Green Nanomaterials for Photocatalytic Degradation of Toxic Organic Compounds

Author(s):  
Saika Ahmed ◽  
Gulshan Ara ◽  
Md. Abu Bin Hasan Susan

Abstract: In recent years, nanomaterials as photocatalysts have gained much popularity for the removal of organic pollutants from tainted water using photodegradation, since the available chemical, physical, and biological methods often are time consuming, involve high cost and dumping complications, sometimes posing serious threat to both human health and environmental elements. Use of nanomaterials is less expensive and does not, in general, form aggregated macromolecules. In addition, nanotechnology for waste-water treatment demolishes or alters the risky chemical wastes to harmless end products like H2O and CO2. Nanomaterials synthesized from natural resources or prepared using green synthetic routes are receiving surge of interest as our consciousness to ecological environment and safety rises. ‘Green’ materials of this kind might also show unique strength features and exceptional biodegradability, along with their other notable advantageous properties like minimum threat to environment, efficient recyclablity and low cost compared to synthetic nanomaterials. Such green nanomaterials can also serve as nanocatalysts to treat toxic organic pollutants in a safer way, including photodegradation to less or non-toxic products. This article reviews latest developments on the synthesis of some promising green nanomaterials aiming towards their efficient uses as photocatalysts for degradation of organic pollutants. Strategies to find new green materials as photocatalysts by modification of technologies, and development of novel methodologies for safer treatment of organic pollutants will also be discussed.

2013 ◽  
Vol 829 ◽  
pp. 386-390 ◽  
Author(s):  
Mehri Imani ◽  
Alimorad Rashidi ◽  
Mojtaba Shariaty-Niassar ◽  
Elahe Sarlak ◽  
Amir Zarghan

Carbon membranes have high adsorption capacitiy with respect to its incredible properties such as unique structural, electronic, optoelectronic, semiconductor, mechanical, chemical and physical. Carbon nanotube (CNT) membranes because of its high permeance have been recently developed.Great attention has been currently paid to the field of fabrication methods capable of producing uniform, well-aligned and monodispersed CNT array. Current research concerns with fabrication of vertically aligned CNT membrane in order to remove heavy metal ion presents in waste water. For this purpose, CNTs are vertically grown up through the holes of anodic aluminium oxide (AAO); as a template, by chemical vapor deposition (CVD) of acetylene gas.In this work a few heavy metals such as Pb (II), Cu (II) and Cd (II) has been examined for checking the perfomance of membrane in aqueous solution. The morphological properties of the aligned CNT membrane were investigated with scanning electron microscopy (SEM). The method has simple technology, low cost, and easy reproduction.


2021 ◽  
Vol 10 (1) ◽  
pp. 1-10
Author(s):  
Swathy Krishna

In recent decades, the eutrophication of surface water has become a major environmental concern. Increased concentration of nutrients such as nitrogen and phosphorous lead to eutrophication condition which highlights the demand for effective and economical methods of removing nitrogen and phosphorous from waste water. Bio flocculation using microalgae is an excellent candidate for satisfying the dual purpose of nutrient removal and waste water treatment. It has so many advantages over conventional methods such as toxic free, no chemical is needed, low cost etc. In this review the bio flocculation of microalgae, its mechanisms, applications and harvesting methods are discussed. Keywords: Bio flocculation, microalgae, nutrient removal, waste water treatment  


2012 ◽  
Vol 60 (2) ◽  
pp. 185-189 ◽  
Author(s):  
Mohammad Arifur Rahman ◽  
S. M. Ruhul Amin ◽  
A. M. Shafiqul Alam

The possible utilization of rice husk activated carbon as an adsorbent for the removal of methylene blue dye from aqueous solutions has been investigated. In this study, activated carbons, prepared from low-cost rice husk by sulfuric acid and zinc chloride activation, were used as the adsorbent for the removal of methylene blue, a basic dye, from aqueous solutions. Effects of various experimental parameters, such as adsorbent dosage and particle size, initial dye concentration, pH and flow rate were investigated in column process. The maximum uptakes of methylene blue by activated rice husk carbon at optimized conditions (particle sizes: 140 ?m; Flow rate: 1.4 mL/min; pH: 10.0; initial volume of methylene blue: 50 mL and initial concentration of methylene blue: 4.0 mg/L etc.) were found to 97.15%. The results indicate that activated carbon of rice husk could be employed as low-cost alternatives to commercial activated carbon in waste water treatment for the removal of basic dyes. This low cost and effective removal method may provide a promising solution for the removal of crystal violet dye from wastewater.DOI: http://dx.doi.org/10.3329/dujs.v60i2.11491 Dhaka Univ. J. Sci. 60(2): 185-189, 2012 (July)


REAKTOR ◽  
2013 ◽  
Vol 14 (3) ◽  
pp. 204
Author(s):  
Darmawan Darmawan ◽  
Dyah Tjahyandari Suryaningtyas ◽  
Juniska Muria Sariningpuri

