WATER AND WASTEWATER
Year:2013 | Volume:24 | Issue:4 (88)|Papers Count:17

Sufficient drinking water supply with acceptable quality has been one of the important challenges that decision makers in urban water systems have always faced. Different natural, non-natural and operational hazards, may threaten different components of urban water systems and they may lead to irreversible consequences. In this research, Fuzzy Hierarchical Risk Assessment model has been presented which is capable of considering the complexities and uncertainties in urban water systems. Different stages of the proposed modeling process include systems components and threatening hazards identification, analyzing the information (i.e. probability of hazard, consequences of hazard and components vulnerabilities) in a fuzzy environment and finally aggregation of estimated risks in different parts of water supply systems and ranking them. Another risk analysis method has been introduced which is based on Monte Carlo simulation using crisp numbers and then results of these models have been compared together for an example of urban water supply system. Presented approaches in this paper, can be very useful for real world risk-based decision making in urban water supply management with respect to the probable hazards.

In situ bioremediation is one of the most regular technologies to clean up petroleum contaminated aquifers. Control process of such a complicated system is difficult and needs more than one management target. This study develops multi objective simulation/optimization model that consider cost and time of remediation process, and concentration violation from standard value as model objectives. For this propose two multi objective ant colony optimization (ACO) models have been developed, cost-time and cost-violations. The BIOPLUMEII model applies to simulate aquifer hydraulics and bioremediation. Injection rate of oxygen and nutrient, extraction rate in wells and well locations are decision variables. Simulated groundwater model is hypothetic and homogenous. For the case studies, the Pareto front is derived which enhances the decision maker to choose one which more suitable for him/her according to the priorities. The results of time-cost trade off curve showed minimum possible time for remediation process. Also, It was found maximum time for remediation before contamination plume reaches to downstream monitoring wells. The results of cost-violation trade off curve showed how to decrease cost of process with relaxation of standard concentration constraint. The following research shows the proposed multi objective models are useful for decision makers and also reveals the capability of ACO in multi objective optimization of groundwater bioremediation system design.

The growing exploitation of surface and ground water resources in Mashad Plain due to agricultural and related industrial development has resulted in a continuous fall in the local groundwater level. Aiming to show a practical way of integrated water resources assessment, the present paper will assess the water resources system in Mashad Plain uner policies in the process of t he economic growth programs. Adopting a system dynamics modeling to better identify the system under study, the paper goes further to suggest local sustainability strategies using the "resource stress", "resource economic productivity", and the "local average water need" indicatiors based on the idea of viability loops. According to the suggested three strategies (the economic growth acknowledging limiting water resources, water allocation based on its value added, and altering to crop pattern) different policy pakcages were designed. The effects of policies on the selected indicators including "groundwater level", "resource stress", "resource economic productivity", "water scarcity", and "the local average water need" were investigated. The results showed that the superposed effect of the all strategies together on the local sustainability will not be as much as the summation of the effects of separate strategies. It was also shown that changing the crop pattern to the one suggested one which is equivalent to wheat with 3000 m3/hr water need per hectare can serve as an effective policy on the local sustainability.

Dyes due to coloring nature are appearance pollutants and destroys the transparency and aesthetic quality of surface waters even at relatively low concentration. Several processes have been used for dye removal from wastewater. In recent years, electrochemical methods have been successfully employed to treat dying wastewater. In this study, the electrocoagulation method with aluminum electrodes were used for polyacrylic textile wastewater treatment. COD of wastewater was 1400 mg/l. This study was conducted in laboratory scale. The sample was placed in to the electrochemical reactor contains 4 electrodes. The electrodes were connected to a DC power supply. Then the effect of the three operational parameters, electrolysis time (20-60 minutes), electrical applied current (0.5-2.5 Ampere) and pH (4-9) on color and COD removal efficiency has been investigated. The results showed that the color and COD removal efficiency is a direct relation with increasing of the reaction time and inverse relation with increase of pH. Optimum operation conditions were in applied current of 1.5 A, the retention time of 60 minutes and pH of 4. In this condition, color and COD removals were 86% and 85%, respectively. This study showed that electrocoagulation process is an effective and efficient method to treatment of polyacrylic textile wastewater.

