Applied Water Science (v.5, #3)

Optimal management of groundwater pumping of the cache critical groundwater area, Arkansas by Haveen Rashid; Haydar Al-Shukri; Hanan Mahdi (209-219).
A simulation model for part of the Mississippi River Valley alluvial aquifer in the Cache area, Arkansas, was coupled with an optimization model to determine maximum optimal pumping from irrigation wells in the areas where cones of depression exist. Groundwater Vistas and Groundwater Management software were used for simulation and optimization model, respectively. The Cache area was designated as a critical groundwater area in 2009 due to the decline in its water level to below 50 % of the saturated thickness of the aquifer. The optimization model was formulated with the objective of maximizing water production from wells subjected to minimum head constraints and drawdown constraints, while limiting groundwater withdrawals to a maximum of 100 and 200 % of the rate pumped in 2010. Four different sets of managed wells were tested in Scenarios 1, 3 (938 wells) and Scenarios 2, 4 (3870 wells). The optimal pumping rates from groundwater in the case of minimum head constraints were 0.59 and 2.43 Mm3/d for Scenarios 1 and 2, respectively. In the case of maximum pumping constraints of the managed wells specified as 200 % of the pumping rate of 2010, the optimal pumping rates from groundwater in the case of minimum head constraints were 0.88 and 3.28 Mm3/d for Scenarios 3 and 4, respectively. The average optimal pumping increased by 6–49 % in the case of the maximum pumping constraint specified as 200 % of the pumping rate of the year 2010.
Keywords: Groundwater flow; Modeling; Groundwater vistas; Optimization; Groundwater management

In this study, a fundamental research had been carried out to explore the removal of pyridine in wastewater by ultrasound radiation. The effects of initial pyridine concentration, radiation time, pH, aeration, and the reaction temperature on the pyridine removal efficiency were investigated. The removal rates of pyridine at 180 min sonication time were found to decrease from 53 to 15 % with increasing the initial concentration from 10 to 100 mg/L. However, the total amount of pyridine degraded after 60 min at 100 mg/L was as much as three times larger than that degraded at 10 mg/L. The optimal pH was found to be 9 which resulted in 25 % pyridine removal after 180 min ultrasound radiation. By observing the change of pH value with the sonication time up to 60 min, it was observed that, pH of the sonicated pyridine aqueous mixture has decreased from 9.2 to 6.2 during the irradiation. The decrease in the pH may be attributed due to the formation of peroxy radicals in the solution and subsequently formation of oxygen free radicals. The simultaneous aeration could improve pyridine removal efficiency of ultrasound irradiation by 24 %. With increasing media temperatures, the removal efficiencies of pyridine increased in the temperature range in this study. In the end, it could be proposed that ultrasound radiation was an effective method for the removal of pyridine from wastewater.
Keywords: Pyridine; Ultrasound radiation; Wastewater treatment; pH; Degradation

Reconnaissance on the suitability of the available groundwater resources for irrigation in Thakurgaon District of northwestern Bangladesh was done by determining pH, TDS, EC, hardness, alkalinity, major cations and anions. The pH values suggest that the water is slightly acidic to strongly basic. The dominant cation and anion in the study area are Ca2+, Mg2+ and HCO3, respectively. Calcium bicarbonate, calcium–magnesium–bicarbonate and calcium carbonate are the dominant hydrochemical facies among the water samples. The groundwater system in the study area may be recharged through infiltration of rain. The above statement is further supported by Gibbs plot where most of the samples fall within the rock-dominance zone. The evolution of these waters may be controlled by precipitation and dissolution of carbonate minerals. The USSL, SAR–EC classification schemes and Wilcox plot confirm that the groundwater samples are good to excellent as irrigation water. However, the groundwater evolution in this study is mainly the result of weathering of carbonate minerals and cation exchange within the aquifer materials, confirming the shallow porous groundwater hydrochemistry characteristics.
Keywords: Hydrogeochemical character; Groundwater; Irrigation water quality; GIS; Bangladesh