APPLICATION OF ELECTROOSMOSIS FOR DEWATERING OF SLUDGE FROM WASTE WATER TREATMENT. Wastewater treatment produces semi-solid residue (sludge) that must be handled carefully during dumping and discharge to avoid polluting the environment. A low cost and easy treatment of dewatering is needed. This research aimed to apply electroosmosis technique for dewatering sludge in order to seek for parameters that can efficiently reduce water content of sludge, including range of voltage, type of electrodes, and distance between electrodes; and to determine the effect of electroosmosis processes on changes of chemical characteristics of sludge. The results showed that: (1) electroosmosis dewatering occurred on the sludge taken from waste water treatment of landfill but not on sludge from water purification plant (PDAM), (2) direct current voltage of 30 volts was the optimum voltage, (3) copper rod cathode provided electroosmosis process as good as stainless steel cathode and both were better than the woven stainless steel cathode, (4) the dewatering time to reduce 1200% (w/w) water content to about 400% was about 40 hours for sludge of 2500 cm3 in volume (laboratory bench scale), (5) the anode need to reinserted gradually approaching the cathode due to current lost when the water content at the anode point reached 400% and sludge at the point shrink, and (6) some chemical elements in the sludge decreased significantly after treatment. Pengolahan limbah cair menghasilkan residu berupa bahan semi padat yang dikenal sebagai sludge. Sludge tersebut juga perlu dikelola penyimpanan dan pembuangannya agar tidak mencemari lingkungan. Salah satu pengelolaan sludge yang perlu dilakukan adalah pengeringan (dewatering). Salahsatu teknik dewatering yang mungkin diterapkan ialah teknik elektroosmosis, yaitu teknik yang memanfaatkan adanya pergerakan air pada media poros di dalam medan istrik searah. Penelitian ini bertujuan untuk mencari parameter sistem dewatering secara elektroosmosis yang dapat menurunkan kadar air sludge paling efisien dan untuk mengetahui pengaruh elektroosmosis terhadap karakteristik kimia sludge. Hasil penelitian menunjukkan bahwa: (1) pengeringan sludge terjadi pada jenis sludge IPAL TPA namun tidak pada jenis lumpur PDAM; (2) tegangan listrik searah sekitar 30 volt merupakan tegangan optimum; (3) katoda batang tembaga menghasilkan proses elektroosmosis yang sebanding katoda batang stainless steel dan lebih baik dibanding katoda stainless steel anyam; (4) waktu pengeringan dari kadar air awal 1200% (b/b) hingga kadar air akhir sekitar 400% untuk volume sludge 2500 cm3 (skala laboratorium) sekitar 40 jam; (5) anoda perlu dipindahkan secara bertahap mendekati katoda karena arus terputus pada saat sludge di titik anoda mencapai kadar air sekitar 400% dan mengalami pengerutan; dan (6) kadar beberapa unsur kimia dalam sludge menurun secara signifikan setelah perlakuan.


1991 ◽  
Vol 24 (5) ◽  
pp. 241-246 ◽  
Author(s):  
A. Batchelor ◽  
R. Bocarro ◽  
P. J. Pybus

An overview of waste-water treatment alternatives in South Africa is presented. A comparison of the capital, operating and maintenance costs of biological filters, bio-discs, stabilisation ponds and an extended-aeration-actiyated sludge system suggest that stabilization ponds may be regarded as a low cost, low energy waste-water treatment system. However, in some instances, due to legal and land requirements they are not appropriate. In these instances a number of interacting factors play a role in determining the lowest cost option. The capital construction and operating costs of constructed wetlands are similar to those of stabilisation ponds but due to lack of full scale operational information they are not yet widely used as a waste-water treatment system.


1991 ◽  
Vol 24 (1) ◽  
pp. 75-82 ◽  
Author(s):  
W. von der Emde ◽  
H. Kroiss

The main goals for the design of waste water treatment plants are high efficiency, high operational reliability and minimal costs. The challenge to have very low investment costs especially exists for industrial plants which are only in operation for several months every year as e.g. in the beet sugar industry in Central Europe. A case study of an Austrian sugar factory treatment plant shows that using very simple and low-cost structures does not affect the efficiency of the treatment. This factory is also one of the rare cases where biologically treated effluent is recirculated to reduce fresh water consumption. Special emphasis is put on the start-up process, the influence of shock loadings in the influent, and design and operation of the plant.


2010 ◽  
Vol 5 (4) ◽  
Author(s):  
N. Tanaka ◽  
H. Soejarwo ◽  
A. Soejarwo

A model system for participatory communal waste water treatment system was developed in densely populated area of Yogyakarta special province. After the community member's awareness for sanitation and motivation for the system was developed, affordable technology was carefully selected. As the community member's income was low and the available space for the system was very limited, rotating biological contactors with three dimensional lattice media was selected. The technology was also characterized with easiness of operation. After short training of operation and maintenance, the system has been continuously operated by community members with their own expense.


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