Applied Water Science (v.5, #2)
Biological removal of phenol from wastewaters: a mini review by N. V. Pradeep; S. Anupama; K. Navya; H. N. Shalini; M. Idris; U. S. Hampannavar (105-112).
Phenol and its derivatives are common water pollutants and include wide variety of organic chemicals. Phenol poisoning can occur by skin absorption, inhalation, ingestion and various other methods which can result in health effects. High exposures to phenol may be fatal to human beings. Accumulation of phenol creates toxicity both for flora and fauna. Therefore, removal of phenol is crucial to perpetuate the environment and individual. Among various treatment methods available for removal of phenols, biodegradation is environmental friendly. Biological methods are gaining importance as they convert the wastes into harmless end products. The present work focuses on assessment of biological removal (biodegradation) of phenol. Various factors influence the efficiency of biodegradation of phenol such as ability of the microorganism, enzymes involved, the mechanism of degradation and influencing factors. This study describes about the sources of phenol, adverse effects on the environment, microorganisms involved in the biodegradation (aerobic and anaerobic) and enzymes that polymerize phenol.
Keywords: Phenol; Aerobic treatment; Anaerobic treatment; Enzymes; Wastewater; Industrial pollutant; Toxicant
Sustainable treatment of landfill leachate by Mohamad Anuar Kamaruddin; Mohd. Suffian Yusoff; Hamidi Abdul Aziz; Yung-Tse Hung (113-126).
Landfill leachate is a complex liquid that contains excessive concentrations of biodegradable and non-biodegradable products including organic matter, phenols, ammonia nitrogen, phosphate, heavy metals, and sulfide. If not properly treated and safely disposed, landfill leachate could be an impending source to surface and ground water contamination as it may percolate throughout soils and subsoils, causing adverse impacts to receiving waters. Lately, various types of treatment methods have been proposed to alleviate the risks of untreated leachate. However, some of the available techniques remain complicated, expensive and generally require definite adaptation during process. In this article, a review of literature reported from 2008 to 2012 on sustainable landfill leachate treatment technologies is discussed which includes biological and physical–chemical techniques, respectively.
Keywords: Landfill leachate treatment; Sustainable treatment; Biological treatment; Physical–chemical treatment
Investigation on trophic state index by artificial neural networks (case study: Dez Dam of Iran) by H. Saghi; L. Karimi; A. H. Javid (127-136).
Dam construction and surface runoff control is one of the most common approaches for water-needs supply of human societies. However, the increasing development of social activities and hence the subsequent increase in environmental pollutants leads to deterioration of water quality in dam reservoirs and eutrophication process could be intensified. So, the water quality of reservoirs is now one of the key factors in operation and water quality management of reservoirs. Hence, maintaining the quality of the stored water and identification and examination of changes along time has been a constant concern of humans that involves the water authorities. Traditionally, empirical trophic state indices of dam reservoirs often defined based on changes in concentration of effective factors (nutrients) and its consequences (increase in chlorophyll a), have been used as an efficient tool in the definition of dam reservoirs quality. In recent years, modeling techniques such as artificial neural networks have enhanced the prediction capability and the accuracy of these studies. In this study, artificial neural networks have been applied to analyze eutrophication process in the Dez Dam reservoir in Iran. In this paper, feed forward neural network with one input layer, one hidden layer and one output layer was applied using MATLAB neural network toolbox for trophic state index (TSI) analysis in the Dez Dam reservoir. The input data of this network are effective parameters in the eutrophication: nitrogen cycle parameters and phosphorous cycle parameters and parameters that will be changed by eutrophication: Chl a, SD, DO and the output data is TSI. Based on the results from estimation of modified Carlson trophic state index, Dez Dam reservoir is considered to be eutrophic in the early July to mid-November and would be mesotrophic with decrease in temperature. Therefore, a decrease in water quality of the dam reservoir during the warm seasons is expectable. The results indicated that artificial neural network (ANN) is a suitable tool for quality modeling of reservoir of dam and increment and decrement of nutrients in trend of eutrophication. Therefore, ANN is a suitable tool for quality modeling of reservoir of dam.
Keywords: Trophic state index; Artificial neural networks; Dez Dam
Geomorphology and its implication in urban groundwater environment: case study from Mumbai, India by V. R. Rani; H. S. Pandalai; K. S. Sajinkumar; A. P. Pradeepkumar (137-151).