Application of respirometric tools in wastewater engineering fields is still not getting familiarity and acceptance by academy or industry in developing countries as compared to the use of conventional biochemical oxygen demand (BOD) approach. To justify the applicability of respirometry, a low-cost respirometric device suitable for monitoring biodegradation process in wastewater has been developed. This device contains six independently operating reactors placed in a temperature control unit for the bioassay of five wastewater samples simultaneously (along with one blank). Each reactor is equipped with a magnetic stirrer for the continuous agitation of the test sample. Six manometers, linked with the individual reactors, measure the pressure and volume changes in the headspace gas phase of the reactor. Working formulae have been derived to convert the ‘volume-change in gas phase’ data to ‘the oxygen depletion in the whole liquid–gas system’ data. The performance of the device has been tested with glucose–glutamic acid standard solution and found satisfactory. Conventional BOD test and the respirometric measurements were performed simultaneously and it is found that in addition to measuring the BOD of the sample, this device gives oxygen uptake profile for further analysis to determine the biokinetic coefficients. Additionally, in some cases, following a specific test protocol, the respirometer can indirectly estimate the carbon dioxide evolved during biodegradation process for calculating respiratory activity parameter such as respiratory quotient. It is concluded that the device can be used in the laboratories associated with the activated sludge plants and also for teaching and research purposes in developing countries.
Keywords: Headspace gas respirometer; Wastewater; Biokinetic coefficients; Oxygen uptake rate; BOD; COD; RQ

The service of providing good quality of drinking water can greatly improve the lives of the community and maintain a normal health standard. For a large number of population in the world, specifically in the developing countries, the availability of safe water for daily sustenance is none. Damaturu is the capital of Yobe State, Nigeria. It hosts a population of more than two hundred thousand, yet only 45 % of the households are connected to the network of Yobe State Water Corporation’s pipe borne water services; this has led people to source for water from any available source and thus, exposed them to the danger of contracting waterborne diseases. In order to address the problem, Yobe State Government has embarked on the construction of a water treatment plant with a capacity and facility to improve the water quality and connect the town with water services network. The objectives of this study are to assess the households’ demand preferences of the heterogeneous water attributes in Damaturu, and to estimate their marginal willingness to pay, using mixed logit model in comparison with conditional logit model. A survey of 300 households randomly sampled indicated that higher education greatly influenced the households’ WTP decisions. The most significant variable from both of the models is TWQ, which is MRS that rates the water quality from the level of satisfactory to very good. 219 % in simple model is CLM, while 126 % is for the interaction model. As for MLM, 685 % is for the simple model and 572 % is for the interaction model. Estimate of MLM has more explanatory powers than CLM. Essentially, this finding can help the government in designing cost-effective management and efficient tariff structure.
Keywords: Choice experiment; Water quality; Household preference; Choice modelling; Willingness to pay; Conditional logit model; Heterogeneous attributes

This study is an effort to trace the spatiotemporal variation in water at Narmada estuarine region through solute concentration. A total of 72 water samples were collected and analyzed from three sampling points along with in situ measurement of tidal height at monthly basis for 2 years. Result shows that spatiotemporal variation of water quality occurs because of the following main mechanisms, i.e., carbonate weathering, dilution and seawater–freshwater mixing. Firstly, points situated toward inland showing the simple dilution effect on receiving high amount of monsoonal precipitation. Secondly, tidal fluctuation pattern has a strong influence on the water quality taken from the point located in near proximity to the coast. Finally, it can be concluded that water quality shows a different response, in accordance with the different tidal phase and the distance from the sea.
Keywords: Narmada estuarine region; Seawater–freshwater (SW–FW) mixing; Tidal fluctuation

Neural network model and isotherm study for removal of phenol from aqueous solution by orange peel ash by Naba Kumar Mondal; Ria Bhaumik; Biswajit Das; Palas Roy; Jayanta Kumar Datta; Siddhartha Bhattacharyya; Siddhartha Bhattacharjee (271-282).
Artificial Neural Network model and isotherm study were done to predict the removal efficiency of phenol. An inexpensive adsorbent was developed from orange peel ash (OPA) for effective uptake of phenol from aqueous solution. The influence of different experimental parameters (initial concentration, pH, adsorbents dose, contact time, stirring rate and temperature) on phenol uptake efficiency was evaluated. Phenol was adsorbed by the OPA up to maximum of 97.34 %. Adsorption of phenol on OPA correlated well with the Langmuir isotherm model, implying monolayer coverage of phenol onto the surface of the adsorbent. The maximum adsorption capacity was found to be 3.55 mg g−1 at 303 K. Pseudo-second-order kinetic model provided a better correlation for the experimental data. Moreover, the activation energy of the adsorption process (Ea) was found to be −18.001 kJ mol−1 indicating physorption nature of phenol onto OPA. A negative enthalpy (∆H°) value indicated that the adsorption process was exothermic. Again multi-layer Neural Network model was in very good agreement with the experimental results.
Keywords: Phenol; Orange peel ash; Isotherm model; Kinetics; Physorption; ANN model

