achieving an inclusive city and expressed the urban governance system of Nigeria based the legal framework set for them. The paper explored the environmental implications of urban governance in Nigeria. It concluded that urban governance has several implications on delivery of urban environmental services in Nigeria. The dualism in urban governance is a factor contributing towards inefficient delivery of environmental services such as water supply, sanitation and solid waste management in Nigeria. The paper recommended, among others, a constitutional reform that will guarantee efficient urban governance and delivery of environmental services in Nigeria.

Key Words
constitution; environmental services; local government; urban governance; urbanization

Address
Oluwole Daramola and Oluwaseun Olowoporoku: Department of Urban and Regional Planning, Obafemi Awolowo University, Ile-Ife, Nigeria

Abstract
The use of Granular Activated Carbon (GAC) and naturally occurring silica (Sand) as filtration media in water and waste water treatment systems is very common. While GAC offers the additional functionality of being an \"intermittent\" manner over extended time, to \"simulate\" performance over the life of the filter bed. The experiments were continued till a significant drop in water flow rate through the bed was observed. A novel \"deposition\" and \"detachment\" rate based transient mathematical model is developed. It is observed that the data from the experiments can be explained by the above model, for different aqueous phase electrolyte concentrations. The model \"parameters\", namely the \"deposition\" and \"detachment\" rates are evaluated for the 2 filter media studied. The model suggests that the significantly better performance of GAC in colloid filtration is probably due to significantly lower detachment of colloids from the same. While the \"deposition\" rates are higher for GAC, the \"detachment\" rates are significantly lower, which makes GAC more effective than sand for colloid removal by over an order of magnitude.

Key Words
water purification; activated carbon; empirical model; filtration; transient model

Address
Jaideep Chatterjee, Shajahan A, Shailendra Pratap and Santosh Kumar Gupta: Unilever R&D, Bangalore Laboratory, 64 Main Road, Whitefield, 560066, Bangalore, India

Abstract
Assessment of seasonal changes in surface water quality is an important aspect for evaluating temporal variations of river pollution due to natural or anthropogenic inputs of point and non-point sources. In this study, surface water quality data for 15 physico-chemical parameters collected from 7 monitoring stations in a river during the years from 2014 to 2016 were analyzed. The principal component analysis technique was employed to evaluate the seasonal correlations of water quality parameters, while the principal factor analysis technique was used to extract the parameters that are most important in assessing seasonal variations of river water quality. Analysis shows that a parameter that is most important in contributing to water quality variation for one season may not be important for another season except alkalinity, which is always the most important parameters in contributing to water quality variations for all three seasons.

Key Words
principal component analysis; seasonal variation; surface water quality

Address
Chitta R. Mohanty and Saroj K. Nayak: Department of Civil Engineering, Veer Surendra Sai University of Technology,
Sambalpur-768018, Odisha, India

Abstract
Mining activities play a significant role in environmental pollution by producing large amounts of tailings which comprise heavy metals. The impressive increase in mining activities in recent decades, due to their high influence on the industry of developing countries, duplicates the need for a substantial effort to develop and apply efficient measures of pollution control, mitigation, and abatement. In this study, our objective was to investigate the effect of simulation of the leachate, pH and inflow intensity of transport of Pb2+, Zn2+, and Cd2+ through Lakan lead and zinc plant tailings, in Iran, and to evaluate the modeling efficiency by comparing the modeling results and the results obtained from previous column studies. We used the HP1 model and the PHREEQC database to simulate metals transport through a saturated soil column during a 15 day time period. The simulations assumed local equilibrium. As expected, a lower pH and inflow intensity increased metal transport. The retardation of heavy metals followed the order Zn2+>Pb2+>Cd2+ and the removal concentrations of Cd, Pb, and Zn at the inflow intensity critical scenario, and Cd and Pb at inflow acidity critical scenario exceeded the allowable EPA and Iranian\'s 1053 standard thresholds. However, although the simulation results generally agreed well with the results of the column study, improvements are expected by using multi-dimensional models and a kinetic modeling approach for the reactions involved. The results of such investigations will be highly useful for designing preventative strategies to control reactive transport of hazardous metals and minimize their environmental effects.

Key Words
lakan plant tailing; HP1; PHREEQC; heavy metals; Cd, Pb, and Zn; lakan lead and zinc plant

Address
Fatemeh Izadi Tameh: Department of Civil and Environmental Engineering, Kharazmi University, Iran
Gholamreza Asadollahfardi: Department of Civil Engineering, Kharazmi University, Tehran, Iran
Ahmad Khodadadi Darban: Department of Mining Engineering, Tarbiat Modares University, Tehran, Iran


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