Landforms of Mumbai Island have been largely modified by the urban sprawl and the demand for groundwater will increase exponentially in the future. Quality and quantity of groundwater occurrence in island are highly influenced by the geomorphic units. As this metropolis receives heavy rainfall, the area rarely faces the issue of water scarcity, nevertheless, quality always remains a question. The landforms of Mumbai Island have been shaped by a combination of fluvial, denudational and marine processes. These landforms are categorized into two broad zones on the basis of its influence in groundwater occurrence. Denudational landforms are categorized as runoff zones whereas the other two are categorized as storage zones. This classification is on the basis of occurrence and storage of groundwater. Mumbai Island is exposed to frequent sea water incursion and groundwater quality has deteriorated. The varied hydrogeological conditions prevalent in this area prevent rapid infiltration. This combined with the overextraction of groundwater resources for agriculture and industry has caused serious concern about the continued availability of potable water. This study aims at validating the geomorphic classification of the landforms with hydrogeochemistry and borehole data and it proved that geomorphology corroborates with groundwater chemistry and subsurface geology.
Keywords: Mumbai; Groundwater; Geomorphology; Sea water incursion; Hydrogeochemistry
Efficacy of mangrove leaf powder for bioremediation of chromium (VI) from aqueous solutions: kinetic and thermodynamic evaluation by Thadikamala Sathish; N. V. Vinithkumar; G. Dharani; R. Kirubagaran (153-160).
Biosorption of heavy metals by bio-materials has been posited as a potential alternative to the existing physicochemical technologies for detoxification and recovery of toxic and valuable metals from wastewaters. In this context, the role of mangrove leaf powder (MLP) as biosorbent for chromium removal was investigated. In the present study, the effect of process parameters such as particle size, solution pH, initial concentration of Cr(VI) ion and adsorbent dose on chromium removal by MLP was investigated. The maximum sorption was observed at particle size 0.5 mm and pH 2.0. The adsorption data follow the pseudo second-order kinetics model. The isotherms denote that Langmuir model is the best fitted than Freundlich model. The maximum adsorption capacity (Q0) of 60.24 mg/g of Cr(VI) at 30 min on MLP was determined using the Langmuir model. The adsorption isotherm model indicates that the chromium is adsorbing as monolayer on the surface of MLP with heterogeneous energetic distribution of active sites. Various thermodynamic parameters, such as Gibb’s free energy (∆G°), enthalpy (∆H°) and entropy (∆S°) have been calculated. The thermodynamic data revealed that the adsorption of chromium ions onto MLP is endothermic in nature and a spontaneous process. The results of the present study suggest that MLP is an effective bioremediation measure for removal of high concentration of Cr(VI) in waste waters.
Keywords: Heavy metals; Adsorption; Mangrove leaf; Isotherms; Andaman and Nicobar islands
Domestic water conservation practices in Tlemcen City (Algeria) by Mohammed Habi; Omar Harrouz (161-169).
During the last three decades, citizens of an Algerian city are concerned with the problem of drinking water supply. Time discontinuation service became the rule. The central idea of the analysis based on interviews is to assess the role of water in the organization of the relationship between habitat and users. The fundamental question is how users, in particular women, incorporate water in their daily lives due to rationing. Having to deal with the discontinuous and frequent weak water supply, the inhabitants of the city of Tlemcen who are connected to the water supply system, as well as those connected to the water system of all Algerian towns, have developed an internal water storage system to sort out this problem. The imposed rationing has proved to be expensive for consumers. The water shortage pushed the consumers to invest in relatively expensive storage and pumping facilities to satisfy their domestic needs. As the frequency of the water supply is on a two times per week basis, the survey reveals a discrepancy in terms of volumes consumed and stored by each household. The use of water depends on the individual storage facility and the frequency of the supply. The life of the households, particularly that of the housewives, depends on the availability of water and thus on the schedules of the Company of Production of Water “Algerian Des Eaux’’ (ADE). This is particularly the case when they are supplied during the night.
Keywords: City of Tlemcen; Water; Rationing; Frequency; Storage system; Supply time
Determination of selected pesticides in water samples adjacent to agricultural fields and removal of organophosphorus insecticide chlorpyrifos using soil bacterial isolates by M. S. Hossain; M. Alamgir Zaman Chowdhury; Md. Kamruzzaman Pramanik; M. A. Rahman; A. N. M. Fakhruddin; M. Khorshed Alam (171-179).
The use of pesticide for crops leads to serious environmental pollution, therefore, it is essential to monitor and develop approaches to remove pesticide from contaminated environment. In this study, water samples were collected to monitor pesticide residues, and degradation of chlorpyrifos was also performed using soil bacteria. Identification of pesticide residues and determination of their levels were performed by high-performance liquid chromatography with photodiode array detector. Among 12 samples, 10 samples were found contaminated with pesticides. Chlorpyrifos was detected in four tested samples and concentrations ranged from 3.27 to 9.31 μg/l whereas fenitrothion ranging from (Below Detection Limit, <0.1 μg/l) to 33.41 μg/l in the tested samples. Parathion was found in two tested samples at the concentration of 0.73 and 6.23 μg/l. None of the tested samples was found contaminated with Methoxychlor, DDT and Ethion. Three soil bacterial isolates, Pseudomonas peli BG1, Burkholderia caryophylli BG4 and Brevundimonas diminuta PD6 degraded chlorpyrifos completely in 8, 10 and 10 days, respectively, when 20 mg/l chlorpyrifos was supplied as sole source of carbon. Whereas, BG1, BG4 and PD6 took 14, 16 and 16 days, respectively, for complete removal of 50 mg/l chlorpyrifos. Chlorpyrifos degradation rates were found maximum by all three isolates at 2nd day of incubation for both tested concentrations. The results of the present study suggest the need for regular monitoring of pesticide residues in water, to protect the aquatic environment. Chlorpyrifos degrading bacterial isolates can be used to clean up environmental samples contaminated with the organophosphate pesticides.