Phenol belongs to the recalcitrant pollutants to conventional physical chemical and biological treatments. These compounds are released in the surface water by a considerable number of industries, constituting an environmental hazard. On the other hand, the advanced oxidation processes (AOPs) have been defined as effective processes for treatment of wastewater containing toxic and persistent organic pollutants. In this work, a mathematical model is developed to quantify the variation of chemical oxygen demand (COD) as a function of time during electrochemical oxidation of phenol for a batch system. Depending on applied current density (iappl) with respect to limiting current density (ilim), which decreased during treatment, different operating regimes were identified. In particular, for high organic concentrations or low current densities (iappl ilim), COD decreased linearly over time, indicating a kinetically controlled process. Conversely, for low organic concentrations or high current densities, electrolysis was under mass-transport control and COD removal followed an exponential trend. Model parameters were: current density, initial phenol concentration and electrode area. The present purpose is to use the model as a design tool for the prediction of specific energy consumption for the elimination of a given organic loading (kg COD h-1). The results showed that the increase of density and applied potential caused increase of specific energy consumption of initial phenol concentration decrease in energy consumed. In the mathematical model validation, the model results were compared with experimental results published in the literature. The good agreement between experimental and model predicted data was obtained in all the examined conditions by accounting root mean square error (RMSE) between 0.013-1.22 and R2>0.91.

Large amount of excess waste from activated sludge is generated in wastewater treatment plants which its treatment, transportation and disposal costs are estimated to be over 50 percent of total plant cost operation. In this research it was tried to decrease the amount of sludge volume and its mass by using relative low cost and low energy consumed process in laboratory scale. By developing suitable environmental conditions and population increase and growth of aquaticTubifex worms in sludge (conventional kinds of worms in wastewater treatment plants) and with measurement of TSS, VSS and worms growth rate, sludge mass and volume reduction were determined. According to the results, in specific growth rate of 0.05 d-1, VSS reduction of 26 mg/l.d and with initial sludge amount of 2850 mg/l and 2000 mg/l, TSS and sludge volume reduction of 40 and 20 percent were observed, respectively.50 percent of soluble COD with initial amount of 500 mg/l was also removed in the laboratory conditions.

Industrial processes produce high volumes of wastewater containing organic pollutants such as phenol and its derivatives. These contaminants include materials that are serious threats for environmental, human and soils characteristics. There are lots of methods for phenol removing from contaminated soils that one of them is biodegradation. In this study with the aim of phenol biodegradation, take action to isolation of bacteria from contaminated soil of Esfahan steel factory. Some properties of soil such as pH, organic matters, electrical conductivity and phenol concentration were determined. Enrichment of isolated bacteria was done. The best indigenous bacterium was selected according to its growth in presence of 400 mg.L-1 of phenol during 24h for further biodegradation studies and molecular identification. Results showed that according to phylogenetic analysis, the best isolated bacterium was the strain of Enterobactersp. that could remove 400 mg.L-1 phenol during 72 hours. The results of this study shown that indigenous bacterium can remove organic pollutant such as phenol from contaminated soil.

Listeriaand in particular Listeria monocytogenes is considered a ubiquitous foodborne pathogen which can lead listeriosis in human and animals. Listeriosis can be serious and may cause meningitis, septicemia and abortion in pregnant women. Although wastewater or sludge may contaminate foods of plant origin, there are no data on occurrence of Listeria spp. in wastewater and sludge in Iran. The purpose of current investigation was to study the occurrence of Listeria spp. in various samples of wastewater and sludge in Isfahan North wastewater treatment plant. Influent, effluent, raw sludge and dried sludge samples were collected from Isfahan North municipal wastewater treatment plant. L. monocytogenes were enumerated by a three–tube most probable number (MPN) assay using enrichment Fraser broth. A total of 65 various samples from five step in 13 visits were collected. The presence of Listeria spp. also was determined using USDA procedure. Then, phenotypically identified L. monocytogenes were further confirmed by Polymerase Chain Reaction amplification. L. monocytogenes isolated from 76.9%, 38.5%, 84.6%, 69.2% and 46.2% of influent, effluent, raw sludge, stabilized sludge and dried sludge respectively. The efficiency of wastewater treatment processes, digester tank and drying bed in removal L. monocytogenes were 69.6%, 64.7% and 73.4% respectively. All phenotypically identified L. monocytogenes were further confirmed by Polymerase Chain Reaction. The results of present study have shown that Listeria spp. and L. monocytogenes in particular, were present in wastewater treatment plant effluents and sludge at high level. The bacteria may spread on agriculture land and contaminate foods of plant origin. This may cause a risk of spreading disease to human and animals.

In order to study, the amount of cadmium and nickel in different plant organs of borage planted in calcareous, following the application of sewage sludge and municipal solid wastes compost, an experiment was conducted in split-plot design based on complete randomized block design in 2009. The main plot was sewage sludge and municipal solid wastes compost at five levels (control, 20, and 40 ton/ha) and the sub plot was years in six treatments (2006, 2006 and 2007, 2006 and 2008, 2006-2008, 2006 and 2007 and 2009, and 2006-2009). The amount of available Cd and Ni in soil and Cd and Ni accumulated in the roots, leaves and flower of Borage were compared with the control. Results indicated that the application of 40 ton/ha sewage sludge and municipal solid wastes compost increased the available Cd and Ni in soil (about 2 and 2.5 times, respectively) and the amount of Cd and Ni in the roots of Borage by 5 and 2.5 times compared to control. The maximum amount of Cd in leaves and flowers of borage was observed in the 40 ton/ha sewage sludge treatment. Furthermore, the treatment of 40 ton/ha sewage sludge and municipal solid wastes compost produced the most amount of Ni in leaves and flowers of Borage, respectively. Meanwhile, the maximum amount of Cd translocated to the shoots was observed in the flower in the 40 ton/ha sewage sludge and Ni in the same organic fertilizer treatments to leaves of borage.