Public concerns related to the fast-growing shale oil and gas industry have increased during recent years. The major concern regarding shale gas production is the potential of fracturing fluids being injected into the well or produced fluids flowing out of the well to contaminate drinking water resources such as surface water and groundwater. Fracturing fluids contain high total dissolved solids (TDS); thus, changes in TDS concentrations in groundwater might indicate influences of fracturing fluids. An increase of methane concentrations in groundwater could also potentially be due to hydraulic fracturing activities. To understand the possible contamination of groundwater by fracturing activities, real-time groundwater monitoring is being implemented in the Denver-Julesburg basin of northeast Colorado. A strategy of monitoring of surrogate parameters was chosen instead of measuring potential contaminants directly, an approach that is not cost effective or operationally practical. Contaminant surrogates of TDS and dissolved methane were proposed in this study, and were tested for correlation and data distribution with laboratory experiments. Correlations between TDS and electrical conductivity (EC), and between methane contamination and oxidation–reduction potential (ORP) were strong at low concentrations of contaminants (1 mg/L TDS and 0.3 mg/L CH4). Dissolved oxygen (DO) was only an effective surrogate at higher methane concentrations (≥2.5 mg/L). The results indicated that EC and ORP are effective surrogates for detecting concentration changes of TDS and methane, respectively, and that a strategy of monitoring for easy to measure parameters can be effective detecting real-time, anomalous behavior relative to a predetermined baseline.
Keywords: Electrical conductivity; Fracturing fluids; Methane; Oxidation–reduction potential; Surrogate; Total dissolved solids

Water supply management using an extended group fuzzy decision-making method: a case study in north-eastern Iran by Yasser Minatour; Hossein Bonakdari; Mahdi Zarghami; Maryam Ali Bakhshi (291-304).
The purpose of this study was to develop a group fuzzy multi-criteria decision-making method to be applied in rating problems associated with water resources management. Thus, here Chen’s group fuzzy TOPSIS method extended by a difference technique to handle uncertainties of applying a group decision making. Then, the extended group fuzzy TOPSIS method combined with a consistency check. In the presented method, initially linguistic judgments are being surveyed via a consistency checking process, and afterward these judgments are being used in the extended Chen’s fuzzy TOPSIS method. Here, each expert’s opinion is turned to accurate mathematical numbers and, then, to apply uncertainties, the opinions of group are turned to fuzzy numbers using three mathematical operators. The proposed method is applied to select the optimal strategy for the rural water supply of Nohoor village in north-eastern Iran, as a case study and illustrated example. Sensitivity analyses test over results and comparing results with project reality showed that proposed method offered good results for water resources projects.
Keywords: Fuzzy multi-criteria decision making; Fuzzy TOPSIS; Group decision making; Water supply management

Water allocation for agriculture in southwestern Iran using a programming model by Abdoulkarim Esmaeili; Zahra Shahsavari (305-310).
Water pricing can play a major role in improving water allocation, encouraging users to conserve scarce water resources, and promoting improvements in productivity. In this study, the economic values of water in farms under Dorodzan Dam in southwestern Iran were calculated using linear programming models. The method was applied to three samples of farms that drew irrigation water from a canal, a well, and both a well and a canal. The results of this study revealed that the shadow prices of water in farms varied based on the water sources and time of year. Additionally, the estimated price for water is obviously higher than the price that farmers currently pay for water in the study area. Due to the different economic values of water calculated for different months, it is recommended that the price of irrigation water be adjusted accordingly during various seasons in a fashion similar to that of electrical energy.
Keywords: Water pricing; Water allocation; Programming model; Southwestern Iran

Knowledge of residual chlorine concentration at various locations in drinking water distribution system is essential final check to the quality of water supplied to the consumers. This paper presents a methodology to find out the residual chlorine concentration at various locations in simple branch network by integrating the hydraulic and water quality model using first-order chlorine decay equation with booster chlorination nodes for intermittent water supply. The explicit equations are developed to compute the residual chlorine in network with a long distribution pipe line at critical nodes. These equations are applicable to Indian conditions where intermittent water supply is the most common system of water supply. It is observed that in intermittent water supply, the residual chlorine at farthest node is sensitive to water supply hours and travelling time of chlorine. Thus, the travelling time of chlorine can be considered to justify the requirement of booster chlorination for intermittent water supply.
Keywords: Drinking water distribution system (DWDS); Intermittent water supply; Residual chlorine; Booster chlorination