Keywords: Pesticides; Agricultural water; HPLC; Organophosphorus insecticide; Chlorpyrifos; Biodegradation; Bangladesh
Microwave green synthesis of biopolymer-stabilized silver nanoparticles and their adsorption behavior for atrazine by Jolly Pal; Manas Kanti Deb; Jayanta Kumar Sircar; Pradeep Kumar Agnihotri (181-190).
The application of silver nanoparticles for the removal of atrazine has been investigated. The silver nanoparticles beads were used as an adsorbent in the present study. Silver nanoparticles were prepared in the laboratory by a microwave irradiation method. The effect of initial concentration on the removal of atrazine was studied by varying the initial concentration of atrazine from 5 to 30 ppm. It was found that the percent removal of atrazine decreases on increasing the initial atrazine concentrations. A contact time of 14 h was found to be sufficient for maximum removal and was recorded as the equilibration time. The pH 6.0 ± 0.6 for atrazine was found most favorable and at this pH the percentage removal is high at room temperature (27 °C). Batch experiments demonstrated that a 2 gm adsorbent dosage is capable of removing maximum amount of atrazine from aqueous solution. Resulting data at room temperature were analyzed by the Freundlich and Langmuir models using linearized equations. Resultant data were analyzed by pseudo-first-order and pseudo-second-order rate equations. Desorption studies were made to elucidate recovery of the adsorbate and adsorbent for the economic competitiveness of the removal system. Findings of the present study revealed that silver nanoparticles beads can be an effective adsorbent for the removal of atrazine from aqueous solution.
Keywords: Microwave irradiation; Silver nanoparticles; Pesticide; Green synthesis
Modeling of biosorption of Cu(II) by alkali-modified spent tea leaves using response surface methodology (RSM) and artificial neural network (ANN) by Arpita Ghosh; Papita Das; Keka Sinha (191-199).
In the present work, spent tea leaves were modified with Ca(OH)2 and used as a new, non-conventional and low-cost biosorbent for the removal of Cu(II) from aqueous solution. Response surface methodology (RSM) and artificial neural network (ANN) were used to develop predictive models for simulation and optimization of the biosorption process. The influence of process parameters (pH, biosorbent dose and reaction time) on the biosorption efficiency was investigated through a two-level three-factor (23) full factorial central composite design with the help of Design Expert. The same design was also used to obtain a training set for ANN. Finally, both modeling methodologies were statistically compared by the root mean square error and absolute average deviation based on the validation data set. Results suggest that RSM has better prediction performance as compared to ANN. The biosorption followed Langmuir adsorption isotherm and it followed pseudo-second-order kinetic. The optimum removal efficiency of the adsorbent was found as 96.12 %.
Keywords: Biosorption; Cu(II); Ca(OH)2-modified spent tea leaves; Response surface methodology; Central composite design; Artificial neural network
Enhancement of zinc oxide-mediated solar light decoloration of Acid Yellow 99 dye by addition of β-CD by Sakthivel Pitchaimuthu; Subramanian Rajalakshmi; Nagarathinam Kannan; Ponnusamy Velusamy (201-208).
In the current work, the commercially available ZnO photocatalyst was used to investigate the photodecoloration of Acid yellow 99 (AY99) dye under solar light radiation. Promising enhancement of photodecoloration of AY99 dye was also achieved by the addition of β-cyclodextrin (β-CD) with the ZnO (ZnO–β-CD). The effects of process parameters such as initial concentration, pH, catalyst loading, and illumination time on the extent of decoloration were investigated. The optimum catalyst loading was observed at 2.0 g/L. The higher photoactivity of ZnO–β-CD/solar light system than ZnO/solar light system can be ascribed due to the ligand to metal charge transfer (LMCT) from β-CD to ZnII. The complexation patterns have been confirmed with UV–visible and FT-IR spectroscopy and the interaction between ZnO and β-CD has been characterized by FE-SEM, powder XRD analysis, and UV–visible diffuse reflectance spectroscopy.
Keywords: Acid Yellow 99 dye; β-Cyclodextrin; ZnO; Solar photocatalytic decoloration