Drought is the interaction between environment and water cycle in the world and affects natural environment of an area when it persists for a longer period. So, developing a suitable index to forecast the spatial and temporal distribution of drought plays an important role in the planning and management of natural resources and water resource systems. In this article, firstly, the drought concept and drought indexes were introduced and then the fuzzy neural networks and fuzzy C-mean clustering were applied to forecast drought via standardized precipitation index (SPI). The results of this research indicate that the SPI index is more capable than the other indexes such as PDSI (Palmer Drought Severity Index), PAI (Palfai Aridity Index) and etc. in drought forecasting process. Moreover, application of adaptive nero-fuzzy network accomplished by C-mean clustering has high efficiency in the drought forecasting.

Land use is one of the most important that effect on the natural cycle of water. The present study evaluates land use changes effect on Zayandehroud river flood hydrograph in Isfahan region. The land used map of the studied basin was obtained from ETM (+) 1990 Landsat and IRS 2008 satellite images using ENVI software. Runoffrainfall events were also simulated using SCS model and the model was calibrated based on the measured hydrographs. The results showed that the coefficient of the SCS model should be considered by 0.21 for the basin. Also the hydrograph obtained from the coupled HEC-HMS model and GIS tools showed that effect of the land use change in the flood peak flow may be decreased with increasing the return period of the floods. For example for 5 year flood, the peak discharge from year 1990 to 2008 to be increased by 39.9% but for the 200 year flood, the value was obtained at 10.3%.

Water and soil pollution by heavy metals is a serious threat to environment and human health. Therefore finding an effective method for removing heavy metals from water is very important. Removal of heavy metals from water by adsorption method has increasingly received much attention in recent years because it is simple relatively low-cost and effective method. The main objective of this research is to investigate the possibility of removing Cu (II) from aqueous solution using modified tea waste with magnetite nanoparticles. Consequently, modified tea waste with magnetite nanoparticles were prepared and characterized by Atomic Force Microscopy (AFM) and Fourier Transform Infrared Spectroscopy (FTIR). The effects of various parameters, such as contact time, pH, Cu concentration and adsorbent dosage were studied. The adsorption isotherm data were fitted to Langmuir and Freundlich equation. The results indicated that the sorption data can be represented by both Langmuir and Freundlich isotherm models, and the Langmuir adsorption capacity, was found to be 22.4 mgg-1. The results indicated that Cu (II) adsorption increased with increasing solution pH. Maximum removal of Cu (II) was obtained at pH=5.5. The results also showed the adsorption were decreased by increasing of initial Cu (II) concentration. An increase in adsorbent dosage increased the removal of Cu (II). The results also revealed that modified tea waste with magnetite nanoparticles can be an attractive option for metal removal from contaminated water.

A series of clay pillaring agents with Ti, Cu, Al and Fe elements were synthesized. These pillaring agents were used to modify montmorillonite clay by ion-exchange reactions. Clay d-spacings increased modestly when Na+-MMT clay was intercalated with these pillaring agents. The modified red mud (MRM) and pillared clay (PILC) complex can be used as a strong absorbent pollutant. In this study, MRM and PILC complex was used for the removal of cadmium from water. The complex was characterized using XRD, SEM and XRF microanalysis and adsorption of cadmium was studied as a function of pH, time, and temperature by AAS method. The maximum adsorption efficiency reached 96.69% when the pH was 6 at 40oC. Langmuir and Freundlich isotherms equation were used to fit the adsorption isotherms. It is evident from this study that MRM and PILC complex is a suitable material for the uptake of Cd (II) from aqueous solutions.

The pump stations are on of the main energy consumers in urban water supply systems, Therefore, it is very important to minimize waste of energy in these stations. Today, pumps are running at their highest possible mechanical efficiency due to their matured technology, As a result, efficiency improvement should be considered in other elements of the network. Among the constituting elements of urban water supply systems, storage tanks play an important role and significant energy saving can be achieved by optimizing their design. In this paper, capacities and dimensions of water storage tanks in different operating conditions in an actual water pump station have been simulated by dynamic modeling in Simulink/MATLAB software. The results could be used as recommendations for optimization of energy saving in water storage tanks in pump stations, the number of operating pumps in the network, the volume of stored water and so on in different operating conditions.